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Sample records for bacterial cellulose membranes

  1. In-vitro Degradation Behaviour of Irradiated Bacterial Cellulose Membrane

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    D. Darwis

    2012-08-01

    Full Text Available Bacterial cellulose membrane synthesized by Acetobacter xylinum in coconut water medium has potential application for Guided bone Regeneration. However, this membrane may not meet some application requirements due to its low biodegradation properties. In this paper, incorporation of gamma irradiation into the membrane is a developed strategy to increase its biodegradability properties. The in–vitro degradation study in synthetic body fluid (SBF of the irradiated membrane has been analyzed during periods of 6 months by means of weight loss, mechanical properties and scanning electron microscopy observation compared to that the un-irradiated one. The result showed that weight loss of irradiated membrane with 25 kGy and 50 kGy and immersed in SBF solution for 6 months reached 18% and 25% respectively. While un-irradiated membrane did not give significant weight loss. Tensile strength of membranes decreases with increasing of irradiation dose and further decreases in tensile strength is observed when irradiated membrane was followed by immersion in SBF solution. Microscope electron image of cellulose membranes shows that un-irradiated bacterial cellulose membrane consists of dense ultrafine fibril network structures, while irradiation result in cleavage of fibrils network of cellulose. The fibrils network become loosely after irradiated membrane immersed in SBF solution due to released of small molecular weight carbohydrates formed during by irradiation from the structure

  2. Bacterial cellulose and bacterial cellulose-vaccarin membranes for wound healing

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    Qiu, Yuyu [Key Laboratory of Eco-textiles, Jiangnan University, Wuxi (China); Laboratory of Natural Medicine, Wuxi Medical School, Jiangnan University (China); Qiu, Liying [Laboratory of Natural Medicine, Wuxi Medical School, Jiangnan University (China); Cui, Jing [Key Laboratory of Eco-textiles, Jiangnan University, Wuxi (China); Wei, Qufu, E-mail: qfwei@jiangnan.edu.cn [Key Laboratory of Eco-textiles, Jiangnan University, Wuxi (China)

    2016-02-01

    Bacterial cellulose (BC) and bacterial cellulose-vaccarin (BC-Vac) membranes were successfully produced in large scale. BC was synthesized by Gluconacetobacter xylinum. BC-Vac membranes were prepared by immersing BC in vaccarin solution. The surface morphologies of BC and BC-Vac membranes were examined by a scanning electron microscope (SEM) and an atomic force microscopy (AFM). The images showed that BC-Vac exhibited the characteristic 3D nanofibrillar network of BC matrix but there was adhesion between fibers. The mechanical properties of BC and BC-Vac membranes were evaluated and the results indicated that the adding of drug vaccarin into the BC membranes increased the malleability indicated by the increment in elongation at break compared with BC. Fourier transform infrared spectroscopy (FTIR) analysis was conducted to confirm the incorporation of vaccarin in BC-Vac and investigate the hydroxyl interactions between BC and drug vaccarin. Cell viability and cell attachment studies demonstrated that BC and BC-Vac membranes had no cytotoxicity and could be a good carrier for cell growth. The wound healing performance was examined in vivo by rat skin models. Histological observations revealed that wounds treated with BC-Vac epithelialized and regenerated faster than treated with BC. Therefore, BC-Vac was considered as a potential candidate for wound dressing materials. - Highlights: • BC and BC-Vac membranes were produced to achieve desirable properties. • BC and BC-Vac membranes could be a good carrier for cell growth. • BC-Vac membranes have potential application for wound healing.

  3. Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

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    Hernane S. Barud

    2011-01-01

    Full Text Available Antimicrobial bacterial cellulose-silver nanoparticles composite membranes have been obtained by “in situ” preparation of Ag nanoparticles from hydrolytic decomposition of silver nitrate solution using triethanolamine as reducing and complexing agent. The formation of silver nanoparticles was evidenced by the X-ray diffraction, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and absorption in the UV-Visible (350 nm to 600 nm. Thermal and mechanical properties together with swelling behavior for water were considered. TEA concentration was observed to be important in order to obtain only Ag particles and not a mixture of silver oxides. It was also observed to control particle size and amount of silver contents in bacterial cellulose. The composite membranes exhibited strong antimicrobial activity against Gram-negative and Gram-positive bacteria.

  4. Electrically conductive bacterial cellulose composite membranes produced by the incorporation of graphite nanoplatelets in pristine bacterial cellulose membranes

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    T. Zhou

    2013-09-01

    Full Text Available Graphite nanoplatelets (GNPs were utilized to improve the electrical conductivity of pristine bacterial cellulose (BC membranes. By physical and chemical methods, flake-shaped GNPs, weaving through the surface layer of web-like cellulose nanofibrils, were indeed fixed or trapped by the adjacent nanofibrils in the BC surface network, for comparison, rod-shaped multi-walled carbon nanotubes (MWCNTs were homogeneously inserted into BC membrane through the pore structures and tunnels within the BC membrane. Strong physical and chemical interaction exists between the BC nanofibrils and the particles of GNP or MWCNT even after 15 h sonication. BC membrane with 8.7 wt% incorporated GNPs reached the maximum electrical conductivity of 4.5 S/cm, while 13.9 wt% MWCNT/BC composite membrane achieved the maximum electrical conductivity of 1.2 S/cm. Compared with one dimensional (1-D MWCNTs, as long as GNPs inserted into BC membranes, the 2-D reinforcement of GNPs was proven to be more effective in improving the electrical conductivity of BC membranes thus not only break the bottleneck of further improvement of the electrical conductivity of BC-based composite membranes but also broaden the applications of BC and GNPs.

  5. Surface physical chemistry properties in coated bacterial cellulose membranes with calcium phosphate.

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    de Olyveira, Gabriel Molina; Basmaji, Pierre; Costa, Ligia Maria Manzine; Dos Santos, Márcio Luiz; Dos Santos Riccardi, Carla; Guastaldi, Fernando Pozzi Semeghini; Scarel-Caminaga, Raquel Mantuaneli; de Oliveira Capote, Ticiana Sidorenko; Pizoni, Elisabeth; Guastaldi, Antônio Carlos

    2017-06-01

    Bacterial cellulose has become established as a new biomaterial, and it can be used for medical applications. In addition, it has called attention due to the increasing interest in tissue engineering materials for wound care. In this work, the bacterial cellulose fermentation process was modified by the addition of chondroitin sulfate to the culture medium before the inoculation of the bacteria. The biomimetic process with heterogeneous calcium phosphate precipitation of biological interest was studied for the guided regeneration purposes on bacterial cellulose. FTIR results showed the incorporation of the chondroitin sulfate in the bacterial cellulose, SEM images confirmed the deposition of the calcium phosphate on the bacterial cellulose surface, XPS analysis showed a selective chemical group influences which change calcium phosphate deposition, besides, the calcium phosphate phase with different Ca/P ratios on bacterial cellulose surface influences wettability. XTT results concluded that these materials did not affect significantly in the cell viability, being non-cytotoxic. Thus, it was produced one biomaterial with the surface charge changes for calcium phosphate deposition, besides different wettability which builds new membranes for Guided Tissue Regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Production and characterization of bacterial cellulose membranes with hyaluronic acid from chicken comb.

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    de Oliveira, Sabrina Alves; da Silva, Bruno Campos; Riegel-Vidotti, Izabel Cristina; Urbano, Alexandre; de Sousa Faria-Tischer, Paula Cristina; Tischer, Cesar Augusto

    2017-04-01

    The bacterial cellulose (BC), from Gluconacetobacter hansenii, is a biofilm with a high degree of crystallinity that can be used for therapeutic purposes and as a candidate for healing wounds. Hyaluronic acid (HA) is a constitutive polysaccharide found in the extracellular matrix and is a material used in tissue engineering and scaffolding for tissue regeneration. In this study, polymeric composites were produced in presence of hyaluronic acid isolated from chicken comb on different days of fermentation, specifically on the first (BCHA-SABT0) and third day (BCHA-SABT3) of fermentation. The structural characteristics, thermal stability and molar mass of hyaluronic acid from chicken comb were evaluated. Native membrane and polymeric composites were characterized with respect to their morphology and crystallinity. The optimized process of extraction and purification of hyaluronic acid resulted in low molar mass hyaluronic acid with structural characteristics similar to the standard commercial hyaluronic acid. The results demonstrate that the polymeric composites (BC/HA-SAB) can be produced in situ. The membranes produced on the third day presented better incorporation of HA-SAB between cellulose microfiber, resulting in membranes with higher thermal stability, higher roughness and lower crystallinity. The biocompatiblily of bacterial cellulose and the importance of hyaluronic acid as a component of extracellular matrix qualify the polymeric composites as promising biomaterials for tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. In situ synthesis of silver chloride nanoparticles into bacterial cellulose membranes

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    Hu Weili; Chen Shiyan; Li Xin; Shi Shuaike; Shen Wei; Zhang Xiang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Key Laboratory of Textile Science and Technology (Ministry of Education), College of Materials Science and Engineering, Donghua University, Shanghai, 201620 (China); Wang Huaping, E-mail: wanghp@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Key Laboratory of Textile Science and Technology (Ministry of Education), College of Materials Science and Engineering, Donghua University, Shanghai, 201620 (China)

    2009-05-05

    In situ synthesis of silver chloride (AgCl) nanoparticles was carried out under ambient conditions in nanoporous bacterial cellulose (BC) membranes as nanoreactors. The growth of the nanoparticles was readily obtained by alternating dipping of BC membranes in the solution of silver nitrate or sodium chloride followed by a rinse step. X-ray diffraction (XRD) patterns indicated the existence of AgCl nanoparticles in the BC and scanning electron microscopy (SEM) images showed that the AgCl nanoparticles well dispersed on the surface of BC and penetrated into the BC network. The AgCl nanoparticle-impregnated BC membranes exhibited high hydrophilic ability and strong antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The preparative procedure is facile and versatile, and provides a simple route to manufacturing of useful antimicrobial membranes, which would be a good alternative for antimicrobial wound dressing.

  8. Bacterial Cellulose Membranes Used as Artificial Substitutes for Dural Defection in Rabbits

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    Chen Xu

    2014-06-01

    Full Text Available To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals.

  9. Effect of growth times on the physical and mechanical properties of hydrophobic and oleophilic silylated bacterial cellulose membranes

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    Zakaria, M. N.; Sukirah, A. R.; Maizatulnisa, O.; Ayuni, J.; Khalisanni, K.; Rosmamuhamadani, R.

    2017-09-01

    Bacterial cellulose is an extracellular natural byproduct of the metabolism of various bacteria. Its physical and mechanical properties were determined by growth period, method of cultivation either static or agitate, fermentation condition and medium. Thispaper presented works done on the effect of culture time on the physical and mechanical properties of silylated bacteria cellulose membranes. Bacterial cellulose (BC) growth under 4, 5, 6 and 7 days had been used as a natural reinforcement material and silane as a hydrophobic coating material. With extended culture time, the tensile strength and tensile modulus were increased linearly as result of more compact structure. Due to hydrophobic properties of silane, the water absorption and thickness swelling improved correspondingly. Contact angle testingusing three different liquid proven the functionality of silane as hydrophobic and oleophilic coating agent. The experimental results suggested that hydropobicand oleophilicsilylatedbacteria cellulose membranes with controlled growth time could be prepared and regarded as a reusable oil spills membrane.

  10. Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration

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    An, Sung-Jun; Lee, So-Hyoun; Huh, Jung-Bo; Jeong, Sung In; Park, Jong-Seok; Gwon, Hui-Jeong; Kang, Eun-Sook; Jeong, Chang-Mo; Lim, Youn-Mook

    2017-01-01

    Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated b...

  11. Eggshell and Bacterial Cellulose Composite Membrane as Absorbent Material in Active Packaging

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    S. Ummartyotin

    2016-01-01

    Full Text Available Bacterial cellulose and eggshell composite was successfully developed. Eggshell was mixed with bacterial cellulose suspension and it was casted as a composite film. CaCO3 derived from eggshell was compared with its commercial availability. It can be noted that good dispersion of eggshell particle was prepared. Eggshell particle was irregular in shape with a variation in size. It existed in bacterial cellulose network. Characterization on composite was focused on thermal and mechanical properties. It showed that flexibility and thermal stability of composite were enhanced. No significant effect of mechanical properties was therefore observed. The thermal stability of composite was stable up to 300°C. The adsorption experiment on water and vegetable oil capacity was performed. The enhancement on adsorption was due to the existence of eggshell in bacterial cellulose composite. It exhibited the potential to be a good candidate for absorbent material in active packaging.

  12. Silver nanowire catalysts on carbon nanotubes-incorporated bacterial cellulose membrane electrodes for oxygen reduction reaction.

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    Kim, Bona; Choi, Youngeun; Cho, Se Youn; Yun, Young Soo; Jin, Hyoung-Joon

    2013-11-01

    Silver nanowires have unique electrical, thermal and optical properties, which support their potential application in numerous fields including catalysis, electronics, optoelectronics, sensing, and surface-enhanced spectroscopy. Especially, their application such as catalysts for alkaline fuel cells (AFCs) have attracted much interest because of their superior electrical conductivity over that of any metal and their lower cost compared to Pt. In this study, multiwalled carbon nanotubes (MWCNTs)-incorporated bacterial cellulose (BC) membrane electrode with silver nanowire catalyst was prepared. First, acid-treated MWCNTs were incorporated into BC membranes and then freeze-dried after solvent exchange to tert-butanol in order to maintain the 3D-network macroporous structure. Second, silver nanowires synthesized by polyol process were introduced onto the surface of the MWCNTs-incorporated BC membrane through easy vacuum filtration. Finally, thermal treatment was carried out to confirm the effect of the PVP on the silver nanowire catalysts toward oxygen reduction reaction. The electrode with thermally treated silver nanowire had great electrocatalytic activity compared with non-treated one. These results suggest that the MWCNTs-incorporated BC electrode with silver nanowire catalysts after thermal treatment could be potentially used in cathodes of AFCs.

  13. Enriched glucose and dextrin mannitol-based media modulates fibroblast behavior on bacterial cellulose membranes

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    Stumpf, Taisa R.; Pértile, Renata A.N. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil); Rambo, Carlos R., E-mail: rambo@intelab.ufsc.br [Department of Electrical Engineering, Federal University of Santa Catarina, Florianópolis 88040-900 (Brazil); Porto, Luismar M. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil)

    2013-12-01

    Bacterial cellulose (BC) produced by Gluconacetobacter hansenii is a suitable biopolymer for biomedical applications. In order to modulate the properties of BC and expand its use as substrate for tissue engineering mainly in the form of biomembranes, glucose or dextrin were added into a BC fermentation mannitol-based medium (BCGl and BCDe, respectively) under static culture conditions. SEM images showed effects on fiber density and porosity on both sides of the BC membranes. Both enriched media decreased the BET surface area, water holding capacity, and rehydration rate. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) analysis revealed no change in the chemical structure of BC. L929 fibroblast cells were seeded on all BC-based membranes and evaluated in aspects of cell adhesion, proliferation and morphology. BCG1 membranes showed the highest biological performance and hold promise for the use in tissue engineering applications. - Highlights: • Glucose and dextrin were used to modify culture media for BC production. • Microarchitecture of BC was different depending on the enriching agent. • Fibroblasts adhered on the surface of BC modified microarchitectures. • Fibroblasts adhered on glucose modified BC exhibited healthy cell morphology.

  14. Nanostructured bacterial cellulose-poly(4-styrene sulfonic acid) composite membranes with high storage modulus and protonic conductivity.

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    Gadim, Tiago D O; Figueiredo, Andrea G P R; Rosero-Navarro, Nataly C; Vilela, Carla; Gamelas, José A F; Barros-Timmons, Ana; Neto, Carlos Pascoal; Silvestre, Armando J D; Freire, Carmen S R; Figueiredo, Filipe M L

    2014-05-28

    The present study reports the development of a new generation of bio-based nanocomposite proton exchange membranes based on bacterial cellulose (BC) and poly(4-styrene sulfonic acid) (PSSA), produced by in situ free radical polymerization of sodium 4-styrenesulfonate using poly(ethylene glycol) diacrylate (PEGDA) as cross-linker, followed by conversion of the ensuing polymer into the acidic form. The BC nanofibrilar network endows the composite membranes with excellent mechanical properties at least up to 140 °C, a temperature where either pure PSSA or Nafion are soft, as shown by dynamic mechanical analysis. The large concentration of sulfonic acid groups in PSSA is responsible for the high ionic exchange capacity of the composite membranes, reaching 2.25 mmol g(-1) for a composite with 83 wt % PSSA/PEGDA. The through-plane protonic conductivity of the best membrane is in excess of 0.1 S cm(-1) at 94 °C and 98% relative humidity (RH), decreasing to 0.042 S cm(-1) at 60% RH. These values are comparable or even higher than those of ionomers such as Nafion or polyelectrolytes such as PSSA. This combination of electric and viscoelastic properties with low cost underlines the potential of these nanocomposites as a bio-based alternative to other polymer membranes for application in fuel cells, redox flow batteries, or other devices requiring functional proton conducting elements, such as sensors and actuators.

  15. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells

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    Henry Fonda Aritonang

    2017-05-01

    Full Text Available Highly dispersed platinum (Pt nanoparticles / multiwalled carbon nanotubes (MWCNTs on bacterial cellulose (BC as anode catalysts for proton exchange membrane fuel cells (PEMFC were prepared with various precursors and their electro-catalytic activities towards hydrogen oxidation at 70 oC under non-humidified conditions. The composite was prepared by deposition of Pt nanoparticles and MWCNTs on BC gel by impregnation method using a water solution of metal precursors and MWCNTs followed by reducing reaction using a hydrogen gas. The composite was characterized by using TEM (transmission electron microscopy, EDS (energy dispersive spectroscopy, and XRD (X-ray diffractometry techniques. TEM images and XRD patterns both lead to the observation of spherical metallic Pt nanoparticles with mean diameter of 3-11 nm well impregnated into the BC fibrils. Preliminary tests on a single cell indicate that renewable BC is a good prospect to be explored as a membrane in fuel cell field. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 26th February 2017; Accepted: 27th February 2017 How to Cite: Aritonang, H.F., Kamu, V.S., Ciptati, C., Onggo, D., Radiman, C.L. (2017. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 287-292 (doi:10.9767/bcrec.12.2.803.287-292 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.803.287-292

  16. Composite membrane of bacterially-derived cellulose and molecularly imprinted polymer for use as a transdermal enantioselective controlled-release system of racemic propranolol.

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    Bodhibukkana, Chatchada; Srichana, Teerapol; Kaewnopparat, Sanae; Tangthong, Naruedom; Bouking, Pisit; Martin, Gary P; Suedee, Roongnapa

    2006-06-12

    A composite membrane for transdermal delivery of S-propranolol enantiomer was developed based on the controlled pore functionalization of bacterial cellulose membranes using a molecularly imprinted polymer (MIP) layer synthesis. The reactive pore-filling of an asymmetric porous cellulose membrane with a MIP thin-layer was effected using a silanized coupler as an additional anchor for the MIP. MIP thin-layers with specific binding sites for S-propranolol were synthesized by copolymerization of methacrylic acid with a cross-linker, ethylene glycol dimethacrylate in the presence of S-propranolol as the template molecule and the latter was subsequently extracted. Selective transport of S-propranolol through the MIP composite membrane was obtained, although this was determined mostly by the parent cellulose membrane with some ancillary contributory effect from the MIP layer. In addition, an enantioselectivity in the transport of propranolol prodrug enantiomers was found, suggesting that the shape and functional groups orientation, which are similar to that of the print molecule were essential for enantiomeric recognition of the MIP composite membrane. The enantioselectivity of S-MIP membranes was also shown when the release of propranolol enantiomers was studied in vitro using rat skin, with racemic propranolol contained in the donor compartment. The composite membrane of bacterially-derived cellulose and molecularly imprinted polymer may have great potential for use as a transdermal enantioselective controlled-release system for racemic propranolol.

  17. Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration

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    Sung-Jun An

    2017-10-01

    Full Text Available Bacterial cellulose (BC is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR using an irradiation technique for applications in the dental field. Electron beam irradiation (EI increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs were evaluated by scanning electron microscopy (SEM, attenuated total reflectance-Fourier transform infrared (ATR-FTIR spectroscopy, thermal gravimetric analysis (TGA, and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05. Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; % than 300k EI-BCMs at 8 weeks after implantation (p < 0.05. Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

  18. Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration.

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    An, Sung-Jun; Lee, So-Hyoun; Huh, Jung-Bo; Jeong, Sung In; Park, Jong-Seok; Gwon, Hui-Jeong; Kang, Eun-Sook; Jeong, Chang-Mo; Lim, Youn-Mook

    2017-10-25

    Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes) were significantly greater than on NI-BCMs after 3 and 7 days ( p NBA; %) than 300k EI-BCMs at 8 weeks after implantation ( p < 0.05). Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

  19. Efficacy of bacterial cellulose membrane for the treatment of lower limbs chronic varicose ulcers: a randomized and controlled trial

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    LUCIANA MARINS CAVALCANTI

    Full Text Available ABSTRACT Objective: to evaluate the efficacy of Bacterial Cellulose (BC membrane dressings in the treatment of lower limb venous ulcers. Methods: we carried out a prospective, randomized, controlled study of 25 patients with chronic venous ulcer disease in the lower limbs from the Angiology and Vascular Surgery Service of the Federal University of Pernambuco Hospital and from the Salgado Polyclinic of the County Health Department, Caruaru, Pernambuco. We randomly assigned patients to two groups: control group, receiving dressings with triglyceride oil (11 patients and experimental group, treated with BC membrane (14 patients. We followed the patients for a period of 120 days. Results: There was a reduction in the wound area in both groups. There were no infections or reactions to the product in any of the groups. Patients in the BC group showed decreased pain and earlier discontinuation of analgesic use. Conclusion: BC membrane can be used as a dressing for the treatment of varicose ulcers of the lower limbs.

  20. Silver nanoparticle/bacterial cellulose gel membranes for antibacterial wound dressing: investigation in vitro and in vivo

    International Nuclear Information System (INIS)

    Wu, Jian; Zheng, Yudong; Wen, Xiaoxiao; Lin, Qinghua; Chen, Xiaohua; Wu, Zhigu

    2014-01-01

    Bacterial cellulose (BC) has attracted increasing attention as a novel wound dressing material, but its antimicrobial activity, which is one of the critical skin-barrier functions in wound healing, is not sufficient for use in practical applications. To overcome such a deficiency, silver nanoparticles were generated and self-assembled on the surface of BC nanofibers, forming a stable and evenly distributed Ag nanoparticle coated BC nanofiber (AgNP-BC). The performance of AgNP-BC was systematically studied in terms of antibacterial activities, cytocompatibility and effects on wound healing. The results showed that AgNP-BC exhibited significant antibacterial activity against Staphylococcus aureus. Moreover, AgNP-BC allowed attachment, and growth of rat fibroblasts with low cytotoxicity emerged. Based on these advantages, AgNP-BC samples were applied in a second-degree rat wound model. Wound flora showed a significant reduction during the healing. The fresh epidermal and dermis thicknesses with AgNP-BC samples were 111 and 855 µm respectively, higher than 74 and 619 µm for BC groups and 57 and 473 µm for untreated control wounds. The results demonstrated that AgNP-BC could reduce inflammation and promote scald wound healing. (paper)

  1. Silver nanoparticle/bacterial cellulose gel membranes for antibacterial wound dressing: investigation in vitro and in vivo.

    Science.gov (United States)

    Wu, Jian; Zheng, Yudong; Wen, Xiaoxiao; Lin, Qinghua; Chen, Xiaohua; Wu, Zhigu

    2014-06-01

    Bacterial cellulose (BC) has attracted increasing attention as a novel wound dressing material, but its antimicrobial activity, which is one of the critical skin-barrier functions in wound healing, is not sufficient for use in practical applications. To overcome such a deficiency, silver nanoparticles were generated and self-assembled on the surface of BC nanofibers, forming a stable and evenly distributed Ag nanoparticle coated BC nanofiber (AgNP-BC). The performance of AgNP-BC was systematically studied in terms of antibacterial activities, cytocompatibility and effects on wound healing. The results showed that AgNP-BC exhibited significant antibacterial activity against Staphylococcus aureus. Moreover, AgNP-BC allowed attachment, and growth of rat fibroblasts with low cytotoxicity emerged. Based on these advantages, AgNP-BC samples were applied in a second-degree rat wound model. Wound flora showed a significant reduction during the healing. The fresh epidermal and dermis thicknesses with AgNP-BC samples were 111 and 855 µm respectively, higher than 74 and 619 µm for BC groups and 57 and 473 µm for untreated control wounds. The results demonstrated that AgNP-BC could reduce inflammation and promote scald wound healing.

  2. Synthesis and characterization of cellulose derivatives obtained from bacterial cellulose

    International Nuclear Information System (INIS)

    Oliveira, Rafael L. de; Barud, Hernane; Ribeiro, Sidney J.L.; Messaddeq, Younes

    2011-01-01

    The chemical modification of cellulose leads to production of derivatives with different properties from those observed for the original cellulose, for example, increased solubility in more traditional solvents. In this work we synthesized four derivatives of cellulose: microcrystalline cellulose, cellulose acetate, methylcellulose and carboxymethylcellulose using bacterial cellulose as a source. These were characterized in terms of chemical and structural changes by examining the degree of substitution (DS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy - NMR 13 C. The molecular weight and degree of polymerization were evaluated by viscometry. The characterization of the morphology of materials and thermal properties were performed with the techniques of X-ray diffraction, electron microscopy images, differential scanning calorimetry (DSC) and thermogravimetric analysis. (author)

  3. Characterization of TEMPO-oxidized bacterial cellulose

    International Nuclear Information System (INIS)

    Nascimento, Eligenes S.; Pereira, Andre L.S.; Lima, Helder L.; Barroso, Maria K. de A.; Barros, Matheus de O.; Morais, Joao P.S.; Borges, Maria de F.; Rosa, Morsyleide de F.

    2015-01-01

    The aim of this study was to characterize the TEMPO-oxidized bacterial cellulose, as a preliminary research for further application in nanocomposites. Bacterial cellulose (BC) was selectively oxidized at C-6 carbon by TEMPO radical. Oxidized bacterial cellulose (BCOX) was characterized by TGA, FTIR, XRD, and zeta potential. BCOX suspension was stable at pH 7.0, presented a crystallinity index of 83%, in spite of 92% of BC, because of decrease in the free hydroxyl number. FTIR spectra showed characteristic BC bands and, in addition, band of carboxylic group, proving the oxidation. BCOX DTG showed, in addition to characteristic BC thermal events, a maximum degradation peak at 233 °C, related to sodium anhydro-glucuronate groups formed during the cellulose oxidation. Thus, BC can be TEMPO-oxidized without great loss in its structure and properties. (author)

  4. Bacterial Cellulose Ionogels as Chemosensory Supports.

    Science.gov (United States)

    Smith, Chip J; Wagle, Durgesh V; O'Neill, Hugh M; Evans, Barbara R; Baker, Sheila N; Baker, Gary A

    2017-11-01

    To fully leverage the advantages of ionic liquids for many applications, it is necessary to immobilize or encapsulate the fluids within an inert, robust, quasi-solid-state format that does not disrupt their many desirable, inherent features. The formation of ionogels represents a promising approach; however, many earlier approaches suffer from solvent/matrix incompatibility, optical opacity, embrittlement, matrix-limited thermal stability, and/or inadequate ionic liquid loading. We offer a solution to these limitations by demonstrating a straightforward and effective strategy toward flexible and durable ionogels comprising bacterial cellulose supports hosting in excess of 99% ionic liquid by total weight. Termed bacterial cellulose ionogels (BCIGs), these gels are prepared using a facile solvent-exchange process equally amenable to water-miscible and water-immiscible ionic liquids. A suite of characterization tools were used to study the preliminary (thermo)physical and structural properties of BCIGs, including no-deuterium nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. Our analyses reveal that the weblike structure and high crystallinity of the host bacterial cellulose microfibrils are retained within the BCIG. Notably, not only can BCIGs be tailored in terms of shape, thickness, and choice of ionic liquid, they can also be designed to host virtually any desired active, functional species, including fluorescent probes, nanoparticles (e.g., quantum dots, carbon nanotubes), and gas-capture reagents. In this paper, we also present results for fluorescent designer BCIG chemosensor films responsive to ammonia or hydrogen sulfide vapors on the basis of incorporating selective fluorogenic probes within the ionogels. Additionally, a thermometric BCIG hosting the excimer-forming fluorophore 1,3-bis(1-pyrenyl)propane was devised which exhibited a ratiometric (two

  5. Bacterial membrane proteomics.

    Science.gov (United States)

    Poetsch, Ansgar; Wolters, Dirk

    2008-10-01

    About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

  6. Cellulose multilayer Membranes manufacture with Ionic liquid

    KAUST Repository

    Livazovic, Sara

    2015-05-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

  7. Methacrylate hydrogels reinforced with bacterial cellulose

    Czech Academy of Sciences Publication Activity Database

    Hobzová, Radka; Dušková-Smrčková, Miroslava; Michálek, Jiří; Karpushkin, Evgeny; Gatenholm, P.

    2012-01-01

    Roč. 61, č. 7 (2012), s. 1193-1201 ISSN 0959-8103 R&D Projects: GA AV ČR KJB400500902 Institutional research plan: CEZ:AV0Z40500505 Keywords : bacterial cellulose * methacrylate hydrogel * composite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.125, year: 2012

  8. Cellulose acetate electrospun nanofibrous membrane: fabrication ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 39; Issue 2. Cellulose acetate electrospun nanofibrous membrane: fabrication, characterization, drug loading and antibacterial properties. NAZNIN SULTANA ... The CA nanofibrous membrane was non-toxic to human skin fibroblast cells. Thus the CA ...

  9. High Performance Regenerated Cellulose Membranes from Trimethylsilyl Cellulose

    KAUST Repository

    Ali, Ola

    2013-05-01

    Regenerated cellulose (RC) membranes are extensively used in medical and pharmaceutical separation processes due to their biocompatibility, low fouling tendency and solvent resistant properties. They typically possess ultrafiltration and microfiltration separation characteristics, but recently, there have been attempts to widen their pool of applications in nanofiltration processes. In this work, a novel method for preparing high performance composite RC membranes was developed. These membranes reveal molecular weight cut-offs (MWCO) of less than 250 daltons, which possibly put them ahead of all commercial RC membranes and in competition with high performance nanofiltration membranes. The membranes were prepared by acidic hydrolysis of dip-coated trimethylsilyl cellulose (TMSC) films. TMSC, with a degree of silylation (DS) of 2.8, was prepared from microcrystalline cellulose by reaction with hexamethyldisilazane under the homogeneous conditions of LiCl/DMAC solvent system. Effects of parameters, such as coating solution concentration and drying rates, were investigated. It was concluded that higher TMSC concentrations as well as higher solvent evaporation rates favor better MWCOs, mainly due to increase in the selective layer thickness. Successful cross-linking of prepared membranes with glyoxal solutions, in the presence of boric acid as a catalyst, resulted in MWCOs less than 250 daltons. The suitability of this crosslinking reaction for large scale productions was already proven in the manufacturing of durable-press fabrics. For us, the inexpensive raw materials as well as the low reaction times and temperatures were of interest. Moreover, the non-toxic nature of glyoxal is a key advantage in medical and pharmaceutical applications. The membranes prepared in this work are strong candidates for separation of small organic solutes from organic solvents streams in pharmaceutical industries. Their hydrophilicity, compared to typical nanofiltration membranes, offer

  10. Preparation of membranes from cellulose obtained of sugarcane bagasse

    International Nuclear Information System (INIS)

    Pereira, Paulo Henrique Fernandes; Cioffi, Maria Odila Hilario; Voorwald, Herman Jacobus Cornelis; Pinho, Maria Noberta de; Silva, Maria Lucia Caetano Pinto da

    2010-01-01

    In this work, cellulose obtained from sugarcane bagasse to produce both cellulose and acetylated cellulose to prepare asymmetric membranes. Membranes was procedure used a mixture of materials of DMAc/ LiCl systemic in different conditions. Cellulose and acetylated cellulose were characterized by thermogravimetric (TG), Xray diffraction (XRD) and scanning Electron Microscopy (SEM). Observed less stability thermal of acetylated cellulose when compared of cellulose. All membranes procedure were asymmetric, characterized by presence of a dense skin and porous support can be observed. SEM showed that the morphology of the superficial of membranes depends on the method preparation. (author)

  11. WOOD CELLULOSE ACETATE MEMBRANE 179

    African Journals Online (AJOL)

    DR. AMINU

    2013-06-01

    Jun 1, 2013 ... Science. 297: 803-806. Guthrie, J.T and Tune, P.D. (1991). The preparation, characterization and application of cellulose-. MMA graft copolymers. J. Polym. Sci. 29, 1301-. 1309. Hamiltion, J..K. and Mitachell, R.L. (1965). Encyclopaedia of polymer science and technology, vol. 3. (Biakales, N..M. edn). .John.

  12. Bacterial Cellulose-Hydroxyapatite Nanocomposites for Bone Regeneration

    Directory of Open Access Journals (Sweden)

    S. Saska

    2011-01-01

    Full Text Available The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl2 followed by Na2HPO4. BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40%–50% of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA, similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration.

  13. Kombucha-synthesized bacterial cellulose: preparation, characterization, and biocompatibility evaluation.

    Science.gov (United States)

    Zhu, Changlai; Li, Feng; Zhou, Xinyang; Lin, Lin; Zhang, Tianyi

    2014-05-01

    Bacterial cellulose (BC) is a natural biomaterial with unique properties suitable for tissue engineering applications, but it has not yet been used for preparing nerve conduits to repair peripheral nerve injuries. The objectives of this study were to prepare and characterize the Kampuchea-synthesized bacterial cellulose (KBC) and further evaluate the biocompatibility of KBC with peripheral nerve cells and tissues in vitro and in vivo. KBC membranes were composed of interwoven ribbons of about 20-100 nm in width, and had a high purity and the same crystallinity as that of cellulose Iα. The results from light and scanning electron microscopy, MTT assay, flow cytometry, and RT-PCR indicated that no significant differences in the morphology and cell function were observed between Schwann cells (SCs) cultured on KBC membranes and glass slips. We also fabricated a nerve conduit using KBC, which was implanted into the spatium intermusculare of rats. At 1, 3, and 6 weeks post-implantation, clinical chemistry and histochemistry showed that there were no significant differences in blood counts, serum biochemical parameters, and tissue reactions between implanted rats and sham-operated rats. Collectively, our data indicated that KBC possessed good biocompatibility with primary cultured SCs and KBC did not exert hematological and histological toxic effects on nerve tissues in vivo. Copyright © 2013 Wiley Periodicals, Inc.

  14. diffusion of metronidazole released through cellulose membrane

    African Journals Online (AJOL)

    prof kokwaro

    Three different topical formulations namely gel, cream and ointment, each containing 1% w/w metronidazole, were prepared and in vitro permeation studies carried out. The permeation of metronidazole from each of the topical formulation was determined using dialyzing cellulose membrane in a dissolution tester. Glycerin,.

  15. Metallization of bacterial cellulose for electrical and electronic device manufacture

    Science.gov (United States)

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

    2010-09-28

    A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

  16. Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

    Science.gov (United States)

    Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

    2018-06-15

    The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Comparison of Bacterial Cellulose Production among Different Strains and Fermented Media

    Directory of Open Access Journals (Sweden)

    Maryam Jalili Tabaii

    2015-12-01

    Full Text Available The effect of different carbon sources on bacterial cellulose production by Gluconacetobacter xylinus (PTCC 1734 and two newly isolated strains (from vinegar under static culture conditions was studied. The production of bacterial cellulose was examined in modified Hestrin-Shramm medium by replacing D-glucose with other carbon sources. The results showed that the yield and characteristics of bacterial cellulose were influenced by the type of carbon source. Glycerol gave the highest yield in all of the studied strains (6%, 9.7% and 3.8% for S, A2 strain and Gluconacetobacter xylinus (PTCC 1734, respectively. The maximum dry bacterial cellulose weight in the glycerol containing medium is due to A2 strain (1.9 g l-1 in comparison to Gluconacetobacter xylinus as reference strain (0.76 g l-1. Although all of the studied strains were in Gluconacetobacter family, each used different sugars for maximum production after glycerol (mannitol and fructose for two newly isolated strains and glucose for Gluconacetobacter xylinus. The maximum moisture content was observed when sucrose and food-grade sucrose were used as carbon source. Contrary to expectations, while the maximum thickness of bacterial cellulose membrane was attained when glycerol was used, bacterial cellulose from glycerol had less moisture content than the others. The oxidized cellulose showed antibacterial activities, which makes it as a good candidate for food-preservatives.

  18. Biosynthesis of highly porous bacterial cellulose nanofibers

    Science.gov (United States)

    Hosseini, Hadi; Kokabi, Mehrdad; Mousavi, Seyyed Mohammad

    2018-01-01

    Bacterial cellulose nanofibers (BCNFs) as a sustainable and biodegradable polymer has drawn tremendous research attention in tissue engineering, bacterial sensors and drug delivery due to its extraordinary properties such as high purity, high crystallinity, high water absorption capacity and excellent mechanical strength in the wet state. This awesome properties, is attributed to BCNFs structure, therefore its characterization is important. In this work, the bacterial strain, Gluconacetobacter xylinus (PTCC 1734, obtained from Iranian Research Organization for Science and Technology (IROST)), was used to produce BCNFs hydrogel using bacterial fermentation under static condition at 29 °C for 10 days in the incubator. Then, the biosynthesized BCNFs wet gel, were dried at ambient temperature and pressure and characterized using Brunauer-Emmett-Teller (BET) and Field emission scanning electron microscopy (FE-SEM) analysis. FESEM image displayed highly interconnected and porous structure composed of web-like continuous, nanofibers with an average diameter of 48.5±2.1 nm. BET result analysis depicted BCNFs dried at ambient conditions had IV isotherm type, according to the IUPAC classification, indicating that BCNFs dried at ambient condition is essentially mesoporous. On the other hand, BET results depicted, mesoporous structure is around 85%. In addition, Specific surface area (SBET) obtained 81.45 m2/g. These results are in accordance with the FESEM observation.

  19. Chain scission and anti fungal effect of electron beam on cellulose membrane

    International Nuclear Information System (INIS)

    Wanichapichart, Pikul; Taweepreeda, Wirach; Nawae, Safitree; Choomgan, Pastraporn; Yasenchak, Dan

    2012-01-01

    Two types of bacterial cellulose (BC) membranes were produced under a modified H and S medium using sucrose as a carbon source, with (CCB) and without (SHB) coconut juice supplement. Both membranes showed similar crystallinity of 69.24 and 71.55%. After being irradiated with E-beams under oxygen limited and ambient condition, the results from water contact angle showed that only the irradiated membrane CCB was increased from 30 to 40 degrees, and irradiation under oxygen ambient condition provided the greatest value. Comparing with the control membranes, smaller water flux was the cases after electron beam irradiation which indicated a reduction of membrane pore area. However, the results from molecular weight cut off (MWCO) revealed that chain scission was greater for membrane SHB and its cut off was increased from 28,000 Da to more than 35,000 Da. FTIR analysis revealed some changes in membrane functional groups, corresponding with the above results. These changes initiated new property of cellulose membranes, an anti-fungal food wrap. - Highlights: ► Electron beam irradiation increased membrane hydrophobicity and molecular weight cut off. ► The irradiation caused chain scissoring and anti fungal property of cellulose membrane. ► FT-IR studies revealed changes in functional groups causing a decrease in membrane moisture. ► Anti fungal test of cellulose membrane showed the same shelf life as polyethylene sheet.

  20. Bacterial cellulose skin masks-Properties and sensory tests.

    Science.gov (United States)

    Pacheco, Guilherme; de Mello, Carolina Véspoli; Chiari-Andréo, Bruna Galdorfini; Isaac, Vera Lucia Borges; Ribeiro, Sidney José Lima; Pecoraro, Édison; Trovatti, Eliane

    2017-09-29

    Bacterial cellulose (BC) is a versatile material produced by microorganisms in the form of a membranous hydrogel, totally biocompatible, and endowed with high mechanical strength. Its high water-holding capacity based on its highly porous nanofibrillar structure allows BC to incorporate and to release substances very fast, thus being suitable for the preparation of skincare masks. The preparation and characterization of cosmetic masks based on BC membranes and active cosmetics. The masks were prepared by the simple incorporation of the cosmetic actives into BC membranes, used as a swelling matrix. The masks were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), sensory tests, and skin moisture tests on volunteers. The results of sensory tests revealed the good performance of BC, being considered effective by the panel of volunteers, specially for adhesion to the skin (7.7 at the score scale), and improvement of the skin moisture (the hydration effect increased 76% in 75% of the volunteers that used vegetable extract mask formulation [VEM]), or a decrease in skin hydration (80% of the volunteers showed 32.6% decrease on skin hydration using propolis extract formulation [PEM] treatment), indicating the BC nanofiber membranes can be used to skincare applications. The results demonstrate the BC can be used as an alternative support for cosmetic actives for skin treatment. © 2017 Wiley Periodicals, Inc.

  1. Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation

    International Nuclear Information System (INIS)

    Zheng, Yi; Yang, Jingxuan; Zheng, Weili; Wang, Xiao; Xiang, Cao; Tang, Lian; Zhang, Wen; Chen, Shiyan; Wang, Huaping

    2013-01-01

    Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe 3 O 4 nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe 3 O 4 nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit. - Highlights: ► Flexible magnetic film is prepared by in situ synthesis on bacterial cellulose. ► Ultrasound and PEG are used together to inhibit the nanoparticle aggregation. ► The magnetic membrane demonstrates the great superparamagnetic behavior

  2. Preparation of cellulose II and IIII films by allomorphic conversion of bacterial cellulose I pellicles

    International Nuclear Information System (INIS)

    Faria-Tischer, Paula C.S.; Tischer, Cesar A.; Heux, Laurent; Le Denmat, Simon; Picart, Catherine; Sierakowski, Maria-R.

    2015-01-01

    The structural changes resulting from the conversion of native cellulose I (Cel I) into allomorphs II (Cel II) and III I (Cel III I ) have usually been studied using powder samples from plant or algal cellulose. In this work, the conversion of Cel I into Cel II and Cel III I was performed on bacterial cellulose films without any mechanical disruption. The surface texture of the films was observed by atomic force microscopy (AFM) and the morphology of the constituting cellulose ribbons, by transmission electron microscopy (TEM). The structural changes were characterized using solid-state NMR spectroscopy as well as X-ray and electron diffraction. The allomorphic change into Cel II and Cel III I resulted in films with different crystallinity, roughness and hydrophobic/hydrophilicity surface and the films remained intact during all process of allomorphic conversion. - Highlights: • Description of a method to modify the allomorphic structure of bacterial cellulose films • Preparation of films with specific morphologies and hydrophobic/hydrophilic surface characters • First report on cellulose III films from bacterial cellulose under swelling conditions • Detailed characterization of cellulose II and III films with complementary techniques • Development of films with specific properties as potential support for cells, enzymes, and drugs

  3. Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

    Science.gov (United States)

    Römling, Ute; Galperin, Michael Y.

    2015-01-01

    Summary Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host. PMID:26077867

  4. High Dehumidification Performance of Amorphous Cellulose Composite Membranes prepared from Trimethylsilyl Cellulose

    KAUST Repository

    Puspasari, Tiara

    2018-04-11

    Cellulose is widely regarded as an environmentally friendly, natural and low cost material which can significantly contribute the sustainable economic growth. In this study, cellulose composite membranes were prepared via regeneration of trimethylsilyl cellulose (TMSC), an easily synthesized cellulose derivative. The amorphous hydrophilic feature of the regenerated cellulose enabled fast permeation of water vapour. The pore-free cellulose layer thickness was adjustable by the initial TMSC concentration and acted as an efficient gas barrier. As a result, a 5,000 GPU water vapour transmission rate (WVTR) at the highest ideal selectivity of 1.1 x 106 was achieved by the membranes spin coated from a 7% (w/w) TMSC solution. The membranes maintained a 4,000 GPU WVTR with selectivity of 1.1 x 104 in the mixed-gas experiments, surpassing the performances of the previously reported composite membranes. This study provides a simple way to not only produce high performance membranes but also to advance cellulose as a low-cost and sustainable membrane material for dehumidification applications.

  5. Ultrafiltration and Nanofiltration Multilayer Membranes Based on Cellulose

    KAUST Repository

    Livazovic, Sara

    2016-06-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

  6. Cellulose microfibril deposition: coordinated activity at the plant plasma membrane

    NARCIS (Netherlands)

    Lindeboom, J.J.; Mulder, B.; Vos, J.W.; Ketelaar, M.J.; Emons, A.M.C.

    2008-01-01

    Plant cell wall production is a membrane-bound process. Cell walls are composed of cellulose microfibrils, embedded inside a matrix of other polysaccharides and glycoproteins. The cell wall matrix is extruded into the existing cell wall by exocytosis. This same process also inserts the cellulose

  7. Effect of Evaporation Time on Separation Performance of Polysulfone/Cellulose Acetate (PSF/CA) Membrane

    Science.gov (United States)

    Syahbanu, Intan; Piluharto, Bambang; Khairi, Syahrul; Sudarko

    2018-01-01

    Polysulfone and cellulose acetate are common material in separation. In this research, polysulfone/cellulose actetate (PSF/CA) blend membrane was prepared. The aim of this research was to study effect of evaporation time in casting of PSF/CA membrane and its performance in filtration. CA was obtained by acetylation process of bacterial cellulose (BC) from fermentation of coconut water. Fourier Transform Infra Red (FTIR) Spectroscopy was used to examine functional groups of BC, CA and commercial cellulose acetate. Subtitution of acetyl groups determined by titration method. Blend membranes were prepared through phase inversion technique in which composition of PSF/PEG/CA/NMP(%w) was 15/5/5/75. Polyethyleneglycol (PEG) and N-methyl-2-pyrrolidone (NMP) were act as pore forming agent and solvent, respectively. Variation of evaporation times were used as parameter to examine water uptake, flux, and morphology of PSF/CA blend membranes. FTIR spectra of CA show characteristic peak of acetyl group at 1220 cm-1 indicated that BC was acetylated succesfully. Degree of subtitution of BCA was found at 2.62. Highest water flux was performed at 2 bar obtained at 106.31 L.m-2.h-1 at 0 minute variation, and decrease as increasing evaporation time. Morphology of PSF/BCA blend membranes were investigated by Scanning Electron Microscopy (SEM) showed that porous asymetric membrane were formed.

  8. Bacterial Cellulose Production from Beet Molasses | Keshk | African ...

    African Journals Online (AJOL)

    The yield of the bacterial cellulose (BC) produced from beet molasses was higher than that using glucose as a sole carbon source. The structure of BC produced in presence of beet molasses was studied using IR spectroscopy and X-ray diffractometry. IR spectra show the relative absorbance of CO- C ether linkage (at 1120 ...

  9. Production and Status of Bacterial Cellulose in Biomedical Engineering

    Science.gov (United States)

    Moniri, Mona; Boroumand Moghaddam, Amin; Abdul Rahim, Raha; Bin Ariff, Arbakariya; Zuhainis Saad, Wan; Navaderi, Mohammad; Mohamad, Rosfarizan

    2017-01-01

    Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.

  10. Magnetically responsive bacterial cellulose: Synthesis and magnetic studies

    Science.gov (United States)

    Vitta, Satish; Drillon, Marc; Derory, A.

    2010-09-01

    Bacterial cellulose with its porous network structure was used as a support to precipitate Ni nanoparticles by room temperature chemical reduction of Ni-chloride hexahydrate. The room temperature reduction in an aqueous environment results in the formation of crystalline Ni nanoparticles of size 10 to 60 nm inside the bacterial cellulose along with Ni(OH)2. The nanocrystals have an equiaxed shape and are found both as individual particles as well as small aggregates depending on the porous network structure of cellulose matrix. The bacterial cellulose does not undergo any change and retains its crystal structure even after chemical reduction reaction. The Ni loaded bacterial cellulose is found to be ferromagnetic at room temperature with a saturation magnetization of 2.81 emu g-1 which increases by an order of magnitude to 21.8 emu g-1 at 1.8 K. The coercive field also increases by two orders of magnitude from 28 G at 300 K to 2900 G at 1.8 K. The zero field cooled magnetization however exhibits a superparamagnetic behavior with a peak at 20 K, the blocking temperature and this behavior is observed even in ac magnetization. The magnetization decrease with increasing temperature up to 400 K, when extrapolated to high temperatures using a power law indicates a Curie transition at 500 K, much lower than the Curie temperature of bulk Ni. The fraction of isolated superparamagnetic nanoparticles present in the composite was estimated from the saturation magnetization and is found to be ˜88%. These results clearly highlight the presence of two separate magnetic phases, superparamagnetic, and ferromagnetic, and the role of various magnetic interactions in the collective magnetic behavior of Ni nanoparticles in the composite structure.

  11. Use of agroindustrial waste in the preparation of nanocomposites based on bacterial cellulose and hydroxyapatite

    International Nuclear Information System (INIS)

    Duarte, Eden B.; Chagas, Bruna S. das; Feitosa, Judith P.A.; Andrade, Fabia K.; Borges, Maria F.; Muniz, Celli R.; Souza Filho, Men de Sa M.; Rosa, Morsyleide F.; Brigida, Ana I.; Morais, Joao P.S.

    2015-01-01

    Environmental issues have supported the interest in renewable sources and agroindustrial residues became a significant resource for the production of new materials. The present work presents the use of agroindustrial residues to obtain bacterial cellulose (BC) for further elaboration of nanocomposites with hydroxyapatite (HA). The production of BC membranes occurred in Hestrin & Schramm medium, cashew juice and sisal liquid waste cultivated under static conditions. After the incubation period, the BC membranes were purified and nanocomposites prepared by successive immersion of the purified membranes in solutions of Calcium Chloride (CaCl 2 ), and Sodium Phosphate (Na 2 HPO 4 ), followed by drying and subsequent characterization. The materials obtained were characterized by Thermogravimetric Analysis (TGA) and X-ray Diffraction (XRD). Additionally, in vitro tests were performed for nanocomposites. The results showed the production of cellulose from the three substrates studied, without the need for further supplementation or pH change. In all characterizations, structure and typical behavior of bacterial cellulose were found. The composites showed bioactivity and the adsorption capacity of proteins, which lead to potential biocompatibility of these materials. (author)

  12. Novel chemically modified bacterial cellulose nanocomposite as potential biomaterial for stem cell therapy applications.

    Science.gov (United States)

    Xavier Acasigua, Gerson Arisoly; de Olyveira, Gabriel Molina; Manzine Costa, Ligia Maria; Braghirolli, Daikelly Iglesias; Medeiros Fossati, Anna Christina; Guastaldi, Antonio Carlos; Pranke, Patricia; Daltro, Gildásio de Cerqueira; Basmaji, Pierre

    2014-03-01

    Bacterial cellulose (BC) has become established as a remarkably versatile biomaterial and can be used in a wide variety of applied scientific applications, especially for medical devices. In this work, the bacterial cellulose fermentation process is modified by the addition of hyaluronic acid and gelatin (1% w/w) to the culture medium before the bacteria is inoculated. Hyaluronic acid and gelatin influence in bacterial cellulose was analyzed using Transmission Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Adhesion and viability studies with human dental pulp stem cells using natural bacterial cellulose/hyaluronic acid as scaffolds for regenerative medicine are presented for the first time in this work. MTT viability assays show higher cell adhesion in bacterial cellulose/gelatin and bacterial cellulose/ hyaluronic acid scaffolds over time with differences due to fiber agglomeration in bacterial cellulose/gelatin. Confocal microscopy images showed that the cell were adhered and well distributed within the fibers in both types of scaffolds.

  13. Cellulose acetate electrospun nanofibrous membrane: fabrication ...

    Indian Academy of Sciences (India)

    Cellulose-based materials are one of the most commonly used materials for biomedical applications, which normally applied as carriers for ... chitosan, chitin, polystyrene, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polylactic ... Product Inc., USA) was used to investigate the wettability properties of the fibres. Briefly ...

  14. Recognition of lysozyme using surface imprinted bacterial cellulose nanofibers.

    Science.gov (United States)

    Saylan, Yeşeren; Tamahkar, Emel; Denizli, Adil

    2017-11-01

    Here, we developed the lysozyme imprinted bacterial cellulose (Lyz-MIP/BC) nanofibers via the surface imprinting strategy that was designed to recognize lysozyme. This study includes the molecular imprinting method onto the surface of bacterial cellulose nanofibers in the presence of lysozyme by metal ion coordination, as well as further characterizations methods FTIR, SEM and contact angle measurements. The maximum lysozyme adsorption capacity of Lyz-MIP/BC nanofibers was found to be 71 mg/g. The Lyz-MIP/BC nanofibers showed high selectivity for lysozyme towards bovine serum albumin and cytochrome c. Overall, the Lyz-MIP/BC nanofibers hold great potential for lysozyme recognition due to the high binding capacity, significant selectivity and excellent reusability.

  15. Effects of variation of chitosan concentration on the characteristics of membrane cellulose bacteria-chitosan biocomposites as candidates for artificial dura mater

    Science.gov (United States)

    Widiyanti, Prihartini; Jabbar, Hajria; Rudyardjo, Djony Izak

    2017-02-01

    This study was conducted to determine the effect of variation in concentration of chitosan on the physical and biological characteristics of the membrane of bacterial cellulose-chitosan biocomposites through immersion precipitation method. Bacterial cellulose membrane was soaked in a solution of chitosan whose concentration variation are 0.1%; 0.3%; 0.5% and 0.7%. The characterization tests which were conducted included the analysis of functional groups (FTIR), tensile strength test, morphology test (SEM), and cytotoxicity assay using MTT Assay method. Based on the cluster analysis test, the results of FTIR spectra indicate changes in the physical bond which means that there is interaction between the bacterial cellulose membrane with chitosan on each sample. The bacteria produced cellulose membrane with tensile strength of 10.53 ± 0.19 MPa while the microbial cellulose membrane by adding 0.5% chitosan concentration had tensile strength value of 8:58 ± 0.19 MPa. It shows that with the addition of chitosan it would decrease the tensile strength in microbial cellulose membrane. This was shown by 496.2 nm - 2,032 µm pore size with a thickness (mm) of 0:35 ± 0.33 to 0.81 ± 0.26. Based on the test results of the analysis of functional groups, tensile strength test, and morphology test, membrane microbial cellulose-chitosan biocomposites have the potential to be used as artificial dura mater candidate.

  16. Bacterial Cellulose (BC) as a Functional Nanocomposite Biomaterial

    Science.gov (United States)

    Nandgaonkar, Avinav Ghanashyam

    Cellulosic is the most abundant biopolymer in the landscape and can be found in many different organisms. It has been already seen use in the medical field, for example cotton for wound dressings and sutures. Although cellulose is naturally occurring and has found a number of applications inside and outside of the medical field, it is not typically produced in its pure state. A lengthy process is required to separate the lignin, hemicelluloses and other molecules from the cellulose in most renewables (wood, agricultural fibers such as cotton, monocots, grasses, etc.). Although bacterial cellulose has a similar chemical structure to plant cellulose, it is easier to process because of the absence of lignin and hemicelluloses which require a lot of energy and chemicals for removal. Bacterial cellulose (BC) is produced from various species of bacteria such as Gluconacetobacter xylinus. Due to its high water uptake, it has the tendency to form gels. It displays high tensile strength, biocompatibility, and purity compared to wood cellulose. It has found applications in fields such as paper, paper products, audio components (e.g., speaker diaphragms), flexible electronics, supercapacitors, electronics, and soft tissue engineering. In my dissertation, we have functionalized and studied BC-based materials for three specific applications: cartilage tissue engineering, bioelectronics, and dye degradation. In our first study, we prepared a highly organized porous material based on BC by unidirectional freezing followed by a freeze-drying process. Chitosan was added to impart additional properties to the resulting BC-based scaffolds that were evaluated in terms of their morphological, chemical, and physical properties for cartilage tissue engineering. The properties of the resulting scaffold were tailored by adjusting the concentration of chitosan over 1, 1.5, and 2 % (by wt-%). The scaffolds containing chitosan showed excellent shape recovery and structural stability after

  17. Preparation and characterization of novel wound dressing based on silver nanoparticle-impregnated bacterial cellulose and bacterial cellulose-aloe vera

    International Nuclear Information System (INIS)

    Ventigan, Sarla V.; Santiago, Karen S.; Balitaan, Jolleen Natalie I.

    2015-01-01

    Ideal wound dressings stimulate wound healing, control unpleasant odors, and provide antimicrobial action in wounds. However, most traditional wound dressings such as gauze and biological dressings exhibit exudate leaking which increases the risk of infection and delayed wound healing of tissues. This study aims to develop and characterize a bio-composite of bacterial cellulose and aloe vera having the ideal features of a wound dressing from Acetobacter xylinum-activated culture medium supplemented with various aloe vera concentrations from )-50% (v/v) and the film which exhibits the most uniform results is used for the incorporation of silver nanoparticle as an antibacterial agent. The biopolymer composites of bacterial cellulose and aloe vera were developed by adding 0-50% aloe vera (v/v) in the A. xylinum-activated coconut water medium during biosynthesis in static cultivation for 10 days. The films obtained after drying the membranes were named as bacterial cellulose-aloe vera (BC-A) films. The moisture content of films reached 99% which indicates that the films may be suitable for providing a moist environment to facilitate wound healing fast. With the addition of aloe vera up to 30% (v/v) during BC synthesis, it resulted in a significant improvement in the water absorption capacity of the films showing a WAC ration of 36.46 (r.s.d.= 12.17%, n=3) compared to the unmodified film having a ratio of 9.03 (r.s.d.= 13.95%, n=3). However, the addition of aloe vera at a concentration greater than 30% (v/v) resulted in a decrease in pellicle formation which can be observed from the very weak properties of the films. The BC-A (30%) displayed significantly improved in comparison to the unmodified BC film. Also, it is capable of absorbing high amount of water than its weight and can act as a potential wound dressing which reduces irritation and inflammation. (author)

  18. Nanocellulose patents trends: a comprehensive review on patents on cellulose nanocrystals, microfibrillated and bacterial cellulose.

    Science.gov (United States)

    Charreau, Hernan; Foresti, Maria L; Vazquez, Analia

    2013-01-01

    Cellulose nanoparticles (i.e. cellulose elements having at least one dimension in the 1-100 nm range) have received increasing attention during the last decade. This is not only evident in academic articles, but it is also manifested by the increasing number of nanocellulose patents that are published every year. In the current review, nanocellulose patents are reviewed using specific software which provides valuable information on the annual number of patents that have been published throughout the years, main patent owners, most prolific inventors, and patents on the field that have received more citations. Patent statistics on rod-like cellulose nanoparticles extracted from plants by acid hydrolysis (nanocrystals), mechanical treatment leading to microfibrillated cellulose (MFC), and microbially produced nanofibrils (bacterial cellulose, BC) are analyzed in detail. The aim of the current review is to provide researchers with patent information which may help them in visualizing the evolution of nanocellulose technology, both as a whole and also divided among the different nanosized particles that are currently the subject of outstanding scientific attention. Then, patents are not only analyzed by their content, but also by global statistics which will reveal the moment at which different cellulose nanoparticles technologies achieved a breakthrough, the relative interest received by different nanocellulose particles throughout the years, the companies that have been most interested in this technology, the most prolific inventors, and the patents that have had more influence in further developments. It is expected that the results showing the explosion that nanocellulose technology is experiencing in current days will still bring more research on the topic and contribute to the expansion of nanocellulosics applications.

  19. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

    Science.gov (United States)

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

    2016-01-01

    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

  20. Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

    Science.gov (United States)

    Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

    2017-01-01

    Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

  1. Drug release kinetics from carboxymethylcellulose-bacterial cellulose composite films.

    Science.gov (United States)

    Juncu, Gheorghe; Stoica-Guzun, Anicuta; Stroescu, Marta; Isopencu, Gabriela; Jinga, Sorin Ion

    2016-08-30

    Composite films of sodium carboxymethyl cellulose and bacterial cellulose (NaCMC-BC) cross-linked with citric acid (CA) were prepared by solution casting method. Ibuprofen sodium salt (IbuNa) has been used to study the mechanism of drug release from composite films. Surface morphology was investigated by scanning electron microscopy (SEM) and proved that the BC content influences the aspect of the films. Fourier transformed infrared spectroscopy (FTIR) revealed specific peaks in IR spectra of composite films which sustain that NaCMC was cross-linked with CA. Starting from swelling observations, the release kinetic of IbuNa was described using a model which neglects the volume expansion due to polymer swelling and which considers non-linear diffusion coefficients for drug and solvent. The IbuNa release is also influenced by BC content, the drug release rate was decreasing with the increase of BC content. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Novel Cu@SiO2/bacterial cellulose nanofibers: Preparation and excellent performance in antibacterial activity

    International Nuclear Information System (INIS)

    Ma, Bo; Huang, Yang; Zhu, Chunlin; Chen, Chuntao; Chen, Xiao; Fan, Mengmeng; Sun, Dongping

    2016-01-01

    The antibacterial composite based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of SiO 2 coated Cu nanoparticles (Cu@SiO 2 /BC) and its properties were characterized. Its chemical structures and morphologies were evaluated by Fourier transformation infrared spectrum (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the SiO 2 coated Cu particles were well homogeneously precipitated on the surface of BC. The Cu@SiO 2 /BC was more resistant to oxidation than the Cu nanoparticles impregnated into BC (Cu/BC) and then Cu@SiO 2 /BC could prolong the antimicrobial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). - Graphical abstract: Schematic illustration of the preparation of Cu@SiO 2 /BC. Due to its unique structure, the Cu@SiO 2 /BC membrane shows excellent antibacterial effects and can be used for a long time. - Highlights: • This work paves the novel way to fabricate antibacterial nanomaterial with good efficiency. • We prepare the antibacterial membrane based on bacterial cellulose by in-situ synthesis of SiO 2 -coated Cu nanoparticles. • The antibacterial membrane is more resistant to oxidation and can prolong the antimicrobial activity.

  3. Bacterial Cellulose From Rice Waste Water With Addition Chitosan, Glycerol, And Silver Nanoparticle

    Directory of Open Access Journals (Sweden)

    Eli Rohaeti

    2016-05-01

    Full Text Available This study aimed to prepare silver nanoparticles chemically, deposite silver nanoparticles on bacterial cellulose-chitosan-glycerol composite based rice waste water, as well as test the antibacterial activity of bacterial cellulose and its composite. Preparation of silver nanoparticles was conducted by chemical reduction of silver nitrate solution, as well as trisodium citrate as the reductor. Bacterial cellulose from rice waste water is fermented by the bacteria Acetobacter xylinum for 7 days. The dried bacterial cellulose was composited with chitosan and glycerol by immersion method on 2% of chitosan solution and 0.5% of glycerol solution. UV-Vis spectroscopy is used to determine the formation of silvernanoparticles and Particle Size Analyzer to test the size and particle size distribution. Characterization was conducted to bacterial cellulose and its composite included functional groups by FTIR, the mechanical properties by Tensile Tester, crystallinity by XRD, surface photograph by SEM, and antibacterial test against S. aureus and E. coli by the shake flask turbidimetry method. Silver nanoparticle characterization indicated that silver nanoparticles are formed at a wavelength of 421.80 nm, yellow, diameter particle size of 61.8 nm. SEM images showed that the surface of bacterial cellulose had deposited silver nanoparticles and antibacterial test showed an inhibitory effect of bacterial cellulose, bacterial cellulose-chitosan composite, and bacterial cellulose-chitosan-glycerol composite which are deposited silver nanoparticles against the growth of S. aureus and E. coli bacteria.

  4. The microwave assisted-synthesis of carboxymethyl cellulose from nata de-coco bacterial cellulose

    Science.gov (United States)

    Ramadhan, L. O. A. N.; Nur Rahmat, M.; Susilowati, P. E.; Ahmad, L. O.; Edy Rusbandi, U.

    2017-07-01

    Bacterial cellulose (BC) is one of natural biopolymers which can be derivatized to make functionalized materials. Carboxymethyl cellulose (CMC) is a candidate derivative for such a direction. The aim of the present study is to investigate the usability of microwave energy to transform BC into CMC. The results showed that CMC was produced in a yellowish white powder by a short irradiation for 30 s at 650 W. The best combination of monochloroacetic acid and BC as anhydrogucose unit was found at the molar ratio of 1:5. The obtained CMC is soluble in distilled water, and aqueous NaOH solution. The highest degree of substitution, viscosity, and molecular weight of the CMC are 0.263, 15.61 Pa·s and 197,187, respectively. This study showed the usefulness of the microwave-assisted reaction to transform BC rapidly into water-soluble ionized derivative.

  5. Biocompatible Bacterial Cellulose-Poly(2-hydroxyethyl methacrylate Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Andrea G. P. R. Figueiredo

    2013-01-01

    Full Text Available A series of bacterial cellulose-poly(2-hydroxyethyl methacrylate nanocomposite films was prepared by in situ radical polymerization of 2-hydroxyethyl methacrylate (HEMA, using variable amounts of poly(ethylene glycol diacrylate (PEGDA as cross-linker. Thin films were obtained, and their physical, chemical, thermal, and mechanical properties were evaluated. The films showed improved translucency compared to BC and enhanced thermal stability and mechanical performance when compared to poly(2-hydroxyethyl methacrylate (PHEMA. Finally, BC/PHEMA nanocomposites proved to be nontoxic to human adipose-derived mesenchymal stem cells (ADSCs and thus are pointed as potential dry dressings for biomedical applications.

  6. Biocompatible bacterial cellulose-poly(2-hydroxyethyl methacrylate) nanocomposite films.

    Science.gov (United States)

    Figueiredo, Andrea G P R; Figueiredo, Ana R P; Alonso-Varona, Ana; Fernandes, Susana C M; Palomares, Teodoro; Rubio-Azpeitia, Eva; Barros-Timmons, Ana; Silvestre, Armando J D; Pascoal Neto, Carlos; Freire, Carmen S R

    2013-01-01

    A series of bacterial cellulose-poly(2-hydroxyethyl methacrylate) nanocomposite films was prepared by in situ radical polymerization of 2-hydroxyethyl methacrylate (HEMA), using variable amounts of poly(ethylene glycol) diacrylate (PEGDA) as cross-linker. Thin films were obtained, and their physical, chemical, thermal, and mechanical properties were evaluated. The films showed improved translucency compared to BC and enhanced thermal stability and mechanical performance when compared to poly(2-hydroxyethyl methacrylate) (PHEMA). Finally, BC/PHEMA nanocomposites proved to be nontoxic to human adipose-derived mesenchymal stem cells (ADSCs) and thus are pointed as potential dry dressings for biomedical applications.

  7. Fabrication and investigation of a biocompatible microfilament with high mechanical performance based on regenerated bacterial cellulose and bacterial cellulose.

    Science.gov (United States)

    Wu, Huan-Ling; Bremner, David H; Wang, Hai-Jun; Wu, Jun-Zi; Li, He-Yu; Wu, Jian-Rong; Niu, Shi-Wei; Zhu, Li-Min

    2017-10-01

    A high-strength regenerated bacterial cellulose (RBC)/bacterial cellulose (BC) microfilament of potential use as a biomaterial was successfully prepared via a wet spinning process. The BC not only consists of a 3-D network composed of nanofibers with a diameter of several hundred nanometers but also has a secondary structure consisting of highly oriented nanofibrils with a diameter ranging from a few nanometers to tens of nanometers which explains the reason for the high mechanical strength of BC. Furthermore, a strategy of partially dissolving BC was used and this greatly enhanced the mechanical performance of spun filament and a method called post-treatment was utilized to remove residual solvents from the RBC/BC filaments. A comparison of structure, properties, as well as cytocompatibility between BC nanofibers and RBC/BC microfilaments was achieved using morphology, mechanical properties, X-ray Diffraction (XRD) and an enzymatic hydrolysis assay. The RBC/BC microfilament has a uniform groove structure with a diameter of 50-60μm and XRD indicated that the crystal form was transformed from cellulose Iα to cellulose III I and the degree of crystallinity of RBC/BC (33.22%) was much lower than the original BC (60.29%). The enzymatic hydrolysis assay proved that the RBC/BC material was more easily degraded than BC. ICP detection indicated that the residual amount of lithium was 0.07mg/g (w/w) and GC-MS analysis showed the residual amount of DMAc to be 8.51μg/g (w/w) demonstrating that the post-treatment process is necessary and effective for removal of residual materials from the RBC/BC microfilaments. Also, a cell viability assay demonstrated that after post-treatment the RBC/BC filaments had good cytocompatibility. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Provision of micro-nano bacterial cellulose as bio plastic filler by sonication method

    Science.gov (United States)

    Maryam; Rahmad, D.; Yunizurwan; Kasim, A.; Novelina; Emriadi

    2017-07-01

    Research and development of bioplastic has increased recently as a solution for substitution of conventional plastic which have many negative impacts to environment. However, physical properties and mechanical properties of its still lower than conventional plastic. An alternative solution for that problem is by using fillers that can increase the strength. Bacterial cellulose is considered as potential source for filler, but still need to be explored more. The privileges of bacterial cellulose are easy to get and does not have lignin, pectin, and hemicelluloses which are impurities in other celluloses. This research focused on gaining bacterial cellulose in micro-nano particle form and its impact on increasing the strength of bio plastic. Ultrasonication has been used as method to form micro-nano particle from bacterial cellulose. The result showed this method may form the particle size of bacterial cellulose approximately ± 3μm. Next step, after getting ± 3μm particle of bacterial cellulose, is making bio plastic with casting method by adding 1% of bacterial cellulose, from the total material in making bio plastic. Physical characteristic of the bio plastic which are tensile strength 11.85 MPa, modulus young 3.13 MPa, elongation 4.11% and density 0.42 g/cm3. The numbers of physical properties showwthat, by adding 1% of bacterial cellulose, the strength of bio plastic was significantly increase, even value of tensile strength has complied the international standard for bio plastic.

  9. Recombinant biosynthesis of bacterial cellulose in genetically modified Escherichia coli.

    Science.gov (United States)

    Buldum, Gizem; Bismarck, Alexander; Mantalaris, Athanasios

    2018-02-01

    Bacterial cellulose (BC) exhibits unique properties such as high purity compared to plant-based cellulose; however, commercial production of BC has remained a challenge, primarily due to the strain properties of cellulose-producing bacteria. Herein, we developed a functional and stable BC production system in genetically modified (GM) Escherichia coli by recombinant expression of both the BC synthase operon (bcsABCD) and the upstream operon (cmcax, ccp Ax). BC production was achieved in GM HMS174 (DE3) and in GM C41 (DE3) by optimization of the culture temperature (22 °C, 30 °C, and 37 °C) and IPTG concentration. BC biosynthesis was detected much earlier in GM C41 (DE3) cultures (3 h after IPTG induction) than those of Gluconacetobacter hansenii. GM HMS174 (DE3) produced dense fibres having a length of approximately 1000-3000 μm and a diameter of 10-20 μm, which were remarkably larger than the fibres of BC typically produced by G. hansenii.

  10. Preparation of cellulose II and III{sub I} films by allomorphic conversion of bacterial cellulose I pellicles

    Energy Technology Data Exchange (ETDEWEB)

    Faria-Tischer, Paula C.S., E-mail: paula.tischer@pq.cnpq.br [BioPol, Departamento de Química, UFPR, Cx. Postal 19081, 81531-980 Curitiba, PR (Brazil); Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000 Grenoble (France); CNRS, CERMAV, F-38000 Grenoble (France); UMR 5628 (LMGP), CNRS and Grenoble Institute of Technology, 3 Parvis Louis Néel, F-38016 Grenoble Cedex 1 (France); Tischer, Cesar A. [BioPol, Departamento de Química, UFPR, Cx. Postal 19081, 81531-980 Curitiba, PR (Brazil); Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000 Grenoble (France); CNRS, CERMAV, F-38000 Grenoble (France); CIME Nanotech, 3 Parvis Louis Néel, F-38016 Grenoble Cedex 1 (France); Heux, Laurent [Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000 Grenoble (France); CNRS, CERMAV, F-38000 Grenoble (France); Le Denmat, Simon; Picart, Catherine [UMR 5628 (LMGP), CNRS and Grenoble Institute of Technology, 3 Parvis Louis Néel, F-38016 Grenoble Cedex 1 (France); Sierakowski, Maria-R. [BioPol, Departamento de Química, UFPR, Cx. Postal 19081, 81531-980 Curitiba, PR (Brazil); and others

    2015-06-01

    The structural changes resulting from the conversion of native cellulose I (Cel I) into allomorphs II (Cel II) and III{sub I} (Cel III{sub I}) have usually been studied using powder samples from plant or algal cellulose. In this work, the conversion of Cel I into Cel II and Cel III{sub I} was performed on bacterial cellulose films without any mechanical disruption. The surface texture of the films was observed by atomic force microscopy (AFM) and the morphology of the constituting cellulose ribbons, by transmission electron microscopy (TEM). The structural changes were characterized using solid-state NMR spectroscopy as well as X-ray and electron diffraction. The allomorphic change into Cel II and Cel III{sub I} resulted in films with different crystallinity, roughness and hydrophobic/hydrophilicity surface and the films remained intact during all process of allomorphic conversion. - Highlights: • Description of a method to modify the allomorphic structure of bacterial cellulose films • Preparation of films with specific morphologies and hydrophobic/hydrophilic surface characters • First report on cellulose III films from bacterial cellulose under swelling conditions • Detailed characterization of cellulose II and III films with complementary techniques • Development of films with specific properties as potential support for cells, enzymes, and drugs.

  11. Effect of Cellulose Nanocrystals and Bacterial Cellulose on Disintegrability in Composting Conditions of Plasticized PHB Nanocomposites

    Directory of Open Access Journals (Sweden)

    Irene Teresita Seoane

    2017-10-01

    Full Text Available Poly(hydroxybutyrate (PHB-based films, reinforced with bacterial cellulose (BC or cellulose nanocrystals (CNC and plasticized using a molecular (tributyrin or a polymeric plasticizer (poly(adipate diethylene, were produced by solvent casting. Their morphological, thermal, wettability, and chemical properties were investigated. Furthermore, the effect of adding both plasticizers (20 wt % respect to the PHB content and biobased selected nanofillers added at different contents (2 and 4 wt % on disintegrability in composting conditions was studied. Results of contact angle measurements and calorimetric analysis validated the observed behavior during composting experiments, indicating how CNC aggregation, due to the hydrophilic nature of the filler, slows down the degradation rate but accelerates it in case of increasing content. In contrast, nanocomposites with BC presented an evolution in composting similar to neat PHB, possibly due to the lower hydrophilic character of this material. The addition of the two plasticizers contributed to a better dispersion of the nanoparticles by increasing the interaction between the cellulosic reinforcements and the matrix, whereas the increased crystallinity of the incubated samples in a second stage in composting provoked a reduction in the disintegration rate.

  12. Cellulose as Sustainable Materials for Separation Membranes

    Science.gov (United States)

    Chu, Benjamin

    2013-03-01

    Polysaccharides, while complex, form one of the most abundant sustainable resources on earth. We want to take advantage of fundamental advances in materials understanding across length and time scales to investigate the interrelationships between structure, morphology, processing, properties, performance, and cost to meet the specific challenges arising from separation membranes for water purification. Non-woven fiber mats have unique properties, such as interconnected pores, a very large surface-to-volume ratio, and a high capacity for surface modifications. The breakthrough concept of combining fibrous mats composed of different fiber diameters for fabricating scaffolds as a unique platform for water purification is presented. Further, we take advantage of recent advances in chemical modifications, structural studies using synchrotron X-rays, and physical scale-up transformations to drastically improve filtration membrane development. Support of this work by the NSF, ONR, NIH and Stony Brook Univ. is gratefully acknowledged. The Chu/Hsiao group on water purification includes Profs. B.S.Hsiao and C.Burger, Drs. H-Y.Ma, D-F.Fang, R.Wang, and grad students: X.Wang, Z. Wang, Y.Su, R. Yang

  13. Plackett-Burman experimental design for bacterial cellulose-silica composites synthesis.

    Science.gov (United States)

    Guzun, Anicuta Stoica; Stroescu, Marta; Jinga, Sorin Ion; Voicu, Georgeta; Grumezescu, Alexandru Mihai; Holban, Alina Maria

    2014-09-01

    Bacterial cellulose-silica hybrid composites were prepared starting from wet bacterial cellulose (BC) membranes using Stöber reaction. The structure and surface morphology of hybrid composites were examined by FTIR and SEM. The SEM pictures revealed that the silica particles are attached to BC fibrils and are well dispersed in the BC matrix. The influence of silica particles upon BC crystallinity was studied using XRD analysis. Thermogravimetric (TG) analysis showed that the composites are stable up to 300°C. A Plackett-Burman design was applied in order to investigate the influence of process parameters upon silica particle sizes and silica content of BC-silica composites. The statistical model predicted that it is possible for silica particles size to vary the synthesis parameters in order to obtain silica particles deposed on BC membranes in the range from 34.5 to 500 nm, the significant parameters being ammonia concentration, reaction time and temperature. The silica content also varies depending on process parameters, the statistical model predicting that the most influential parameters are water-tetraethoxysilane (TEOS) ratio and reaction temperature. The antimicrobial behavior on Staphylococcus aureus of BC-silica composites functionalized with usnic acid (UA) was also studied, in order to create improved surfaces with antiadherence and anti-biofilm properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Assessing the loading and release of metronidazole from bacterial cellulose film as a pharmaceutical dressing

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Salehi

    2017-08-01

    Full Text Available Background: Bacterial cellulose membrane (BCM produced by Gluconacetobacter xylinus is an advantageous bacterial product and because of its unique properties could be used as an ideal dressing. The aim of this study was to consider the capability of this biomaterial in the release of Metronidazole. In the case of proving this capability, it provides the basis for the production of a dressing containing this type of antibiotic. Materials and Methods: In this study, BCM was initially synthesized by Gluconacetobacter xylinus. The BCM was loaded by Metronidazole. Then the release process was considered in distilled water and buffer phosphate Saline. The ultra violet spectrophotometry was applied for measuring the concentration of the released drug. Results: The chemical structure of bacterial cellulose was confirmed by Fourier Transform Infrared (FT-IR spectroscopy. The release of Metronidazole in distilled water and phosphate buffered Saline was reached to 84.27% and 84.71%, respectively. Due to higher release in phosphate buffered Saline media, it seems that the trend of release in vitro provides efficient results. Conclusion: Results of this study provides the basis for future research on supplying an ideal dressing from this microbial product.

  15. Investigation of polyvinylchloride and cellulose acetate blend membranes for desalination

    Science.gov (United States)

    El-Gendi, Ayman; Abdallah, Heba; Amin, Ashraf; Amin, Shereen Kamel

    2017-10-01

    The pollution of water resources, severe climate changes, rapid population growth, increasing agricultural demands, and rapid industrialization insist the development of innovative technologies for generating potable water. Polyvinylchloride/cellulose acetate (PVC/CA) membranes were prepared using phase inversion technique for seawater reverse osmosis (SWRO). The membrane performance was investigated using Red Sea water (El-Ein El-Sokhna-Egypt). The membrane performance indicated that the prepared membranes were endowed to work under high pressure; increasing in feeding operating pressure led to increase permeate flux and rejection. Increasing feed operating pressure from zero to 40 bar led to increase in the salt rejection percent. Salt rejection percent reached to 99.99% at low feed concentration 5120 ppm and 99.95% for Red Sea water (38,528 ppm). The prepared membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry, and mechanical properties. SEM, FTIR and mechanical results were used to distinguish the best membrane for desalination. According to characterization results, one prepared membrane was selected to run performance test in desalination testing unit. The membrane (M3) showed excellent performance and stability under different operating conditions and during the durability test for 36 days.

  16. Time-dependent rheological behaviour of bacterial cellulose hydrogel.

    Science.gov (United States)

    Gao, Xing; Shi, Zhijun; Kuśmierczyk, Piotr; Liu, Changqing; Yang, Guang; Sevostianov, Igor; Silberschmidt, Vadim V

    2016-01-01

    This work focuses on time-dependent rheological behaviour of bacterial cellulose (BC) hydrogel. Due to its ideal biocompatibility, BC hydrogel could be employed in biomedical applications. Considering the complexity of loading conditions in human body environment, time-dependent behaviour under relevant conditions should be understood. BC specimens are produced by Gluconacetobacter xylinus ATCC 53582 at static-culture conditions. Time-dependent behaviour of specimens at several stress levels is experimentally determined by uniaxial tensile creep tests. We use fraction-exponential operators to model the rheological behaviour. Such a representation allows combination of good accuracy in analytical description of viscoelastic behaviour of real materials and simplicity in solving boundary value problems. The obtained material parameters allow us to identify time-dependent behaviour of BC hydrogel at high stress level with sufficient accuracy. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Transport Parameters in a Porous Cellulose Acetate Membrane

    Science.gov (United States)

    DiPolo, R.; Sha'afi, R. I.; Solomon, A. K.

    1970-01-01

    The transport parameters of a cellulose acetate membrane prepared from a mixture of cellulose acetate, formamide, and acetone, 25:25:50 by weight, were studied. The membrane consists of a thin, porous layer, the skin, in series with a thick, highly porous layer, the coarse support. In the skin the diffusional permeability coefficient, ω, of a number of small amides and alcohols depends critically upon the partition coefficient, Ks, the size of the molecule, and the apparent hydrogen-bonding ability, Ns, of the solute. These observations are in general agreement with our earlier conclusions on the properties of nonporous membranes. On the other hand, the corrected reflection coefficient, σ', is not a very sensitive function of either Ns or Ks taken separately. The correlation between σ' and molecular diameter is reasonably good; however, it is much improved when both Ns and Ks are taken into consideration. Isotope interaction was also studied in the present preparation and was found to provide only a small (5–8%) contribution to the diffusional permeability coefficient of ethylene glycol. The contribution of solute-water friction was found to be less than 24% of the total solute friction. PMID:5410490

  18. Preparation of Esterified Bacterial Cellulose for Improved Mechanical Properties and the Microstructure of Isotactic Polypropylene/Bacterial Cellulose Composites

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2016-04-01

    Full Text Available Bacterial cellulose (BC has great potential to be used as a new filler to reinforce isotactic polypropylene (iPP due to its high crystallinity, biodegradability, and efficient mechanical properties. In this study, esterification was used to modify BC, which improved the surface compatibility of the iPP and BC. The results indicated that the cellulose octoate (CO changed the surface properties from hydrophilic to lipophilic. Compared to the pure iPP, the tensile strength, charpy notched impact strength, and tensile modulus of the iPP/BC composites increased by 9.9%, 7.77%, and 15.64%, respectively. However, the addition of CO reinforced the iPP/CO composites. The tensile strength, charpy notched impact strength, and tensile modulus of the iPP/CO composites increased by 14.23%, 14.08%, and 17.82% compared to the pure iPP. However, the elongation at break of both the composites is decreased. The SEM photographs and particle size distribution of the composites showed improvements when the change of polarity of the BC surface, interface compatibility, and dispersion of iPP improved.

  19. Synthesis of bacterial cellulose using hot water extracted wood sugars.

    Science.gov (United States)

    Erbas Kiziltas, Esra; Kiziltas, Alper; Gardner, Douglas J

    2015-06-25

    Bacterial cellulose (BC), a type of nanopolymer produced by Acetobacter xylinum is a nanostructured material with unique properties and wide applicability. However, a standard medium used for the cultivation of BC, the Hestrin-Schramm medium, is expensive and prevents wide scale extension of BC applications. In this research, a relatively low-cost culture media was successfully developed from wood hot water extracts for the Acetobacter xylinus 23769 strain. Hot water extract (HWE) is a residual material originating from pulp mills and lignocellulosic biorefineries and consists of mainly monomeric sugars, organic acids and organics. The effects of different pH (5, 6, 7 and 8) and temperatures (26, 28 and 30°C) were also examined in this research. There were no significant differences in the crystallinity and the recorded Iα fraction of cellulose produced between Hestrin-Schramm and the HWE medium. The maximum production of 0.15g/l of BC was obtained at a pH of 8 and temperature of 28°C. Glucose and xylose in the HWE were the main nutrient sources utilized in all BC cultivations based on high-pressure liquid chromatography (HPLC) results. HWE was shown to be a suitable carbon source for BC production, and a process was established for BC production from lignocellulosic feedstocks without using any modification of the HWE. HWE is an abundant and relatively inexpensive forest by-product. Using HWE for BC production could reduce burdens on the environment and also, achieve the goal of large scale BC production at low cost without using added culture nutrients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Genome sequence and plasmid transformation of the model high-yield bacterial cellulose producer Gluconacetobacter hansenii ATCC 53582.

    Science.gov (United States)

    Florea, Michael; Reeve, Benjamin; Abbott, James; Freemont, Paul S; Ellis, Tom

    2016-03-24

    Bacterial cellulose is a strong, highly pure form of cellulose that is used in a range of applications in industry, consumer goods and medicine. Gluconacetobacter hansenii ATCC 53582 is one of the highest reported bacterial cellulose producing strains and has been used as a model organism in numerous studies of bacterial cellulose production and studies aiming to increased cellulose productivity. Here we present a high-quality draft genome sequence for G. hansenii ATCC 53582 and find that in addition to the previously described cellulose synthase operon, ATCC 53582 contains two additional cellulose synthase operons and several previously undescribed genes associated with cellulose production. In parallel, we also develop optimized protocols and identify plasmid backbones suitable for transformation of ATCC 53582, albeit with low efficiencies. Together, these results provide important information for further studies into cellulose synthesis and for future studies aiming to genetically engineer G. hansenii ATCC 53582 for increased cellulose productivity.

  1. Nanostructured composites obtained by ATRP sleeving of bacterial cellulose nanofibers with acrylate polymers.

    Science.gov (United States)

    Lacerda, Paula S S; Barros-Timmons, Ana M M V; Freire, Carmen S R; Silvestre, Armando J D; Neto, Carlos P

    2013-06-10

    Novel nanostructured composite materials based on bacterial cellulose membranes (BC) and acrylate polymers were prepared by in situ atom transfer radical polymerization (ATRP). BC membranes were functionalized with initiating sites, by reaction with 2-bromoisobutyryl bromide (BiBBr), followed by atom transfer radical polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA), catalyzed by copper(I) bromide and N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDETA), using two distinct initiator amounts and monomer feeds. The living characteristic of the system was proven by the growth of PBA block from the BC-g-PMMA membrane. The BC nanofiber sleeving was clearly demonstrated by SEM imaging, and its extent can be tuned by controlling the amount of initiating sites and the monomer feed. The ensuing nanocomposites showed high hydrophobicity (contact angles with water up to 134°), good thermal stability (initial degradation temperature in the range 241-275 °C), and were more flexible that the unmodified BC membranes.

  2. Polyol mediated synthesis of ZnO nanoparticles templated by bacterial cellulose.

    Science.gov (United States)

    Chen, Shiyan; Zhou, Bihui; Hu, Weili; Zhang, Wen; Yin, Na; Wang, Huaping

    2013-02-15

    Zinc oxide nanoparticles have been successfully synthesized through a facile polyol method using bacterial cellulose (BC) as a template. BC membrane was used as a host matrix to introduce quantitatively Zn(2+) ions and then as nanoreactors to fabricate ZnO nanoparticles by hydrolysis of zinc acetate in a polyol medium. The influence of the concentration of zinc acetate and hydrolytic time on the morphologies and size of ZnO nanoparticles were investigated. The results indicated that the uniform spherical ZnO nanoparticles were incorporated into BC fibers. The resulting nanocomposites show good mechanical properties and high photocatalytic activity in the degradation of methyl orange. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  3. Sensing the Structural Differences in Cellulose from Apple and Bacterial Cell Wall Materials by Raman and FT-IR Spectroscopy

    Science.gov (United States)

    Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur

    2011-01-01

    Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913

  4. Bacterial Cellulose Production from Industrial Waste and by-Product Streams

    Directory of Open Access Journals (Sweden)

    Erminda Tsouko

    2015-07-01

    Full Text Available The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L and commercial sucrose (4.9 g/L were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

  5. CELLULOSE SYNTHASE INTERACTIVE1 Is Required for Fast Recycling of Cellulose Synthase Complexes to the Plasma Membrane in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Lei; Singh, Abhishek; Bashline, Logan; Li, Shundai; Yingling, Yaroslava G.; Gu, Ying

    2015-10-06

    Plants are constantly subjected to various biotic and abiotic stresses and have evolved complex strategies to cope with these stresses. For example, plant cells endocytose plasma membrane material under stress and subsequently recycle it back when the stress conditions are relieved. Cellulose biosynthesis is a tightly regulated process that is performed by plasma membrane-localized cellulose synthase (CESA) complexes (CSCs). However, the regulatory mechanism of cellulose biosynthesis under abiotic stress has not been well explored. In this study, we show that small CESA compartments (SmaCCs) or microtubule-associated cellulose synthase compartments (MASCs) are critical for fast recovery of CSCs to the plasma membrane after stress is relieved in Arabidopsis thaliana. This SmaCC/MASC-mediated fast recovery of CSCs is dependent on CELLULOSE SYNTHASE INTERACTIVE1 (CSI1), a protein previously known to represent the link between CSCs and cortical microtubules. Independently, AP2M, a core component in clathrin-mediated endocytosis, plays a role in the formation of SmaCCs/MASCs. Together, our study establishes a model in which CSI1-dependent SmaCCs/MASCs are formed through a process that involves endocytosis, which represents an important mechanism for plants to quickly regulate cellulose synthesis under abiotic stress.

  6. The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

    Science.gov (United States)

    Pirahmadi, Pegah; Kokabi, Mehrdad

    2018-01-01

    Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

  7. Production and Characterization of a New Bacterial Cellulose/Poly(Vinyl Alcohol Nanocomposite

    Directory of Open Access Journals (Sweden)

    Miguel Gama

    2013-05-01

    Full Text Available Bacterial cellulose (BC is characterized for its high water holding capacity, high crystallinity, an ultrafine fiber network and high tensile strength. This work demonstrates the production of a new interpenetrated polymer network nanocomposite obtained through the incorporation of poly(vinyl alcohol (PVA on the BC matrix and evaluates the effect of oven drying on the morphological, mechanical and mass transfer properties of the composite membranes. Both the addition of PVA and oven drying induce the appearance of larger pores (circa 1–3 µm in average diameter in dried BC/PVA membranes. Both types of treatments also affect the permeability of the composite, as assessed by the diffusion coefficients of polyethylene glycol (PEG molecules (900, 8,000, 35,000 and 100,000 Da across the membranes. Finally, the Young’s modulus of dry pristine BC decreases following PVA incorporation, resulting in a change from 3.5 GPa to 1 GPa and a five-fold loss in tensile strength.

  8. Box-Behnken experimental design for chromium(VI) ions removal by bacterial cellulose-magnetite composites.

    Science.gov (United States)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Mihalache, Nicoleta; Botez, Adriana; Matei, Cristian; Berger, Daniela; Damian, Celina Maria; Ionita, Valentin

    2016-10-01

    In this study bacterial cellulose-magnetite composites were synthesised for the removal of chromium(VI) from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the bacterial cellulose-magnetite composites and to reveal the uniform dispersion of nanomagnetite in the BC matrix. Magnetic properties were also measured to confirm the magnetite immobilization on bacterial cellulose membrane. The effects of initial Cr(VI) concentration, solution pH and solid/liquid ratio upon chromium removal were examined using the statistical Box-Behnken Design. Because of the possibility of magnetite dissolution during chromium(VI) adsorption, the degree of iron leaching was also analysed in the same conditions as Cr(VI) adsorption. From the factors affecting chromium(VI) adsorption the most important was solution pH. The highest Cr(VI) removal efficiency was observed at pH 4, accompanied by the lowest iron leaching in the solution. The adsorption experiments also indicated that the adsorption process of chromium(VI) is well described by Freundlich adsorption model. Our results proved that the BC-magnetite composites could be used for an efficient removal of chromium(VI) from diluted solutions with a minimum magnetite dissolution during operation. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Characterization of TEMPO-oxidized bacterial cellulose; Caracterizacao de celulose bacteriana tempo-oxidada

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Eligenes S.; Pereira, Andre L.S.; Lima, Helder L.; Barroso, Maria K. de A., E-mail: eligenessampaio@hotmail.com [Universidade Federal Ceara (UFC), Fortaleza, CE (Brazil); Barros, Matheus de O. [Instituto Federal do Ceara (IFCE), Fortaleza, CE (Brazil); Morais, Joao P.S. [Embrapa Algodao, Campina Grande, PB (Brazil); Borges, Maria de F.; Rosa, Morsyleide de F. [Embrapa Agroindustria Tropical, Fortaleza, CE (Brazil)

    2015-07-01

    The aim of this study was to characterize the TEMPO-oxidized bacterial cellulose, as a preliminary research for further application in nanocomposites. Bacterial cellulose (BC) was selectively oxidized at C-6 carbon by TEMPO radical. Oxidized bacterial cellulose (BCOX) was characterized by TGA, FTIR, XRD, and zeta potential. BCOX suspension was stable at pH 7.0, presented a crystallinity index of 83%, in spite of 92% of BC, because of decrease in the free hydroxyl number. FTIR spectra showed characteristic BC bands and, in addition, band of carboxylic group, proving the oxidation. BCOX DTG showed, in addition to characteristic BC thermal events, a maximum degradation peak at 233 °C, related to sodium anhydro-glucuronate groups formed during the cellulose oxidation. Thus, BC can be TEMPO-oxidized without great loss in its structure and properties. (author)

  10. Crosslinked cellulose thin film composite nanofiltration membranes with zero salt rejection

    KAUST Repository

    Puspasari, Tiara

    2015-05-14

    We report a new synthetic route of fabricating regenerated cellulose nanofiltration membranes. The membranes are composite membranes with a thin selective layer of cellulose, which was prepared by regeneration of trimethylsilyl cellulose (a hydrophobic cellulose derivative) film followed by crosslinking. Filtration experiments using mixtures of sugar and sodium chloride showed that solutes above 300 Da were highly rejected whereas practically no rejection was observed for NaCl. This is a big advantage for a complete desalination as the existing commercial nanofiltration membranes typically exhibit NaCl rejection in the range of 30–60%. Membranes with zero NaCl rejection are required for recovery and purification applications in food, chemical and pharmaceutical industry.

  11. Novel Cu@SiO{sub 2}/bacterial cellulose nanofibers: Preparation and excellent performance in antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Bo [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China); Department of Life Sciences of Lianyungang Teacher' s College, Sheng Hu Lu 28, Lianyungang 222006 (China); Huang, Yang; Zhu, Chunlin; Chen, Chuntao; Chen, Xiao; Fan, Mengmeng [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China); Sun, Dongping, E-mail: sundpe301@163.com [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China)

    2016-05-01

    The antibacterial composite based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of SiO{sub 2} coated Cu nanoparticles (Cu@SiO{sub 2}/BC) and its properties were characterized. Its chemical structures and morphologies were evaluated by Fourier transformation infrared spectrum (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the SiO{sub 2} coated Cu particles were well homogeneously precipitated on the surface of BC. The Cu@SiO{sub 2}/BC was more resistant to oxidation than the Cu nanoparticles impregnated into BC (Cu/BC) and then Cu@SiO{sub 2}/BC could prolong the antimicrobial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). - Graphical abstract: Schematic illustration of the preparation of Cu@SiO{sub 2}/BC. Due to its unique structure, the Cu@SiO{sub 2}/BC membrane shows excellent antibacterial effects and can be used for a long time. - Highlights: • This work paves the novel way to fabricate antibacterial nanomaterial with good efficiency. • We prepare the antibacterial membrane based on bacterial cellulose by in-situ synthesis of SiO{sub 2}-coated Cu nanoparticles. • The antibacterial membrane is more resistant to oxidation and can prolong the antimicrobial activity.

  12. Development of wet-dry reversible reverse osmosis membrane with high performance from cellulose acetate and cellulose triactate blend

    NARCIS (Netherlands)

    Vasarhelyi, K.; Ronner, J.A.; Mulder, M.H.V.; Smolders, C.A.

    1987-01-01

    Wet-dry reversible membrane were prepared bt a two-step coagulation procedure. A cast film containing a blend of cellulose triacetate as polymers, dioxane and acetone as solvents and maleic acid and methanol as additives was immersed consecutively in two aqueous coagulation baths, the first bath

  13. Arabidopsis cortical microtubules position cellulose synthase delivery to the plasma membrane and interact with cellulose synthase trafficking compartments.

    NARCIS (Netherlands)

    Gutierrez, R.; Lindeboom, J.J.; Paredez, A.R.; Emons, A.M.C.; Ehrhardt, D.W.

    2009-01-01

    Plant cell morphogenesis relies on the organization and function of two polymer arrays separated by the plasma membrane: the cortical microtubule cytoskeleton and cellulose microfibrils in the cell wall. Studies using in vivo markers confirmed that one function of the cortical microtubule array is

  14. Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching

    NARCIS (Netherlands)

    Olde riekerink, M.B.; Engbers, G.H.M.; Wessling, Matthias; Feijen, Jan

    2002-01-01

    Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF4) or carbon dioxide (CO2), 47¿49 W, 0.04¿0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top

  15. Primary study of ethyl cellulose nanofiber for oxygen-enrichment membrane

    Directory of Open Access Journals (Sweden)

    Shen Jing

    2016-01-01

    Full Text Available Ethyl cellulose is widely used for oxygen-enrichment membrane, however, its nanofiber membrane was rarely developed though it behaves more excellent performance. This paper gives a preliminary study to produce oxygen-enrichment membrane by bubbfil spinning.

  16. Recent developments in the production and applications of bacterial cellulose fibers and nanocrystals.

    Science.gov (United States)

    Reiniati, Isabela; Hrymak, Andrew N; Margaritis, Argyrios

    2017-06-01

    Cellulosic nanomaterials provide a novel and sustainable platform for the production of high performance materials enabled by nanotechnology. Bacterial cellulose (BC) is a highly crystalline material and contains pure cellulose without lignin and hemicellulose. BC offers an opportunity to provide control of the products' properties in-situ, via specific BC production methods and culture conditions. The BC potential in advanced material applications are hindered by a limited knowledge of optimal BC production conditions, efficient process scale-up, separation methods, and purification methods. There is a growing body of work on the production of bacterial cellulose nanocrystals (BCNs) from BC fibers. However, there is limited information regarding the effect of BC fibers' characteristics on the production of nanocrystals. This review describes developments in BC and BCNs production methods and factors affecting their yield and physical characteristics.

  17. Ultrathin cellulose nanosheet membranes for superfast separation of oil-in-water nanoemulsions

    Science.gov (United States)

    Zhou, Ke; Zhang, Qiu Gen; Li, Hong Mei; Guo, Nan Nan; Zhu, Ai Mei; Liu, Qing Lin

    2014-08-01

    Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective separation of oil-in-water nanoemulsions. The newly developed ultrathin cellulose membranes have a wide application in oily wastewater treatment, separation and purification of nanomaterials.Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective

  18. Surface modification of cellulose acetate membrane using thermal annealing to enhance produced water treatment

    Science.gov (United States)

    Kusworo, T. D.; Aryanti, N.; Firdaus, M. M. H.; Sukmawati, H.

    2015-12-01

    This study is performed primarily to investigate the effect of surface modification of cellulose acetate using thermal annealing on the enhancement of membrane performance for produced water treatment. In this study, Cellulose Acetate membranes were casted using dry/wet phase inversion technique. The effect of additive and post-treatment using thermal annealing on the membrane surface were examined for produced water treatment. Therma annealing was subjected to membrane surface at 60 and 70 °C for 5, 10 and 15 second, respectively. Membrane characterizations were done using membrane flux and rejection with produced water as a feed, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR) analysis. Experimental results showed that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion technique. The results from the Scanning Electron Microscopy (FESEM) analysis was also confirmed that polyethylene glycol as additivie in dope solution and thermal annealing was affected the morphology and membrane performance for produced water treatment, respectively. Scanning electron microscopy micrographs showed that the selective layer and the substructure of membrane became denser and more compact after the thermal annealing processes. Therefore, membrane rejection was significantly increased while the flux was slighty decreased, respectively. The best membrane performance is obtained on the composition of 18 wt % cellulose acetate, poly ethylene glycol 5 wt% with thermal annealing at 70° C for 15 second.

  19. Surface modification of cellulose acetate membrane using thermal annealing to enhance produced water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kusworo, T. D., E-mail: tdkusworo@che.undip.ac.id; Aryanti, N., E-mail: nita.aryanti@gmail.com; Firdaus, M. M. H.; Sukmawati, H. [Chemical Engineering, Faculty of Engineering, Diponegoro University Prof. Soedarto Street, Tembalang, Semarang, 50239, Phone/Fax : (024)7460058 (Indonesia)

    2015-12-29

    This study is performed primarily to investigate the effect of surface modification of cellulose acetate using thermal annealing on the enhancement of membrane performance for produced water treatment. In this study, Cellulose Acetate membranes were casted using dry/wet phase inversion technique. The effect of additive and post-treatment using thermal annealing on the membrane surface were examined for produced water treatment. Therma annealing was subjected to membrane surface at 60 and 70 °C for 5, 10 and 15 second, respectively. Membrane characterizations were done using membrane flux and rejection with produced water as a feed, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR) analysis. Experimental results showed that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion technique. The results from the Scanning Electron Microscopy (FESEM) analysis was also confirmed that polyethylene glycol as additivie in dope solution and thermal annealing was affected the morphology and membrane performance for produced water treatment, respectively. Scanning electron microscopy micrographs showed that the selective layer and the substructure of membrane became denser and more compact after the thermal annealing processes. Therefore, membrane rejection was significantly increased while the flux was slighty decreased, respectively. The best membrane performance is obtained on the composition of 18 wt % cellulose acetate, poly ethylene glycol 5 wt% with thermal annealing at 70° C for 15 second.

  20. Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis

    Science.gov (United States)

    Kafle, Kabindra; Shin, Heenae; Lee, Christopher M.; Park, Sunkyu; Kim, Seong H.

    2015-01-01

    A comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood, and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlate with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization, and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. It was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component. PMID:26463274

  1. Preparation and characterization of regenerated cellulose membranes from natural cotton fiber

    Directory of Open Access Journals (Sweden)

    Yanjuan CAO

    2015-06-01

    Full Text Available A series of organic solutions with different cellulose concentrations are prepared by dissolving natural cotton fibers in lithium chloride/dimethyl acetamide (LiCl/DMAC solvent system after the activation of cotton fibers. Under different coagulating bath, the regenerated cellulose membranes are formed in two kinds of coagulation baths, and two coating methods including high-speed spin technique (KW-4A spin coating machine and low-speed scraping (AFA-Ⅱ Film Applicator are selected in this paper. The macromolecular structure, mechanical properties, crystallinity, thermal stability and wetting property of the regenerated cellulose membrane are characterized by Scanning Electron Microscope(SEM, Fourier Transform Infrared Spectroscopy (FT-IR,X-ray diffraction (XRD, Thermogravimetric analysis (TG and contacting angle tester. The effects of mass fraction, coagulation bath type, membrane forming process on the regenerated membrane properties are investigated. Experimental results show that the performance of regenerated cellulose membrane is relatively excellent under the condition of using the KW-4A high-speed spin method, water coagulation bath, and when mass fraction of cellulose is 3.5%. The crystallinity of the regenerated cellulose membrane changes a lot compared with natural cotton fibers. The variation trend of thermal stability is similar with that of cotton fiber. But thermal stability is reduced to some degree, while the wetting ability is improved obviously.

  2. Comparison of pharyngocutaneous fistula closure with and without bacterial cellulose in a rat model.

    Science.gov (United States)

    Demir, Berat; Sarı, Murat; Binnetoglu, Adem; Yumusakhuylu, Ali Cemal; Filinte, Deniz; Tekin, İshak Özel; Bağlam, Tekin; Batman, Abdullah Çağlar

    2018-04-01

    The present study aimed to compare the effects of bacterial cellulose used for closure of pharyngocutaneous fistulae, a complication of total laryngectomy, with those of primary sutures in a rat model. Thirty female Sprague-Dawley underwent experimental pharyngoesophagotomy and were grouped depending on the material used for pharyngocutaneous fistula closure: group I, which received primary sutures alone, group II, which received bacterial cellulose alone; and group III, which received both. After 7 days, the rats were sacrificed. Pharyngocutaneous fistula development was assessed, the gross wound was inspected, and histological examination was conducted. Pharyngocutaneous fistulae developed in 12 rats (41%) in all: 6 from group I (21%), 4 from group II (14%) and 2 from group III (7%). Fibroblast density and inflammatory cell infiltration were significantly greater in group III than group I. We concluded that bacterial cellulose may be useful for pharyngocutaneous fistula closure. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. The effect of acid hydrolysis pretreatment on crystallinity and solubility of kenaf cellulose membrane

    Energy Technology Data Exchange (ETDEWEB)

    Saidi, Anis Syuhada Mohd; Zakaria, Sarani; Chia, Chin Hua; Jaafar, Sharifah Nabihah Syed; Padzil, Farah Nadia Mohammad [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2015-09-25

    Cellulose was extracted from kenaf core pulp (KCP) by series of bleaching steps in the sequence (DEED) where D and E are referred as acid and alkali treatment. The bleached kenaf pulp (BKCP) is then pretreated with acid hydrolysis at room temperature for 1 and 3 h respectively. The pretreated cellulose is dissolved in lithium hydroxide/urea (LiOH/urea) and cellulose solution produced was immersed in distilled water bath. BKCP without treatment was also conducted for comparison purpose. The effects of acid hydrolysis pretreatment on solubility and crystallinity are investigated. Higher solubility of cellulose solution is achieved for treated samples. Cellulose II formation and crystallinity index of the cellulose membrane were determined by X-ray diffraction (XRD)

  4. New biphasic monocomponent composite material obtained by the partial oxypropylation of bacterial cellulose

    International Nuclear Information System (INIS)

    Rosa, Joyce Rover; Silva, Ingrid S.V. da; Pasquini, Daniel; Santos, Daniele B. dos; Barud, Hernane S.; Ribeiro, Sidney J.L.

    2011-01-01

    This study aimed to partial oxypropylation of bacterial cellulose (CB), as well as the characterization of pure CB, oxypropylated CB (CBO) and oxypropylated CB after Soxhlet extraction with hexane (CBOE). The oxypropylation reaction was carried out by propylene oxide polymerization, catalyzed by KOH, in the presence of CB The CB samples, before and after modification, were subjected to analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was possible verify that the partial transformation of bacterial cellulose by inserting a layer of thermoplastic polymer on its surface occurred efficiently, obtaining a biphasic monocomponent composite material. (author)

  5. Cellulose acetate-based molecularly imprinted polymeric membrane for separation of vanillin and o-vanillin

    OpenAIRE

    Zhang,Chunjing; Zhong,Shian; Yang,Zhengpeng

    2008-01-01

    Cellulose acetate-based molecularly imprinted polymeric membranes were prepared using vanillin as template molecule. The microscopic structure of the resultant polymeric membranes was characterized by SEM and FTIR spectroscopy, and the selective binding properties and separation capacity of the membranes for vanillin and o-vanillin were tested with binding experiments and separate experiments, respectively. The results showed that the vanillin-imprinted polymeric membranes displayed higher bi...

  6. Improvement production of bacterial cellulose by semi-continuous process in molasses medium.

    Science.gov (United States)

    Cakar, Fatih; Ozer, Işılay; Aytekin, A Özhan; Sahin, Fikrettin

    2014-06-15

    Bacterial cellulose (BC) has unique properties such as structural, functional, physical and chemical. The mass production of BC for industrial application has recently become attractive to produce more economical and high productive cellulose. In this study, to improve the productivity of bacterial cellulose (BC), BC production by Gluconacetobacter xylinus FC01 was investigated in molasses medium with static semi-continuous operation mode. Cell dry weight, polysaccharide, sugar and cellulose concentrations were monitored and cellulose was characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The highest cellulose yield (1.637 g/L) was obtained in SCP50-7d, which molasses of 1/2 ratio for 7 days by static semi-continuous operation mode. The results show that BC can be highly produced by G. xylinus in molasses with static semi-continuous process than batch process. We claimed that low-cost medium with semi-continuous operation mode in static culture is a good candidate for industrial scale BC productions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Characterization of the bacterial cellulose dissolved on dimethylacetamide/lithium chloride

    International Nuclear Information System (INIS)

    Lima, Glaucia de Marco; Sierakowski, Maria Rita; Faria-Tischer, Paula C.S.; Tischer, Cesar A.

    2009-01-01

    The main barrier to the use of cellulose is his insolubility on water or organic solvents, but derivates can be obtained with the use of ionic solvents. Bacterial cellulose, is mainly produced by the bacterium Acetobacter xylinum, and is identical to the plant, but free of lignin and hemi cellulose, and with several unique physical-chemical properties. Cellulose produced in a 4 % glucose medium with static condition was dissoluted on heated DMAc/LiCl (120 '0 C, 150 '0 C or 170 '0 C). The product of dissolved cellulose was observed with 13 C-NMR and the effect on crystalline state was seen with x-ray crystallography. The crystalline structure was lost in the dissolution, becoming an amorphous structure, as well as Avicel. The process of dissolution of the bacterial cellulose is basics for the analysis of these water insoluble polymer, facilitating the analysis of these composites, by 13 C-NMR spectroscopy, size exclusion chromatography and light scattering techniques. (author)

  8. Characterization of the bacterial cellulose dissolved on dimethylacetamide/lithium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Glaucia de Marco [Universidade do Vale do Itajai (PMCF/UNIVALI), Itajai, SC (Brazil). Programa de Mestrado em Ciencias Farmaceuticas; Sierakowski, Maria Rita; Faria-Tischer, Paula C.S.; Tischer, Cesar A., E-mail: cesar.tischer@pq.cnpq.b [Universidade Federal do Parana (BIOPOL/UFPR), Curitiba, PR (Brazil). Lab. de Biopolimeros

    2009-07-01

    The main barrier to the use of cellulose is his insolubility on water or organic solvents, but derivates can be obtained with the use of ionic solvents. Bacterial cellulose, is mainly produced by the bacterium Acetobacter xylinum, and is identical to the plant, but free of lignin and hemi cellulose, and with several unique physical-chemical properties. Cellulose produced in a 4 % glucose medium with static condition was dissoluted on heated DMAc/LiCl (120 '0 C, 150 '0 C or 170 '0 C). The product of dissolved cellulose was observed with 13 C-NMR and the effect on crystalline state was seen with x-ray crystallography. The crystalline structure was lost in the dissolution, becoming an amorphous structure, as well as Avicel. The process of dissolution of the bacterial cellulose is basics for the analysis of these water insoluble polymer, facilitating the analysis of these composites, by 13 C-NMR spectroscopy, size exclusion chromatography and light scattering techniques. (author)

  9. Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    H Ma; B Hsiao; B Chu

    2011-12-31

    The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux and rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.

  10. Effect of media components on cell growth and bacterial cellulose production from Acetobacter aceti MTCC 2623.

    Science.gov (United States)

    Dayal, Manmeet Singh; Goswami, Navendu; Sahai, Anshuman; Jain, Vibhor; Mathur, Garima; Mathur, Ashwani

    2013-04-15

    Acetobacter aceti MTCC 2623 was studied as an alternative microbial source for bacterial cellulose (BC) production. Effect of media components on cell growth rate, BC production and cellulose characteristics were studied. FTIR results showed significant variations in cellulose characteristics produced by A. aceti in different media. Results have shown the role of fermentation time on crystallinity ratio of BC in different media. Further, effect of six different media components on cell growth and BC production was studied using fractional factorial design. Citric acid was found to be the most significant media component for cell growth rate (95% confidence level, R(2)=0.95). However, direct role of these parameters on cellulose production was not established (p-value>0.05). Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Fibrillar assembly of bacterial cellulose in the presence of wood-based hemicelluloses.

    Science.gov (United States)

    Penttilä, Paavo A; Imai, Tomoya; Sugiyama, Junji

    2017-09-01

    Composite materials mimicking the plant cell wall structure were made by culturing cellulose-producing bacteria together with secondary-wall hemicelluloses from wood. The effects of spruce galactoglucomannan (GGM) and beech xylan on the nanoscale morphology of bacterial cellulose were studied in the original, hydrated state with small-angle X-ray scattering (SAXS). The SAXS intensities were fitted with a model covering multiple levels of the hierarchical structure. Additional information on the structure of dried samples was obtained using scanning and transmission electron microscopy and infra-red spectroscopy. Both hemicelluloses induced a partial conversion of the cellulose crystal structure from I α to I β and a reduction of the cross-sectional dimensions of the cellulose microfibrils, thereby affecting also their packing into bundles. The differences were more pronounced in samples with xylan instead of GGM, and they became more significant with higher hemicellulose concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Fabrication, characterization and evaluation of bacterial cellulose-based capsule shells for oral drug delivery

    DEFF Research Database (Denmark)

    Ullah, Hanif; Badshah, Munair; Mäkilä, Ermei

    2017-01-01

    Bacterial cellulose (BC) was investigated for the first time for the preparation of capsule shells for immediate and sustained release of drugs. The prepared capsule shells were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The BC...... to gelatin capsules with both immediate and sustained drug release properties depending upon the compositions of the encapsulated materials....

  13. In situ development of nanosilver-impregnated bacterial cellulose for sustainable released antimicrobial wound dressing.

    Science.gov (United States)

    Mohite, Bhavana V; Patil, Satish V

    2016-04-06

    Bacterial cellulose (BC) is an interesting biomaterial found application in various fields due to its novel characteristics like purity, water holding capacity, degree of polymerization and mechanical strength. BC as wound dressing material has limitation because it has no antimicrobial activity. To circumvent this problem, the present study was carried out by impregnation of silver on bacterial cellulose surface. Bacterial cellulose was produced by Gluconoacetobacter hansenii (strain NCIM 2529) by shaking culture method. The sodium borohydride and classical Tollens reaction was used for silver nanoparticle synthesis. The effectiveness of sodium borohydride method compared with Tollens reaction was evaluated on the basis of silver nanoparticle formation and its impregnation on BC as evidenced by UV-Vis spectrum analysis, FE-SEM-EDS analysis and FT-IR spectrum. The potential of nano silver impregnated BC was determined for sustained release antimicrobial wound dressing material by swelling ratio, mechanical properties and antimicrobial activity against Staphylococcus aureus. Thus the nanosilver impregnated bacterial cellulose as promising antimicrobial wound dressing material was evidenced.

  14. Hierarchical architecture of bacterial cellulose and composite plant cell wall polysaccharide hydrogels using small angle neutron scattering.

    Science.gov (United States)

    Martínez-Sanz, Marta; Gidley, Michael J; Gilbert, Elliot P

    2016-02-07

    Small angle neutron scattering (SANS) has been applied to characterise the structure of pure bacterial cellulose hydrogels, and composites thereof, with two plant cell wall polysaccharides (arabinoxylan and xyloglucan). Conventional published models, which assume that bacterial cellulose ribbons are solid one-phase systems, fail to adequately describe the SANS data of pure bacterial cellulose. Fitting of the neutron scattering profiles instead suggests that the sub-structure of cellulose microfibrils contained within the ribbons results in the creation of regions with distinct values of neutron scattering length density, when the hydrogels are subjected to H2O/D2O exchange. This may be represented within a core-shell formalism that considers the cellulose ribbons to comprise a core containing impermeable crystallites surrounded by a network of paracrystalline cellulose and tightly bound water, and a shell containing only paracrystalline cellulose and water. Accordingly, a fitting function comprising the sum of a power-law term to account for the large scale structure of intertwined ribbons, plus a core-shell cylinder with polydisperse radius, has been applied; it is demonstrated to simultaneously describe all SANS contrast variation data of pure and composite bacterial cellulose hydrogels. In addition, the resultant fitting parameters indicate distinct interaction mechanisms of arabinoxylan and xyloglucan with cellulose, revealing the potential of this approach to investigate the role of different plant cell wall polysaccharides on the biosynthesis process of cellulose.

  15. Fermentative hydrogen production from hydrolyzed cellulosic feedstock prepared with a thermophilic anaerobic bacterial isolate

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Yung Chung [Department of Chemical Engineering, National Cheng Kung University, No. 1 University Road, Tainan 701 (China); Huang, Chi-Yu.; Fu, Tzu-Ning [Department of Environmental Engineering and Science, Tunghai University, Taichung 407 (China); Chen, Chun-Yen; Chang, Jo-Shu [Department of Chemical Engineering, National Cheng Kung University, No. 1 University Road, Tainan 701 (China); Sustainable Environment Research Center, National Cheng Kung University, Tainan (China)

    2009-08-15

    Hydrogen gas was produced via dark fermentation from natural cellulosic materials and {alpha}-cellulose via a two-step process, in which the cellulosic substrates were first hydrolyzed by an isolated cellulolytic bacterium Clostridium strain TCW1, and the resulting hydrolysates were then used as substrate for fermentative H{sub 2} production. The TCW1 strain was able to hydrolyze all the cellulosic materials examined to produce reducing sugars (RS), attaining the best reducing sugar production yield of 0.65 g reducing sugar/g substrate from hydrolysis of {alpha}-cellulose. The hydrolysates of those cellulosic materials were successfully converted to H{sub 2} via dark fermentation using seven H{sub 2}-producing bacterial isolates. The bioH{sub 2} production performance was highly dependent on the type of cellulosic feedstock used, the initial reducing sugar concentration (C{sub RS,o}) (ranging from 0.7 to 4.5 mg/l), as well as the composition of sugar and soluble metabolites present in the cellulosic hydrolysates. It was found that Clostridium butyricum CGS5 displayed the highest H{sub 2}-producing efficiency with a cumulative H{sub 2} production of 270 ml/l from {alpha}-cellulose hydrolysate (C{sub RS,o} = 4.52 mg/l) and a H{sub 2} yield of 7.40 mmol/g RS (or 6.66 mmol/g substrate) from napier grass hydrolysate (C{sub RS,o} = 1.22 g/l). (author)

  16. Characterisation of bacterial cellulose partly acetylated by dimethylacetamide/lithium chloride

    International Nuclear Information System (INIS)

    Lima, G. de Marco; Sierakowski, M.-R.; Faria-Tischer, P.C.S.; Tischer, C.A.

    2011-01-01

    Cellulose is a water-insoluble polysaccharide used at an industrial scale for the manufacture of paper and films or in the dust form, natural, hydrolysed or derivatised. The cellulose produced by G. hansenii (former A. xylinum) has a structure identical to that of plants, but is free of lignin and hemicellulose, with several unique physical-chemical properties. The main barrier to the use of cellulose is its insolubility in water and most organic solvents, but soluble derivatives can be obtained with the use of ionic solvents. Bacterial cellulose, produced in a static, 4% glucose medium, was dissolved in hot DMAc/LiCl (120, 150 or 170 deg. C). The solution was analysed by 13 C NMR, and the effect of the dissolution on the crystalline state was shown by X-ray crystallography. The crystalline structure was lost upon dissolution, becoming amorphous; this was also observed for Avicel plant cellulose. The soluble cellulose was partly acetylated in acetic anhydride with acetic anhydride-cellulose ratios of 1:50, 1:6 and 1:12 (w/v). The resulting cellulose acetates were examined by infrared spectroscopy, and the best result was 43% (w/v). The degree of acetylation was determined via 1 H NMR spectroscopy by comparing the area of the glucose ring at 2.60-5.20 ppm and that of the methyl proton of the acetate group at 1.80-2.20 ppm. The 13 C NMR spectra showed acetylation at C6 >> C2 > C3 at 60-80 ppm, with C1 signals at ∼ 100-104 ppm. The derivatisation of bacterial cellulose in DMAc/LiCl/acetic anhydride (1:4:50, v/v/v) gave rise to 87% substitution. The process of dissolution of the bacterial cellulose is essential for the analysis of the insoluble polymer in water, facilitating analysis and characterisation of these composites by 13 C NMR spectroscopy, size exclusion chromatography and light scattering techniques.

  17. Preparation of amino-functionalized regenerated cellulose membranes with high catalytic activity.

    Science.gov (United States)

    Wang, Wei; Bai, Qian; Liang, Tao; Bai, Huiyu; Liu, Xiaoya

    2017-09-01

    The modification of regenerated cellulose (RC) membranes was carried out by using silane coupling agents presenting primary and secondary amino-groups. The grafting of the amino groups onto the modified cellulose molecule was confirmed by X-ray photoelectron spectroscopies and 13 C nuclear magnetic resonance spectroscopic analyses. The crystallinity of the cellulose membranes (CM) decreased after chemical modification as indicated by the X-ray diffraction results. Moreover, a denser structure was observed at the surface and cross section of the modified membranes by SEM images. The contact angle measurements showed that the silane coupling treatment enhanced the hydrophobicity of the obtained materials. Then the catalytic properties of two types of modified membranes were studied in a batch process by evaluating their catalytic performance in a Knoevenagel condensation. The results indicated that the cellulose membrane grafted with many secondary amines exhibited a better catalytic activity compared to the one grafted only by primary amines. In addition, the compact structure of the modified membranes permitted their application in a pervaporation catalytic membrane reactor. Therefore, functional CM that prepared in this paper represented a promising material in the field of industrial catalysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Interaction of multiple biomimetic antimicrobial polymers with model bacterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Baul, Upayan, E-mail: upayanb@imsc.res.in; Vemparala, Satyavani, E-mail: vani@imsc.res.in [The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai 600113 (India); Kuroda, Kenichi, E-mail: kkuroda@umich.edu [Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan 48109 (United States)

    2014-08-28

    Using atomistic molecular dynamics simulations, interaction of multiple synthetic random copolymers based on methacrylates on prototypical bacterial membranes is investigated. The simulations show that the cationic polymers form a micellar aggregate in water phase and the aggregate, when interacting with the bacterial membrane, induces clustering of oppositely charged anionic lipid molecules to form clusters and enhances ordering of lipid chains. The model bacterial membrane, consequently, develops lateral inhomogeneity in membrane thickness profile compared to polymer-free system. The individual polymers in the aggregate are released into the bacterial membrane in a phased manner and the simulations suggest that the most probable location of the partitioned polymers is near the 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) clusters. The partitioned polymers preferentially adopt facially amphiphilic conformations at lipid-water interface, despite lacking intrinsic secondary structures such as α-helix or β-sheet found in naturally occurring antimicrobial peptides.

  19. Preparation of membranes from cellulose obtained of sugarcane bagasse; Preparacao de membranas a partir de celulose obtida do bagaco de cana-de-acucar

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Paulo Henrique Fernandes; Cioffi, Maria Odila Hilario; Voorwald, Herman Jacobus Cornelis, E-mail: fernandes_eng@yahoo.com.b [UNESP, Guaratingueta, SP (Brazil). Fac. de Engenharia; Pinho, Maria Noberta de [Instituto Superior Tecnico de Lisboa (IST) (Portugal), Dept. de Engenharia; Silva, Maria Lucia Caetano Pinto da [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia

    2010-07-01

    In this work, cellulose obtained from sugarcane bagasse to produce both cellulose and acetylated cellulose to prepare asymmetric membranes. Membranes was procedure used a mixture of materials of DMAc/ LiCl systemic in different conditions. Cellulose and acetylated cellulose were characterized by thermogravimetric (TG), Xray diffraction (XRD) and scanning Electron Microscopy (SEM). Observed less stability thermal of acetylated cellulose when compared of cellulose. All membranes procedure were asymmetric, characterized by presence of a dense skin and porous support can be observed. SEM showed that the morphology of the superficial of membranes depends on the method preparation. (author)

  20. In vitro chondrogenesis with lysozyme susceptible bacterial cellulose as a scaffold.

    Science.gov (United States)

    Yadav, Vikas; Sun, Lin; Panilaitis, Bruce; Kaplan, David L

    2015-12-01

    A current focus of tissue engineering is the use of adult human mesenchymal stem cells (hMSCs) as an alternative to autologous chondrocytes for cartilage repair. Several natural and synthetic polymers (including cellulose) have been explored as a biomaterial scaffold for cartilage tissue engineering. While bacterial cellulose (BC) has been used in tissue engineering, its lack of degradability in vivo and high crystallinity restricts widespread applications in the field. Recently we reported the formation of a novel bacterial cellulose that is lysozyme-susceptible and -degradable in vivo from metabolically engineered Gluconacetobacter xylinus. Here we report the use of this modified bacterial cellulose (MBC) for cartilage tissue engineering using hMSCs. MBC's glucosaminoglycan-like chemistry, combined with in vivo degradability, suggested opportunities to exploit this novel polymer in cartilage tissue engineering. We have observed that, like BC, MBC scaffolds support cell attachment and proliferation. Chondrogenesis of hMSCs in the MBC scaffolds was demonstrated by real-time RT-PCR analysis for cartilage-specific extracellular matrix (ECM) markers (collagen type II, aggrecan and SOX9) as well as histological and immunohistochemical evaluations of cartilage-specific ECM markers. Further, the attachment, proliferation, and differentiation of hMSCs in MBC showed unique characteristics. For example, after 4 weeks of cultivation, the spatial cell arrangement and collagen type-II and ACAN distribution resembled those in native articular cartilage tissue, suggesting promise for these novel in vivo degradable scaffolds for chondrogenesis. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Conductivity of Cellulose Acetate Membranes from Pandan Duri Leaves (Pandanus tectorius for Li-ion Battery

    Directory of Open Access Journals (Sweden)

    Laksono Endang W.

    2016-01-01

    Full Text Available The purpose of this research is to know the influence of lithium chloride composition on membrane conductivity. Cellulose was extracted from pandan duri leaves (P. tectorius by dilute alkaline and bleaching with 0.5% NaOCl followed by synthesis of cellulose acetate using acetic anhydride as acetylating agent, acetic acid as solvent and sulfuric acid as catalyst. The membranes were prepared by casting polymer solution method and the composition of CA/LiCl were 60/40, 65/35, 70/30, 75/25, 80/20 and 100/0. Structural analysis was carried out by FTIR and X-ray diffraction. The conductivity was measured using Elkahfi 100. The highest conductivity of cellulose acetate membrane was 2.20 × 10-4 S cm-1 that measured at room temperature for 65/35 composition

  2. The effect of Nanocrystalline cellulose/Gum Arabic conjugates in crosslinked membrane for antibacterial, chlorine resistance and boron removal performance.

    Science.gov (United States)

    Asim, Saba; Wasim, Maria; Sabir, Aneela; Shafiq, Muhammad; Andlib, Huma; Khuram, Sania; Ahmad, Adnan; Jamil, Tahir

    2018-02-05

    In this work, we developed hybrid membranes integrated with Nanocrystalline cellulose (NCC)/Gum Arabic (GuA) conjugates using crosslinked Poly (vinyl alcohol) (PVA) as a matrix phase with the addition of PEO-PPO-PEO block copolymer that insured pore formation. At first, the NCC was prepared from microcrystalline cellulose via acid hydrolysis process. The performance property of hybrid NCC/GuA was measured using boron removal. The results showed that the rejection capability enhanced as compared to the control membranes, especially at 0.1wt% of NCC the selectivity is up to 92.4% with the flux rate of 21.3L/m 2 .h. Moreover, the GuA in NCC/GuA conjugate significantly enhances the antibacterial activity by hindering the bacterial attachment to the surface as both of them carry the negative charge. Also by providing the active sites responsible for hydrogen bonding thus enhancing the hydrophilic character resulted in increased permeation flux rate. Therefore, the NCC/GuA conjugated membranes have great potentials for boron removal. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Application of thin film cellulose composite membrane for dye wastewater reuse

    KAUST Repository

    Puspasari, Tiara

    2016-09-22

    The use of low cost membranes with high salt/dye selectivity and high flux is ideal for an economic and eco-friendly treatment of dye wastewater. Here, regenerated cellulose membranes prepared from trimethylsilyl cellulose are studied for treating artificial dye effluents. In the experiments using a feed containing Congo Red and high NaCl concentration, the membrane featured impressive dye removal with zero salt rejection combined with high flux. More interestingly, the membrane reached as much as 600 LMH flux at 80 °C and 4 bar while maintaining high dye rejection close to 98%. In prolonged experiments up to 75 h the membrane exhibited good antifouling behavior with nearly 100% flux recovery. This study may provide a promising alternative of dye effluent treatment where high amounts of monovalent salts are present. © 2016

  4. Characterization of cellulose membranes modified with luminescent silicon quantum dots nanoparticles.

    Science.gov (United States)

    Campos, B B; Gelde, L; Algarra, M; Esteves da Silva, J C G; Vázquez, M I; Benavente, J

    2016-10-20

    A highly hydrophilic planar membrane fabricated with regenerated cellulose (RC-4 membrane), a biocompatible polymer, was modified by inclusion of water-soluble silicon quantum dot nanoparticles (SiQDs). Both bare SiQDs and SiQDs coated with a PAMAM-OH dendrimer were employed in order to obtain luminescent and thermally stable membrane systems (RC-4/SiQDs and RC-4/SiQDs-PAMAM-OH membranes). Original and SiQDs-modified membranes were characterized by fluorescence spectroscopy (steady and confocal), derivative thermogravimetric analysis and impedance spectroscopy measurements. According to these results, both SiQDs-regenerated cellulose composite membranes present luminescent character as well as higher thermal resistance and conductivity than the original sample, although the dendrimer coverage of the SiQDs might partially shield such effects. Moreover, the permanence of SiQDs nanoparticles in the structure of the cellulosic support in aqueous environments and their effect on diffusive transport were determined by water uptake as well as by membrane potential measurements at different concentrations of a model electrolyte (KCl). These results demonstrate the possible use of these stable nano-engineered membranes, which are based on SiQDs nanoparticles, in electrochemical devices under flow conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.

    Science.gov (United States)

    Olde Riekerink, M B; Engbers, G H M; Wessling, M; Feijen, J

    2002-01-15

    Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO(2) plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0-15 min for CTA and 5-60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO(2) plasma treatment whereas CF(4) plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained.

  6. A Molecularly Complete Planar Bacterial Outer Membrane Platform

    Science.gov (United States)

    Hsia, Chih-Yun; Chen, Linxiao; Singh, Rohit R.; DeLisa, Matthew P.; Daniel, Susan

    2016-01-01

    The bacterial outer membrane (OM) is a barrier containing membrane proteins and liposaccharides that fulfill crucial functions for Gram-negative bacteria. With the advent of drug-resistant bacteria, it is necessary to understand the functional role of this membrane and its constituents to enable novel drug designs. Here we report a simple method to form an OM-like supported bilayer (OM-SB), which incorporates native lipids and membrane proteins of gram-negative bacteria from outer membrane vesicles (OMVs). We characterize the formation of OM-SBs using quartz crystal microbalance with dissipation (QCM-D) and fluorescence microscopy. We show that the orientation of proteins in the OM-SB matches the native bacterial membrane, preserving the characteristic asymmetry of these membranes. As a demonstration of the utility of the OM-SB platform, we quantitatively measure antibiotic interactions between OM-SBs and polymyxin B, a cationic peptide used to treat Gram-negative infections. This data enriches understanding of the antibacterial mechanism of polymyxin B, including disruption kinetics and changes in membrane mechanical properties. Combining OM-SBs with microfluidics will enable higher throughput screening of antibiotics. With a broader view, we envision that a molecularly complete membrane-scaffold could be useful for cell-free applications employing engineered membrane proteins in bacterial membranes for myriad technological purposes. PMID:27600663

  7. Composite scaffolds for cartilage tissue engineering based on natural polymers of bacterial origin, thermoplastic poly(3-hydroxybutyrate) and micro-fibrillated bacterial cellulose

    Czech Academy of Sciences Publication Activity Database

    Akaraonye, E.; Filip, J.; Šafaříková, Miroslava; Salih, V.; Keshavarz, T.; Knowles, J.C.; Roy, I.

    2016-01-01

    Roč. 65, č. 7 (2016), s. 780-791 ISSN 0959-8103 Institutional support: RVO:60077344 Keywords : polyhydroxyalkanoates * poly(3-hydroxybutyrate) * bacterial cellulose * micro-fibrillated cellulose * tissue engineering scaffold * composite materials Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.070, year: 2016

  8. High energy irradiation of bacterial membrane vesicles

    International Nuclear Information System (INIS)

    De La Rosa, M.A.M.

    1977-01-01

    The interactions of membrane components and two well-defined transport systems in the E. coli ML 308-225 membrane vesicles with 60 Co gamma radiation were investigated. The results presented show that gamma radiation can monitor membrane components and functions of varying radiosensitivities. The possible application of high-energy radiation as a physical probe of membrane structure and functions is indeed promising

  9. The preparation and study of cellulose carbamates and their regenerated membranes.

    Science.gov (United States)

    Yu, Guomin; Teng, Yun; Lai, Weidong; Yin, Cuiyu

    2016-12-01

    Using wood pulps with the average degree of polymerization 300-350 and urea as raw materials, cellulose carbamates were successfully synthesized by esterification reaction in N, N-dimethylacetamide(DMAc), an inexpensive, high boiling aprotic and polar solvent, for the purpose of improving the solubility of cellulose, reducing costs and environmental pollution. The products were dissolved in 9% sodium hydroxide solution at a low temperature after washing and drying and the cellulose carbamates solutions were obtained. The solutions were uniformly casted on a glass support after degassing. The regenerated cellulose membranes (CMs) were prepared by immersing the support in coagulation bath for some minutes. The structures of cellulose carbamates were characterized by Fourier transform infrared spectroscopy (FT-IR), 13 C solid state nuclear magnetic resonance spectrometry ( 13 C NMR), Thermal gravimetric analysis(TG), Scanning electron microscopy (SEM) and X-ray diffractometry(XRD). The filtration performances of CMs were tested. The results reveal that part groups of cellulose were substituted by amino in the medium, the cellulose carbamates were prepared with the reducing crystallinity and thermal decomposition temperature. The CMs have good separation performance for methylene blue. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Cellulose acetate membranes functionalized with resveratrol by covalent immobilization for improved osseointegration

    Science.gov (United States)

    Pandele, A. M.; Neacsu, P.; Cimpean, A.; Staras, A. I.; Miculescu, F.; Iordache, A.; Voicu, S. I.; Thakur, V. K.; Toader, O. D.

    2018-04-01

    Covalent immobilization of resveratrol onto cellulose acetate polymeric membranes used as coating on a Mg-1Ca-0.2Mn-0.6Zr alloy is presented for potential application in the improvement of osseointegration processes. For this purpose, cellulose acetate membrane is hydrolysed in the presence of potassium hydroxide, followed by covalent immobilization of aminopropyl triethoxy silane. Resveratrol was immobilized onto membranes using glutaraldehyde as linker. The newly synthesised functional membranes were thoroughly characterized for their structural characteristics determination employing X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA/DTG) and scanning electron microscopy (SEM) techniques. Subsequently, in vitro cellular tests were performed for evaluating the cytotoxicity biocompatibility of synthesized materials and also the osseointegration potential of obtained derivatised membrane material. It was demonstrated that both polymeric membranes support viability and proliferation of the pre-osteoblastic MC3T3-E1 cells, thus providing a good protection against the potential harmful effects of the compounds released from coated alloys. Furthermore, cellulose acetate membrane functionalized with resveratrol exhibits a significant increase in alkaline phosphatase activity and extracellular matrix mineralization, suggesting its suitability to function as an implant surface coating for guided bone regeneration.

  11. Flexible and monolithic zinc oxide bionanocomposite foams by a bacterial cellulose mediated approach for antibacterial applications.

    Science.gov (United States)

    Wang, Peipei; Zhao, Jun; Xuan, Ruifei; Wang, Yun; Zou, Chen; Zhang, Zhiquan; Wan, Yizao; Xu, Yan

    2014-05-14

    The use of self-assembled biomacromolecules in the development of functional bionanocomposite foams is one of the best lessons learned from nature. Here, we show that monolithic, flexible and porous zinc oxide bionanocomposite foams with a hierarchical architecture can be assembled through the mediation of bacterial cellulose. The assembly is achieved by controlled hydrolysis and solvothermal crystallization using a bacterial cellulose aerogel as a template in a non-aqueous polar medium. The bionanocomposite foam with a maximum zinc oxide loading of 70 wt% is constructed of intimately packed spheres of aggregated zinc oxide nanocrystals exhibiting a BET surface area of 92 m(2) g(-1). The zinc oxide bionanocomposite foams show excellent antibacterial activity, which give them potential value as self-supporting wound dressing and water sterilization materials.

  12. Magnetically modified bacterial cellulose: A promising carrier for immobilization of affinity ligands, enzymes, and cells

    Czech Academy of Sciences Publication Activity Database

    Baldíková, E.; Pospíšková, K.; Ladakis, D.; Kookos, I.K.; Koutinas, A.A.; Šafaříková, Miroslava; Šafařík, Ivo

    2017-01-01

    Roč. 71, February (2017), s. 214-221 ISSN 0928-4931 Institutional support: RVO:60077344 Keywords : bacterial cellulose * Komagataeibacter sucrofermentans * copper phthalocyanine * crystal violet * yeast cells * trypsin Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Bioproducts (products that are manufactured using biological material as feedstock) biomaterials, bioplastics, biofuels, bioderived bulk and fine chemicals, bio-derived novel materials Impact factor: 4.164, year: 2016

  13. Nanomaterials from bacterial cellulose for antimicrobial wound dressing

    Science.gov (United States)

    Liyaskina, E.; Revin, V.; Paramonova, E.; Nazarkina, M.; Pestov, N.; Revina, N.; Kolesnikova, S.

    2017-01-01

    Bacterial nanocellulose (BNC) is widely used in biomedical applications. BNC has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity. To get over this problem in the present study the BNC was saturated with antibiotic fusidic acid (FA). The subject of the experiment was BNC, produced by bacteria Gluconacetobacter sucrofermentans B-11267. The resulting biocomposites have high antibiotic activity against Staphylococcus aureus and can be used in medicine as a wound dressing. The structure of BNC was analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).

  14. Nanomaterials from bacterial cellulose for antimicrobial wound dressing

    International Nuclear Information System (INIS)

    Liyaskina, E; Revin, V; Paramonova, E; Nazarkina, M; Pestov, N; Revina, N; Kolesnikova, S

    2017-01-01

    Bacterial nanocellulose (BNC) is widely used in biomedical applications. BNC has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity. To get over this problem in the present study the BNC was saturated with antibiotic fusidic acid (FA). The subject of the experiment was BNC, produced by bacteria Gluconacetobacter sucrofermentans B-11267. The resulting biocomposites have high antibiotic activity against Staphylococcus aureus and can be used in medicine as a wound dressing. The structure of BNC was analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). (paper)

  15. A simple cellulose acetate membrane-based small lanes technique for protein electrophoresis.

    Science.gov (United States)

    Na, Na; Liu, Tingting; Yang, Xiaojun; Sun, Binjie; Ouyang, Jenny; Ouyang, Jin

    2012-08-01

    Combining electrophoresis with a cellulose acetate membrane-based technique, we developed a simple and low-cost method, named cellulose acetate membrane-based small lanes (CASL), for protein electrophoresis. A home-made capillary plotter controlled by a 3D moving stage was used to create milli-to-micro channels by printing poly(dimethylsiloxane) on to a hydrophilic cellulose acetate membrane. In the hydrophilic channels, 5 nL protein mixture was separated on the basis of electro-migration under an electric field. Compared with polyacrylamide gel electrophoresis (PAGE), CASL resulted in higher protein signal intensity for separation of mixtures containing the same mass of protein. The platform was easily fabricated at low cost (approx. $0.005 for each 1-mm-wide channel), and separation of three protein mixtures was completed in 15 min. Both electrophoresis time and potential affected the separation. Rather than chromatographic separation, this method accomplished application of microchannel techniques for cellulose acetate membrane-based protein electrophoresis. It has potential in proteomic analysis, especially for rapid, low-cost, and low-volume sample analysis in clinical diagnosis.

  16. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane

    Directory of Open Access Journals (Sweden)

    A. G. Gaikwad

    2012-06-01

    Full Text Available Transport of carbonate ions was explored through fiber supported solid membrane. A novel fiber supported solid membrane was prepared by chemical modification of cellulose fiber with citric acid, 2′2-bipyridine and magnesium carbonate. The factors affecting the permeability of carbonate ions such as immobilization of citric acid-magnesium metal ion -2′2-bipyridine complex (0 to 2.5 mmol/g range over cellulose fiber, carbon-ate ion concentration in source phase and NaOH concentration in receiving phase were investigated. Ki-netic of carbonate, sulfate, and nitrate ions was investigated through fiber supported solid membrane. Transport of carbonate ions with/without bubbling of CO2 (0 to 10 ml/min in source phase was explored from source to receiving phase. The novel idea is to explore the adsorptive transport of CO2 from source to receiving phase through cellulose fiber containing magnesium metal ion organic framework. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 25th November 2011; Revised: 17th December 2011; Accepted: 19th December 2011[How to Cite: A.G. Gaikwad. (2012. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 49– 57.  doi:10.9767/bcrec.7.1.1225.49-57][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1225.49-57 ] | View in 

  17. Interactions between membrane-bound cellulose synthases involved in the synthesis of the secondary cell wall

    NARCIS (Netherlands)

    Timmers, J.F.P.; Vernhettes, S.; Desprez, T.; Vincken, J.P.; Visser, R.G.F.; Trindade, L.M.

    2009-01-01

    It has not yet been reported how the secondary CESA (cellulose synthase) proteins are organized in the rosette structure. A membrane-based yeast two-hybrid (MbYTH) approach was used to analyze the interactions between the CESA proteins involved in secondary cell wall synthesis of Arabidopsis and the

  18. Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes

    KAUST Repository

    Puspasari, Tiara

    2016-08-30

    To date, it is still a challenge to prepare high-flux and highselectivity microporous membranes thinner than 20 nm without introducing defects. In this work, we report for the first time the application of cellulose membranes for selective separation of small molecules. A freestanding cellulose membrane as thin as 10 nm has been prepared through regeneration of trimethylsilyl cellulose (TMSC). The freestanding membrane can be transferred to any desired substrate and shows a normalized flux as high as 700 L m−2 h−1 bar−1 when supported by a porous alumina disc. According to filtration experiments, the membrane exhibits precise size-sieving performances with an estimated pore size between 1.5–3.5 nm depending on the regeneration period and initial TMSC concentration. A perfect discrimination of anionic molecules over neutral species is demonstrated. Moreover, the membrane demonstrates high reproducibility, high scale-up potential, and excellent stability over two months.

  19. Exploring bacterial outer membrane barrier to combat bad bugs.

    Science.gov (United States)

    Ghai, Ishan; Ghai, Shashank

    2017-01-01

    One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.

  20. Exploring bacterial outer membrane barrier to combat bad bugs

    Directory of Open Access Journals (Sweden)

    Ghai I

    2017-08-01

    Full Text Available Ishan Ghai,1 Shashank Ghai2 1School of Engineering and Life Sciences, Jacobs University, Bremen, 2Leibniz University, Hannover, Germany Abstract: One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels. Keywords: antibiotics, Gram-negative bacteria, cell envelope, protein channels, nanopores, influx, antibiotic resistance

  1. Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat.

    Science.gov (United States)

    Pankratov, Timofey A; Ivanova, Anastasia O; Dedysh, Svetlana N; Liesack, Werner

    2011-07-01

    Northern peatlands represent a major global carbon store harbouring approximately one-third of the global reserves of soil organic carbon. A large proportion of these peatlands consists of acidic Sphagnum-dominated ombrotrophic bogs, which are characterized by extremely low rates of plant debris decomposition. The degradation of cellulose, the major component of Sphagnum-derived litter, was monitored in long-term incubation experiments with acidic (pH 4.0) peat extracts. This process was almost undetectable at 10°C and occurred at low rates at 20°C, while it was significantly accelerated at both temperature regimes by the addition of available nitrogen. Cellulose breakdown was only partially inhibited in the presence of cycloheximide, suggesting that bacteria participated in this process. We aimed to identify these bacteria by a combination of molecular and cultivation approaches and to determine the factors that limit their activity in situ. The indigenous bacterial community in peat was dominated by Alphaproteobacteria and Acidobacteria. The addition of cellulose induced a clear shift in the community structure towards an increase in the relative abundance of the Bacteroidetes. Increasing temperature and nitrogen availability resulted in a selective development of bacteria phylogenetically related to Cytophaga hutchinsonii (94-95% 16S rRNA gene sequence similarity), which densely colonized microfibrils of cellulose. Among isolates obtained from this community only some subdivision 1 Acidobacteria were capable of degrading cellulose, albeit at a very slow rate. These Acidobacteria represent indigenous cellulolytic members of the microbial community in acidic peat and are easily out-competed by Cytophaga-like bacteria under conditions of increased nitrogen availability. Members of the phylum Firmicutes, known to be key players in cellulose degradation in neutral habitats, were not detected in the cellulolytic community enriched at low pH. © 2011 Society for

  2. In vitro and in vivo investigation of bacterial cellulose dressing containing uniform silver sulfadiazine nanoparticles for burn wound healing

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Wen

    2015-06-01

    Full Text Available Silver sulfadiazine (SSD particles in homogeneous dispersion state were prepared by an ultrasonic method and then nano- and microparticles were separated using centrifugation. SSD particles with narrow size distribution were impregnated with bacterial cellulose (BC to produce BC–SSD composite membrane used as burn wound dressing. A scanning electron microscope (SEM was used to examine the surface morphology of BC–SSD membranes. The incorporation of SSD in BC–SSD was confirmed by X-ray diffraction (XRD. Antimicrobial tests in vitro indicated that BC–SSD showed excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The effects of BC–SSD on burn wound healing were assessed by rat models. The comparative study confirmed that the wound treated with BC–SSD showed high healing rate. The bacteria count in BC–SSD group was far less than control group. Histological analysis showed that epithelialization progressed better in wound treated with BC–SSD. These values demonstrated that the BC–SSD composite membrane could be a promising wound dressing for burn.

  3. Membrane treatment of alkaline bleaching effluents from elementary chlorine free kraft softwood cellulose production.

    Science.gov (United States)

    Oñate, Elizabeth; Rodríguez, Edgard; Bórquez, Rodrigo; Zaror, Claudio

    2015-01-01

    This paper reports experimental results on the sequential use of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) to fractionate alkaline extraction bleaching effluents from kraft cellulose production. The aim was to unveil the way key pollutants are distributed when subjected to sequential UF/NF/RO membrane separation processes. Alkaline bleaching effluents were obtained from a local pinewood-based mill, featuring elementary chlorine free bleaching to produce high-brightness cellulose. The experimental system was based on a laboratory-scale membrane system, DSS LabStak® M20 Alfa Laval, using Alfa Laval UF and NF/RO membranes, operated at a constant transmembrane pressure (6 bar for UF membranes and 32 bar for NF/RO membranes), at 25°C. Results show that 78% chemical oxygen demand (COD) and total phenols, 82% adsorbable organic halogens (AOX) and 98% colour were retained by UF membranes which have molecular weight cut-off (MWCO) above 10 kDa. In all, 16% of original COD, total phenols and AOX, and the remaining 2% colour were retained by UF membranes within the 1 to 10 kDa MWCO range. Chloride ions were significantly present in all UF permeates, and RO was required to obtain a high-quality permeate with a view to water reuse. It is concluded that UF/NF/RO membranes offer a feasible option for water and chemicals recovery from alkaline bleaching effluents in kraft pulp production.

  4. Evaluation of fungal laccase immobilized on natural nanostructured bacterial cellulose

    Directory of Open Access Journals (Sweden)

    Lin eChen

    2015-11-01

    Full Text Available The aim of this work was to assess the possibility of using native bacterial nanocellulose (BC as a carrier for laccase immobilization. BC was synthesized by Gluconacetobacter xylinus, which was statically cultivated in a mannitol-based medium and was freeze-dried to form BC sponge after purification. For the first time, fungal laccase from Trametes versicolor was immobilized on the native nanofibril network-structured BC sponge through physical adsorption and cross-linking with glutaraldehyde. The properties including morphologic and structural features of the BC as well as the immobilized enzyme were thoroughly investigated. It was found that enzyme immobilized by cross-linking exhibited broader pH operation range of high catalytic activity as well as higher running stability compared to free and adsorbed enzyme. Using ABTS as substrate, the optimum pH value was 3.5 for the adsorption-immobilized laccase and 4.0 for the crosslinking-immobilized laccase. The immobilized enzyme retained 69% of the original activity after being recycled 7 times. Novel applications of the BC-immobilized enzyme tentatively include active packaging, construction of biosensors, and establishment of bioreactors.

  5. A Molecular Description of Cellulose Biosynthesis

    Science.gov (United States)

    McNamara, Joshua T.; Morgan, Jacob L.W.; Zimmer, Jochen

    2016-01-01

    Cellulose is the most abundant biopolymer on Earth, and certain organisms from bacteria to plants and animals synthesize cellulose as an extracellular polymer for various biological functions. Humans have used cellulose for millennia as a material and an energy source, and the advent of a lignocellulosic fuel industry will elevate it to the primary carbon source for the burgeoning renewable energy sector. Despite the biological and societal importance of cellulose, the molecular mechanism by which it is synthesized is now only beginning to emerge. On the basis of recent advances in structural and molecular biology on bacterial cellulose synthases, we review emerging concepts of how the enzymes polymerize glucose molecules, how the nascent polymer is transported across the plasma membrane, and how bacterial cellulose biosynthesis is regulated during biofilm formation. Additionally, we review evolutionary commonalities and differences between cellulose synthases that modulate the nature of the cellulose product formed. PMID:26034894

  6. Enzymatic membrane reactor for full saccharification of ionic liquid-pretreated microcrystalline cellulose.

    Science.gov (United States)

    Lozano, Pedro; Bernal, Berenice; Jara, Antonio G; Belleville, Marie-Pierre

    2014-01-01

    Ultrafiltration reactors based on polymeric or ceramic membranes were shown to be suitable catalytic systems for fast enzymatic saccharification of cellulose, allowing the full recovery and reuse of enzymes. By pre-treating cellulose with the IL 1-butyl-3-methylimidazolium chloride, the suitability of this substrate for enzymatic saccharification in a reactor based on polymeric ultrafiltration membranes was demonstrated, leading to 95% cellulose hydrolysis in 4h at 50°C. The filtration process gave a clear glucose solution (up to 113 mM) at constant permeate flow (24.7 L h(-1) m(-2)), allowing the enzyme to be reused for 9 operation cycles under semi-continuous operation, without any loss of enzyme activity. Under continuous operation mode and using ceramic ultrafiltration membranes at different residence times, the enzymatic reactor showed constant profiles in both the permeate flow rate and the glucose concentration, demonstrating the excellent suitability of the proposed approach for the saccharification of cellulose. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Effective Young's modulus of bacterial and microfibrillated cellulose fibrils in fibrous networks.

    Science.gov (United States)

    Tanpichai, Supachok; Quero, Franck; Nogi, Masaya; Yano, Hiroyuki; Young, Robert J; Lindström, Tom; Sampson, William W; Eichhorn, Stephen J

    2012-05-14

    The deformation micromechanics of bacterial cellulose (BC) and microfibrillated cellulose (MFC) networks have been investigated using Raman spectroscopy. The Raman spectra of both BC and MFC networks exhibit a band initially located at ≈ 1095 cm(-1). We have used the intensity of this band as a function of rotation angle of the specimens to study the cellulose fibril orientation in BC and MFC networks. We have also used the change in this peak's wavenumber position with applied tensile deformation to probe the stress-transfer behavior of these cellulosic materials. The intensity of this Raman band did not change significantly with rotation angle, indicating an in-plane 2D network of fibrils with uniform random orientation; conversely, a highly oriented flax fiber exhibited a marked change in intensity with rotation angle. Experimental data and theoretical analysis shows that the Raman band shift rate arising from deformation of networks under tension is dependent on the angles between the axis of fibrils, the strain axis, the incident laser polarization direction, and the back scattered polarization configurations. From this analysis, the effective moduli of single fibrils of BC and MFC in the networks were estimated to be in the ranges of 79-88 and 29-36 GPa, respectively. It is shown also that for the model to fit the data it is necessary to use a negative Poisson's ratio for MFC networks and BC networks. Discussion of this in-plane "auxetic" behavior is given.

  8. Biomimetic design of a bacterial cellulose/hydroxyapatite nanocomposite for bone healing applications

    International Nuclear Information System (INIS)

    Zimmermann, Kristen A.; LeBlanc, Jill M.; Sheets, Kevin T.; Fox, Robert W.; Gatenholm, Paul

    2011-01-01

    This study describes the design and synthesis of bacterial cellulose/hydroxyapatite nanocomposites for bone healing applications using a biomimetic approach. Bacterial cellulose (BC) with various surface morphologies (pellicles and tubes) was negatively charged by the adsorption of carboxymethyl cellulose (CMC) to initiate nucleation of calcium-deficient hydroxyapatite (cdHAp). The cdHAp was grown in vitro via dynamic simulated body fluid (SBF) treatments over a one week period. Characterization of the mineralized samples was done with X-ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive Spectroscopy (EDS). The amount of cdHAp observed varied among different samples. XPS demonstrated that the atomic presence of calcium and phosphorus ranged from 0.44 at.% to 7.71 at.% Ca and 0.27 at.% to 11.18 at.% P. The Ca/P overall ratio ranged from 1.22 to 1.92. FESEM images showed that the cdHAp crystal size increased with increasing nanocellulose fibril density. To determine the viability of the scaffolds in vitro, the morphology and differentiation of osteoprogenitor cells was analyzed using fluorescence microscopy and alkaline phosphatase gene expression. The presence of cdHAp crystals on BC surfaces resulted in increased cell attachment.

  9. Diblock copolymer of bacterial cellulose and poly(methyl methacrylate) initiated by chain-end-type radicals produced by mechanical scission of glycosidic linkages of bacterial cellulose.

    Science.gov (United States)

    Sakaguchi, Masato; Ohura, Takeshi; Iwata, Tadahisa; Takahashi, Shuhei; Akai, Shuji; Kan, Toshiyuki; Murai, Hisao; Fujiwara, Motoyasu; Watanabe, Osamu; Narita, Mamiko

    2010-11-08

    Bacterial cellulose (BC) was mechanically fractured in vacuum at 77 K; this resulted in the scission of the β-1,4 glycosidic linkages of BC. The chain-end-type radicals (mechanoradicals) generated from the scissions were assigned by electron spin resonance (ESR) spectral analyses. A diblock copolymer of BC and poly(methyl methacrylate) (BC-block-PMMA) was produced by the mechanical fracture of BC with MMA (methyl methacrylate) in vacuum at 77 K. Radical polymerization of MMA was initiated by the mechanoradicals located on the BC surface. The BC surface was fully covered with the PMMA chains of the BC-block-PMMA. Novel modification of the BC surface with the BC-block-PMMA was confirmed by spectral analyses of ESR, Fourier-transform infrared, (1)H NMR, and gel permeation chromatography.

  10. Enhanced starch hydrolysis using α-amylase immobilized on cellulose ultrafiltration affinity membrane.

    Science.gov (United States)

    Konovalova, Viktoriia; Guzikevich, Kateryna; Burban, Anatoliy; Kujawski, Wojciech; Jarzynka, Karolina; Kujawa, Joanna

    2016-11-05

    In order to prepare ultrafiltration membranes possessing biocatalytic properties, α-amylase has been immobilized on cellulose membranes. Enzyme immobilization was based on a covalent bonding between chitosan and a surface of cellulose membrane, followed by an attachment of Cibacron Blue F3G-A dye as affinity ligand. Various factors affecting the immobilization process, such as enzyme concentration, pH of modifying solution, zeta-potential of membrane surface, and stability of immobilized enzyme were studied. The applicability of immobilized α-amylase has been investigated in ultrafiltration processes. The immobilization of α-amylase on membrane surface allows to increase the value of mass transfer coefficient and to decrease the concentration polarization effect during ultrafiltration of starch solutions. The enzyme layer on the membrane surface prevents a rapid increase of starch concentration due to the amylase hydrolysis of starch in the boundary layer. The presented affinity immobilization technique allows also for the regeneration of membranes from inactivated enzyme. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Effect of coagulant bath on the gas permeation properties of cellulose acetate asymmetric membrane

    Science.gov (United States)

    Mohamed, F.; Hasbullah, H.; Jami'an, W. N. R.; Salleh, W. N. H. W.; Ibrahim, N.; Ali, R. R.

    2016-06-01

    Membrane based gas separation process technology has been recognized as one of the most efficient and advanced unit operation for gas separation. One of the problems in membrane gas separation is membrane performance. This paper explores the application of cellulose acetate (CA) membrane for natural gas purification and separation by improving its permeability and selectivity. The main interest in this research is to study the effect of quench medium on the gas separation performance towards its physical characteristics and gas separation performance of CA membrane. Cellulose acetate polymer was dissolved in n- methyl-2-pyrrolidone solvent and casted onto a glass plate using a pneumatically controlled casting system with fixed shear rate and solvent evaporation times. The parameter varied was the non-solvent used as quench medium during membrane post treatment that were methanol and n-hexane. The different quench media as post treatment affected the O2 and N2 gas permeation and O2/N2 selectivity as well as the tensile strength of the flat sheet asymmetric membrane. Combination of methanol and n-hexane as quench media gave the best result than the other steps. This solvent exchange step influenced the morphology by producing thin skin layer and thus gives better gas separation performance than other steps

  12. Preparation of Cellulosic Membrane Containing Pyrrolidone Moiety Via Radiation Induced Grafting and its Application in Wastewater Treatment

    OpenAIRE

    A. S. Aly; H. H. Sokker; A. Hashem; A. Hebeish

    2005-01-01

    Radiation induced grafting of vinyl pyrrolidone onto cellulose wood pulp was carried out in heterogeneous and homogenous media using gamma radiation. Cellulose wood pulp was used in different forms; a) in a homogenous solution by dissolving the wood pulp in N,N- dimethylacetamide/Lithium chloride (DMAc/LiCl) mixture , b) in a membrane form, by precipitating the cellulose solution in water and c) in a powder form. Factors affecting on the grafting such as radiation dos...

  13. Electrospinning of silver nanoparticles loaded highly porous cellulose acetate nanofibrous membrane for treatment of dye wastewater

    Science.gov (United States)

    Wang, Ke; Ma, Qian; Wang, Shu-Dong; Liu, Hua; Zhang, Sheng-Zhong; Bao, Wei; Zhang, Ke-Qin; Ling, Liang-Zhong

    2016-01-01

    In this paper, silver nanoparticles (NPs) were reduced form silver nitrate. Morphology and distribution of the synthesized silver NPs were characterized. In order to obtain cellulose acetate (CA), nanofibrous membrane with high effective adsorption performance to carry silver NPs for treatment of dye wastewater, different solvent systems were used to fabricate CA nanofibrous membranes with different morphologies and porous structures via electrospinning. Morphologies and structures of the obtained CA nanofibrous membranes were compared by scanning electron microscopy (SEM), which showed that CA nanofibrous membrane obtained from acetone/dichloromethane (1/2, v/v) was with the highly porous structure. SEM, energy-dispersive spectrometry and Fourier transform infrared spectrometry showed that the silver NPs were effectively incorporated in the CA nanofibrous membrane and the addition of silver NPs did not damage the porous structure of the CA nanofibrous membrane. Adsorption of dye solution (rhodamine B aqueous solution) revealed that the highly porous CA nanofibrous membrane exhibited effective adsorption performance and the addition of silver NPs did not affect the adsorption of the dye. Antibacterial property of the CA nanofibrous membrane showed that the silver-loaded highly porous CA nanofibrous membrane had remarkable antibacterial property when compared to the CA nanofibrous membrane without silver NPs. The silver-loaded highly porous CA nanofibrous membrane could be considered as an ideal candidate for treatment of the dye wastewater.

  14. Cellulose acetate butyrate membrane containing TiO{sub 2} nanoparticle: Preparation, characterization and permeation study

    Energy Technology Data Exchange (ETDEWEB)

    Asgarkhani, Mohammad Ali Haj; Mousavi, Seyed Mahmoud; Saljoughi, Ehsan [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2013-09-15

    Cellulose acetate butyrate/TiO{sub 2} hybrid membranes were prepared via phase inversion by dispersing the TiO{sub 2} nanoparticles in casting solutions. The influence of TiO{sub 2} nanoparticles on the morphology and performance of membranes was investigated. The scanning electron microscope images and experiments of membrane performance showed that the membrane thickness and pure water flux were first increased by adding the TiO{sub 2} nanoparticles to the casting solution up to 4 wt% and then decreased with the addition of further nanoparticles to it. The obtained results indicated that the addition of TiO{sub 2} in the casting solution enhanced the rejection and permeate flux in filtration of bovine serum albumin solution. Furthermore, increasing the TiO{sub 2} nanoparticle concentration in the casting solution increased the flux recovery and consequently decreased the fouling of membrane.

  15. Cellulose Acetate 398-10 Asymmetric Membrane Capsules for Osmotically Regulated Delivery of Acyclovir

    Directory of Open Access Journals (Sweden)

    Alka Sonkar

    2016-01-01

    Full Text Available The study was aimed at developing cellulose acetate asymmetric membrane capsules (AMCs of acyclovir for its controlled delivery at the absorption site. The AMCs were prepared by phase inversion technique using wet process. A 23 full factorial design assessed the effect of independent variables (level(s of polymer, pore former, and osmogen on the cumulative drug release from AMCs. The buoyant optimized formulation F7 (low level of cellulose acetate; high levels of both glycerol and sodium lauryl sulphate displayed maximum drug release of 97.88±0.77% in 8 h that was independent of variation in agitational intensity and intentional defect on the cellulose acetate AMC. The in vitro data best fitted zero-order kinetics (r2=0.9898. SEM micrograph of the transverse section confirmed the asymmetric nature of the cellulose acetate capsular membrane. Statistical analysis by Design Expert software indicated no interaction between the independent variables confirming the efficiency of the design in estimating the effects of variables on drug release. The optimized formulation F7 (desirability = 0.871 displayed sustenance of drug release over the drug packed in AMC in pure state proving the superiority of osmotically active formulation. Conclusively the AMCs have potential for controlled release of acyclovir at its absorption site.

  16. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO{sub 4} for lithium ion battery application

    Energy Technology Data Exchange (ETDEWEB)

    Nurhadini,, E-mail: nur-chem@yahoo.co.id; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institiut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO{sub 4} membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10{sup −4} S/cm was observed in SA/PEO/LiClO{sub 4} membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  17. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO4 for lithium ion battery application

    Science.gov (United States)

    Nurhadini, Arcana, I. Made

    2015-09-01

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO4 membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10-4 S/cm was observed in SA/PEO/LiClO4 membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  18. Structural Aspects of Bacterial Outer Membrane Protein Assembly.

    Science.gov (United States)

    Calmettes, Charles; Judd, Andrew; Moraes, Trevor F

    2015-01-01

    The outer membrane of Gram-negative bacteria is predominantly populated by β-Barrel proteins and lipid anchored proteins that serve a variety of biological functions. The proper folding and assembly of these proteins is essential for bacterial viability and often plays a critical role in virulence and pathogenesis. The β-barrel assembly machinery (Bam) complex is responsible for the proper assembly of β-barrels into the outer membrane of Gram-negative bacteria, whereas the localization of lipoproteins (Lol) system is required for proper targeting of lipoproteins to the outer membrane.

  19. Facilitated olefin transport by reversible olefin coordination to silver ions in a dry cellulose acetate membrane.

    Science.gov (United States)

    Ryu, J H; Lee, H; Kim, Y J; Kang, Y S; Kim, H S

    2001-04-01

    The highly selective dry complex membrane AgBF4-cellulose acetate (CA) was prepared and tested for the separation of ethylene/ethane and propylene/propane mixtures. The maximum selectivity for olefin over paraffin was found to be 280 for the ethylene/ethane mixture and 200 for the propylene/propane mixture. Solid-state interactions of AgBF4 with cellulose acetate (CA) and/or olefins have been investigated by using FT-IR, UV, and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS studies clearly show that the silver ions are coordinated by carbonyl oxygen atoms among three different types of oxygen atoms present in CA-two in the acetate group and one in the ether linkage. Upon incorporation of AgBF4 into CA, the carbonyl stretching frequency of the free cellulose acetate at 1750 cm(-1) shifts to a lower frequency by about 41 cm(-1). The binding energy corresponding to a carbonyl oxygen atom in the O 1s XPS spectrum shifts to a more positive binding energy by the incorporation of AgBF4. Reversible olefin coordination to silver ions has been observed by FT-IR and UV studies. Treatment of the AgBF4-CA membrane placed in a gas cell with propylene produces a propylene-coordinated membrane in which coordinated propylene is easily replaced by other olefins such as 1,3-butadiene.

  20. Bacterial nanocellulose/Nafion composite membranes for low temperature polymer electrolyte fuel cells

    Science.gov (United States)

    Jiang, Gao-peng; Zhang, Jing; Qiao, Jin-li; Jiang, Yong-ming; Zarrin, Hadis; Chen, Zhongwei; Hong, Feng

    2015-01-01

    Novel nanocomposite membranes aimed for both proton-exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC) are presented in this work. The membranes are based on blending bacterial nanocellulose pulp and Nafion (abbreviated as BxNy, where x and y indicates the mass ratio of bacterial cellulose to Nafion). The structure and properties of BxNy membranes are characterized by FTIR, SEM, TG, DMA and EIS, along with water uptake, swelling behavior and methanol permeability tests. It is found that the BxNy composite membranes with reinforced concrete-like structure show excellent mechanical and thermal stability regardless of annealing. The water uptake plus area and volume swelling ratios are all decreased compared to Nafion membranes. The proton conductivities of pristine and annealed B1N9 are 0.071 and 0.056 S cm-1, respectively, at 30 °C and 100% humidity. Specifically, annealed B1N1 exhibited the lowest methanol permeability of 7.21 × 10-7 cm2 s-1. Through the selectivity analysis, pristine and annealed B1N7 are selected to assemble the MEAs. The performances of annealed B1N7 in PEMFC and DMFC show the maximum power densities of 106 and 3.2 mW cm-2, respectively, which are much higher than those of pristine B1N7 at 25 °C. The performances of the pristine and annealed B1N7 reach a level as high as 21.1 and 20.4 mW cm-2 at 80 °C in DMFC, respectively.

  1. Preparation of microporous Cellulose/Poly(vinylidene fluoride-hexafluoropropylene) membrane for lithium ion batteries by phase inversion method

    Science.gov (United States)

    Asghar, Muhammad Rehman; Zhang, Yao; Wu, Aiming; Yan, Xiaohui; Shen, Shuiyun; Ke, Changchun; Zhang, Junliang

    2018-03-01

    In this work, a porous and honeycomb-structured Cellulose/Poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) membrane is prepared via a facile and ecofriendly phase inversion method by using glycerol as pore forming agent. Cellulose acetate, the source of cellulose, is easily converted into cellulose by hydrolysis in the presence of lithium hydroxide. Owing to the unique microstructure, the Cellulose/PVDF-HFP membrane offers several advantages, including high porosity, elevated electrolyte uptake, high ion conductivity, and wide electrochemical window (5.35 V). Compared with conventional polypropylene (PP) separator and PVDF-HFP membrane, the membrane developed in this work enables higher discharge capacity, higher lithium-ion transference number (0.89) and improved rate performance, which is able to maintain a high discharge capacity of 136 mAh g-1 at 8 C, using LiCoO2 as cathode and Li metal as anode. In addition, the Cellulose/PVDF-HFP membrane based batteries exhibit superior cycling performance that can maintain 91.7% capacity after 100 cycles at 0.2 C. The characterization and battery test results demonstrate that the membrane is highly compatible with lithium ion batteries.

  2. Mechanism of bacterial membrane poration by Antimicrobial Peptides

    Science.gov (United States)

    Arora, Ankita; Mishra, Abhijit

    2015-03-01

    Bacterial resistance to conventional antibiotics is a major health concern. Antimicrobial peptides (AMPs), an important component of mammalian immune system, are thought to utilize non-specific interactions to target common features on the outer membranes of pathogens; hence development of resistance to such AMPs may be less pronounced. Most AMPs are amphiphilic and cationic in nature. Most AMPs form pores in the bacterial membranes causing them to lyse, however, the exact mechanism is unknown. Here, we study the AMP CHRG01 (KSSTRGRKSSRRKK), derived from human β defensin 3 (hBD3) with all Cysteine residues substituted with Serine. Circular Dichorism studies indicate that CHRG01 shows helicity and there is change in helicity as it interacts with the lipid membrane. The AMP was effective against different species of bacteria. Leakage of cellular components from bacterial cells observed by SEM and AFM indicates AMP action by pore formation. Confocal microscopy studies on giant vesicles incubated with AMP confirm poration. The effect of this AMP on model bacterial membranes is characterized using Small Angle X-ray scattering and Fluorescence spectroscopy to elucidate the mechanism behind antimicrobial activity.

  3. Property evaluations of dry-cast reconstituted bacterial cellulose/tamarind xyloglucan biocomposites.

    Science.gov (United States)

    de Souza, Clayton F; Lucyszyn, Neoli; Woehl, Marco A; Riegel-Vidotti, Izabel C; Borsali, Redouane; Sierakowski, Maria Rita

    2013-03-01

    We describe the mechanical defibrillation of bacterial cellulose (BC) followed by the dry-cast generation of reconstituted BC films (RBC). Xyloglucan (XGT), extracted from tamarind seeds, was incorporated into the defibrillated cellulose at various compositions, and new films were created using the same process. Microscopy and contact angle analyses of films revealed an increase in the microfibre adhesion, a reduced polydispersity in the diameters of the microfibrils and increased hydrophobic behaviour as a function of %XGT. X-ray diffraction analysis revealed changes to the crystallographic planes of the RBC and the biocomposite films with preferential orientation along the (110) plane. Compared with BC, RBC/XGT biocomposite with 10% XGT exhibited improvement in its thermal properties and in Young's modulus. These results indicated a reorganisation of the microfibres with mechanical treatment, which when combined with hydrocolloids, can create cellulose-based materials that could be applied as scaffolding for tissue engineering and drug release. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis.

    Science.gov (United States)

    Li, Guoliang; Wang, Jun; Hou, Deyin; Bai, Yu; Liu, Huijuan

    2016-07-01

    Polyethylene terephthalate mesh (PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis (FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2μm. The performance of the optimal FO membrane was tested using 0.2mol/L NaCl as the feed solution and 1.5mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47L/(m(2)·hr) and salt rejection of 95.48% in FO mode. While in pressure retarded osmosis (PRO) mode, the water flux was 4.74L/(m(2)·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes. Copyright © 2016. Published by Elsevier B.V.

  5. Effect of evaporation time on cellulose acetate membrane for gas separation

    Science.gov (United States)

    Jami'an, W. N. R.; Hasbullah, H.; Mohamed, F.; Yusof, N.; Ibrahim, N.; Ali, R. R.

    2016-06-01

    Throughout this decades, membrane technology has been the desirable option among the others gas separation technologies. However, few issues have been raised regarding the membrane gas separation application including the trade-off between its permeability and selectivity and also its effects towards environment. Therefore, for this research, a biopolymer membrane for gas separation application will be developed with reasonably high on both permeability and selectivity. The main objective of this research is to study the effect of solvent evaporation time on the flat sheet asymmetric membrane morphology and gas separation performance. The membranes were produced by a simple dry/wet phase inversion technique using a pneumatically controlled casting system. The dope solution for the membrane casting was prepared by dissolving the cellulose acetate (CA) polymer in N-Methyl-2-pyrrolidone (NMP) and the solvent evaporation time was varied. Permeability and selectivity of the membrane was performed by using pure gases of carbon dioxide, CO2 and methane, CH4. The increase in solvent evaporation time had improved the membrane morphologies as the porosity of the membrane surface decrease and formation of a more mature skin layer. The gas permeation tests determined that increasing in solvent evaporation time had increased the selectivity of CO2/CH4 but reduce the permeability of both gases

  6. Physicochemical characterization of cellulose nanocrystal and nanoporous self-assembled CNC membrane derived from Ceiba pentandra.

    Science.gov (United States)

    Mohamed, Mohamad Azuwa; W Salleh, W N; Jaafar, Juhana; Ismail, A F; Abd Mutalib, Muhazri; Mohamad, Abu Bakar; M Zain, M F; Awang, Nor Asikin; Mohd Hir, Zul Adlan

    2017-02-10

    This research involves the rare utilisation of the kapok fibre (Ceiba pentandra) as a raw material for the fabrication of cellulose nanocrystal (CNC) and self-assembled CNC membranes. The isolation of CNC from Ceiba pentandra began with the extraction of cellulose via the chemical alkali extraction by using 5wt% NaOH, followed by the typical acidified bleaching method and, finally, the CNC production through acid hydrolysis with 60wt% H 2 SO 4 at the optimum time of 60min. The prepared CNC was then employed for the preparation of self-assembled membrane through the water suspension casting evaporation technique. The obtained CNC membrane was characterised in terms of its composition, crystallinity, thermal stability, as well as, structural and morphological features with the use of several techniques including FTIR, XRD, AFM, TEM, FESEM, and TGA. The FESEM and AFM analyses had illustrated the achievement of a self-assembled CNC membrane with a smooth surface and a well-distributed nano-porous structure, with the porosity of 52.82±7.79%. In addition, the findings proved that the self-assembled CNC membrane displayed good adsorption capability indicated by the recorded efficiency of 79% and 85% for 10mg/L and 5mg/L of methylene blue in an aqueous solution, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Metal nanoparticles/ionic liquid/cellulose: polymeric membrane for hydrogenation reactions

    Directory of Open Access Journals (Sweden)

    Marcos Alexandre Gelesky

    2014-01-01

    Full Text Available Rhodium and platinum nanoparticles were supported in polymeric membranes with 10, 20 and 40 µm thickness. The polymeric membranes were prepared combining cellulose acetate and the ionic liquid (IL 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonylimide (BMI.(NTf2. The presence of metal nanoparticles induced an increase in the polymeric membrane surface areas. The increase of the IL content resulted in an improvement of elasticity and decrease in tenacity and toughness, whereas the stress at break was not affected. The presence of IL probably causes an increase in the separation between the cellulose molecules that result in a higher flexibility and processability of the polymeric membrane. The CA/IL/M(0 combinations exhibit an excellent synergistic effect that enhances the activity and durability of the catalyst for the hydrogenation of cyclohexene. The CA/IL/M(0 polymeric membrane displays higher catalytic activity (up to 7.353 h-1 for the 20 mm of CA/IL/Pt(0 and stability than the nanoparticles dispersed only in the IL.

  8. The wettability of a cellulose acetate membrane in the presence of bovine serum albumin

    Science.gov (United States)

    Białopiotrowicz, Tomasz; Jańczuk, Bronisław

    2002-11-01

    The measurements of the contact angle for water (W), glycerol (G), formamide (F), ethylene glycol (E) and diiodomethane (D) on a bare cellulose acetate membrane and covered by adsorptive bovine serum albumin (BSA) films were made. The adsorption was performed from solutions in concentration range 0-100 mg/ml. An influence of the membrane porosity on an apparent contact angle was discussed and Cassie and Baxter equation was used for that purpose. It was suggested that some liquids could penetrate in to membrane pores reducing its apparent porosity. To explain such behaviour, the spreading coefficient and the work of adhesion was calculated for the studied liquids. Components and parameters of the surface free energy of a bare cellulose acetate membrane and covered by an adsorptive BSA film were determined for W-G-D, W-F-D and G-F-D three-liquid systems and they were similar for these systems. However, for the hydrated BSA layer those components and parameters for the systems W-G-D, W-F-D were different than those for the system G-F-D. It was stated that after BSA adsorption on that membrane percentage of empty pores decreased, reducing their number almost to 0, at the highest BSA concentrations.

  9. Improvement of bacterial cellulose production by manipulating the metabolic pathways in which ethanol and sodium citrate involved.

    Science.gov (United States)

    Li, Yuanjing; Tian, Chunjie; Tian, Hua; Zhang, Jiliang; He, Xin; Ping, Wenxiang; Lei, Hong

    2012-12-01

    Nowadays, bacterial cellulose has played more and more important role as new biological material for food industry and medical and industrial products based on its unique properties. However, it is still a difficult task to improve the production of bacterial cellulose, especially a large number of byproducts are produced in the metabolic biosynthesis processes. To improve bacterial cellulose production, ethanol and sodium citrate are added into the medium during the fermentation, and the activities of key enzymes and concentration of extracellular metabolites are measured to assess the changes of the metabolic flux of the hexose monophosphate pathway (HMP), the Embden-Meyerhof-Parnas pathway (EMP), and the tricarboxylic acid cycle (TCA). Our results indicate that ethanol functions as energy source for ATP generation at the early stage of the fermentation in the HMP pathway and the supplementation of ethanol significantly reduces glycerol generation (a major byproduct). While in the EMP pathway, sodium citrate plays a key role, and its supplementation results in the byproducts (mainly acetic acid and pyruvic acid) entering the gluconeogenesis pathway for cellulose synthesis. Furthermore, by adding ethanol and sodium citrate, the main byproduct citric acid in the TCA cycle is also reduced significantly. It is concluded that bacterial cellulose production can be improved by increasing energy metabolism and reducing the formation of metabolic byproducts through the metabolic regulations of the bypasses.

  10. An investigation into solvent-membrane interactions when assessing drug release from organic vehicles using regenerated cellulose membranes.

    Science.gov (United States)

    Reid, Monica L; Brown, Marc B; Moss, Gary P; Jones, Stuart A

    2008-09-01

    The influence of organic solvents on artificial membranes when assessing drug release from topical formulations is, generally, poorly characterised yet current guidelines require no characterisation of the membrane before, during or after an experiment. Therefore, the aim of this study was to determine the effect of solvent-membrane interactions when using in-vitro Franz cell methods for the assessment of corticosteroid release and to assess compliance or otherwise with Higuchi's equation. The rate of beclometasone dipropionate monohydrate (BDP) and betamethasone 17-valerate (BMV) release across a regenerated cellulose membrane (RCM), from both saturated solutions and commercial formulations, was determined. Increasing the ratio of organic solvent, compared with aqueous phase, in the donor fluid (DF) resulted in up to a 416-fold increase in steady-state flux. Further, alterations in the receiver fluid (RF) composition caused, in some cases, 337-fold increases in flux. Analysis indicated that the RCM remained chemically unchanged, that its pore size remained constant and that no drug partitioned into the membrane, regardless of the DF or RF employed. However, it was observed that the organic solvents had a thinning effect on the RCM, resulting in enhanced flux, which was potentially due to the variation in the diffusional path length. Such findings raise issues of the veracity of data produced from any membrane release study involving a comparison of formulations with differing solvent content.

  11. BACTERIAL OUTER MEMBRANE VESICLES AND VACCINE APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Reinaldo eAcevedo

    2014-03-01

    Full Text Available Vaccines based on outer membrane vesicles (OMV were developed more than 20 years ago against Neisseria meningitidis serogroup B. These nano-sized structures exhibit remarkable potential for immunomodulation of immune responses and delivery of self meningococcal antigens or unrelated antigens incorporated into the vesicle structure. This paper reviews different applications in OMV Research and Development (R&D and provides examples of OMV developed and evaluated at the Finlay Institute in Cuba. A Good Manufacturing Practice (GMP process was developed at the Finlay Institute to produce OMV from N. meningitidis serogroup B (dOMVB using detergent extraction. Subsequently, OMV from N. meningitidis, serogroup A (dOMVA, serogroup W (dOMVW and serogroup X (dOMVX were obtained using this process. More recently, the extraction process has also been applied effectively for obtaining OMV on a research scale from Vibrio cholerae (dOMVC, Bordetella pertussis (dOMVBP, Mycobacterium smegmatis (dOMVSM and BCG (dOMVBCG. The immunogenicity of the OMV have been evaluated for specific antibody induction, and together with functional bactericidal and challenge assays in mice have shown their protective potential. dOMVB has been evaluated with non-self neisserial antigens, including with a herpes virus type 2 glycoprotein, ovalbumin and allergens. In conclusion, OMV are proving to be more versatile than first conceived and remain an important technology for development of vaccine candidates.

  12. Synthesis and Characterization of Methyl Cellulose/Keratin Hydrolysate Composite Membranes

    Directory of Open Access Journals (Sweden)

    Bernd M. Liebeck

    2017-03-01

    Full Text Available It is known that aqueous keratin hydrolysate solutions can be produced from feathers using superheated water as solvent. This method is optimized in this study by varying the time and temperature of the heat treatment in order to obtain a high solute content in the solution. With the dissolved polypeptides, films are produced using methyl cellulose as supporting material. Thereby, novel composite membranes are produced from bio-waste. It is expected that these materials exhibit both protein and polysaccharide properties. The influence of the embedded keratin hydrolysates on the methyl cellulose structure is investigated using Fourier transform infrared spectroscopy (FTIR and wide angle X-ray diffraction (WAXD. Adsorption peaks of both components are present in the spectra of the membranes, while the X-ray analysis shows that the polypeptides are incorporated into the semi-crystalline methyl cellulose structure. This behavior significantly influences the mechanical properties of the composite films as is shown by tensile tests. Since further processing steps, e.g., crosslinking, may involve a heat treatment, thermogravimetric analysis (TGA is applied to obtain information on the thermal stability of the composite materials.

  13. Construction of proton exchange membranes under ultrasonic irradiation based on novel fluorine functionalizing sulfonated polybenzimidazole/cellulose/silica bionanocomposite.

    Science.gov (United States)

    Esmaielzadeh, Sheida; Ahmadizadegan, Hashem

    2018-03-01

    Novel sulfonated polybenzimidazole (s-PBI)/cellulose/silica bionanocomposite membranes were prepared from fluorine-containing s-PBI copolymer with a cellulose/silica precursor and a bonding agent. The introduction of the bonding agent results in the reinforcing interfacial interaction between s-PBI chains and the cellulose/silica nanoparticles. Commercially available silica nanoparticles were modified with biodegradable nanocellolose through ultrasonic irradiation technique. Transmission electron microscopy (TEM) analyses showed that the cellulose/silica composites were well dispersed in the s-PBI matrix on a nanometer scale. The mechanical properties and the methanol barrier ability of the s-PBI films were improved by the addition of cellulose/silica. The modulus of the s-PBI/10 wt% cellulose/silica nanocomposite membranes had a 45% increase compared to the pure s-PBI films, and the methanol permeability decreased by 62% with respect to the pure s-PBI membranes. The conductivities of the s-PBI/cellulose/silica nanocomposites were slightly lower than the pure s-PBI. The antibacterial activity of (s-PBI)/cellulose/silica was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7 and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of cellulose/silica. All of the synthesized (s-PBI)/cellulose/silica were found to have high antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Modulation of population density and size of silver nanoparticles embedded in bacterial cellulose via ammonia exposure: visual detection of volatile compounds in a piece of plasmonic nanopaper

    Science.gov (United States)

    Heli, B.; Morales-Narváez, E.; Golmohammadi, H.; Ajji, A.; Merkoçi, A.

    2016-04-01

    The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and from amber to a grey or taupe colour upon fish or meat spoilage exposure. These phenomena are proposed as a simple visual detection of volatile compounds in a flexible, transparent, permeable and stable single-use nanoplasmonic membrane, which opens the way to innovative approaches and capabilities in gas sensing and smart packaging.The localized surface plasmon resonance exhibited by noble metal nanoparticles can be sensitively tuned by varying their size and interparticle distances. We report that corrosive vapour (ammonia) exposure dramatically reduces the population density of silver nanoparticles (AgNPs) embedded within bacterial cellulose, leading to a larger distance between the remaining nanoparticles and a decrease in the UV-Vis absorbance associated with the AgNP plasmonic properties. We also found that the size distribution of AgNPs embedded in bacterial cellulose undergoes a reduction in the presence of volatile compounds released during food spoilage, modulating the studied nanoplasmonic properties. In fact, such a plasmonic nanopaper exhibits a change in colour from amber to light amber upon the explored corrosive vapour exposure and

  15. Comparison of Hydrophilicity and Mechanical Properties of Nanocomposite Membranes with Cellulose Nanocrystals and Carbon Nanotubes.

    Science.gov (United States)

    Bai, Langming; Bossa, Nathan; Qu, Fangshu; Winglee, Judy; Li, Guibai; Sun, Kai; Liang, Heng; Wiesner, Mark R

    2017-01-03

    The inherent properties of hydrophilicity and mechanical strength of cellulose nanocrystals (CNCs) make them a possible alternative to carbon nanotubes (CNTs) that may present fewer objections to application water-treatment membranes. In this work, the hydrophilicity and mechanical properties of CNCs and CNTs nanocomposite poly(ether sulfone) (PES) membranes were characterized and compared. Membrane pore geometry was analyzed by scanning electron microscopy (SEM). Overall porosity and mean pore radius were calculated based on a wet-dry method. Results showed that PES polymers were loosely packed in the top layer of both the CNC- and CNT-composite membranes (CNC-M and CNT-M). The porosity of the CNC-M was greater than that of the CNT-M. Membrane hydrophilicity, measured by water-contact angle, free energy of cohesion, and water flux, was increased through the addition of either CNCs or functionalized CNTs to an otherwise hydrophobic polymer membrane. The hydrophilicity of the CNC-M was greater than the CNT-M. In addition, the Young's modulus and tensile strength was enhanced for both the CNC-M and CNT-M. While smaller concentrations of CNTs were required to achieve an equal increase in Young's modulus compared with the CNCs, the elasticity of the CNC-composite membranes was greater.

  16. Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ

    Directory of Open Access Journals (Sweden)

    Marlon Osorio

    2017-01-01

    Full Text Available We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC grown by fermentation in the presence of polyvinyl alcohol (PVA followed by physical crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment.

  17. Thermal Adaptation of the Archaeal and Bacterial Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Yosuke Koga

    2012-01-01

    Full Text Available The physiological characteristics that distinguish archaeal and bacterial lipids, as well as those that define thermophilic lipids, are discussed from three points of view that (1 the role of the chemical stability of lipids in the heat tolerance of thermophilic organisms: (2 the relevance of the increase in the proportion of certain lipids as the growth temperature increases: (3 the lipid bilayer membrane properties that enable membranes to function at high temperatures. It is concluded that no single, chemically stable lipid by itself was responsible for the adaptation of surviving at high temperatures. Lipid membranes that function effectively require the two properties of a high permeability barrier and a liquid crystalline state. Archaeal membranes realize these two properties throughout the whole biological temperature range by means of their isoprenoid chains. Bacterial membranes meet these requirements only at or just above the phase-transition temperature, and therefore their fatty acid composition must be elaborately regulated. A recent hypothesis sketched a scenario of the evolution of lipids in which the “lipid divide” emerged concomitantly with the differentiation of archaea and bacteria. The two modes of thermal adaptation were established concurrently with the “lipid divide.”

  18. Thermal Adaptation of the Archaeal and Bacterial Lipid Membranes

    Science.gov (United States)

    Koga, Yosuke

    2012-01-01

    The physiological characteristics that distinguish archaeal and bacterial lipids, as well as those that define thermophilic lipids, are discussed from three points of view that (1) the role of the chemical stability of lipids in the heat tolerance of thermophilic organisms: (2) the relevance of the increase in the proportion of certain lipids as the growth temperature increases: (3) the lipid bilayer membrane properties that enable membranes to function at high temperatures. It is concluded that no single, chemically stable lipid by itself was responsible for the adaptation of surviving at high temperatures. Lipid membranes that function effectively require the two properties of a high permeability barrier and a liquid crystalline state. Archaeal membranes realize these two properties throughout the whole biological temperature range by means of their isoprenoid chains. Bacterial membranes meet these requirements only at or just above the phase-transition temperature, and therefore their fatty acid composition must be elaborately regulated. A recent hypothesis sketched a scenario of the evolution of lipids in which the “lipid divide” emerged concomitantly with the differentiation of archaea and bacteria. The two modes of thermal adaptation were established concurrently with the “lipid divide.” PMID:22927779

  19. Hydrophylicity Enhancement of Modified Cellulose Acetate Membrane to Improve the Membrane Performance in Produced Water Treatment

    Directory of Open Access Journals (Sweden)

    Kusworo Tutuk Djoko

    2018-01-01

    Full Text Available Produced water is a wastewater generated from petroleum industry with high concentration of pollutants such as Total Dissolved Solid, Organic content, and Oil and grease. Membrane technology has been currently applied for produced water treatment due to its efficiency, compact, mild and clean process. The main problem of produced water using membrane is fouling on the membrane surface which causes on low permeate productivity. This paper is majority focused on the improvement of anti-fouling performance through several modifications to increase CA membrane hydrophilicity. The membrane was prepared by formulating the dope solution consists of 18 wt-% CA polymer, acetone, and PEG additive (3 wt-%, 5 wt-%, and 7 wt-%. The membranes are casted using NIPS method and being irradiated under UV light exposure. The SEM images show that parepared membrane has asymmetric structure consist of dense layer, intermediete layer, and finger-like support layer. The filtration test shows that PEG addition increase the membrane hydrophilicity and the permeate flux increases. UV light exposure on the membrane improves the membrane stability and hydrophilicity. The imrpovement of membrane anti-fouling performance is essential to achieve the higher productivity without lowering its pollutants rejection.

  20. Development of cellulose-polypyrrole microfiber membranes and assessment of their capability on water softening

    Science.gov (United States)

    Barrera, C.; Arrieta, A.; Escobar, N.; Gañan, P.; Castro, C.

    2013-11-01

    The application of conducting polymer composite for water softening is based on the use of pyrrole's electrochemical properties joined with the flexibility and relatively high surface areas associated with cellulose fibers, to develop a new hybrid material that exhibits the inherent proprieties of both components. This hybrid would allow to promote an ion exchange reaction between the composite membrane and the hard water. The cellulose membranes obtained from banana plant agricultural waste (raquis), were uniform with individual and well separated fibers. The fibers were encapsulated by a continuous coating of polypyrrole by an in situ oxidative chemical polymerization. The amount of polypyrrole deposited on the fiber increased by increasing the monomer concentration, behavior that was identified through the observation of differences on the intensity of the light to dark color shift that coated the fibers after the polymerization. The ion removal capability of the membrane coted with the conducting polymer was tested using an experimental device, finding reductions on the conductivity for hard water within 23 to 66 μs/cm after 6 hours of the assay.

  1. Interaction of antimicrobial biomimetics with bacterial and cytoplasmic membrane models

    Science.gov (United States)

    Gidalevitz, David

    2010-03-01

    Non-natural mimics of antimicrobial peptides are excellent candidates for anti-infectious agents due to their stability towards enzymatic degradation and broad adjustability of physicochemical properties. This study examines how structural rigidity affects interactions of the AMP analogs with model Langmuir monolayers of phospholipids at the air-liquid interface mimicking bacterial and mammalian lipid membrane surfaces. Flexible acyl-lysine olygomer was more efficient in disrupting Gram-negative rather than Gram-positive bacterial model membrane. Electron density profiles across the film, derived from XR data, demonstrate that following OAK and arylamide insertion into bacterial membrane mimics their hydrophobic cores were located within the lipid acyl chains, inducing opposite local curvatures. Moreover, flexible OAK molecules were found to penetrate the six acyl chains lipid A better than two chain DPPG, while conformationally restrained arylamide molecules, as well as previously characterized natural antimicrobial peptides LL-37, protegrin-1 and SMAP-29, insert into DPPG monolayer with almost identical or better efficiency.

  2. Surface and charge transport characterization of polyaniline-cellulose acetate composite membranes.

    Science.gov (United States)

    Qaiser, Asif A; Hyland, Margaret M; Patterson, Darrell A

    2011-02-24

    This study elucidates the charge transport processes of polyaniline (PANI) composite membranes and correlates them to the PANI deposition site and the extent of PANI surface layering on the base microporous membranes. PANI was deposited either as a surface layer or inside the pores of cellulose acetate microporous membranes using various in situ chemical polymerization techniques. The extent of PANI layering at the surface of the base membrane and its oxidation and doping states were characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). PANI deposition on the membranes showed a strong dependence on the polymerization technique and polymerization time within a single technique. In XPS, the deconvolution of C 1s and N 1s core-level spectra of the composite membranes was used to quantify the extent of PANI layering at the surface along with its oxidation and doping states. PANI incompletely covered the surface of the base microporous membranes for all the employed techniques. However, the extent of the layering increased with the polymerization time in a particular technique. The charge transport through the bulk membrane and charge transfer at the membrane/electrode interface were studied by electrochemical impedance spectroscopy (EIS). The data were analyzed using the equivalent circuit modeling technique. The modeling parameters revealed that PANI deposition at the surface enhanced the interfacial charge transfer but the process depended on the extent of the surface coverage of the membrane. In addition, the charge transport in the bulk membrane depended on the PANI intercalation level, which varied depending on the polymerization technique employed. In addition, the EIS of electrolyte-soaked membranes was also conducted to evaluate the effects of PANI deposition site on charge transport in the presence of an electrolyte. PANI layering at the pore walls of the base membrane from diaphragmatic polymerization

  3. Tiny but mighty: bacterial membrane vesicles in food biotechnological applications.

    Science.gov (United States)

    Liu, Yue; Alexeeva, Svetlana; Defourny, Kyra Ay; Smid, Eddy J; Abee, Tjakko

    2018-02-01

    Membrane vesicle (MV) production is observed in all domains of life. Evidence of MV production accumulated in recent years among bacterial species involved in fermentation processes. These studies revealed MV composition, biological functions and properties, which made us recognize the potential of MVs in food applications as delivery vehicles of various compounds to other bacteria or the human host. Moreover, MV producing strains can deliver benefits as probiotics or starters in fermentation processes. Next to the natural production of MVs, we also highlight possible methods for artificial generation of bacterial MVs and cargo loading to enhance their applicability. We believe that a more in-depth understanding of bacterial MVs opens new avenues for their exploitation in biotechnological applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Bacterial cellulose production from cotton-based waste textiles: enzymatic saccharification enhanced by ionic liquid pretreatment.

    Science.gov (United States)

    Hong, Feng; Guo, Xiang; Zhang, Shuo; Han, Shi-fen; Yang, Guang; Jönsson, Leif J

    2012-01-01

    Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5-7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. SEM and TEM for structure and properties characterization of bacterial cellulose/hydroxyapatite composites.

    Science.gov (United States)

    Arkharova, Natalia A; Suvorova, Elena I; Severin, Alexander V; Khripunov, Albert K; Krasheninnikov, Sergey V; Klechkovskaya, Vera V

    2016-11-01

    Preparation of composites with different properties and gradient of components is aimed at better performance of materials for bone substitution. Bacterial cellulose-hydroxyapatite (BC-HAP) composites with various mass ratio of the components (BC-25HAP, BC-4HAP, and BC-HAP) were prepared by a novel method of growing HAP nanocrystals (the linear size ≤30 nm) in water solutions in the presence of the BC gel-film micro-fragments. Varying the BC-HAP ratios leads to a gradual change of the physical properties of the materials. It was found that an increase in the BC content results in a decrease of the HAP crystal length and specific surface area, porosity, and pore volume while the values of density and Young's modulus values increase. SCANNING 38:757-765, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  6. A slow-release system of bacterial cellulose gel and nanoparticles for hydrophobic active ingredients.

    Science.gov (United States)

    Numata, Yukari; Mazzarino, Leticia; Borsali, Redouane

    2015-01-01

    A combination of bacterial cellulose (BC) gel and amphiphilic block copolymer nanoparticles was investigated as a drug delivery system (DDS) for hydrophobic active ingredients. Poly(ethylene oxide)-b-poly(caprolactone) (PEO-b-PCL) and retinol were used as the block copolymer and hydrophobic active ingredient, respectively. The BC gel was capable of incorporating copolymer nanoparticles and releasing them in an acetic acid-sodium acetate buffer solution (pH 5.2) at 37 °C. The percentage of released copolymer reached a maximum value of approximately 60% after 6h and remained constant after 24h. The percentage of retinol released from the copolymer-containing BC gel reached a maximum value at 4h. These results show that the combination of BC gel and nanoparticles is a slow-release system that may be useful in the cosmetic and biomedical fields for skin treatment and preparation. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Simple preparation of Fenton catalyst@bacterial cellulose for waste water treatment

    Science.gov (United States)

    Wibowo, Arie; Febi Indrawan, Radian; Triadhi, Untung; Hasdi Aimon, Akfiny; Iskandar, Ferry; Ardy, Husaini

    2018-02-01

    Heterogeneous fenton catalyst is one of the attractive technologies for destruction of persistent and non-biodegradable pollutant in wastewater, because it can be used in wide range of pH and recyclable. Herein, commercial bacterial celluloses (BCs) were used as an alternative support of fenton catalyst to improve their catalytic activity. Scanning Electron Microscope (SEM) observations indicated that the presence of BCs and decreasing precursor concentration might promote formation of smaller particle sizes of catalyst from 3.5 μm of bare catalyst to 0.7 μm of catalyst@BC. UV-vis measurement showed that fast degradation of dyes with half-time degradation at around 25 min was observed in sample using catalyst@BCs with precursor concentration of 0.01 M. Successful preparation of heterogeneous fenton catalyst with smaller particle size and better catalytic activity is important for their application in wastewater treatment.

  8. Nanoporous layered silicate AMH-3/cellulose acetate nanocomposite membranes for gas separations

    KAUST Repository

    Kim, Wun-gwi

    2013-08-01

    Nanoporous layered silicate/polymer composite membranes are of interest because they can exploit the high aspect ratio of exfoliated selective flakes/layers to enhance molecular sieving and create a highly tortuous transport path for the slower molecules. In this work, we combine membrane synthesis, detailed microstructural characterization, and mixed gas permeation measurements to demonstrate that nanoporous flake/polymer membranes allows significant improvement in gas permeability while maintaining selectivity. We begin with the primary-amine-intercalated porous layered silicate SAMH-3 and show that it can be exfoliated using a high shear rate generated by a high-speed mixer. The exfoliated SAMH-3 flakes were used to form SAMH-3/cellulose acetate (CA) membranes. Their microstructure was analyzed by small angle X-ray scattering (SAXS), revealing a high degree of exfoliation of AMH-3 layers in the CA membrane with a small number of layers (4-8) in the exfoliated flakes. TEM analysis visualized the thickness of the flakes as 15-30nm, and is consistent with the SAXS analysis. The CO2/CH4 gas separation performance of the CA membrane was significantly increased by incorporating only 2-6wt% of SAMH-3 flakes. There was a large increase in CO2 permeability with maintenance of selectivity. This cannot be explained by conventional models of transport in flake-containing membranes, and indicates complex transport paths in the membrane. It is also in contrast to the much higher loadings of isotropic particles required for similar enhancements. The present approach may allow avoidance of particle aggregation and poor interfacial adhesion associated with larger quantities of inorganic fillers. © 2013 Elsevier B.V.

  9. Dual-skinned polyamide/poly(vinylidene fluoride)/cellulose acetate membranes with embedded woven

    KAUST Repository

    Duong, Phuoc H.H.

    2016-08-31

    We propose multilayer membranes including (i) a thin selective polyamide (PA) layer prepared via interfacial polymerization, (ii) a poly (vinylidene fluoride) (PVDF) asymmetric porous support with high adhesion to the PA layer and high mechanical strength, (iii) a strong woven fabric, and (iv) fouling resistant porous cellulose acetate (CA) layer. The PA layer rejects solutes of the draw solution. The PVDF/woven fabric/CA (PVDF/CA) integrated layer performs as a mechanical support with unique properties for forward osmosis (FO) applications. It consists of a modified PVDF top layer suitable for the deposition of a PA layer and a highly hydrophilic bottom layer (CA) with a tunable pore size to minimize foulant deposition and intrusion onto and into the support. The experimental results using bovine serum albumin (BSA) as a model foulant show that the presence of the CA layer at the bottom of the FO membrane (PA/PVDF/CA) reduces 75% fouling propensity compared to the simple FO membrane made of PVDF, woven fabric and PA (PA/PVDF). Fouling tests with 2000 ppm oily feed faced the bottom of the FO membranes further indicate the superiority of the PA/PVDF/CA membrane compared to the PA/PVDF membrane. Moreover, the bottom CA layer can be adjusted with a flexible range of pore size, varied from sub-micron to sub-nanometer depending on the feed composition. The newly developed multilayer FO membrane has comparable performance to the state-of-the-art membrane with added tailored fouling resistance for specific wastewater feeds.

  10. A simple route to develop transparent doxorubicin-loaded nanodiamonds/cellulose nanocomposite membranes as potential wound dressings.

    Science.gov (United States)

    Luo, Xiaogang; Zhang, Hao; Cao, Zhenni; Cai, Ning; Xue, Yanan; Yu, Faquan

    2016-06-05

    The objective of this study is to develop transparent porous nanodiamonds/cellulose nanocomposite membranes with controlled release of doxorubicin for potential applications as wound dressings, which were fabricated by tape casting method from dispersing carboxylated nanodiamonds and dissolving cellulose homogeneously in 7 wt% NaOH/12 wt% urea aqueous solution. By adjusting the carboxylated nanodiamonds content, various nanocomposite membranes were obtained. The structure and properties of these membranes have been investigated by light transmittance measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), tensile tests, water loss analyses, etc. The drug loading and release was investigated using doxorubicin hydrochloride as a model drug. In vitro cytotoxicity assay of the membranes was also studied. This work presented a proof-of-concept utility of these membranes for loading and release of bioactive compounds to be employed as a candidate for wound dressing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    Science.gov (United States)

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    Science.gov (United States)

    Liu, Chuang; Yang, Dong; Wang, Yuangui; Shi, Jiafu; Jiang, Zhongyi

    2012-08-01

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total "biologic" route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  13. Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chuang [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China); Yang Dong; Wang Yuangui [Tianjin University, Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology (China); Shi Jiafu; Jiang Zhongyi, E-mail: zhyjiang@tju.edu.cn [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China)

    2012-08-15

    In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total 'biologic' route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

  14. A plasma modified cellulose-chitosan porous membrane allows efficient DNA binding and provides antibacterial properties: A step towards developing a new DNA collecting card.

    Science.gov (United States)

    Chumwangwapee, Sasiwimon; Chingsungnoen, Artit; Siri, Sineenat

    2016-11-01

    In forensic DNA analyses, biological specimens are collected and stored for subsequent recovery and analysis of DNA. A cost-effective and efficient DNA recovery approach is therefore a need. This study aims to produce a plasma modified cellulose-chitosan membrane (pCE-CS) that efficiently binds and retains DNA as a potential DNA collecting card. The pCE-CS membrane was produced by a phase separation of ionic liquid dissolving CE and CS in water with subsequent surface-modification by a two-step exposure of argon plasma and nitrogen gas. Through plasma modification, the pCE-CS membrane demonstrated better DNA retention after a washing process and higher rate of DNA recovery as compared with the original CE-CS membrane and the commercial FTA card. In addition, the pCE-CS membrane exhibited anti-bacterial properties against both Escherichia coli and Staphylococcus aureus. The results of this work suggest a potential function of the pCE-CS membrane as a DNA collecting card with a high recovery rate of captured DNA. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Vaginal epithelial cells regulate membrane adhesiveness to co-ordinate bacterial adhesion.

    Science.gov (United States)

    Younes, Jessica A; Klappe, Karin; Kok, Jan Willem; Busscher, Henk J; Reid, Gregor; van der Mei, Henny C

    2016-04-01

    Vaginal epithelium is colonized by different bacterial strains and species. The bacterial composition of vaginal biofilms controls the balance between health and disease. Little is known about the relative contribution of the epithelial and bacterial cell surfaces to bacterial adhesion and whether and how adhesion is regulated over cell membrane regions. Here, we show that bacterial adhesion forces with cell membrane regions not located above the nucleus are stronger than with regions above the nucleus both for vaginal pathogens and different commensal and probiotic lactobacillus strains involved in health. Importantly, adhesion force ratios over membrane regions away from and above the nucleus coincided with the ratios between numbers of adhering bacteria over both regions. Bacterial adhesion forces were dramatically decreased by depleting the epithelial cell membrane of cholesterol or sub-membrane cortical actin. Thus, epithelial cells can regulate membrane regions to which bacterial adhesion is discouraged, possibly to protect the nucleus. © 2015 John Wiley & Sons Ltd.

  16. Use of agroindustrial waste in the preparation of nanocomposites based on bacterial cellulose and hydroxyapatite; Utilizacao de residuos agroindustriais na elaboracao de bionanocompositos baseados em celulose bacteriana e hidroxiapatita

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Eden B.; Chagas, Bruna S. das; Feitosa, Judith P.A. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Andrade, Fabia K.; Borges, Maria F.; Muniz, Celli R.; Souza Filho, Men de Sa M.; Rosa, Morsyleide F., E-mail: morsyleide.rosa@embrapa.br [Embrapa Agroindustria Tropical, Fortaleza, CE (Brazil); Brigida, Ana I. [Embrapa Agroindustria de Alimentos, Barra de Guaratiba, Rio de Janeiro, RJ (Brazil); Morais, Joao P.S. [Embrapa Algodao, Campina Grande, PB (Brazil)

    2015-07-01

    Environmental issues have supported the interest in renewable sources and agroindustrial residues became a significant resource for the production of new materials. The present work presents the use of agroindustrial residues to obtain bacterial cellulose (BC) for further elaboration of nanocomposites with hydroxyapatite (HA). The production of BC membranes occurred in Hestrin & Schramm medium, cashew juice and sisal liquid waste cultivated under static conditions. After the incubation period, the BC membranes were purified and nanocomposites prepared by successive immersion of the purified membranes in solutions of Calcium Chloride (CaCl{sub 2}), and Sodium Phosphate (Na{sub 2}HPO{sub 4}), followed by drying and subsequent characterization. The materials obtained were characterized by Thermogravimetric Analysis (TGA) and X-ray Diffraction (XRD). Additionally, in vitro tests were performed for nanocomposites. The results showed the production of cellulose from the three substrates studied, without the need for further supplementation or pH change. In all characterizations, structure and typical behavior of bacterial cellulose were found. The composites showed bioactivity and the adsorption capacity of proteins, which lead to potential biocompatibility of these materials. (author)

  17. Interlaced CNT Electrodes for Bacterial Fouling Reduction of Microfiltration Membranes.

    Science.gov (United States)

    Zhang, Qiaoying; Arribas, Paula; Remillard, E Marielle; García-Payo, M Carmen; Khayet, Mohamed; Vecitis, Chad D

    2017-08-15

    Interlaced carbon nanotube electrodes (ICE) were prepared by vacuum filtering a well-dispersed carbon nanotube-Nafion solution through a laser-cut acrylic stencil onto a commercial polyvinylidene fluoride (PVDF) microfiltration (MF) membrane. Dead-end filtration was carried out using 10 7 and 10 8 CFU mL -1 Pseudomonas fluorescens to study the effects of the electrochemically active ICE on bacterial density and morphology, as well as to evaluate the bacterial fouling trend and backwash (BW) efficacy, respectively. Finally, a simplified COMSOL model of the ICE electric field was used to help elucidate the antifouling mechanism in solution. At 2 V DC and AC (total cell potential), the average bacterial log removal of the ICE-PVDF increased by ∼1 log compared to the control PVDF (3.5-4 log). Bacterial surface density was affected by the presence and polarity of DC electric potential, being 87-90% lower on the ICE cathode and 59-93% lower on the ICE anode than that on the PVDF after filtration, and BW further reduced the density on the cathode significantly. The optimal operating conditions (2 V AC) reduced the fouling rate by 75% versus the control and achieved up to 96% fouling resistance recovery (FRR) during BW at 8 V AC using 155 mM NaCl. The antifouling performance should mainly be due to electrokinetic effects, and the electric field simulation by COMSOL model suggested electrophoresis and dielectrophoresis as likely mechanisms.

  18. Removal of radionuclides by reverse osmosis using a cellulose acetate membrane, (2)

    International Nuclear Information System (INIS)

    Nishimaki, Kenzo; Koyama, Akio; Saji, Minoru; Tutui, Tenson.

    1990-01-01

    Experiments were performed on the removal of radionuclides from radioactive liquid waste by reverse osmosis using asymmetric cellulose acetate membranes. In previous papers, we reported such removal properties as the dependence on solute concentration and the influence of co-existing material. In this paper we performed experiments on some separation properties, especially on the formation and the disappearance of concentration polarization layer of membrane surface. These experiments are necessary for the theoretical explanation of findings shown in previous papers. Concentration polarization layer is formed on the surface of the membrane, when pressurized feed solution is not stirred during reverse osmosis operation. This layer grows with elapsed time and reaches the equilibrium. The thickness of this concentration polarization layer and solute concentrations in this layer are calculated by a simple model. The formation and disappearance of this layer are experimented with intermittent stirring. The influence of intensity of stirring on the formation of concentration polarization layer is observed. These are important information on property of membrane for removing solute by reverse osmosis. (author)

  19. Nanoporous membranes with cellulose nanocrystals as functional entity in chitosan: removal of dyes from water.

    Science.gov (United States)

    Karim, Zoheb; Mathew, Aji P; Grahn, Mattias; Mouzon, Johanne; Oksman, Kristiina

    2014-11-04

    Fully biobased composite membranes for water purification were fabricated with cellulose nanocrystals (CNCs) as functional entities in chitosan matrix via freeze-drying process followed by compacting. The chitosan (10 wt%) bound the CNCs in a stable and nanoporous membrane structure with thickness of 250-270 μm, which was further stabilized by cross-linking with gluteraldehyde vapors. Scanning electron microscopy (SEM) studies revealed well-individualized CNCs embedded in a matrix of chitosan. Brunauer, Emmett and Teller (BET) measurements showed that the membranes were nanoporous with pores in the range of 13-10nm. In spite of the low water flux (64 Lm(-2) h(-1)), the membranes successfully removed 98%, 84% and 70% respectively of positively charged dyes like Victoria Blue 2B, Methyl Violet 2B and Rhodamine 6G, after a contact time of 24h. The removal of dyes was expected to be driven by the electrostatic attraction between negatively charged CNCs and the positively charged dyes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Effects of the Membrane Action of Tetralin on the Functional and Structural Properties of Artificial and Bacterial Membranes

    NARCIS (Netherlands)

    SIKKEMA, J; POOLMAN, B; KONINGS, WN; DEBONT, JAM

    Tetralin is toxic to bacterial cells at concentrations below 100-mu-mol/liter. To assess the inhibitory action of tetralin on bacterial membranes, a membrane model system, consisting of proteoliposomes in which beef heart cytochrome c oxidase was reconstituted as the proton motive force-generating

  1. In vitro behaviors of rat mesenchymal stem cells on bacterial celluloses with different moduli

    Energy Technology Data Exchange (ETDEWEB)

    Taokaew, Siriporn [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906 (United States); Phisalaphong, Muenduen [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Zhang Newby, Bi-min, E-mail: bimin@uakron.edu [Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906 (United States)

    2014-05-01

    Compressive moduli of bacteria-synthesized cellulose (BC) were altered by two drying techniques: ambient-air drying and freeze drying. While no significant differences in dry weight were found, their cross-sectional structures and thickness varied greatly. Freeze dried BCs had loose cross-sectional structures and a thickness of ∼ 4.7 mm, whereas air dried BCs had more compacted cross-sectional structures and a thickness of ∼ 0.1 mm. The compressive moduli of the rehydrated freeze dried and rehydrated air dried BCs were measured to be 21.06 ± 0.22 kPa and 90.09 ± 21.07 kPa, respectively. When rat mesenchymal stem cells (rMSCs) were seeded on these BCs, they maintained a round morphology in the first 3 days of cultivation. More spread-out morphology and considerable proliferation on freeze dried BCs were observed in 7 days, but not on air-dried BCs. The cells were further grown for 3 weeks in the absence and presence of differentiation agents. Without using any differentiation agents, no detectable differentiation was noticed for rMSCs further cultivated on both types of BC. With differentiation inducing agents, chondrogenic differentiation, visualized by histological staining, was observed in some area of the rehydrated freeze dried BCs; while osteogenic differentiation was noticed on the stiffer rehydrated air dried BCs. - Graphical abstract: In the presence of induction agents, rat mesenchymal stem cells (rMSCs) preferentially differentiated into osteocytes on stiffer air dried BC films. - Highlights: • Bacterial cellulose (BC) sheets with different moduli generated by drying differently • Air-dried BC exhibited a modulus similar to that of bone. • Freeze-dried BC showed a modulus in the range of that of muscle. • Air-dried BC promoted the differentiation of rMSCs into osteocytes. • Freeze-dried BC promoted the differentiation of rMSCs into chondrocytes.

  2. Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources

    Directory of Open Access Journals (Sweden)

    Andrea F. S. Costa

    2017-10-01

    Full Text Available Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin–Schramm (HS medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL]. A jeans laundry was also tested. None of the tested sources (beside CSL worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film

  3. Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources

    Science.gov (United States)

    Costa, Andrea F. S.; Almeida, Fabíola C. G.; Vinhas, Glória M.; Sarubbo, Leonie A.

    2017-01-01

    Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC) is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin–Schramm (HS) medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose) and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL)]. A jeans laundry was also tested. None of the tested sources (beside CSL) worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The values

  4. Effect of extremely low frequency electromagnetic fields on bacterial membrane.

    Science.gov (United States)

    Oncul, Sule; Cuce, Esra M; Aksu, Burak; Inhan Garip, Ayse

    2016-01-01

    The effect of extremely low frequency electromagnetic fields (ELF-EMF) on bacteria has attracted attention due to its potential for beneficial uses. This research aimed to determine the effect of ELF-EMF on bacterial membrane namely the membrane potential, surface potential, hydrophobicity, respiratory activity and growth. Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were subjected to ELF-EMF, 50 Hz, 1 mT for 2 h. Membrane potential was determined by fluorescence spectroscopy with or without EDTA (Ethylenediaminetetraacetic acid) with DisC3(5) (3,3-dipropylthiacarbocyanine iodide), zeta potential measurements were performed by electrophoretic mobility, hydrophobicity of the membrane was measured with MATH (Microbial Adhesion to Hydrocarbons) test, respiratory activity was determined with CTC (5-Cyano-2,3-ditolyl tetrazolium chloride), colony forming unit (CFU) and DAPI (4',6-diamidino-2-phenylindole, dihydrochloride) was used for growth determinations. ELF-EMF caused changes in physicochemical properties of both Gram-positive and Gram-negative bacteria. Hyperpolarization was seen in S. aureus and EDTA-treated E. coli. Surface potential showed a positive shift in S. aureus contrariwise to the negative shift seen in EDTA-untreated E. coli. Respiratory activity increased in both bacteria. A slight decrease in growth was observed. These results show that ELF-EMF affects the crucial physicochemical processes in both Gram-positive and Gram-negative bacteria which need further research.

  5. Novel cellulose ester substrates for high performance flat-sheet thin-film composite (TFC) forward osmosis (FO) membranes

    KAUST Repository

    Ong, Rui Chin

    2015-01-01

    A novel hydrophilic cellulose ester with a high intrinsic water permeability and a water partition coefficient was discovered to construct membrane supports for flat-sheet thin film composite (TFC) forward osmosis (FO) membranes for water reuse and seawater desalination with high performance. The performance of TFC-FO membranes prepared from the hydrophilic cellulose ester containing a high degree of OH and a moderate degree of Pr substitutions clearly surpasses those prepared from cellulose esters and other polymers with moderate hydrophilicity. Post-treatments of TFC-FO membranes using sodium dodecyl sulfate (SDS) and glycerol followed by heat treatment further enhance the water flux without compromising the selectivity. Positron annihilation lifetime analyses have confirmed that the SDS/glycerol post-treatment increases the free volume size and fractional free volume of the polyamide selective layer. The newly developed post-treated TFC-FO membranes exhibit a remarkably high water flux up to 90 LMH when the selective layer is oriented towards the draw solution (i.e., PRO mode) using 1. M NaCl as the draw solution and DI water as the feed. For seawater desalination, the membranes display a high water flux up to 35 LMH using a 2. M NaCl draw solution. These water fluxes exceeded the water fluxes achieved by other types of FO membranes reported in literatures. © 2014 Elsevier B.V.

  6. Comparative research of effectiveness of cellulose and fiberglass porous membrane carriers for bio sampling in veterinary and food industry monitoring

    Science.gov (United States)

    Gusev, Alexander; Vasyukova, Inna; Zakharova, Olga; Altabaeva, Yuliya; Saushkin, Nikolai; Samsonova, Jeanne; Kondakov, Sergey; Osipov, Alexander; Snegin, Eduard

    2017-11-01

    The aim of proposed research is to study the applicability of fiberglass porous membrane materials in a new strip format for dried blood storage in food industry monitoring. A comparative analysis of cellulosic and fiberglass porous membrane materials was carried out to obtain dried samples of serum or blood and the possibility of further species-specific analysis. Blood samples of Sus scrofa were used to study the comparative effectiveness of cellulose and fiberglass porous membrane carriers for long-term biomaterial storage allowing for further DNA detection by real-time polymerase chain reaction (PCR) method. Scanning electron microscopy of various membranes - native and with blood samples - indicate a fundamental difference in the form of dried samples. Membranes based on cellulosic materials sorb the components of the biological fluid on the surface of the fibers of their structure, partially penetrating the cellulose fibers, while in the case of glass fiber membranes the components of the biological fluid dry out as films in the pores of the membrane between the structural filaments. This fundamental difference in the retention mechanisms affects the rate of dissolution of the components of dry samples and contributes to an increase in the efficiency of the desorption process of the sample before subsequent analysis. Detecting of pig DNA in every analyzed sample under the performed Real-time PCR as well as good state of the biomaterial preservation on the glass fiber membranes was clearly demonstrated. Good biomaterials preservation has been revealed on the test cards for 4 days as well as for 1 hour.

  7. Technical note concerning the use of cellulose ester filtering membranes in the determination of plutonium in urine

    International Nuclear Information System (INIS)

    Harduin, J.C.; Montels, P.

    1968-01-01

    During the last stage of the determination of plutonium in biological media, cellulose ester filtering membranes are used for collecting, with the help of a special device, the very fine precipitate resulting from the co-precipitation of plutonium and lanthanum fluorides. The membranes are then dried, and stuck on to flat watch-glasses for a α counting. A method is then given for purifying the lanthanum so as to keep the background noise during counting as low as possible. (author) [fr

  8. Separation of nitrogen-krypton by the freeze-dried cellulose acetate membrane

    International Nuclear Information System (INIS)

    Tanioka, Akihiko; Ishikawa, Kinzo; Kakuta, Akio; Ozaki, Osamu; Oono, Masanori.

    1977-01-01

    The utility of freeze-dried cellulose acetate membranes, which consist of a thin skin layer supported upon a more porous matrix substructure, was examined for separation of nitrogen-radioactive krypton 85. The high permeable and separative membranes were prepared by fixed freezed-drying of swollen membrane after evaporation of acetone for 4-6 minutes. The permeation rate of nitrogen was 10 -1 -10 -3 (cc/cm 2 .sec.atm). Knudsen flow was predominant, since the permeation rate was inversely proportional to square root of molecular weight of gases. The influence of viscous flow was also observed by slight dependence on the pressure. The mean pore size was calculated by the equation of gas permeation in porous media. There exist fine pores of 30-40A radii in the skin layer. The separation factor (dilution of Kr) was about 0.7 and the separation efficiency was 60%. The collision between different gas molecules (Present-de Bethunes' effect) and the influence of viscous flow depreciates the efficiency. The separation efficiency which was determined by the experiment coincided with the one predicted according to the Present-de Bethunes' equation, supposing that the pore size in skin layer was 10-25A. (auth.)

  9. Embedding of bacterial cellulose nanofibers within PHEMA hydrogel matrices: tunable stiffness composites with potential for biomedical applications

    Czech Academy of Sciences Publication Activity Database

    Hobzová, Radka; Hrib, Jakub; Širc, Jakub; Karpushkin, Evgeny; Michálek, Jiří; Janoušková, Olga; Gatenholm, P.

    2018-01-01

    Roč. 2018, 17 January (2018), s. 1-11, č. článku 5217095. ISSN 1687-4110 R&D Projects: GA ČR(CZ) GA16-04863S; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : bacterial cellulose * PHEMA * biomedical application Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.871, year: 2016

  10. Two-Sided Surface Oxidized Cellulose Membranes Modified with PEI: Preparation, Characterization and Application for Dyes Removal

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-09-01

    Full Text Available Porous regenerated cellulose (RC membranes were prepared with cotton linter pulp as a raw material. These membranes were first oxidized on both sides by a modified (2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO oxidation system using a controlled oxidation reaction technique. Then, the oxidized RC membranes were functionalized with polyethylenimine (PEI via the glutaraldehyde crosslinking method to obtain bifunctional (carboxyl and amino porous RC membranes, as revealed by Fourier transform infrared spectroscopy (FT-IR, elemental analysis and zeta potential measurement. The scanning electron microscopy (SEM and the tests of the mechanical properties and permeability characteristics of modified RC membranes demonstrated that the porous structure and certain mechanical properties could be retained. The adsorption performance of the modified membranes towards dyes was subsequently investigated. The modified membranes displayed good adsorption capacities, rapid adsorption equilibrium and removal efficiencies towards both anionic (xylenol orange (XO and cationic (methylene blue (MB dyes, making them suitable bioadsorbents for wastewater treatment.

  11. Production of bacterial cellulose using different carbon sources and culture media.

    Science.gov (United States)

    Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

    2015-03-06

    In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Bacterial cellulose production by Gluconacetobacter xylinus by employing alternative culture media.

    Science.gov (United States)

    Jozala, Angela Faustino; Pértile, Renata Aparecida Nedel; dos Santos, Carolina Alves; de Carvalho Santos-Ebinuma, Valéria; Seckler, Marcelo Martins; Gama, Francisco Miguel; Pessoa, Adalberto

    2015-02-01

    Bacterial cellulose (BC) is used in different fields as a biological material due to its unique properties. Despite there being many BC applications, there still remain many problems associated with bioprocess technology, such as increasing productivity and decreasing production cost. New technologies that use waste from the food industry as raw materials for culture media promote economic advantages because they reduce environmental pollution and stimulate new research for science sustainability. For this reason, BC production requires optimized conditions to increase its application. The main objective of this study was to evaluate BC production by Gluconacetobacter xylinus using industry waste, namely, rotten fruits and milk whey, as culture media. Furthermore, the structure of BC produced at different conditions was also determined. The culture media employed in this study were composed of rotten fruit collected from the disposal of free markets, milk whey from a local industrial disposal, and their combination, and Hestrin and Schramm media was used as standard culture media. Although all culture media studied produced BC, the highest BC yield-60 mg/mL-was achieved with the rotten fruit culture. Thus, the results showed that rotten fruit can be used for BC production. This culture media can be considered as a profitable alternative to generate high-value products. In addition, it combines environmental concern with sustainable processes that can promote also the reduction of production cost.

  13. Using wastewater after lipid fermentation as substrate for bacterial cellulose production by Gluconacetobacter xylinus.

    Science.gov (United States)

    Huang, Chao; Guo, Hai-Jun; Xiong, Lian; Wang, Bo; Shi, Si-Lan; Chen, Xue-Fang; Lin, Xiao-Qing; Wang, Can; Luo, Jun; Chen, Xin-De

    2016-01-20

    In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Novel keratin modified bacterial cellulose nanocomposite production and characterization for skin tissue engineering.

    Science.gov (United States)

    Keskin, Zalike; Sendemir Urkmez, Aylin; Hames, E Esin

    2017-06-01

    As it is known that bacterial cellulose (BC) is a biocompatible and natural biopolymer due to which it has a large set of biomedical applications. But still it lacks some desired properties, which limits its uses in many other applications. Therefore, the properties of BC need to be boosted up to an acceptable level. Here in this study for the first time, a new natural nanocomposite was produced by the incorporating keratin (isolated from human hair) to the BC (produced by Acetobacter xylinum) to enhance dermal fibroblast cells' attachment. Two different approaches were used in BC based nanocomposite production: in situ and post modifications. BC/keratin nanocomposites were characterized using SEM, FTIR, EDX, XRD, DSC and XPS analyses. Both production methods have yielded successful results for production of BC based nanocomposite-containing keratin. In vitro cell culture experiments performed with human skin keratinocytes and human skin fibroblast cells indicate the potential of the novel BC/keratin nanocomposites for use in skin tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Esophageal replacement by hydroxylated bacterial cellulose patch in a rabbit model.

    Science.gov (United States)

    Zhu, Changlai; Liu, Fang; Qian, Wenbo; Wang, Yingjie; You, Qingsheng; Zhang, Tianyi; Li, Feng

    2015-01-01

    To repair esophageal defects by hydroxylated and kombucha-synthesized bacterial cellulose (HKBC) patch in a rabbit model. Semicircular esophageal defects 1 cm in length of the cervical esophagus were initially created in 18 Japanese big-ear rabbits and then repaired with HKBC patch grafts. The clinical outcomes including survival rate, weight change, food intake, and hematological and radiologic evaluation were observed. After X-ray evaluation, the rabbits were sacrificed sequentially at 1, 3, and 6 months for histopathologic analysis with light microscopy and scanning electron microscopy. Survival rate during the first month was 88.9% (n = 16). Two rabbits died from anastomotic leakage during the entire follow-up. Postoperatively, feeding function and body weight were gradually restored in the surviving animals. No hematological abnormalities were found, and no obvious anastomotic leakage, stenosis, or obstruction was observed under X-ray examination. The histopathologic results showed a progressive regeneration of the esophagus in the graft area, where the neo-esophagus tissue had characteristics similar to native esophageal tissue after 3 months of surgery. HKBC is beneficial for esophageal tissue regeneration and may be a promising material for esophageal reconstruction.

  16. Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07.

    Science.gov (United States)

    Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

    2016-02-25

    Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis.

  17. Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel.

    Science.gov (United States)

    Gao, Xing; Shi, Zhijun; Lau, Andrew; Liu, Changqin; Yang, Guang; Silberschmidt, Vadim V

    2016-05-01

    This study is focused on anomalous strain-rate-dependent behaviour of bacterial cellulose (BC) hydrogel that can be strain-rate insensitive, hardening, softening, or strain-rate insensitive in various ranges of strain rate. BC hydrogel consists of randomly distributed nanofibres and a large content of free water; thanks to its ideal biocompatibility, it is suitable for biomedical applications. Motivated by its potential applications in complex loading conditions of body environment, its time-dependent behaviour was studied by means of in-aqua uniaxial tension tests at constant temperature of 37 °C at various strain rates ranging from 0.000 1s(-1) to 0.3s(-1). Experimental results reflect anomalous strain-rate-dependent behaviour that was not documented before. Micro-morphological observations allowed identification of deformation mechanisms at low and high strain rates in relation to microstructural changes. Unlike strain-rate softening behaviours in other materials, reorientation of nanofibres and kinematics of free-water flow dominate the softening behaviour of BC hydrogel at high strain rates. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Mechanical and thermal properties of bacterial-cellulose-fibre-reinforced Mater-Bi® bionanocomposite

    Directory of Open Access Journals (Sweden)

    Hamonangan Nainggolan

    2013-05-01

    Full Text Available The effects of the addition of fibres of bacterial cellulose (FBC to commercial starch of Mater-Bi® have been investigated. FBC produced by cultivating Acetobacter xylinum for 21 days in glucose-based medium were purified by sodium hydroxide 2.5 wt % and sodium hypochlorite 2.5 wt % overnight, consecutively. To obtain water-free BC nanofibres, the pellicles were freeze dried at a pressure of 130 mbar at a cooling rate of 10 °C min−1. Both Mater-Bi and FBC were blended by using a mini twin-screw extruder at 160 °C for 10 min at a rotor speed of 50 rpm. Tensile tests were performed according to ASTM D638 to measure the Young’s modulus, tensile strength and elongation at break. A field emission scanning electron microscope was used to observe the morphology at an accelerating voltage of 10 kV. The crystallinity (Tc and melting temperature (Tm were measured by DSC. Results showed a significant improvement in mechanical and thermal properties in accordance with the addition of FBC into Mater-Bi. FBC is easily incorporated in Mater-Bi matrix and produces homogeneous Mater-Bi/FBC composite. The crystallinity of the Mater-Bi/FBC composites decrease in relation to the increase in the volume fraction of FBC.

  19. Preparation of Pd/Bacterial Cellulose Hybrid Nanofibers for Dopamine Detection

    Directory of Open Access Journals (Sweden)

    Dawei Li

    2016-05-01

    Full Text Available Palladium nanoparticle-bacterial cellulose (PdBC hybrid nanofibers were synthesized by in-situ chemical reduction method. The obtained PdBC nanofibers were characterized by a series of analytical techniques. The results revealed that Pd nanoparticles were evenly dispersed on the surfaces of BC nanofibers. Then, the as-prepared PdBC nanofibers were mixed with laccase (Lac and Nafion to obtain mixture suspension, which was further modified on electrode surface to construct novel biosensing platform. Finally, the prepared electrochemical biosensor was employed to detect dopamine. The analysis result was satisfactory, the sensor showed excellent electrocatalysis towards dopamine with high sensitivity (38.4 µA·mM−1, low detection limit (1.26 µM, and wide linear range (5–167 µM. Moreover, the biosensor also showed good repeatability, reproducibility, selectivity and stability and was successfully used in the detection of dopamine in human urine, thus providing a promising method for dopamine analysis in clinical application.

  20. Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application

    Directory of Open Access Journals (Sweden)

    Pengfei Lv

    2016-03-01

    Full Text Available Novel nanocomposites comprised of bacterial cellulose (BC with carboxylic multi-walled carbon nanotubes (c-MWCNTs incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC were prepared using BC/c-MWCNTs composite injected by laccase (Lac and glucose oxidase (GOD with the aid of glutaraldehyde (GA crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scanning electron microscope (SEM, and Fourier Transform Infrared (FTIR. The experimental results indicated the successful incorporation of c-MWCNTs into the BC. The electrochemical and biofuel performance were evaluated by cyclic voltammetry (CV and linear sweep voltammetry (LSV. The power density and current density of EBFCs were recorded at 32.98 µW/cm3 and 0.29 mA/cm3, respectively. Additionally, the EBFCs also showed acceptable stability. Preliminary tests on double cells indicated that renewable BC have great potential in the application field of EBFCs.

  1. Synthesis and in vitro safety assessment of magnetic bacterial cellulose with porcine aortic smooth muscle cells.

    Science.gov (United States)

    Pastrana, Homero F; Cooper, Christy L; Alucozai, Milad; Reece, Lisa M; Avila, Alba G; Allain, Jean Paul

    2016-11-01

    Bacterial cellulose (BC) has been used as a scaffold for tissue regeneration (TR). Improving functional TR requires highly selective strategies for specific cell attraction. Embedding iron oxide nanoparticles into a BC matrix can drive magnetically labeled cells to specific tissues where they may begin to heal injured tissue. This article focuses on characterization and in vitro toxicity assessment of magnetic BC (MBC). We proposed to detect the production of radical oxygen species (ROS), esterase activity, and apoptosis to study cytotoxic interactions of MBC within its bioenvironment. Morphological characterization was performed using scanning electron microscopy where evidence shows that the diameter of MBC fibers compared to BC fibers was 33% smaller, and the pore areas were 25% bigger. Cytotoxicity assays in porcine aortic smooth muscle cells exposed for 24 hours to BC, MBC, and poly(ethylene glycol)-coated MBC (MBC-PEG) reveals 96% viability and 9% ROS production for MBC-PEG. In contrast, 25% of cells exposed to MBC were apoptotic, suggesting that even when the cells were metabolically active, MBC can induce damage. These outcomes support the need for more integral assessment in the hopes of assessing the potential biosafety and uses of nanocomposites for TR. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2801-2809, 2016. © 2016 Wiley Periodicals, Inc.

  2. Identification of Uncultured Bacterial Species from Firmicutes, Bacteroidetes and CANDIDATUS Saccharibacteria as Candidate Cellulose Utilizers from the Rumen of Beef Cows

    Directory of Open Access Journals (Sweden)

    Lee James Opdahl

    2018-02-01

    Full Text Available The ability of ruminants to utilize cellulosic biomass is a result of the metabolic activities of symbiotic microbial communities that reside in the rumen. To gain further insight into this complex microbial ecosystem, a selection-based batch culturing approach was used to identify candidate cellulose-utilizing bacterial consortia. Prior to culturing with cellulose, rumen contents sampled from three beef cows maintained on a forage diet shared 252 Operational Taxonomic Units (OTUs, accounting for 41.6–50.0% of bacterial 16S rRNA gene sequences in their respective samples. Despite this high level of overlap, only one OTU was enriched in cellulose-supplemented cultures from all rumen samples. Otherwise, each set of replicate cellulose supplemented cultures originating from a sampled rumen environment was found to have a distinct bacterial composition. Two of the seven most enriched OTUs were closely matched to well-established rumen cellulose utilizers (Ruminococcus flavefaciens and Fibrobacter succinogenes, while the others did not show high nucleotide sequence identity to currently defined bacterial species. The latter were affiliated to Prevotella (1 OTU, Ruminococcaceae (3 OTUs, and the candidate phylum Saccharibacteria (1 OTU, respectively. While further investigations will be necessary to elucidate the metabolic function(s of each enriched OTU, these results together further support cellulose utilization as a ruminal metabolic trait shared across vast phylogenetic distances, and that the rumen is an environment conducive to the selection of a broad range of microbial adaptations for the digestion of plant structural polysaccharides.

  3. Studies of thermal annealing and dope composition on the enhancement of separation performance cellulose acetate membrane for brackish water treatment from Jepara

    Directory of Open Access Journals (Sweden)

    Tutuk Djoko Kusworo

    2014-08-01

    Full Text Available Membrane is an alternative technology of water treatment with filtration principle that is being widely developed and used for water treatment. The main objective of this study was to make an asymmetric membrane using cellulose acetate polymer and study the effect of additive and annealing treatment on the morphology structure and performance of cellulose acetate membranes in brackish water treatment. Asymmetric membranes for brackish water treatment were casted using a casting machine process from dope solutions containing cellulose acetates and acetone as a solvent. Membranes was prepared by phase inversion method  with variation of polyethylene glycol (PEG concentration of 1 and 5 wt% and with thermal annealing at 60 oC in 10 seconds and without thermal annealing behavior. Membrane characterization consists of calculation of membrane flux and rejection with brackish water as a feed from Jepara. The research concluded that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion method. The more added concentration of PEG will be resulted the larger pore of membrane. Meanwhile the higher temperature and the longer time of annealing treatment, the skin layer of membrane become denser. Membrane with the composition of 18 wt% cellulose acetate, 5 wt% PEG, 1 wt% distilled water, with heat treatment at temperature of 60 oC for 10 seconds is obtained optimal performance.

  4. Molecular automata assembly: principles and simulation of bacterial membrane construction.

    Science.gov (United States)

    Lahoz-Beltra, R

    1997-01-01

    The motivation to understand the basic rules and principles governing molecular self-assembly may be relevant to explain in the context of molecular biology the self-organization and biological functions exhibited within cells. This paper presents a molecular automata model to simulate molecular self-assembly introducing the concept of molecular programming to simulate the biological function or operation performed by an assembled molecular state machine. The method is illustrated modelling Escherichia coli membrane construction including the assembly and operation of ATP synthase as well as the assembly of the bacterial flagellar motor. Flagellar motor operation was simulated using a different approach based on state machine definition used in virtual reality systems. The proposed methodology provides a modelling framework for simulation of biological functions performed by cellular components and other biological systems suitable to be modelled as molecular state machines.

  5. Bacterial membrane vesicles as novel nanosystems for drug delivery

    Directory of Open Access Journals (Sweden)

    Jain S

    2017-08-01

    Full Text Available Sapna Jain, Jonathan Pillai Implants, Devices and Drug Delivery Systems Laboratory, Centre for Biodesign and Diagnostics, Translational Health Science and Technology Institute, Faridabad, Haryana, India Abstract: Bacterial membrane vesicles (BMVs are closed spherical nanostructures that are shed naturally and ubiquitously by most bacterial species both in vivo and in vitro. Researchers have elucidated their roles in long-distance transport of a wide array of cargoes, such as proteins, toxins, antigens, virulence factors, microbicidal agents and antibiotics. Given that these natural carriers are important players in intercellular communication, it has been hypothesized that they are equally well attuned for transport and delivery of exogenous therapeutic cargoes. Additionally, BMVs appear to possess specific properties that enable their utilization as drug delivery vehicles. These include their ability to evade the host immune system, protection of the therapeutic payload and natural stability. Using bioengineering approaches, BMVs have been applied as carriers of therapeutic moieties in vaccines and for targeted delivery in cancer. In this article, we explore BMVs from the perspective of understanding their applicability to drug delivery. BMV biology, including biogenesis, physiology and pathology, is briefly reviewed. Practical issues related to bioprocessing, loading of therapeutic moieties and characterization for enabling scalability and commercial viability are evaluated. Finally, challenges to clinical translation and rational design approaches for novel BMV formulations are presented. Although the realization of the full potential of BMVs in drug delivery hinges on the development of scalable approaches for their production as well as the refinement of targeting and loading methods, they are promising candidates for development of a novel generation of drug delivery vehicles in future. Keywords: bacteria, membrane vesicles, immune system

  6. Electrophoretic deposition of cellulose nanocrystals (CNs) and CNs/alginate nanocomposite coatings and free standing membranes.

    Science.gov (United States)

    Chen, Qiang; de Larraya, Uxua Pérez; Garmendia, Nere; Lasheras-Zubiate, María; Cordero-Arias, Luis; Virtanen, Sannakaisa; Boccaccini, Aldo R

    2014-06-01

    This study presents the electrophoretic deposition (EPD) of cellulose nanocrystals (CNs) and CNs-based alginate composite coatings for biomedical applications. The mechanism of anodic deposition of CNs and co-deposition of CNs/alginate composites was analyzed based on the results of zeta-potential, Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) analyses. The capability of the EPD technique for manipulating the orientation of CNs and for the preparation of multilayer CNs coatings was demonstrated. The nanotopographic surface roughness and hydrophilicity of the deposited coatings were measured and discussed. Electrochemical testing demonstrated that a significant degree of corrosion protection of stainless steel could be achieved when CNs-containing coatings were present. Additionally, the one-step EPD-based processing of free-standing CNs/alginate membranes was demonstrated confirming the versatility of EPD to fabricate free-standing membrane structures compared to a layer-by-layer deposition technique. CNs and CNs/alginate nanocomposite coatings produced by EPD are potential candidates for biomedical, cell technology and drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Intrauterine bacterial findings in postpartum cows with retained fetal membranes.

    Science.gov (United States)

    Bekana, M; Jonsson, P; Ekman, T; Kindahl, H

    1994-11-01

    Eleven Swedish postpartum cows with retained fetal membranes (RFM) were studied to determine the intrauterine bacterial flora. Bacteriological examination was performed from twice weekly uterine biopsies. A total of 161 biopsies were collected during the first 8 weeks postpartum of which 82 (50.9%) were found with bacterial growth. Seventy-one of the 82 bacteria-positive biopsies (86.6%) showed mixed infections whereas the remaining 11 (13.4%) were pure cultures. Generally, a total of 322 isolates belonging to 12 different genera of bacteria, 6 facultative and 6 obligate anaerobic pathogens were identified. Mixed infections were most frequent for Actinomyces pyogenes together with obligate anaerobic bacteria, especially Bacteroides levii/spp. and Fusobacterium necrophorum. All of the studied cows had an infection that involved the first two genera of bacteria, whereas F. necrophorum was found in 8 of the 11 animals. The present work suggests that a possible pathogenic synergism between A. pyogenes and the two main Gram-negative anaerobes might have caused early endometritis and/or persistent infection.

  8. Grafting of Bacterial Polyhydroxybutyrate (PHB) onto Cellulose via In Situ Reactive Extrusion with Dicumyl Peroxide

    Science.gov (United States)

    Liqing Wei; Armando G. McDonald; Nicole M. Stark

    2015-01-01

    Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin...

  9. Gram's Stain Does Not Cross the Bacterial Cytoplasmic Membrane.

    Science.gov (United States)

    Wilhelm, Michael J; Sheffield, Joel B; Sharifian Gh, Mohammad; Wu, Yajing; Spahr, Christian; Gonella, Grazia; Xu, Bolei; Dai, Hai-Lung

    2015-07-17

    For well over a century, Hans Christian Gram's famous staining protocol has been the standard go-to diagnostic for characterizing unknown bacteria. Despite continuous and ubiquitous use, we now demonstrate that the current understanding of the molecular mechanism for this differential stain is largely incorrect. Using the fully complementary time-resolved methods: second-harmonic light-scattering and bright-field transmission microscopy, we present a real-time and membrane specific quantitative characterization of the bacterial uptake of crystal-violet (CV), the dye used in Gram's protocol. Our observations contradict the currently accepted mechanism which depicts that, for both Gram-negative and Gram-positive bacteria, CV readily traverses the peptidoglycan mesh (PM) and cytoplasmic membrane (CM) before equilibrating within the cytosol. We find that not only is CV unable to traverse the CM but, on the time-scale of the Gram-stain procedure, CV is kinetically trapped within the PM. Our results indicate that CV, rather than dyes which rapidly traverse the PM, is uniquely suited as the Gram stain.

  10. Direct observation of bacterial deposition on and detachment from nanocomposite membranes embedded with silver nanoparticles.

    Science.gov (United States)

    Liu, Yaolin; Rosenfield, Eric; Hu, Meng; Mi, Baoxia

    2013-06-01

    A microscope-equipped online monitoring system was used to investigate the bacterial deposition and detachment kinetics of a nanocomposite membrane that was synthesized by embedding silver nanoparticles in a polysulfone membrane. A pure polysulfone membrane was used as a control in the experiments. The deposition experiments with live bacteria showed that the bacterial deposition rates were the same for the nanocomposite and control polysulfone membranes. After the rinsing experiments, however, on average a high bacterial detachment ratio of 75% was observed for the nanocomposite membrane, compared with 18% for the control polysulfone membrane. These results indicate that the presence of silver nanoparticles as an antibacterial agent enhances the antiadhesive property of the nanocomposite membrane by decreasing the capability of bacteria in permanently attaching to the membrane surface. A quartz crystal microbalance with dissipation was used to study silver leaching. It was found that silver leaching significantly decreased within the first few hours. Deposition and rinsing experiments with dead bacterial cells revealed that the dead cell deposition rates were similar for both membranes, and so were the detachment ratios. Since the nanocomposite membrane did not show any antiadhesive action against dead cells, its antiadhesive property was most likely attributed to its ability to inhibit biological activities. Results of the antibacterial experiments confirmed that the nanocomposite membrane was highly effective in inhibiting bacterial growth with an antibacterial efficiency of over 98%, which did not decrease even after the membrane was soaked in DI water for seven days. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Rheological performance of bacterial cellulose based nonmineralized and mineralized hydrogel scaffolds

    Science.gov (United States)

    Basu, Probal; Saha, Nabanita; Bandyopadhyay, Smarak; Saha, Petr

    2017-05-01

    Bacterial cellulose (BC) based hydrogels (BC-PVP and BC-CMC) are modified with β-tri-calcium phosphate (β-TCP) and hydroxyapatite (HA) to improve the structural and functional properties of the existing hydrogel scaffolds. The modified hydrogels are then biomineralized with CaCO3 following liquid diffusion technique, where salt solutions of Na2CO3 (5.25 g/100 mL) and CaCl2 (7.35 g/100 mL) were involved. The BC-PVP and BC-CMC are being compared with the non-mineralized (BC-PVP-β-TCP/HA and BC-CMC-β-TCP/HA) and biomineralized (BC-PVP-β-TCP/HA-CaCO3 and BC-CMC-β-TCP/HA-CaCO3) hydrogels on the basis of their structural and rheological properties. The Fourier Transform Infrared (FTIR) spectral analysis demonstrated the presence of BC, CMC, PVP, β-TCP, HA in the non-mineralized and BC, CMC, PVP, β-TCP, HA and CaCO3 in the biomineralized samples. Interestingly, the morphological property of non-mineralized and biomineralized, hydrogels are different than that of BC-PVP and BC-CMC based novel biomaterials. The Scanning Electron Microscopic (SEM) images of the before mentioned samples reveal the denser structures than BC-PVP and BC-CMC, which exhibits the changes in their pore sizes. Concerning rheological analysis point of view, all the non-mineralized and biomineralized hydrogel scaffolds have shown significant elastic property. Additionally, the complex viscosity (η*) values have also found in decreasing order with the increase of angular frequency (ω) 0.1 rad.sec-1 to 100 rad.sec-1. All these BC based hydrogel scaffolds are elastic in nature, can be recommended for their application as an implant for bone tissue engineering.

  12. Bacterial Cellulose Shifts Transcriptome and Proteome of Cultured Endothelial Cells Towards Native Differentiation.

    Science.gov (United States)

    Feil, Gerhard; Horres, Ralf; Schulte, Julia; Mack, Andreas F; Petzoldt, Svenja; Arnold, Caroline; Meng, Chen; Jost, Lukas; Boxleitner, Jochen; Kiessling-Wolf, Nicole; Serbest, Ender; Helm, Dominic; Kuster, Bernhard; Hartmann, Isabel; Korff, Thomas; Hahne, Hannes

    2017-09-01

    Preserving the native phenotype of primary cells in vitro is a complex challenge. Recently, hydrogel-based cellular matrices have evolved as alternatives to conventional cell culture techniques. We developed a bacterial cellulose-based aqueous gel-like biomaterial, dubbed Xellulin, which mimics a cellular microenvironment and seems to maintain the native phenotype of cultured and primary cells. When applied to human umbilical vein endothelial cells (HUVEC), it allowed the continuous cultivation of cell monolayers for more than one year without degradation or dedifferentiation. To investigate the impact of Xellulin on the endothelial cell phenotype in detail, we applied quantitative transcriptomics and proteomics and compared the molecular makeup of native HUVEC, HUVEC on collagen-coated Xellulin and collagen-coated cell culture plastic (polystyrene).Statistical analysis of 12,475 transcripts and 7831 proteins unveiled massive quantitative differences of the compared transcriptomes and proteomes. K -means clustering followed by network analysis showed that HUVEC on plastic upregulate transcripts and proteins controlling proliferation, cell cycle and protein biosynthesis. In contrast, HUVEC on Xellulin maintained, by and large, the expression levels of genes supporting their native biological functions and signaling networks such as integrin, receptor tyrosine kinase MAP/ERK and PI3K signaling pathways, while decreasing the expression of proliferation associated proteins. Moreover, CD34-an endothelial cell differentiation marker usually lost early during cell culture - was re-expressed within 2 weeks on Xellulin but not on plastic. And HUVEC on Xellulin showed a significantly stronger functional responsiveness to a prototypic pro-inflammatory stimulus than HUVEC on plastic.Taken together, this is one of the most comprehensive transcriptomic and proteomic studies of native and propagated HUVEC, which underscores the importance of the morphology of the cellular

  13. Characterization of TEMPO-oxidized bacterial cellulose scaffolds for tissue engineering applications

    International Nuclear Information System (INIS)

    Luo, Honglin; Xiong, Guangyao; Hu, Da; Ren, Kaijing; Yao, Fanglian; Zhu, Yong; Gao, Chuan; Wan, Yizao

    2013-01-01

    Introduction of active groups on the surface of bacterial cellulose (BC) nanofibers is one of the promising routes of tailoring the performance of BC scaffolds for tissue engineering. This paper reported the introduction of aldehyde groups to BC nanofibers by 2,2,6,6-tetramethylpyperidine-1-oxy radical (TEMPO)-mediated oxidation and evaluation of the potential of the TEMPO-oxidized BC as tissue engineering scaffolds. Periodate oxidation was also conducted for comparison. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses were carried out to determine the existence of aldehyde groups on BC nanofibers and the crystallinity. In addition, properties relevant to scaffold applications such as morphology, fiber diameter, mechanical properties, and in vitro degradation were characterized. The results indicated that periodate oxidation could introduce free aldehyde to BC nanofibers and the free aldehyde groups on the TEMPO-oxidized BC tended to transfer to acetal groups. It was also found that the advantageous 3D structure of BC scaffolds remained unchanged and that no significant changes in morphology, fiber diameter, tensile structure and in vitro degradation were found after TEMPO-mediated oxidation while significant differences were observed upon periodate oxidation. The present study revealed that TEMPO-oxidation could impart BC scaffolds with new functions while did not degrade their intrinsic advantages. - Highlights: • TEMPO-mediated oxidation on BC scaffold for tissue engineering use was conducted. • TEMPO-mediated oxidation did not degrade the intrinsic advantages of BC scaffold. • TEMPO-mediated oxidation could impart BC scaffold with new functional groups. • Feasibility of TEMPO-oxidized BC as tissue engineering scaffold was confirmed

  14. The silica-doped sulfonated poly(fluorenyl ether ketone)s membrane using hydroxypropyl methyl cellulose as dispersant for high temperature proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.F.; Wang, S.J.; Xiao, M.; Bian, S.G.; Meng, Y.Z. [State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, Sun Yat-sen University, Xingangxi Road, Guangzhou 510275 (China)

    2009-05-15

    The sulfonated poly(fluorenyl ether ketone)s (SPFEK) membranes doped with SiO{sub 2} and dispersed by hydroxypropyl methyl cellulose (HPMC) were prepared and investigated for polymer electrolyte membrane fuel cells (PEMFCs) used at high temperature and low relative humidity (RH). The above membrane was prepared by solution dispersion of SPFEK and SiO{sub 2} using HPMC as dispersant. The physio-chemical properties of the hybrid membrane were studied by means of scanning electron microscope (SEM), ion-exchange capacity (IEC), proton conductivity, and single cell performance tests. The hybrid membranes dispersed by HPMC were well dispersed when compared with common organic/inorganic hybrid membranes. The hybrid membranes showed superior characteristics as a proton exchange membrane (PEM) for PEMFC application, such as high ionic exchange content (IEC) of 1.51 equiv/g, high temperature operation properties, and the satisfactory ability of anti-H{sub 2} crossover. The single cell performances of the hybrid membranes were examined in a 5 cm{sup 2} commercial single cell at both 80 C and 120 C under different relative humidity (RH) conditions. The hybrid membrane dispersed by HPMC gave the best performance of 260 mW/cm{sup 2} under conditions of 0.4 V, 120 C, 50% RH and ambient pressure. The results demonstrated HPMC being an efficient dispersant for the organic/inorganic hybrid membrane used for PEM fuel cell. (author)

  15. Preparation, characterization and thermal studies of polymer inclusion cellulose acetate membrane with calix[4]resorcinarenes as carriers

    Energy Technology Data Exchange (ETDEWEB)

    Benosmane, Nadjib [Laboratoire de Chimie Organique Appliquee (Groupe Heterocycles Associe CRAPC), Faculte de Chimie, Universite des Sciences et de la Technologie Houari Boumediene, BP 32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Guedioura, Bouzid [Division reacteur/Centre de Recherche Nucleaire de Draria, CRND, BP 43 Draria, Alger (Algeria); Hamdi, Safouane Mohammed [Laboratoire de Biochimie-Purpan, Institut Federatif de Biologie, CHU Toulouse 330, avenue de Grande-Bretagne - F-31059 Toulouse Cedex 9 (France); Hamdi, Maamar [Laboratoire de Chimie Organique Appliquee (Groupe Heterocycles Associe CRAPC), Faculte de Chimie, Universite des Sciences et de la Technologie Houari Boumediene, BP 32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria); Boutemeur, Baya, E-mail: bayakheddis@hotmail.com [Laboratoire de Chimie Organique Appliquee (Groupe Heterocycles Associe CRAPC), Faculte de Chimie, Universite des Sciences et de la Technologie Houari Boumediene, BP 32, El-Alia, 16111 Bab-Ezzouar, Alger (Algeria)

    2010-07-20

    A polymer inclusion membrane (PIM) system with cellulose acetate polymer as support and calix[4]resorcinarenes as carriers has been developed. Special attention was paid to PIM characterization using scanning electron microscopy, Fourier-transform infra-red study, X-ray scattering and thermogravimetric analyses. The efficiency of the membrane transport was optimized as a function of pH, stirring speed, aqueous phases and membrane composition. The results suggested that the transport mechanism is a counter-transport of protons, the mechanism was mainly controlled by the diffusion of the complex formed in the membrane core. Analysis of lead(II) transport through these PIMs was performed. It was found that calix[4]resorcinarenes containing membranes were flexible, resistant and heterogeneous without plasticizer addition.

  16. Superhydrophilic graphene oxide@electrospun cellulose nanofiber hybrid membrane for high-efficiency oil/water separation.

    Science.gov (United States)

    Ao, Chenghong; Yuan, Wei; Zhao, Jiangqi; He, Xu; Zhang, Xiaofang; Li, Qingye; Xia, Tian; Zhang, Wei; Lu, Canhui

    2017-11-01

    Inspired from fishscales, membranes with special surface wettability have been applied widely for the treatment of oily waste water. Herein, a novel superhydrophilic graphene oxide (GO)@electrospun cellulose nanofiber (CNF) membrane was successfully fabricated. This membrane exhibited a high separation efficiency, excellent antifouling properties, as well as a high flux for the gravity-driven oil/water separation. Moreover, the GO@CNF membrane was capable to effectively separate oil/water mixtures in a broad pH range or with a high concentration of salt, suggesting that this membrane was quite promising for future real-world practice in oil spill cleanup and oily wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Methanogenic degradation of toilet-paper cellulose upon sewage treatment in an anaerobic membrane bioreactor at room temperature.

    Science.gov (United States)

    Chen, Rong; Nie, Yulun; Kato, Hiroyuki; Wu, Jiang; Utashiro, Tetsuya; Lu, Jianbo; Yue, Shangchao; Jiang, Hongyu; Zhang, Lu; Li, Yu-You

    2017-03-01

    Toilet-paper cellulose with rich but refractory carbon sources, are the main insoluble COD fractions in sewage. An anaerobic membrane bioreactor (AnMBR) was configured for sewage treatment at room temperature and its performance on methanogenic degradation of toilet paper was highlighted. The results showed, high organic removal (95%), high methane conversion (90%) and low sludge yield (0.08gVSS/gCOD) were achieved in the AnMBR. Toilet-paper cellulose was fully biodegraded without accumulation in the mixed liquor and membrane cake layer. Bioconversion efficiency of toilet paper approached 100% under a high organic loading rate (OLR) of 2.02gCOD/L/d and it could provide around 26% of total methane generation at most of OLRs. Long sludge retention time and co-digestion of insoluble/soluble COD fractions achieving mutualism of functional microorganisms, contributed to biodegradation of toilet-paper cellulose. Therefore the AnMBR successfully implemented simultaneously methanogenic bioconversion of toilet-paper cellulose and soluble COD in sewage at room temperature. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Novel proton exchange membranes based on structure-optimized poly(ether ether ketone ketone)s and nanocrystalline cellulose

    Science.gov (United States)

    Ni, Chuangjiang; Wei, Yingcong; Zhao, Qi; Liu, Baijun; Sun, Zhaoyan; Gu, Yan; Zhang, Mingyao; Hu, Wei

    2018-03-01

    Two sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were synthesized as the matrix of composite proton exchange membranes by directly sulfonating copolymer precursors comprising non-sulfonatable fluorinated segments and sulfonatable fluorenyl-containing segments. Surface-modified nanocrystalline cellulose (NCC) was produced as the "performance-enhancing" filler by treating the microcrystalline cellulose with acid. Two families of SFPEEKK/NCC nanocomposite membranes with various NCC contents were prepared via a solution-casting procedure. Results revealed that the insertion of NCC at a suitable ratio could greatly enhance the proton conductivity of the pristine membranes. For example, the proton conductivity of SFPEEKK-60/NCC-4 (SFPEEKK with 60% fluorenyl segments in the repeating unit, and inserted with 4% NCC) composite membrane was as high as 0.245 S cm-1 at 90 °C, which was 61.2% higher than that of the corresponding pure SFPEEKK-60 membrane. This effect could be attributed to the formation of hydrogen bond networks and proton conduction paths through the interaction between -SO3H/-OH groups on the surface of NCC particles and -SO3H groups on the SFPEEKK backbones. Furthermore, the chemically modified NCC filler and the optimized chemical structure of the SFPEEKK matrix also provided good dimensional stability and mechanical properties of the obtained nanocomposites. In conclusion, these novel nanocomposites can be promising proton exchange membranes for fuel cells at moderate temperatures.

  19. Layer-by-layer structured polysaccharides-based multilayers on cellulose acetate membrane: Towards better hemocompatibility, antibacterial and antioxidant activities

    Science.gov (United States)

    Peng, Lincai; Li, Hui; Meng, Yahong

    2017-04-01

    The development of multifunctional cellulose acetate (CA) membranes with enhanced hemocompatibility and antibacterial and antioxidant activities is extremely important for biomedical applications. In this work, significant improvements in hemocompatibility and antibacterial and antioxidant activities of cellulose acetate (CA) membranes were achieved via layer-by-layer (LBL) deposition of chitosan (CS) and water-soluble heparin-mimicking polysaccharides (i.e., sulfated Cantharellus cibarius polysaccharides, SCP) onto their surface. The surface chemical compositions, growth manner, surface morphologies, and wetting ability of CS/SCP multilayer-modified CA membranes were characterized, respectively. The systematical evaluation of hemocompatibility revealed that CS/SCP multilayer-modified CA membranes significantly improved blood compatibility including resistance to non-specific protein adsorption, suppression of platelet adhesion and activation, prolongation of coagulation times, inhibition of complement activation, as well as reduction in blood hemolysis. Meanwhile, CS/SCP multilayer-modified CA membranes exhibited strong growth inhibition against Escherichia coli and Staphylococcus aureus, as well as high scavenging abilities against superoxide and hydroxyl radicals. In summary, the CS/SCP multilayers could confer CA membranes with integrated hemocompatibility and antibacterial and antioxidant activities, which might have great potential application in the biomedical field.

  20. TEKNOLOGI PERVAPORASI UNTUK PENINGKATAN KADAR PATCHOULI ALKOHOL MINYAK NILAM MENGGUNAKAN MEMBRAN SELULOSA ASETAT (Pervaporation Technology to Increase Patchouli Alcohol Content in Patchouli Oil Using Cellulose Acetate Membrane

    Directory of Open Access Journals (Sweden)

    Yuliani Aisyah

    2013-07-01

    Full Text Available An attempt to increase patchouli alcohol content in patchouli oil using membrane pervaporation has been carried out in this study. The preparation of cellulose acetate membrane in this study by was done using phase inversion method. The pervaporation process of patchouli oil was carried out at 30 °C, 40 °C, 50 °C, 60 °C and pervaporation time of 1, 2, 3 and 4 hours. Analysis of patchouli oil was carried out using gas chromatography, the separation performance membrane were expressed as a permeability (flux and selectivity. There are significant effect of pervaporation temperature and time on patchouli alcohol content, flux and selectivity. The pervaporation process of patchouli oil using cellulose acetate membrane showed that the patchouli alcohol content increased 1.89 times of the initial content of patchouli alcohol before pervaporation, by using pervaporation temperature of 60 °C and pervaporation time of 4 hours. The highest value of flux 0,163 kg/m2 hr and selectivity 2,77. Keywords: patchouli alcohol, cellulose acetate, pervaporation, flux, selectivity   ABSTRAK Telah dilakukan penelitian yang bertujuan untuk meningkatkan kadar patchouli alkohol di dalam minyak nilam. Pembuatan membran dilakukan dengan menggunakan metoda inversi fasa. Pervaporasi minyak nilam dilakukan dengan menggunakan suhu 30 °C, 40 °C, 50 °C, 60 °C dan waktu pervaporasi 1, 2, 3 dan 4 jam. Analisis kadar patchouli alkohol dilakukan menggunakan kromatografi gas, sedangkan kinerja membran dinyatakan sebagai permeabilitas (fluks dan selektivitas. Hasil penelitian menunjukkan bahwa suhu dan waktu pervaporasi berpengaruh signifikan terhadap kadar patchouli alkohol, fluks dan selektivitas. Proses pervaporasi minyak nilam dapat meningkatkan kadar patchouli alkohol 1,89 kali dari kadar patchouli alkohol sebelum dilakukan pervaporasi, yaitu dengan menggunakan suhu pervaporasi 60 °C dan waktu pervaporasi 4 jam. Nilai fluks 0,163 kg/m2 hr dan selektivitas 2,77. Kata

  1. Assessing the impact of lyophilization process in production of implants based on the bacterial cellulose using Raman spectroscopy method

    Science.gov (United States)

    Timchenko, E. V.; Timchenko, P. E.; Pisareva, E. V.; Vlasov, M. Yu; Revin, V. V.; Klenova, N. A.; Asadova, A. A.

    2017-01-01

    In this article we present the research results of lyophilization process influence on the composition of hybrid materials based on the bacterial cellulose (BC) using Raman spectroscopy method. As an object of research was used BC, as well as hybrids based on it, comprising the various combinations of hydroxyapatite (HAP) and collagen. Our studies showed that during the lyophilization process changes the ratio of the individual components. It was found that for samples hybrid based on BC with addition of HAP occurs increase of PO4 3- peak intensity in the region 956 cm-1 with decreasing width, which indicates a change in the degree of HAP crystallinity.

  2. Assessing the impact of lyophilization process in production of implants based on the bacterial cellulose using Raman spectroscopy method

    International Nuclear Information System (INIS)

    Timchenko, E V; Timchenko, P E; Pisareva, E V; Vlasov, M Yu; Revin, V V; Klenova, N A; Asadova, A A

    2017-01-01

    In this article we present the research results of lyophilization process influence on the composition of hybrid materials based on the bacterial cellulose (BC) using Raman spectroscopy method. As an object of research was used BC, as well as hybrids based on it, comprising the various combinations of hydroxyapatite (HAP) and collagen. Our studies showed that during the lyophilization process changes the ratio of the individual components. It was found that for samples hybrid based on BC with addition of HAP occurs increase of PO 4 3- peak intensity in the region 956 cm -1 with decreasing width, which indicates a change in the degree of HAP crystallinity. (paper)

  3. Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground Water Quality and Remediation Progress at DoD Sites for Perchlorate and Explosives Compounds (ER-0313)

    Science.gov (United States)

    2010-09-30

    Printed on recycled paper TECHNICAL REPORT TR-2341-ENV Final Technical Report DEMONSTRATION AND VALIDATION OF A REGENERATED CELLULOSE...rigid polypropylene cylinders with hydrophilic cellulose acetate or polysulfone flat filter membranes covering each end (Ronen et al. 1987; Magaritz

  4. Development of Nano-hybrid Cellulose Acetate/TiO2 Membrane for Eugenol Purification from Crude Clove Leaf Oil

    Directory of Open Access Journals (Sweden)

    Kusworo Tutuk Djoko

    2018-01-01

    Full Text Available Chemical separation and purification are the important part of the chemical industry which consumes up to 70% energy cost. The separation technology such as distillation and absorption are well known in essential oil purification. The purification of clove leaf oil needs an attention because the current technology still consumes high energy and produces chemical wastes. The employment of membrane separation for clove leaf purification is a novel concept that needs many improvements. The main problem of polymeric membrane utilization is eugenol ability to dissolve the polymer membrane. Cellulose acetate is one of membrane polymers that is insoluble in eugenol. This paper reveals the performance of nanohybrid CA/TiO2 membrane for eugenol purification. The stability of produced membrane as an organic solvent nanofiltration (OSN is evaluated in this study. The SEM image result shows that fabricated membrane has an asymmetric structure of membrane sub-layer. The different nano-particles loading shows the variation of permeate fluxes, the increase of nano-particles in polymer blend tends to increase the permeability. Thus, this study provides an overview of the potential CA/TiO2 for OSN development by incorporating inorganic nano-particles in membrane polymers for eugenol purification that can be integrated in upstream separation process.

  5. Facile fouling resistant surface modification of microfiltration cellulose acetate membranes by using amino acid L-DOPA.

    Science.gov (United States)

    Azari, Sara; Zou, Linda; Cornelissen, Emile; Mukai, Yasushito

    2013-01-01

    A major obstacle in the widespread application of microfiltration membranes in the wet separation processes such as wastewater treatment is the decline of permeates flux as a result of fouling. This study reports on the surface modification of cellulose acetate (CA) microfiltration membrane with amino acid L-3,4-dihydroxy-phenylalanine (L-DOPA) to improve fouling resistance of the membrane. The membrane surface was characterised using Fourier transform infrared spectroscopy (FTIR), water contact angle and zeta potential measurement. Porosity measurement showed a slight decrease in membrane porosity due to coating. Static adsorption experiments revealed an improved resistance of the modified membranes towards the adhesion of bovine serum albumin (BSA) as the model foulant. Dead end membrane filtration tests exhibited that the fouling resistance of the modified membranes was improved. However, the effect of the modification depended on the foulant solution concentration. It is concluded that L-DOPA modification is a convenient and non-destructive approach to enable low-BSA adhesion surface modification of CA microfiltration membranes. Nevertheless, the extent of fouling resistance improvement depends on the foulant concentration.

  6. Structural, chemical surface and transport modifications of regenerated cellulose dense membranes due to low-dose γ-radiation

    International Nuclear Information System (INIS)

    Vazquez, M.I.; Heredia-Guerrero, J.A.; Galan, P.; Benitez, J.J.; Benavente, J.

    2011-01-01

    Research highlights: → Low dose γ-radiation causes slight structural, chemical and morphological changes on regenerated cellulose films. → Induced structural changes increase the fragility of irradiated films. → Structural modifications reduce ion permeability of films. - Abstract: Modifications caused in commercial dense regenerated cellulose (RC) flat membranes by low-dose γ-irradiation (average photons energy of 1.23 MeV) are studied. Slight structural, chemical and morphological surface changes due to irradiation in three films with different RC content were determined by ATR-FTIR, XRD, XPS and AFM. Also, the alteration of their mechanical elasticity has been studied. Modification of membrane performance was determined from solute diffusion coefficient and effective membrane fixed charge concentration obtained from NaCl diffusion measurements. Induced structural changes defining new and effective fracture propagation directions are considered to be responsible for the increase of fragility of irradiated RC membranes. The same structural changes are proposed to explain the reduction of the membrane ion permeability through a mechanism involving either ion pathways elongation and/or blocking.

  7. Manipulation of host membranes by the bacterial pathogens Listeria, Francisella, Shigella and Yersinia.

    Science.gov (United States)

    Pizarro-Cerdá, Javier; Charbit, Alain; Enninga, Jost; Lafont, Frank; Cossart, Pascale

    2016-12-01

    Bacterial pathogens display an impressive arsenal of molecular mechanisms that allow survival in diverse host niches. Subversion of plasma membrane and cytoskeletal functions are common themes associated to infection by both extracellular and intracellular pathogens. Moreover, intracellular pathogens modify the structure/stability of their membrane-bound compartments and escape degradation from phagocytic or autophagic pathways. Here, we review the manipulation of host membranes by Listeria monocytogenes, Francisella tularensis, Shigella flexneri and Yersinia spp. These four bacterial model pathogens exemplify generalized strategies as well as specific features observed during bacterial infection processes. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Performance of cellulose acetate - polyethersulphone blend membrane prepared using microwave heating for palm oil mill effluent treatment.

    Science.gov (United States)

    Idris, A; Ahmed, I; Jye, H W

    2007-01-01

    The objective of this research is to investigate the performance of blend cellulose acetate (CA)-polyethersulphone (PES) membranes prepared using microwave heating (MWH) techniques and then compare it with blend CA-PES membranes prepared using conventional heating (CH) methods using bovine serum albumin solution. The superior membranes were then used in the treatment of palm oil mill effluent (POME). Various blends of CA-PES have been blended with PES in the range of 1-5 wt%. This distinctive series of dope formulations of blend CA/PES and pure CA was prepared using N, N-dimethylformamide (DMF) as solvent. The dope solution was prepared by MW heating for 5 min at a high pulse and the membranes were prepared by phase inversion method. The performances of these membranes were evaluated in terms of pure water and permeate flux, percentage removal of total suspended solids (TSS), chemical oxygen demand (COD) and biochemical oxygen demand (BOD). The results indicate that blend membranes prepared using the microwave technique is far more superior compared to that prepared using CH. Blend membranes with 19% CA, 1-3% PES and 80% of DMF solvent were found to be the best membrane formulation.

  9. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

  10. Nano- and macroscale structural and mechanical properties of in situ synthesized bacterial cellulose/PEO-b-PPO-b-PEO biocomposites.

    Science.gov (United States)

    Tercjak, Agnieszka; Gutierrez, Junkal; Barud, Hernane S; Domeneguetti, Rafael R; Ribeiro, Sidney J L

    2015-02-25

    Highly transparent biocomposite based on bacterial cellulose (BC) mat modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer (EPE) were fabricated in situ during biosynthesis of bacterial cellulose in a static culture from Gluconacetobacter xylinum. The effect of the addition to the culture medium of water-soluble EPE block copolymer on structure, morphology, crystallinity, and final properties of the novel biocomposites was investigated at nano- and macroscale. High compatibility between components was confirmed by ATR-FTIR indicating hydrogen bond formation between the OH group of BC and the PEO block of EPE block copolymer. Structural properties of EPE/BC biocomposites showed a strong effect of EPE block copolymer on the morphology of the BC mats. Thus, the increase of the EPE block copolymer content lead to the generation of spherulites of PEO block, clearly visualized using AFM and MO technique, changing crystallinity of the final EPE/BC biocomposites investigated by XRD. Generally, EPE/BC biocomposites maintain thermal stability and mechanical properties of the BC mat being 1 wt % EPE/BC biocomposite material with the best properties. Biosynthesis of EPE/BC composites open new strategy to the utilization of water-soluble block copolymers in the preparation of BC mat based biocomposites with tunable properties.

  11. In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

    Science.gov (United States)

    Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

    2014-02-15

    Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Membrane Made of Cellulose Acetate with Polyacrylic Acid Reinforced with Carbon Nanotubes and Its Applicability for Chromium Removal

    Directory of Open Access Journals (Sweden)

    J. A. Sánchez-Márquez

    2015-01-01

    Full Text Available Membranes made of carbon nanotubes and cellulose acetate with polyacrylic acid were designed in order to study their properties and their applicability for chromium removal. The membranes were prepared by phase inversion method using cellulose acetate and polyacrylic acid. Carbon nanotubes were added to the membrane during their process of synthesis in proportions of 1% by weight. The pores in the material are formed in layers, giving the effect of depth and forming a network. Both the carbon nanotubes and membranes were characterized by IR, Raman, and SEM spectroscopy. In addition, the concentration of acidic and basic sites and the surface charge in the materials were determined. The concentration of acid sites for oxidized nanotubes was 4.0 meq/g. The removal of Cr(VI was studied as a function of contact time and of initial concentration of Cr(VI. The removal of Cr(VI (~90% mainly occurs in a contact time from 32 to 64 h when the initial concentration of Cr(VI is 1 mg/L.

  13. Cytotoxicity and Acute Gastrointestinal Toxicity of Bacterial Cellulose-Poly (acrylamide-sodium acrylate Hydrogel: A Carrier for Oral Drug Delivery

    Directory of Open Access Journals (Sweden)

    Manisha Pandey 1,2 * , Hira Choudhury 1, Mohd Cairul Iqbal Mohd Amin 2

    2016-12-01

    Full Text Available Background: Preliminary safety evaluation of polymer intended to use as drug delivery carrier is essential. Methods: In this study polyacrylamide grafted bacterial cellulose (BC/AM hydrogel was prepared by microwave irradiation initiated free radical polymerization. The synthesized hydrogel was subjected to in vitro cytotoxicity and acute gastrointestinal toxicity studies to evaluate its biological safety as potential oral drug delivery carrier. Results: The results indicate that hydrogel was non cytotoxic and did not show any histopathological changes in GI tract after a high dose of oral administration. Conclusion: The results revealed that hydrogel composed of bacterial cellulose and polyacrylamide is safe as oral drug delivery carrier.

  14. Transferrins selectively cause ion efflux through bacterial and artificial membranes

    NARCIS (Netherlands)

    Aguilera, O; Quiros, LM; Fierro, JF

    2003-01-01

    Serum transferrin, ovotransferrin and lactoferrin constitute the most notable members of the transferrin family. Among their multiple biological functions, they possess an important antibacterial activity. These proteins can permeate the Escherichia coli outer membrane, reaching the inner membrane

  15. Functionalization of regenerated cellulose membrane via surface initiated atom transfer radical polymerization for boron removal from aqueous solution.

    Science.gov (United States)

    Wei, Yu-Ting; Zheng, Yu-Ming; Chen, J Paul

    2011-05-17

    In this study, an adsorptive membrane was prepared for efficient boron removal. Poly(glycidyl methacrylate) was grafted on the surfaces of the regenerated cellulose (RC) membrane via surface-initiated atom transfer radical polymerization, and N-methylglucamine was used to further react with epoxide rings to introduce polyhydroxyl functional groups, which served as the major binding sites for boron. The pristine and modified membranes were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), dynamic water contact angle measurement, and scanning electron microscopy. It was shown that the designed functional groups were successfully grafted onto the RC membrane, and surface modification contributed to higher boron binding capability. The optimal pH range for boron adsorption was 4-8. Under a neutral pH condition, the maximum adsorption capacity of the modified membrane was determined to be 0.75 mmol/g, which was comparable with those of commercial resins. Studies of electrolyte influence indicated the formation of inner-sphere surface complexes on the membrane surface. The ATR-FTIR and XPS analyses showed that secondary alcohol and tertiary amine groups were mainly involved in boron adsorption, and tetrahedral boron complexes were found on the membrane surface.

  16. Cellulose utilization in forest litter and soil: identification of bacterial and fungal decomposers

    Czech Academy of Sciences Publication Activity Database

    Štursová, Martina; Žifčáková, Lucia; Leigh, M. B.; Burgess, R.; Baldrian, Petr

    2012-01-01

    Roč. 80, č. 3 (2012), s. 735-746 ISSN 0168-6496 R&D Projects: GA ČR GA526/08/0751; GA MŠk(CZ) ME10028 Institutional research plan: CEZ:AV0Z50200510 Keywords : cellobiohydrolase * decomposition * cellulose Subject RIV: EE - Microbiology, Virology Impact factor: 3.563, year: 2012

  17. Honeycomb membranes prepared from 3-O-amino acid functionalized cellulose derivatives.

    Science.gov (United States)

    Xu, William Z; Bar-Nir, Batia Ben-Aroya; Kadla, John F

    2014-01-16

    The development of value-added wood-derived polymer products is of significant importance. Of particular interest is the synthesis of advanced bioactive cellulosic materials. In the present research, novel cellulosic honeycomb films are reported. Cellulose was reacted with dimethylthexylsilyl chloride to form regioselective 2,6-di-O-thexyldimethylsilyl cellulose followed by substitution of the C3 with functionalized poly(ethylene glycol) (PEG). The free end of the PEG side chains of the regioselective 3-O-poly(ethylene glycol)-2,6-di-O-thexyldimethylsilyl cellulose served as an attachment point for bioactive molecules. As an example, Fmoc-Gly-OH was linked to the free end of PEG to produce 3-O-Fmoc-Gly-poly(ethylene glycol)-2,6-di-O-thexyldimethylsilyl cellulose. Honeycomb films were produced through film casting under a humid airflow. AFM analysis revealed the directed self-assembly of the 3-O-Fmoc-Gly-poly(ethylene glycol)-2,6-di-O-thexyldimethylsilyl cellulose wherein the pendent 3-O-Fmoc-Gly-poly(ethylene glycol) groups allocated preferentially around the edges of the honeycomb pores. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Development of Low Cost Membranes (Ta, Nb & Cellulose Acetate) for H2/CO2 Separation in WGS Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Seetala, Naidu [Grambling State Univ., LA (United States); Siriwardane, Upali [Louisiana Tech Univ., Ruston, LA (United States)

    2011-12-15

    The main aim of this work is to synthesize low temperature bimetallic nanocatalysts for Water Gas Shift reaction (WGS) for hydrogen production from CO and steam mixture; and develop low-cost metal (Nb/Ta)/ceramic membranes for H2 separation and Cellulose Acetate membranes for CO2 separation. .

  19. Characterisation and comparison of bacterial communities on reverse osmosis membranes of a full-scale desalination plant by bacterial 16S rRNA gene metabarcoding

    OpenAIRE

    Nagaraj, Veena; Skillman, Lucy; Ho, Goen; Li, Dan; Gofton, Alexander

    2017-01-01

    Microbiomes of full-scale seawater reverse osmosis membranes are complex and subject to variation within and between membrane units. The pre-existing bacterial communities of unused membranes before operation have been largely ignored in biofouling studies. This study is novel as unused membranes were used as a critical benchmark for comparison. Fouled seawater reverse osmosis membrane biofilm communities from an array of autopsied membrane samples, following a 7-year operational life-span in...

  20. Electrospinning polyvinylidene fluoride fibrous membranes containing anti-bacterial drugs used as wound dressing.

    Science.gov (United States)

    He, Ting; Wang, Jingnan; Huang, Peilin; Zeng, Baozhen; Li, Haihong; Cao, Qingyun; Zhang, Shiying; Luo, Zhuo; Deng, David Y B; Zhang, Hongwu; Zhou, Wuyi

    2015-06-01

    The aim of this study was to synthesis drug-loaded fibrous membrane scaffolds for potential applications as wound dressing. Polyvinylidene fluoride (PVDF) fibrous membranes were loaded with enrofloxacin (Enro) drugs by using an electrospinning process, and their mechanical strength, drug release profile and anti-bacterial properties were evaluated. Enro drug-loaded PVDF membranes exhibited good elasticity, flexibility and excellent mechanical strength. The electrospinning Enro/PVDF membranes showed a burst drug release in the initial 12h, followed by sustained release for the next 3 days, which was an essential property for antibiotic drugs applied for wound healing. The drug-loaded PVDF fibrous membranes displayed excellent anti-bacterial activity toward Escherichia coli and Staphylococcus aureus. The results suggest that electrospinning PVDF membrane scaffolds loaded with drugs can be used as wound dressing. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Electrochemical Characterization of a Polymer Inclusion Membrane Made of Cellulose Triacetate and Aliquat 336 and Its Application to Sulfonamides Separation

    Directory of Open Access Journals (Sweden)

    Juana Benavente

    2018-01-01

    Full Text Available An electrochemical characterization of a polymer inclusion membrane (PIM fabricated with the ionic liquid (IL Aliquat 336 (26% and the polymer cellulose triacetate (CTA (76% is presented. Considering the use of PIMs in separation systems to remove pollutants from water, the characterization was performed with NaCl solutions by measuring membrane potential, electrochemical impedance spectroscopy, and salt diffusion and results were compared with those obtained from dry membranes. Results showed a significant reduction in the membrane diffusive permeability and electrical conductivity as well as the transport number of cation Na+ across the PIM when compared with solution values, which could be mainly related to the dense character of the membrane. Membrane application in the separation of different sulfonamides (sulfathiazole, sulfapyridine, sulfamethazine, and sulfamethoxazole from water, with 1 M NaCl solution as striping phase, was also considered. These results indicated that the different chemical characteristics of the compounds, as well as the compact structure of the PIM, limited the transport of the organic molecules though it.

  2. Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

    KAUST Repository

    Chen, Si Cong

    2013-11-08

    We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

  3. Modification of Bacterial Cellulose with Quaternary Ammonium Compounds Based on Fatty Acids and Amino Acids and the Effect on Antimicrobial Activity.

    Science.gov (United States)

    Żywicka, Anna; Fijałkowski, Karol; Junka, Adam F; Grzesiak, Jakub; El Fray, Miroslawa

    2018-04-02

    In the present work, bacterial cellulose (BC) membranes have been modified with bioactive compounds based on long chain dimer of C18 linoleic acid, referred to as the dilinoleic acid (DLA) and tyrosine (Tyr), a natural amino acid capable of forming noncovalent cation-π interactions with positively charged ethylene diamine (EDA). This new compound, [EDA][DLA-Tyr], has been synthesized by simple coupling reaction, and its chemical structure was characterized by 1 H NMR and Fourier transform infrared spectroscopy. The antimicrobial activity of a new compound against S. aureus and S. epidermidis, two cocci associated with skin and wound infections, was assessed. The [EDA][DLA-Tyr] impregnated BC exhibited strong and long-term antimicrobial activity against both staphylococcal species. The results showed a 57-66% and 56-60% reduction in S. aureus and S. epidermidis viability, respectively, depending on [EDA][DLA-Tyr] concentration used. Importantly, [EDA][DLA-Tyr] molecules were released gradually from the BC pellicle, while a reference antibiotic, erythromycine (ER), did not show any antibacterial activity against S. aureus and S. epidermidis after 48 h of soaking in deionized water. Thus, a combination of [EDA][DLA-Tyr] and BC could be a promising new class of wound dressing displaying both biocompatibility and antimicrobial activity.

  4. Targeting bacterial membrane function: an underexploited mechanism for treating persistent infections

    OpenAIRE

    Hurdle, Julian G.; O’Neill, Alex J.; Chopra, Ian; Lee, Richard E.

    2011-01-01

    Persistent infections involving slow-growing or non-growing bacteria are hard to treat with antibiotics that target biosynthetic processes in growing cells. Consequently, there is a need for antimicrobials that can treat infections containing dormant bacteria. In this Review, we discuss the emerging concept that disrupting the bacterial membrane bilayer or proteins that are integral to membrane function (including membrane potential and energy metabolism) in dormant bacteria is a strategy for...

  5. Integration of bacterial lytic polysaccharide monooxygenases into designer cellulosomes promotes enhanced cellulose degradation.

    Science.gov (United States)

    Arfi, Yonathan; Shamshoum, Melina; Rogachev, Ilana; Peleg, Yoav; Bayer, Edward A

    2014-06-24

    Efficient conversion of cellulose into soluble sugars is a key technological bottleneck limiting efficient production of plant-derived biofuels and chemicals. In nature, the process is achieved by the action of a wide range of cellulases and associated enzymes. In aerobic microrganisms, cellulases are secreted as free enzymes. Alternatively, in certain anaerobic microbes, cellulases are assembled into large multienzymes complexes, termed "cellulosomes," which allow for efficient hydrolysis of cellulose. Recently, it has been shown that enzymes classified as lytic polysaccharide monooxygenases (LPMOs) were able to strongly enhance the activity of cellulases. However, LPMOs are exclusively found in aerobic organisms and, thus, cannot benefit from the advantages offered by the cellulosomal system. In this study, we designed several dockerin-fused LPMOs based on enzymes from the bacterium Thermobifida fusca. The resulting chimeras exhibited activity levels on microcrystalline cellulose similar to that of the wild-type enzymes. The dockerin moieties of the chimeras were demonstrated to be functional and to specifically bind to their corresponding cohesin partner. The chimeric LPMOs were able to self-assemble in designer cellulosomes alongside an endo- and an exo-cellulase also converted to the cellulosomal mode. The resulting complexes showed a 1.7-fold increase in the release of soluble sugars from cellulose, compared with the free enzymes, and a 2.6-fold enhancement compared with free cellulases without LPMO enhancement. These results highlight the feasibility of the conversion of LPMOs to the cellulosomal mode, and that these enzymes can benefit from the proximity effects generated by the cellulosome architecture.

  6. Sorting of bacterial lipoproteins to the outer membrane by the Lol system.

    Science.gov (United States)

    Narita, Shin-ichiro; Tokuda, Hajime

    2010-01-01

    Bacterial lipoproteins comprise a subset of membrane proteins with a lipid-modified cysteine residue at their amino termini through which they are anchored to the membrane. In Gram-negative bacteria, lipoproteins are localized on either the inner or the outer membrane. The Lol system is responsible for the transport of lipoproteins to the outer membrane.The Lol system comprises an inner-membrane ABC transporter LolCDE complex, a periplasmic carrier protein, LolA, and an outer membrane receptor protein, LolB. Lipoproteins are synthesized as precursors in the cytosol and then translocated across the inner membrane by the Sec translocon to the outer leaflet of the inner membrane, where lipoprotein precursors are processed to mature lipoproteins. The LolCDE complex then mediates the release of outer membrane-specific lipoproteins from the inner membrane while the inner membrane-specific lipoproteins possessing Asp at position 2 are not released by LolCDE because it functions as a LolCDE avoidance signal, causing the retention of these lipoproteins in the inner membrane. A water-soluble lipoprotein-LolA complex is formed as a result of the release reaction mediated by LolCDE. This complex traverses the hydrophilic periplasm to reach the outer membrane, where LolB accepts a lipoprotein from LolA and then catalyzes its incorporation into the inner leaflet of the outer membrane.

  7. Evaluating the possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater for bacterial cellulose production by Gluconacetobacter xylinus.

    Science.gov (United States)

    Huang, C; Yang, X-Y; Xiong, L; Guo, H-J; Luo, J; Wang, B; Zhang, H-R; Lin, X-Q; Chen, X-D

    2015-05-01

    To reduce the cost of bacterial cellulose (BC) production, the possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater with high COD value (18 050 mg l(-1) ) for BC production by Gluconacetobacter xylinus was evaluated. After 7 days of fermentation, the highest BC yield (1·34 g l(-1) ) was obtained. The carbon sources including sugars (glucose and xylose), organic acids (acetic acid and butyric acid) and alcohol compounds (ethanol and butanol) were utilized by G. xylinus simultaneously during fermentation. Although the COD decrease ratio (about 14·7%) was low, the highest BC yield on COD consumption (56·2%, g g(-1) ) was relatively high and the remaining wastewater could be used for further BC fermentation. Besides, the environment of ABE fermentation wastewater showed small influence on the BC structure by comparison with the BC products obtained in traditional HS medium using field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Overall, ABE fermentation wastewater is one promising substrate for BC production. The possibility of using acetone-butanol-ethanol (ABE) fermentation wastewater for bacterial cellulose (BC) production by Gluconacetobacter xylinus was evaluated in this study. This is the first time that ABE fermentation wastewater was used as substrate for BC fermentation. The results provide detail information of metabolism of G. xylinus in ABE fermentation wastewater and the influence of wastewater environment on the structure of BC samples. Overall, this bioconversion could reduce the cost of BC production greatly. © 2015 The Society for Applied Microbiology.

  8. Modified nanocrystal cellulose/fluorene-containing sulfonated poly(ether ether ketone ketone) composites for proton exchange membranes

    Science.gov (United States)

    Wei, Yingcong; Shang, Yabei; Ni, Chuangjiang; Zhang, Hanyu; Li, Xiaobai; Liu, Baijun; Men, Yongfeng; Zhang, Mingyao; Hu, Wei

    2017-09-01

    Highly sulfonated poly(ether ether ketone ketone)s (SFPEEKKs) with sulfonation degrees of 2.34 (SFPEEKK5) and 2.48 (SFPEEKK10) were synthesized through the direct sulfonation of a fluorene-containing poly(ether ether ketone ketone) under a relatively mild reaction condition. Using the solution blending method, sulfonated nanocrystal cellulose (sNCC)-enhanced SFPEEKK composites (SFPEEKK/sNCC) were successfully prepared for investigation as proton exchange membranes. Transmission electron microscopy showed that sNCC was uniformly distributed in the composite membranes. The properties of the composite membranes, including thermal stability, mechanical properties, water uptake, swelling ratio, oxidative stability and proton conductivity were thoroughly evaluated. Results indicated that the insertion of sNCC could contribute to water management and improve the mechanical performance of the membranes. Notably, the proton conductivity of SFPEEKK5/sNCC-5 was as high as 0.242 S cm-1 at 80 °C. All data proved the potential of SFPEEKK/sNCC composites for proton exchange membranes in medium-temperature fuel cells.

  9. Differing prevalence and diversity of bacterial species in fetal membranes from very preterm and term labor.

    Directory of Open Access Journals (Sweden)

    Hannah E Jones

    Full Text Available BACKGROUND: Intrauterine infection may play a role in preterm delivery due to spontaneous preterm labor (PTL and preterm prolonged rupture of membranes (PPROM. Because bacteria previously associated with preterm delivery are often difficult to culture, a molecular biology approach was used to identify bacterial DNA in placenta and fetal membranes. METHODOLOGY/PRINCIPAL FINDINGS: We used broad-range 16S rDNA PCR and species-specific, real-time assays to amplify bacterial DNA from fetal membranes and placenta. 74 women were recruited to the following groups: PPROM <32 weeks (n = 26; 11 caesarean; PTL with intact membranes <32 weeks (n = 19; all vaginal birth; indicated preterm delivery <32 weeks (n = 8; all caesarean; term (n = 21; 11 caesarean. 50% (5/10 of term vaginal deliveries were positive for bacterial DNA. However, little spread was observed through tissues and species diversity was restricted. Minimal bacteria were detected in term elective section or indicated preterm deliveries. Bacterial prevalence was significantly increased in samples from PTL with intact membranes [89% (17/19 versus 50% (5/10 in term vaginal delivery p = 0.03] and PPROM (CS [55% (6/11 versus 0% (0/11 in term elective CS, p = 0.01]. In addition, bacterial spread and diversity was greater in the preterm groups with 68% (13/19 PTL group having 3 or more positive samples and over 60% (12/19 showing two or more bacterial species (versus 20% (2/10 in term vaginal deliveries. Blood monocytes from women with PTL with intact membranes and PPROM who were 16S bacterial positive showed greater level of immune paresis (p = 0.03. A positive PCR result was associated with histological chorioamnionitis in preterm deliveries. CONCLUSION/SIGNIFICANCE: Bacteria are found in both preterm and term fetal membranes. A greater spread and diversity of bacterial species were found in tissues of women who had very preterm births. It is unclear to what extent the greater bacterial prevalence

  10. Application of Molecular Techniques to Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site

    International Nuclear Information System (INIS)

    Field, Erin K.; D'Imperio, Seth; Miller, Amber R.; VanEngelen, Michael R.; Gerlach, Robin; Lee, Brady D.; Apel, William A.; Peyton, Brent M.

    2010-01-01

    Low-level radioactive waste sites, including those at various U.S. Department of Energy (DOE) sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a non-radioactive model low-level waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rDNA clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both the clone library and PhyloChip results revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more unique Operational Taxonomic Units (OTUs), and therefore more relative diversity, than the clone libraries. Calculated diversity indices suggest that diversity is lowest in the Fill (F) and Fill Waste (FW) layers and greater in the Wood Waste (WW) and Waste Clay (WC) layers. Principal coordinates analysis and lineage specific analysis determined that Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose degrading microorganisms suggests the FW layer is an enrichment environment for cellulose degradation. Overall, these results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.

  11. Rapid Production of a Porous Cellulose Acetate Membrane for Water Filtration Using Readily Available Chemicals

    Science.gov (United States)

    Kaiser, Adrian; Stark, Wendelin J.; Grass, Robert N.

    2017-01-01

    A chemistry laboratory experiment using everyday items and readily available chemicals is described to introduce advanced high school students and undergraduate college students to porous polymer membranes. In a three-step manufacturing process, a membrane is produced at room temperature. The filtration principle of the membrane is then…

  12. Distribution and diversity of members of the bacterial phylum Fibrobacteres in environments where cellulose degradation occurs.

    Science.gov (United States)

    Ransom-Jones, Emma; Jones, David L; Edwards, Arwyn; McDonald, James E

    2014-10-01

    The Fibrobacteres phylum contains two described species, Fibrobacter succinogenes and Fibrobacter intestinalis, both of which are prolific degraders of cellulosic plant biomass in the herbivore gut. However, recent 16S rRNA gene sequencing studies have identified novel Fibrobacteres in landfill sites, freshwater lakes and the termite hindgut, suggesting that members of the Fibrobacteres occupy a broader ecological range than previously appreciated. In this study, the ecology and diversity of Fibrobacteres was evaluated in 64 samples from contrasting environments where cellulose degradation occurred. Fibrobacters were detected in 23 of the 64 samples using Fibrobacter genus-specific 16S rRNA gene PCR, which provided their first targeted detection in marine and estuarine sediments, cryoconite from Arctic glaciers, as well as a broader range of environmental samples. To determine the phylogenetic diversity of the Fibrobacteres phylum, Fibrobacter-specific 16S rRNA gene clone libraries derived from 17 samples were sequenced (384 clones) and compared with all available Fibrobacteres sequences in the Ribosomal Database Project repository. Phylogenetic analysis revealed 63 lineages of Fibrobacteres (95% OTUs), with many representing as yet unclassified species. Of these, 24 OTUs were exclusively comprised of fibrobacters derived from environmental (non-gut) samples, 17 were exclusive to the mammalian gut, 15 to the termite hindgut, and 7 comprised both environmental and mammalian strains, thus establishing Fibrobacter spp. as indigenous members of microbial communities beyond the gut ecosystem. The data highlighted significant taxonomic and ecological diversity within the Fibrobacteres, a phylum circumscribed by potent cellulolytic activity, suggesting considerable functional importance in the conversion of lignocellulosic biomass in the biosphere. Copyright © 2014 Elsevier GmbH. All rights reserved.

  13. Impact of Membrane Phospholipid Alterations in Escherichia coli on Cellular Function and Bacterial Stress Adaptation.

    Science.gov (United States)

    Rowlett, Veronica W; Mallampalli, Venkata K P S; Karlstaedt, Anja; Dowhan, William; Taegtmeyer, Heinrich; Margolin, William; Vitrac, Heidi

    2017-07-01

    Bacteria have evolved multiple strategies to sense and rapidly adapt to challenging and ever-changing environmental conditions. The ability to alter membrane lipid composition, a key component of the cellular envelope, is crucial for bacterial survival and adaptation in response to environmental stress. However, the precise roles played by membrane phospholipids in bacterial physiology and stress adaptation are not fully elucidated. The goal of this study was to define the role of membrane phospholipids in adaptation to stress and maintenance of bacterial cell fitness. By using genetically modified strains in which the membrane phospholipid composition can be systematically manipulated, we show that alterations in major Escherichia coli phospholipids transform these cells globally. We found that alterations in phospholipids impair the cellular envelope structure and function, the ability to form biofilms, and bacterial fitness and cause phospholipid-dependent susceptibility to environmental stresses. This study provides an unprecedented view of the structural, signaling, and metabolic pathways in which bacterial phospholipids participate, allowing the design of new approaches in the investigation of lipid-dependent processes involved in bacterial physiology and adaptation. IMPORTANCE In order to cope with and adapt to a wide range of environmental conditions, bacteria have to sense and quickly respond to fluctuating conditions. In this study, we investigated the effects of systematic and controlled alterations in bacterial phospholipids on cell shape, physiology, and stress adaptation. We provide new evidence that alterations of specific phospholipids in Escherichia coli have detrimental effects on cellular shape, envelope integrity, and cell physiology that impair biofilm formation, cellular envelope remodeling, and adaptability to environmental stresses. These findings hold promise for future antibacterial therapies that target bacterial lipid biosynthesis

  14. Structural basis for alginate secretion across the bacterial outer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, J.C.; Robinson, H.; Hay, I. D.; Li, C.; Eckford, P. D. W.; Amaya, M. F.; Wood, L. F.; Ohman, D. E.; Bear, C. E.; Rehm, B. H.; Howell, P. L.

    2011-08-09

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  15. Structural Basis for Alginate Secretion Across the Bacterial Outer Membrane

    Energy Technology Data Exchange (ETDEWEB)

    J Whitney; I Hay; C Li; P Eckford; H Robinson; M Amaya; L Wood; D Ohman; C Bear; et al.

    2011-12-31

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  16. Probing Induced Structural Changes in Biomimetic Bacterial Cell Membrane Interactions with Divalent Cations

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Allison M [ORNL; Standaert, Robert F [ORNL; Jubb, Aaron M [ORNL; Katsaras, John [ORNL; Johs, Alexander [ORNL

    2017-01-01

    Biological membranes, formed primarily by the self-assembly of complex mixtures of phospholipids, provide a structured scaffold for compartmentalization and structural processes in living cells. The specific physical properties of phospholipid species present in a given membrane play a key role in mediating these processes. Phosphatidylethanolamine (PE), a zwitterionic lipid present in bacterial, yeast, and mammalian cell membranes, is exceptional. In addition to undergoing the standard lipid polymorphic transition between the gel and liquid-crystalline phase, it can also assume an unusual polymorphic state, the inverse hexagonal phase (HII). Divalent cations are among the factors that drive the formation of the HII phase, wherein the lipid molecules form stacked tubular structures by burying the hydrophilic head groups and exposing the hydrophobic tails to the bulk solvent. Most biological membranes contain a lipid species capable of forming the HII state suggesting that such lipid polymorphic structural states play an important role in structural biological processes such as membrane fusion. In this study, the interactions between Mg2+ and biomimetic bacterial cell membranes composed of PE and phosphatidylglycerol (PG) were probed using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), and fluorescence spectroscopy. The lipid phase transitions were examined at varying ratios of PE to PG and upon exposure to physiologically relevant concentrations of Mg2+. An understanding of these basic interactions enhances our understanding of membrane dynamics and how membrane-mediated structural changes may occur in vivo.

  17. Living Membranes as Environmental Detectors

    Science.gov (United States)

    2016-02-19

    the original proposal. Working with the bacterial cellulose “ Living Membrane” system, we have addressed the major design and structural impediments...cloning of the cellulose genetic machinery. We have also identified potential future directions to optimize and 1. REPORT DATE (DD-MM-YYYY) 4. TITLE...Oct-2011 30-Sep-2015 Approved for Public Release; Distribution Unlimited Final Report: Living Membranes as Environmental Detectors The views, opinions

  18. Secretion of Bacterial Lipoproteins: Through the Cytoplasmic Membrane, the Periplasm and Beyond

    Science.gov (United States)

    Zückert, Wolfram R.

    2014-01-01

    Bacterial lipoproteins are peripherally anchored membrane proteins that play a variety of roles in bacterial physiology and virulence in monoderm (single membrane-enveloped, e.g., grampositive) and diderm (double membrane-enveloped, e.g., gram-negative) bacteria. After export of prolipoproteins through the cytoplasmic membrane, which occurs predominantly but not exclusively via the general secretory or Sec pathway, the proteins are lipid-modified at the cytoplasmic membrane in a multistep process that involves sequential modification of a cysteine residue and cleavage of the signal peptide by the signal II peptidase Lsp. In both monoderms and diderms, signal peptide processing is preceded by acylation with a diacylglycerol through preprolipoprotein diacylglycerol transferase (Lgt). In diderms but also some monoderms, lipoproteins are further modified with a third acyl chain through lipoprotein N-acyl transferase (Lnt). Fully modified lipoproteins that are destined to be anchored in the inner leaflet of the outer membrane (OM) are selected, transported and inserted by the Lol (lipoprotein outer membrane localization) pathway machinery, which consists of the inner-membrane (IM) ABC transporterlike LolCDE complex, the periplasmic LolA chaperone and the OM LolB lipoprotein receptor. Retention of lipoproteins in the cytoplasmic membrane results from Lol avoidance signals that were originally described as the “+2 rule”. Surface localization of lipoproteins in diderms is rare in most bacteria, with the exception of several spirochetal species. Type 2 (T2SS) and type 5 (T5SS) secretion systems are involved in secretion of specific surface lipoproteins of γ-proteobacteria. In the model spirochete Borrelia burgdorferi, surface lipoprotein secretion does not follow established sorting rules, but remains dependent on N-terminal peptide sequences. Secretion through the outer membrane requires maintenance of lipoproteins in a translocation-competent unfolded conformation

  19. Integrated photografted molecularly imprinted polymers with a cellulose acetate membrane for the extraction of melamine from dry milk before HPLC analysis.

    Science.gov (United States)

    Akbari-Adergani, Behrouz; Sadeghian, Gholam-Hossein; Alimohammadi, Alireza; Esfandiari, Zahra

    2017-03-01

    In this study, a new separation technique based on membrane extraction is described for the determination of melamine in dry milk. The water-compatible cellulose acetate membrane, which is photografted by melamine imprinted nanospheres, was prepared by placing the membrane into the polymerization solution containing methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as cross-linker, acetonitrile as porogen, and melamine as the template molecule. The characterization of the polymeric membrane was performed by Fourier transmission infrared spectroscopy and scanning electron microscopy. This integrated composite membrane was used as a solid-phase extraction medium for the extraction of melamine from dry milk samples. Various parameters affecting the extraction efficiency of the membrane were evaluated. The results showed higher binding capacity for melamine imprinted membranes in comparison with the nonimprinted membranes. High-performance liquid chromatography analysis showed that the extraction of melamine from dry milk by the photografted cellulose acetate membrane had a linear calibration curve in the range of 0.02-11.80 μg/mL with an excellent precision of 2.73%. The limit of detection and quantification of melamine was 0.007 and 0.020 μg/mL, respectively. The recoveries of melamine were in the range of 88.7-94.8%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Molecular mechanism of pore creation in bacterial membranes by amyloid proteins

    International Nuclear Information System (INIS)

    Tsigelny, I F; Sharikov, Y; Miller, M A; Masliah, E

    2009-01-01

    This study explores the mechanism of pore creation in cellular membranes by MccE92 bacterial proteins. The results of this study are then compared with the mechanism of alpha-synuclein (aS)-based pore formation in mammalian cells, and its role in Parkinson's disease.

  1. Life without a cell membrane: Challenging the specificity of bacterial endophytes within Bryopsis (Bryopsidales, Chlorophyta

    Directory of Open Access Journals (Sweden)

    Hollants Joke

    2011-11-01

    Full Text Available Abstract Background The siphonous green macroalga Bryopsis has some remarkable characteristics. Besides hosting a rich endophytic bacterial flora, Bryopsis also displays extraordinary wound repair and propagation mechanisms. This latter feature includes the formation of protoplasts which can survive in the absence of a cell membrane for several minutes before regenerating into new individuals. This transient 'life without a membrane' state, however, challenges the specificity of the endophytic bacterial communities present and raises the question whether these bacteria are generalists, which are repeatedly acquired from the environment, or if there is some specificity towards the Bryopsis host. Results To answer this question, we examined the temporal stability and the uniqueness of endobiotic bacterial communities within Bryopsis samples from the Mexican west coast after prolonged cultivation. DGGE analysis revealed that Bryopsis endophytic bacterial communities are rather stable and clearly distinct from the epiphytic and surrounding cultivation water bacterial communities. Although these endogenous communities consist of both facultative and obligate bacteria, results suggest that Bryopsis owns some intrinsic mechanisms to selectively maintain and/or attract specific bacteria after repeated wounding events in culture. Conclusions This suggests that Bryopsis algae seem to master transient stages of life without a cell membrane well as they harbor specific - and possibly ecological significant - endophytic bacteria.

  2. A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

    Directory of Open Access Journals (Sweden)

    Haojie Fei

    2017-10-01

    Full Text Available The flexible supercapacitors (SCs of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2 and reduced graphene oxide (RGO nanosheet-piled hydrogel films and a novel bacterial cellulose (BC-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4 neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles.

  3. Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass.

    Science.gov (United States)

    Minty, Jeremy J; Singer, Marc E; Scholz, Scott A; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E; Liao, James C; Lin, Xiaoxia Nina

    2013-09-03

    Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system's performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator-cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals.

  4. Evaluation of the effect of the structure of bacterial cellulose on full thickness skin wound repair on a microfluidic chip.

    Science.gov (United States)

    Li, Ying; Wang, Shiwen; Huang, Rong; Huang, Zhuo; Hu, Binfeng; Zheng, Wenfu; Yang, Guang; Jiang, Xingyu

    2015-03-09

    Bacterial cellulose (BC) is a kind of nanobiomaterial for tissue engineering. How the nanoscale structure of BC affects skin wound repair is unexplored. Here, the hierarchical structure of BC films and their different effects on skin wound healing were studied both in vitro and in vivo. The bottom side of the BC film had a larger pore size, and a looser and rougher structure than that of the top side. By using a microfluidics-based in vitro wound healing model, we revealed that the bottom side of the BC film can better promote the migration of cells to facilitate wound healing. Furthermore, the full-thickness skin wounds on Wistar rats demonstrated that, compared with gauze and the top side of the BC film, the wound covered by the bottom side of the BC film showed faster recovery rate and less inflammatory response. The results indicate that the platform based on the microfluidic chip provide a rapid, reliable, and repeatable method for wound dressing screening. As an excellent biomaterial for wound healing, the BC film displays different properties on different sides, which not only provides a method to optimize the biocompatibility of wound dressings but also paves a new way to building heterogeneous BC-based biomaterials for complex tissue engineering.

  5. Development of Chitosan/Bacterial Cellulose Composite Films Containing Nanodiamonds as a Potential Flexible Platform for Wound Dressing

    Directory of Open Access Journals (Sweden)

    Fatemeh Ostadhossein

    2015-09-01

    Full Text Available Chitosan/bacterial cellulose composite films containing diamond nanoparticles (NDs with potential application as wound dressing are introduced. Microstructural studies show that NDs are uniformly dispersed in the matrix, although slight agglomeration at concentrations above 2 wt % is seen. Fourier transform infrared spectroscopy reveals formation of hydrogen bonds between NDs and the polymer matrix. X-ray diffraction analysis indicates reduced crystallinity of the polymer matrix in the presence of NDs. Approximately 3.5-fold increase in the elastic modulus of the composite film is obtained by the addition of 2 wt % NDs. The results of colorimetric analysis show that the composite films are transparent but turn to gray-like and semitransparent at high ND concentrations. Additionally, a decrease in highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO gap is also seen, which results in a red shift and higher absorption intensity towards the visible region. Mitochondrial activity assay using L929 fibroblast cells shows that the nanocomposite films are biocompatible (>90% after 24 h incubation. Multiple lamellapodia and cell-cell interaction are shown. The results suggest that the developed films can potentially be used as a flexible platform for wound dressing.

  6. Phase behavior of medium and high internal phase water-in-oil emulsions stabilized solely by hydrophobized bacterial cellulose nanofibrils.

    Science.gov (United States)

    Lee, Koon-Yang; Blaker, Jonny J; Murakami, Ryo; Heng, Jerry Y Y; Bismarck, Alexander

    2014-01-21

    Water-in-oil emulsions stabilized solely by bacterial cellulose nanofibers (BCNs), which were hydrophobized by esterification with organic acids of various chain lengths (acetic acid, C2-; hexanoic acid, C6-; dodecanoic acid, C12-), were produced and characterized. When using freeze-dried C6-BCN and C12-BCN, only a maximum water volume fraction (ϕw) of 60% could be stabilized, while no emulsion was obtained for C2-BCN. However, the maximum ϕw increased to 71%, 81%, and 77% for C2-BCN, C6-BCN, and C12-BCN, respectively, 150 h after the initial emulsification, thereby creating high internal phase water-in-toluene emulsions. The observed time-dependent behavior of these emulsions is consistent with the disentanglement and dispersion of freeze-dried modified BCN bundles into individual nanofibers with time. These emulsions exhibited catastrophic phase separation when ϕw was increased, as opposed to catastrophic phase inversion observed for other Pickering emulsions.

  7. Production of bacterial cellulose by Gluconacetobacter hansenii CGMCC 3917 using only waste beer yeast as nutrient source.

    Science.gov (United States)

    Lin, Dehui; Lopez-Sanchez, Patricia; Li, Rui; Li, Zhixi

    2014-01-01

    In order to improve the use of waste beer yeast (WBY) for bacterial cellulose production by Gluconacetobacter hansenii CGMCC 3917, a two-step pre-treatment was designed. First WBY was treated by 4 methods: 0.1M NaOH treatment, high speed homogenizer, ultrasonication and microwave treatment followed by hydrolysis (121°C, 20 min) under mild acid condition (pH 2). The optimal pre-treatment conditions were evaluated by the reducing sugar yield after hydrolysis. 15% WBY treated by ultrasonication for 40 min had the highest reducing sugar yield (29.19%), followed by NaOH treatment (28.98%), high speed homogenizer (13.33%) and microwaves (13.01%). Treated WBY hydrolysates were directly supplied as only nutrient source for BC production. A sugar concentration of 3% WBY hydrolysates treated by ultrasonication gave the highest BC yield (7.02 g/L), almost 6 times as that from untreated WBY (1.21 g/L). Furthermore, the properties of the BC were as good as those obtained from the conventional chemical media. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  8. In Situ Self-Assembled Nanocomposites from Bacterial Cellulose Reinforced with Eletrospun Poly(lactic acid/Lipids Nanofibers

    Directory of Open Access Journals (Sweden)

    Chunhui Xiang

    2017-05-01

    Full Text Available The goal of this study is to explore a new strategy to improve the mechanical and hydrophobic properties of bacterial cellulose (BC mats. The present work is the first to report the preparation of in situ self-assembled BC nanocomposites using electrospun hydrophobic poly(lactic acid (PLA or PLA/lipids (PLA/Lip nanofiber mats as foundation for BC nanofiber growth. Adding electrospun PLA mats to the BC culture media led to a two-fold increase in toughness with a 52% increase in elongation of the nanocomposites with regard to BC. The incorporation of electrospun PLA and PLA/Lip nanofiber mats lowered the moisture regain and water vapor transmission of BC nanocomposites relative to pure BC mats. The interfacial bonding between the individual components of a nanocomposite is a key factor for the improvement of composite strength, stiffness, and barrier properties; thus additional strategies to improve interaction between hydrophilic BC and hydrophobic PLA fibers need to be explored.

  9. Nano-gold assisted highly conducting and biocompatible bacterial cellulose-PEDOT:PSS films for biology-device interface applications.

    Science.gov (United States)

    Khan, Shaukat; Ul-Islam, Mazhar; Ullah, Muhammad Wajid; Israr, Muhammad; Jang, Jae Hyun; Park, Joong Kon

    2018-02-01

    This study reports the fabrication of highly conducting and biocompatible bacterial cellulose (BC)-gold nanoparticles (AuNPs)-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) (BC-AuNPs-PEDOT:PSS) composites for biology-device interface applications. The composites were fabricated using ex situ incorporation of AuNPs and PEDOT:PSS into the BC matrix. Structural characterization, using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD) analysis, confirmed the uniform nature of the synthesized BC-AuNPs and BC-AuNPs-PEDOT:PSS composites. Four-point probe analysis indicated that the BC-AuNPs and BC-AuNPs-PEDOT:PSS films had high electrical conductivity. The composites were also tested for biocompatibility with animal osteoblasts (MC3T3-E1). The composite films supported adhesion, growth, and proliferation of MC3T3-E1 cells, indicating that they are biocompatible and non-cytotoxic. AuNPs and PEDOT:PSS, imparted a voltage response, while BC imparted biocompatibility and bio-adhesion to the nanocomposites. Therefore, our BC-AuNPs-PEDOT:PSS composites are candidate materials for biology-device interfaces to produce implantable devices in regenerative medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Glycerol as a Cheaper Carbon Source in Bacterial Cellulose (BC) Production by Gluconacetobacter Xylinus DSM46604 in Batch Fermentation System

    International Nuclear Information System (INIS)

    Azila Adnan; Nair, G.R.; Roslan Umar; Roslan Umar

    2015-01-01

    Bacterial cellulose (BC) is a polymer of glucose monomers, which has unique properties including high crystallinity and high strength. It has potential to be used in biomedical applications such as making artificial blood vessel, wound dressings, and in the paper making industry. Extensive study on BC aimed to improve BC production such as by using glycerol as a cheaper carbon source. BC was produced in shake flask culture using five different concentrations of glycerol (10, 20, 30, 40 and 50 g/ L). Using concentration of glycerol above 20 g/ L inhibited culture growth and BC production. Further experiments were performed in batch culture (3-L bioreactor) using 20 g/ L glycerol. It produced yield and productivity of 0.15 g/ g and 0.29 g/ L/ day BC, respectively. This is compared with the control medium, 50 g/ L glucose, which only gave yield and productivity of 0.05 g/ g and 0.23 g/ L/ day, respectively. Twenty g/ L of glycerol enhanced BC production by Gluconacetobacter xylinus DSM46604 in batch fermentation system. (author)

  11. Bactericidal activity of curcumin I is associated with damaging of bacterial membrane.

    Directory of Open Access Journals (Sweden)

    Poonam Tyagi

    Full Text Available Curcumin, an important constituent of turmeric, is known for various biological activities, primarily due to its antioxidant mechanism. The present study focused on the antibacterial activity of curcumin I, a significant component of commercial curcumin, against four genera of bacteria, including those that are Gram-positive (Staphylococcus aureus and Enterococcus faecalis and Gram-negative (Escherichia coli and Pseudomonas aeruginosa. These represent prominent human pathogens, particularly in hospital settings. Our study shows the strong antibacterial potential of curcumin I against all the tested bacteria from Gram-positive as well as Gram-negative groups. The integrity of the bacterial membrane was checked using two differential permeabilization indicating fluorescent probes, namely, propidium iodide and calcein. Both the membrane permeabilization assays confirmed membrane leakage in Gram-negative and Gram-positive bacteria on exposure to curcumin I. In addition, scanning electron microscopy and fluorescence microscopy were employed to confirm the membrane damages in bacterial cells on exposure to curcumin I. The present study confirms the broad-spectrum antibacterial nature of curcumin I, and its membrane damaging property. Findings from this study could provide impetus for further research on curcumin I regarding its antibiotic potential against rapidly emerging bacterial pathogens.

  12. Effects of membrane lipid composition and antibacterial drugs on the rigidity of Escherichia coli: Different contributions of various bacterial substructures.

    Science.gov (United States)

    Li, Ming; Gan, Chaoye; Shao, Wenxiang; Yu, Chuan; Wang, Xingguo; Chen, Yong

    2016-01-01

    The rigidity/stiffness is an important biomechanical property of bacteria and potentially correlated with many bacterial activities. While the rigidity or fluidity of the bacterial membrane has been extensively studied, the contributions of different bacterial substructures to the bacterial rigidity are less investigated. Here, we utilized four Escherichia coli (E. coli) strains with different membrane lipid compositions and three antibacterial drugs (EDTA, lysozyme, and streptomycin) to specifically alter bacterial substructures. By using atomic force microscopy (AFM), we found that the average height and Young's modulus of phosphatidylethanolamine (PE)-deficient E. coli strains were larger than those of PE(+) strains and that EDTA, EDTA plus lysozyme instead of lysozyme alone, and streptomycin all caused significant decreases in height and Young's modulus of the four E. coli strains. Our data imply that membrane lipid composition, the integrated outer membrane, the cell wall, and the cytoplasmic content are all responsible for bacterial rigidity but to different extents. © Wiley Periodicals, Inc.

  13. Ultrafine nano-network structured bacterial cellulose as reductant and bridging ligands to fabricate ultrathin K-birnessite type MnO2 nanosheets for supercapacitors

    Science.gov (United States)

    Zhang, Xiaojuan; He, Mingqian; He, Ping; Li, Caixia; Liu, Huanhuan; Zhang, Xingquan; Ma, Yongjun

    2018-03-01

    In this work, nanostructured ultrathin K-birnessite type MnO2 nanosheets are successfully prepared by a rapid and environmently friendly hydrothermal method, which involves only a facile redox reaction between KMnO4 and nano-network structured bacterial cellulose with abundant hydroxyl groups. The results show that the unique three-dimensional interwoven structured bacterial cellulose acts as not only reductant but also bridging ligands for assembling nanoscaled building units to control the desired morphology of prepared MnO2. Furthermore, electrochemical performances of prepared MnO2 are investigated as electrode materials for supercapacitors by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M Na2SO4 electrolyte. The resulting ultrathin K-birnessite type MnO2 nanosheets based electrode exhibits higher capacitance (328.2 F g-1 at 0.2 A g-1), excellent rate capability (328.2 F g-1 and 200.4 F g-1 at 0.2 A g-1 and 2.0 A g-1, respectively) and satisfactory cyclic stability (91.6% of initial capacitance even after 2000 cycles at 3.0 A g-1). This work suggests that bacterial cellulose as reductant is a promising candidate in the development of nanostructures of metal oxides.

  14. Affinities and in-plane stress forces between glycopeptide antibiotics and biomimetic bacterial membranes

    Directory of Open Access Journals (Sweden)

    Sisi Bi

    2015-03-01

    Full Text Available Understanding the molecular basis of interactions between antibiotics affecting bacterial cell wall biosynthesis and cellular membranes is important in rational drug design of new drugs to overcome resistance. However, a precise understanding of how bacteriostatic antibiotics effect action often neglects the effect of biophysical forces involved following antibiotic-receptor binding events. We have employed a combination of a label-free binding biosensor (surface plasmon resonance, SPR and a force biosensor (in-plane stress cantilever, together with model membrane systems to study the complex interplay between glycopeptide antibiotics, their cognate ligands and different model membranes. Bacterial cell wall precursor analogue N-α-Docosanoyl-ε-acetyl-Lys-d-Alanine-d-Alanine (doc-KAA was inserted into lipid layers comprised of zwitterionic or anionic lipids then exposed to either vancomycin or the membrane-anchored glycopeptide antibiotic teicoplanin. Binding affinities and kinetics of the antibiotics to these model membranes were influenced by electrostatic interactions with the different lipid backgrounds, in addition to ligand affinities. In addition, cantilever sensors coated with model membranes showed that planar surface stress changes were induced by glycopeptide antibiotics adsorption and caused compressive surface stress generation in a ligand-dependent manner.

  15. Electrochemical characterization of pore formation by bacterial protein toxins on hybrid supported membranes.

    Science.gov (United States)

    Wilkop, Thomas; Xu, Danke; Cheng, Quan

    2008-05-20

    The interaction of pore-forming streptolysin O (SLO) with biomimetic lipid membranes has been studied by electrochemical methods. Phosphatidylcholine lipid vesicles were deposited onto gold electrodes modified with supporting layers of hexyl thioctate (HT) or thioctic acid tri(ethylene glycol) ester (TA-TEGE), and integrity and permeability of the resulting membranes were characterized by cyclic voltammetry and impedance spectroscopy. Both positively and negatively charged electrochemical probes, potassium ferrocyanide, hexaammineruthenium(III) chloride, and ferrocene carboxylic acid (FCA), were employed to evaluate their suitability to probe the membrane permeability properties, with FCA exhibiting ideal behavior and thus employed throughout the work. Fusion of vesicles incubated with SLO on the electrodes yielded membranes that showed a distinctive response pattern for FCA as a function of SLO concentration. A direct dependence of both the currents and peak separation of FCA in the cyclic voltammograms was observed over a concentration range of 0-10 hemolytic units (HU)/microL of the toxin. The interaction of SLO with preformed supported lipid membranes was also investigated, and much lower response was observed, suggesting a different extent of membrane-toxin interactions on such an interface. Nonionic surfactant Triton was found to disrupt the vesicle structure but could not completely remove a preformed membrane to fully restore the electrode response. The information reported here offers some unique insight into toxin-surface interactions on a hybrid membrane, facilitating the development of electrochemically based sensing platforms for detecting trace amounts of bacterial toxins via the perforation process.

  16. Biomimetic spiral-cylindrical scaffold based on hybrid chitosan/cellulose/nano-hydroxyapatite membrane for bone regeneration.

    Science.gov (United States)

    Jiang, Hong; Zuo, Yi; Zou, Qin; Wang, Huanan; Du, Jingjing; Li, Yubao; Yang, Xiaochao

    2013-11-27

    Natural bone is a complex material with well-designed architecture. To achieve successful bone integration and regeneration, the constituent and structure of bone-repairing scaffolds need to be functionalized synergistically based on biomimetics. In this study, a hybrid membrane composed of chitosan (CS), sodium carboxymethyl cellulose (CMC), and nano-hydroxyapatite (n-HA) was curled in a concentric manner to generate an anisotropic spiral-cylindrical scaffold, with compositional and structural properties mimicking natural bone. After optimization in terms of morphology, hydrophilicity, swelling and degradation pattern, the osteoblast cells seeded on the membrane of 60 wt% n-HA exhibited the highest cell viability and osteocalcin expression. In vivo osteogenesis assessment revealed that the spiral-cylindrical architecture played a dominant role in bone regeneration and osseointegration. Newly formed bone tissue grew through the longitudinal direction of the cylinder-shaped scaffold bridging both ends of the defect, bone marrow penetrated the entire scaffold and formed a medullary cavity in the center of the spiral cylinder. This study for the first time demonstrates that the spiral-cylindrical scaffold can promote complete infiltration of bone tissues in vivo, leading to successful osteointegration and functional reconstruction of bone defects. It suggests that the biomimetic spiral-cylindrical scaffold could be a promising candidate for bone regeneration applications.

  17. Microfibrillated cellulose sheets coating oxygen-permeable PDMS membranes induce rat hepatocytes 3D aggregation into stably-attached 3D hemispheroids.

    Science.gov (United States)

    Evenou, Fanny; Couderc, Sandrine; Kim, Beomjoon; Fujii, Teruo; Sakai, Yasuyuki

    2011-01-01

    Here we report the use of natural, chemically-unmodified, microfibrillated cellulose (MFC) as a matrix for hepatocyte culture. We developed an original cell-culture design composed of a thin 3D-microstructured fibrous substrate consisting of a MFC sheet coating a highly O(2)-permeable polydimethylsiloxane (PDMS) membrane. The MFC-coated PDMS membranes were obtained according to a simple process where cellulose fibres were deposited from an aqueous suspension on the PDMS surfaces and the films were dried under mild conditions. To enable oxygen diffusion through the membranes, they were assembled on bottomless frames ('O(2)+' condition). Rat hepatocytes primary-cultured on such MFC-PDMS membranes quickly organized themselves into large hemispherical 3D aggregates which were tightly anchored to the MFC sheets. In contrast, hepatocytes cultured on smooth PDMS membranes in the O(2)+ system (O(2)+, PDMS) organized into unstable 2D monolayers which easily detached from the surfaces. Hepatocyte 3D cultures obtained on MFC-PDMS membranes exhibited higher liver-specific functions over a 2-week culture period, as assessed by both the higher albumin secretion and urea synthesis rate. The MFC-PDMS membranes appear suitable for obtaining stably-attached and functional hepatocyte 3D cultures and appear interesting for drug/chemical screenings in a microplate format, but also for microfluidic applications.

  18. Pectin and Xyloglucan Influence the Attachment of Salmonella enterica and Listeria monocytogenes to Bacterial Cellulose-Derived Plant Cell Wall Models.

    Science.gov (United States)

    Tan, Michelle S F; Rahman, Sadequr; Dykes, Gary A

    2016-01-15

    Minimally processed fresh produce has been implicated as a major source of foodborne microbial pathogens globally. These pathogens must attach to the produce in order to be transmitted. Cut surfaces of produce that expose cell walls are particularly vulnerable. Little is known about the roles that different structural components (cellulose, pectin, and xyloglucan) of plant cell walls play in the attachment of foodborne bacterial pathogens. Using bacterial cellulose-derived plant cell wall models, we showed that the presence of pectin alone or xyloglucan alone affected the attachment of three Salmonella enterica strains (Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028, and Salmonella enterica subsp. indica M4) and Listeria monocytogenes ATCC 7644. In addition, we showed that this effect was modulated in the presence of both polysaccharides. Assays using pairwise combinations of S. Typhimurium ATCC 14028 and L. monocytogenes ATCC 7644 showed that bacterial attachment to all plant cell wall models was dependent on the characteristics of the individual bacterial strains and was not directly proportional to the initial concentration of the bacterial inoculum. This work showed that bacterial attachment was not determined directly by the plant cell wall model or bacterial physicochemical properties. We suggest that attachment of the Salmonella strains may be influenced by the effects of these polysaccharides on physical and structural properties of the plant cell wall model. Our findings improve the understanding of how Salmonella enterica and Listeria monocytogenes attach to plant cell walls, which may facilitate the development of better ways to prevent the attachment of these pathogens to such surfaces. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  19. Cellulose Aerogel Membranes with a Tunable Nanoporous Network as a Matrix of Gel Polymer Electrolytes for Safer Lithium-Ion Batteries.

    Science.gov (United States)

    Wan, Jiqiang; Zhang, Jinming; Yu, Jian; Zhang, Jun

    2017-07-26

    Cellulose aerogel membranes (CAMs) are proposed as a matrix for gel polymer electrolyte to the fabrication of lithium-ion batteries (LIBs) with superior thermal stability. The CAMs are obtained from a cellulose-ionic liquid solution via a dissolution-regeneration-supercritical drying route. The presence of high porosity, the nanoporous network structure, and numerous polar hydroxyl groups benefits the quick absorption of liquid electrolytes for gelation of the CAMs and improves the ionic conductivity of the gelled CAMs. LIBs assembled with the gelled CAMs display excellent electrochemical performance at room temperature, and more importantly, the intrinsic thermal resistance of cellulose allows the LIBs to run stably for at least 30 min at working temperatures as high as 120 °C. The CAMs, with their excellent thermal stability, are promising for the development of highly safe, cost-effective, and high-performance LIBs.

  20. Electrically conductive cellulose composite

    Science.gov (United States)

    Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

    2010-05-04

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  1. Utilization of composite membrane polyethyleneglycol-polystyrene-cellulose acetate from pineapple leaf fibers in lowering levels of methyl orange batik waste

    Science.gov (United States)

    Delsy, E. V. Y.; Irmanto; Kazanah, F. N.

    2017-02-01

    Pineapple leaves are agricultural waste from the pineapple that the fibers can be utilized as raw material in cellulose acetate membranes. First, made pineapple leaf fibers into pulp and then converted into cellulose acetate by acetylation process in four stages consisting of activation, acetylation, hydrolysis and purification. Cellulose acetate then used as the raw material to manufacture composite membrane with addition of polystyrene and poly (ethylene glycol) as porogen. Composite membrane is made using phase inversion method with dichloromethane-acetone as a solvent. The result of FTIR analysis (Fourier transform infra-red) showed that the absorption of the carbonyl group (C=O) is at 1643.10 cm-1 and acetyl group (C-O ) at 1227.01 cm-1, with a molecular weight of 8.05 x 104 g/mol and the contents (rate) of acetyl is 37.31%. PS-PEG-CA composite membrane had also been characterized by measuring the water flux values and its application to decrease methyl orange content (level) in batik waste. The results showed that the water flux value is of 25.62 L/(m2.hour), and the decrease percentage of methyl orange content in batik waste is 71.53%.

  2. Cell proliferation, viability, and in vitro differentiation of equine mesenchymal stem cells seeded on bacterial cellulose hydrogel scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Favi, Pelagie M.; Benson, Roberto S. [Department of Materials Science and Engineering, College of Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Neilsen, Nancy R. [Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996 (United States); Hammonds, Ryan L. [Department of Materials Science and Engineering, College of Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Bates, Cassandra C. [Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996 (United States); Stephens, Christopher P. [Department of Surgery, Graduate School of Medicine, University of Tennessee, Knoxville, TN 37996 (United States); Center for Materials Processing, University of Tennessee, Knoxville, TN 37996 (United States); Dhar, Madhu S., E-mail: mdhar@utk.edu [Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996 (United States)

    2013-05-01

    The culture of multipotent mesenchymal stem cells on natural biopolymers holds great promise for treatments of connective tissue disorders such as osteoarthritis. The safety and performance of such therapies relies on the systematic in vitro evaluation of the developed stem cell-biomaterial constructs prior to in vivo implantation. This study evaluates bacterial cellulose (BC), a biocompatible natural polymer, as a scaffold for equine-derived bone marrow mesenchymal stem cells (EqMSCs) for application in bone and cartilage tissue engineering. An equine model was chosen due to similarities in size, load and types of joint injuries suffered by horses and humans. Lyophilized and critical point dried BC hydrogel scaffolds were characterized using scanning electron microscopy (SEM) to confirm nanostructure morphology which demonstrated that critical point drying induces fibre bundling unlike lyophilisation. EqMSCs positively expressed the undifferentiated pluripotent mesenchymal stem cell surface markers CD44 and CD90. The BC scaffolds were shown to be cytocompatible, supporting cellular adhesion and proliferation, and allowed for osteogenic and chondrogenic differentiation of EqMSCs. The cells seeded on the BC hydrogel were shown to be viable and metabolically active. These findings demonstrate that the combination of a BC hydrogel and EqMSCs are promising constructs for musculoskeletal tissue engineering applications. - Highlights: ► Critical point drying induces fibre bundling unlike lyophilisation. ► Cells positively expressed undifferentiated pluripotent stem cell markers. ► BCs were cytocompatible, supported cell adhesion, proliferation and differentiation ► Cells seeded on BC scaffolds were viable and metabolically active. ► Findings demonstrate that BC and EqMSCs are promising tissue engineered constructs.

  3. Natural Products at Work: Structural Insights into Inhibition of the Bacterial Membrane Protein MraY.

    Science.gov (United States)

    Koppermann, Stefan; Ducho, Christian

    2016-09-19

    Natural(ly) fit: The X-ray crystal structure of the bacterial membrane protein MraY in complex with its natural product inhibitor muraymycin D2 is discussed. MraY catalyzes one of the membrane-associated steps in peptidoglycan biosynthesis and, therefore, represents a promising target for novel antibiotics. Structural insights derived from the protein-inhibitor complex might now pave the way for the development of new antimicrobial drugs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Method for the preparation of cellulose acetate flat sheet composite membranes for forward osmosis—Desalination using MgSO4 draw solution

    KAUST Repository

    Sairam, M.

    2011-06-01

    A lab scale method for the preparation of defect free flat sheet composite membranes for forward osmosis (FO) has been developed. Membranes containing a thin layer of cellulose acetate (CA) cast on a nylon fabric of 50μm thick were prepared by phase inversion in water. Cellulose acetate (CA) membranes with an overall thickness of 70-80μm have been prepared with lactic acid, maleic acid and zinc chloride as pore forming agents, at different annealing temperatures, for forward osmosis. These membranes have been tested in the desalination of saline feeds (35g·L-1 of NaCl) using magnesium sulphate solution (150g·L-1) as the draw solution. The water flux, and rejection of NaCl, were compared with those of commercially available membranes tested under the same FO conditions. The commercially available FO membrane from Hydration Technologies Inc, OR (M1) has a permeability of 0.13L·h-1·m-2·bar-1 with a NaCl rejection of 97% when tested with 150g·L-1 of MgSO4 in the draw solution. Another commercially available membrane for FO from Hydration Technologies Inc, OR, M2 has a water permeability of 0.014L·h-1·m-2·bar-1 with NaCl rejection of 100%. The flux and rejection of the CA membranes prepared in this work are found to be dependent on the nature of the pore forming agent, and annealing temperature. Impregnation of an inorganic filler, sodium montmorrillonite in CA membranes and coating of CA membranes with hydrophilic PVA did not enhance the flux of base CA membranes. Cellulose acetate membranes cast from dope solutions containing acetone/isopropanol and lactic acid, maleic acid and zinc chloride as pore forming agents have water permeabilities of 0.13, 0.09 and 0.68L·h-1·m-2·bar-1 respectively, with NaCl rejections of 97.7, 99.3 and 88% when annealed at 50°C. CA membranes prepared with zinc chloride as a pore forming agent have good permeability of 0.27L·h-1·m-2·bar-1 with a NaCl rejection of 95% when annealed at 70°C. © 2011.

  5. Characterization of membranes based on cellulose acetate butyrate/poly(caprolactone)triol/doxycycline and their potential for guided bone regeneration application.

    Science.gov (United States)

    Marques, Morgana Souza; Zepon, Karine Modolon; Petronilho, Fabrícia Cardoso; Soldi, Valdir; Kanis, Luiz Alberto

    2017-07-01

    This paper discusses the feasibility of using membranes based on cellulose acetate butyrate/poly(caprolactone)triol loaded with doxycycline for guided bone regeneration. Those membranes were obtained by solvent casting varying the cellulose acetate butyrate: poly(caprolactone)triol:doxycycline (CAB:PCL-T:DOX) mass ratios and characterized by scanning electron microscopy, differential scanning calorimetry, dynamical mechanical analysis, swelling and weight loss, drug release, in vitro antimicrobial activity and in vivo inflammatory response. Neat CAB and CAB:PCL-T:DOX membranes exhibited inner porous structure, which has a pore-size reduced with increasing of the PCL-T ratio. DSC results demonstrated that the molecular dispersion of the DOX into the CAB:PCL-T membrane was conditioned by PCL-T amount. Elastic modulus reduced noticeably with increased of the PCL-T ratio in the membrane from 2 to 3, while the strain at failure showed an increase of ca. 10-fold on the same condition. The DOX release mechanism from the membranes was found to be Fickian or quasi-Fickian diffusion. Membranes assessed immediately after the preparation, and even as the membranes immersed in synthetic saliva during 7 days, demonstrated significant inhibition in the growth of Staphylococcus aureus and Escherichia coli. Subcutaneous implant test on rat in vivo showed that the CAB:PCL-T:DOX membrane (7:3:1) did not trigger chronic inflammatory responses. These results suggest the feasibility in applying the CAB:PCL-T:DOX membrane as a barrier for guided bone regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Secretion of bacterial lipoproteins: through the cytoplasmic membrane, the periplasm and beyond.

    Science.gov (United States)

    Zückert, Wolfram R

    2014-08-01

    Bacterial lipoproteins are peripherally anchored membrane proteins that play a variety of roles in bacterial physiology and virulence in monoderm (single membrane-enveloped, e.g., gram-positive) and diderm (double membrane-enveloped, e.g., gram-negative) bacteria. After export of prolipoproteins through the cytoplasmic membrane, which occurs predominantly but not exclusively via the general secretory or Sec pathway, the proteins are lipid-modified at the cytoplasmic membrane in a multistep process that involves sequential modification of a cysteine residue and cleavage of the signal peptide by the signal II peptidase Lsp. In both monoderms and diderms, signal peptide processing is preceded by acylation with a diacylglycerol through preprolipoprotein diacylglycerol transferase (Lgt). In diderms but also some monoderms, lipoproteins are further modified with a third acyl chain through lipoprotein N-acyl transferase (Lnt). Fully modified lipoproteins that are destined to be anchored in the inner leaflet of the outer membrane (OM) are selected, transported and inserted by the Lol (lipoprotein outer membrane localization) pathway machinery, which consists of the inner-membrane (IM) ABC transporter-like LolCDE complex, the periplasmic LolA chaperone and the OM LolB lipoprotein receptor. Retention of lipoproteins in the cytoplasmic membrane results from Lol avoidance signals that were originally described as the "+2 rule". Surface localization of lipoproteins in diderms is rare in most bacteria, with the exception of several spirochetal species. Type 2 (T2SS) and type 5 (T5SS) secretion systems are involved in secretion of specific surface lipoproteins of γ-proteobacteria. In the model spirochete Borrelia burgdorferi, surface lipoprotein secretion does not follow established sorting rules, but remains dependent on N-terminal peptide sequences. Secretion through the outer membrane requires maintenance of lipoproteins in a translocation-competent unfolded conformation

  7. Predominant membrane localization is an essential feature of the bacterial signal recognition particle receptor

    Directory of Open Access Journals (Sweden)

    Graumann Peter

    2009-11-01

    Full Text Available Abstract Background The signal recognition particle (SRP receptor plays a vital role in co-translational protein targeting, because it connects the soluble SRP-ribosome-nascent chain complex (SRP-RNCs to the membrane bound Sec translocon. The eukaryotic SRP receptor (SR is a heterodimeric protein complex, consisting of two unrelated GTPases. The SRβ subunit is an integral membrane protein, which tethers the SRP-interacting SRα subunit permanently to the endoplasmic reticulum membrane. The prokaryotic SR lacks the SRβ subunit and consists of only the SRα homologue FtsY. Strikingly, although FtsY requires membrane contact for functionality, cell fractionation studies have localized FtsY predominantly to the cytosolic fraction of Escherichia coli. So far, the exact function of the soluble SR in E. coli is unknown, but it has been suggested that, in contrast to eukaryotes, the prokaryotic SR might bind SRP-RNCs already in the cytosol and only then initiates membrane targeting. Results In the current study we have determined the contribution of soluble FtsY to co-translational targeting in vitro and have re-analysed the localization of FtsY in vivo by fluorescence microscopy. Our data show that FtsY can bind to SRP-ribosome nascent chains (RNCs in the absence of membranes. However, these soluble FtsY-SRP-RNC complexes are not efficiently targeted to the membrane. In contrast, we observed effective targeting of SRP-RNCs to membrane-bond FtsY. These data show that soluble FtsY does not contribute significantly to cotranslational targeting in E. coli. In agreement with this observation, our in vivo analyses of FtsY localization in bacterial cells by fluorescence microscopy revealed that the vast majority of FtsY was localized to the inner membrane and that soluble FtsY constituted only a negligible species in vivo. Conclusion The exact function of the SRP receptor (SR in bacteria has so far been enigmatic. Our data show that the bacterial SR is

  8. Reducing the bioavailability of PCBs in soil to plant by biochars assessed with triolein-embedded cellulose acetate membrane technique

    International Nuclear Information System (INIS)

    Wang, Yu; Wang, Yu-Jun; Wang, Lei; Fang, Guo-Dong; Cang, Long; Herath, H.M.S.K.; Zhou, Dong-Mei

    2013-01-01

    Coupling with triolein-embedded cellulose acetate membrane (TECAM) technique, hydroxypropyl β-cyclodextrins (HPCD) extraction method, and the greenhouse pot experiments, the influences of biochars on polychlorinated biphenyls (PCBs) bioavailability in soil to plant (Brassica chinensis L. and Daucus carota) were investigated. Addition of 2% biochars to soils significantly reduced the uptake of PCBs in plant, especially for di-, tri- and tetra-chlorobiphenyls. PCBs concentrations in the roots of B. chinensis and D. carota were reduced for 61.5–93.7%, and 12.7–62.4%, respectively in the presence of biochars. The kinetic study showed that in the soils amended with/without biochars, PCBs concentrations accumulated in TECAM, as well as in the HPCD extraction solution, followed significant linear relationships with those in plant roots. Application of biochars to soil is a potentially promising method to reduce PCBs bioavailability whereas TECAM technique can be a useful tool to predict the bioavailability of PCBs in soil. -- Highlights: ► Application of biochars significantly reduced the uptake of PCBs in plant. ► TECAM was a new and effective method to predict the PCBs bioavailability in soil. ► PCBs accumulated in TECAM followed significant linear relationships with plant. ► PCBs in TECAM were more similar with the plant uptake than HPCD solution. -- The reduced PCBs concentrations in plant roots by biochars show good linear relationship with those in TECAM

  9. The effects of a co-solvent on fabrication of cellulose acetate membranes from solutions in 1-ethyl-3-methylimidazolium acetate

    KAUST Repository

    Kim, Dooli

    2016-08-15

    Ionic liquids have been considered green solvents for membrane fabrication. However, the high viscosity of their polymer solutions hinders the formation of membranes with strong mechanical properties. In this study, acetone was explored as a co-solvent with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) to dissolve cellulose acetate. The effects of acetone on the thermodynamic and kinetic aspects of the polymer solutions were studied and the physicochemical properties and separation capability of their resultant membranes were analyzed. The Hansen solubility parameters of [EMIM]OAc were measured by the software HSPiP and these data demonstrated that acetone was a suitable co-solvent to increase the solubility of cellulose acetate. The Gibbs free energy of mixing ΔGm was estimated to determine the proper composition of the polymer solution with better solubility. The study of the kinetics of phase separation showed that the demixing rate of the CA polymer solution in acetone and [EMIM]OAc was higher than that for solutions in [EMIM]OAc only. The membranes prepared from the former solution had higher water permeance and better mechanical stability than those prepared from the later solution. Adding acetone as a co-solvent opened the opportunity of fabricating membranes with higher polymer concentrations for higher separation capability and better mechanical properties. © 2016

  10. Preparation and characterization of biocellulose membranes obtained by biosynthesis of bacteria komagataeibacter rhaeticus

    International Nuclear Information System (INIS)

    Machado, Rachel Temperani A.; Tercjak, Agnieszka; Gutierrez, Juncal; Barud, Hernane S.

    2015-01-01

    This work shows preparation and characterization of bacterial cellulose membranes (CB) produced by Komagataeibacter rhaeticus strain, and strain from ATCC bank, Gluconacetobacter hansenii (ATCC 23769) used as a comparative. Physicochemical assay were done, such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy couplet to Energy-dispersive X-ray spectroscopy (SEM/EDX). SEM images reveled a compact structure formed by cellulose nanofibers. FTIR spectra are shown characteristics bands of cellulosic materials and XRD shows cellulose native structure, type I cellulose. (author)

  11. Urethral reconstruction with a 3D porous bacterial cellulose scaffold seeded with lingual keratinocytes in a rabbit model

    International Nuclear Information System (INIS)

    Huang, Jian-Wen; Lv, Xiang-Guo; Song, Lu-Jie; Feng, Chao; Xie, Min-Kai; Li, Chao; Li, Hong-Bin; Wang, Ji-Hong; Zhu, Wei-Dong; Xu, Yue-Min; Li, Zhe; Chen, Shi-Yan; Wang, Hua-Ping

    2015-01-01

    The goal of this study was to evaluate the effects of urethral reconstruction with a three-dimensional (3D) porous bacterial cellulose (BC) scaffold seeded with lingual keratinocytes in a rabbit model. A novel 3D porous BC scaffold was prepared by gelatin sponge interfering in the BC fermentation process. Rabbit lingual keratinocytes were isolated, expanded, and seeded onto 3D porous BC. BC alone (group 1, N  =  10), 3D porous BC alone (group 2, N  =  10), and 3D porous BC seeded with lingual keratinocytes (group 3, N  =  10) were used to repair rabbit ventral urethral defects (2.0   ×   0.8 cm). Scanning electron microscopy revealed that BC consisted of a compact laminate while 3D porous BC was composed of a porous sheet buttressed by a dense outer layer. The average pore diameter and porosity of the 3D porous BC were 4.23   ±   1.14 μm and 67.00   ±   6.80%, respectively. At 3 months postoperatively, macroscopic examinations and retrograde urethrograms of urethras revealed that all urethras maintained wide calibers in group 3. Strictures were found in all rabbits in groups 1 and 2. Histologically, at 1 month postoperatively, intact epithelium occurred in group 3, and discontinued epithelium was found in groups 1 and 2. However, groups 2 and 3 exhibited similar epithelial regeneration, which was superior to that of group 1 at 3 months (p  <  0.05). Comparisons of smooth muscle content and endothelia density among the three groups revealed a significant increase at each time point (p  <  0.05). Our results demonstrated that 3D porous BC seeded with lingual keratinocytes enhanced urethral tissue regeneration. 3D porous BC could potentially be used as an optimized scaffold for urethral reconstruction. (paper)

  12. PENINGKATAN KADAR PATCHOULI ALKOHOL MINYAK NILAM (Pogostemon cablin Benth DENGAN MENGGUNAKAN MEMBRAN SELULOSA ASETAT Increase of the Content of Patchouli Alcohol in Patchouli Oil (Pogostemon cablin Benth Using Cellulose Acetate Membrane

    Directory of Open Access Journals (Sweden)

    Yuliani Aisyah

    2012-05-01

    Full Text Available The aims of this research were to increase patchouli alcohol content of patchouli oil using cellulose acetate membrane and evaluated performance  of the membrane. The nanofiltration  cellulose acetate membrane used in this study was the Vivaspin 15R. The filtration process of patchouli oil was carried out using centrifugation speed 212, 850 and 1912 g, and centrifugation time 10, 20, 30, 40, 50 and 6 minutes. Analysis of patchouli oil was carried out using gas chromatography, meanwhile  the separation performance membrane can be described as a permeability  (flux and selectivity. The nanofiltration  process of patchouli oil using cellulose acetate membrane showed that the patchouli  alcohol content increase 2 times (58.11 % of the initial content of patchouli alcohol (30.08 % by using centrifugation speed of 1912 g and centrifugation time of 50 minutes. There are significant effect of centrifugation speed and centrifugation time on patchouli alcohol content, flux and selectivity. The highest value of flux is 166,81 L/m2.jam and selectivity is 44.91 %. ABSTRAK Telah dilakukan penelitian yang bertujuan untuk meningkatkan kadar patchouli alkohol dalam minyak nilam dengan menggunakan membran nanofiltrasi  selulosa asetat dan mengevaluasi  kinerja membran yang digunakan. Membran yang digunakan adalah membran nanofiltrasi selulosa asetat tipe Vivaspin 15R. Proses filtrasi  minyak  nilam  dilakukan dengan menggunakan kecepatan sentrifugasi 212 , 850, dan 1912 g serta  waktu sentrifugasi 10, 20, 30, 40, 50, dan 60 menit.  �adar patchouli  alkohol  di analisis menggunakan kromatografi  gas, sedangkan kinerja  membran dinyatakan sebagai permeabilitas (fluks dan selektivitas. Hasil penelitian menunjukkan bahwa filtrasi dengan menggunakan membran nanofiltrasi selulosa asetat dapat meningkatkan  kadar patchouli  alkohol  sebesar 2 kali (61,52 % dari kadar patchouli alkohol awal (30,08% pada kecepatan sentrifgasi 1912 g dan waktu

  13. Antimicrobial Nanoplexes meet Model Bacterial Membranes: the key role of Cardiolipin

    Science.gov (United States)

    Marín-Menéndez, Alejandro; Montis, Costanza; Díaz-Calvo, Teresa; Carta, Davide; Hatzixanthis, Kostas; Morris, Christopher J.; McArthur, Michael; Berti, Debora

    2017-01-01

    Antimicrobial resistance to traditional antibiotics is a crucial challenge of medical research. Oligonucleotide therapeutics, such as antisense or Transcription Factor Decoys (TFDs), have the potential to circumvent current resistance mechanisms by acting on novel targets. However, their full translation into clinical application requires efficient delivery strategies and fundamental comprehension of their interaction with target bacterial cells. To address these points, we employed a novel cationic bolaamphiphile that binds TFDs with high affinity to form self-assembled complexes (nanoplexes). Confocal microscopy revealed that nanoplexes efficiently transfect bacterial cells, consistently with biological efficacy on animal models. To understand the factors affecting the delivery process, liposomes with varying compositions, taken as model synthetic bilayers, were challenged with nanoplexes and investigated with Scattering and Fluorescence techniques. Thanks to the combination of results on bacteria and synthetic membrane models we demonstrate for the first time that the prokaryotic-enriched anionic lipid Cardiolipin (CL) plays a key-role in the TFDs delivery to bacteria. Moreover, we can hypothesize an overall TFD delivery mechanism, where bacterial membrane reorganization with permeability increase and release of the TFD from the nanoplexes are the main factors. These results will be of great benefit to boost the development of oligonucleotides-based antimicrobials of superior efficacy.

  14. Structure of a bacterial type III secretion system in contact with a host membrane in situ

    Science.gov (United States)

    Nans, Andrea; Kudryashev, Mikhail; Saibil, Helen R.; Hayward, Richard D.

    2015-12-01

    Many bacterial pathogens of animals and plants use a conserved type III secretion system (T3SS) to inject virulence effector proteins directly into eukaryotic cells to subvert host functions. Contact with host membranes is critical for T3SS activation, yet little is known about T3SS architecture in this state or the conformational changes that drive effector translocation. Here we use cryo-electron tomography and sub-tomogram averaging to derive the intact structure of the primordial Chlamydia trachomatis T3SS in the presence and absence of host membrane contact. Comparison of the averaged structures demonstrates a marked compaction of the basal body (4 nm) occurs when the needle tip contacts the host cell membrane. This compaction is coupled to a stabilization of the cytosolic sorting platform-ATPase. Our findings reveal the first structure of a bacterial T3SS from a major human pathogen engaged with a eukaryotic host, and reveal striking `pump-action' conformational changes that underpin effector injection.

  15. The participation of outer membrane proteins in the bacterial sensitivity to nanosilver

    Directory of Open Access Journals (Sweden)

    Anna Kędziora

    2016-06-01

    Full Text Available The presented study is to analyze the participation of outer membrane proteins of Gram- negative bacteria in sensitivity to silver nanomaterials. The mechanism of interaction of silver with the bacterial cell is best described in this group of microorganisms. There are several theories regarding the effectiveness of antimicrobial ions and nanosilver, and at the indicated differences in the way they work. Outer membrane proteins of Gram-negative bacteria are involved in the procurement of silver from the environment and contribute to the development mechanisms of resistance to nanometals. They are measurable parameter in the field of cell phenotypic response to the presence of Gram-negative bacteria in the environment silver nanoforms: its properties, chemical composition, content or times of action. Proteomic methods (including two dimensional electrophoresis and MALDI‑TOF MS are therefore relevant techniques for determining the susceptibility of bacteria to silver and the changes taking place in the outer membrane under the influence: uptime/exposure and physical and chemical parameters of silver nanomaterials. Many products containing nanosilver is still in the research phase in terms of physico‑chemical characteristics and biological activity, others have been already implemented in many industries. During the very fast nanotechnology developing and introduction to the market products based on the nanosilver the bacterial answer to nanosilver is needed.

  16. Stretchable and strong cellulose nanopaper structures based on polymer-coated nanofiber networks: an alternative to nonwoven porous membranes from electrospinning.

    Science.gov (United States)

    Sehaqui, Houssine; Morimune, Seira; Nishino, Takashi; Berglund, Lars A

    2012-11-12

    Nonwoven membranes based on electrospun fibers are of great interest in applications such as biomedical, filtering, and protective clothing. The poor mechanical performance is a limitation, as is some of the electrospinning solvents. To address these problems, porous nonwoven membranes based on nanofibrillated cellulose (NFC) modified by a hydroxyethyl cellulose (HEC) polymer coating are prepared. NFC/HEC aqueous suspensions are subjected to simple vacuum filtration in a paper-making fashion, followed by supercritical CO(2) drying. These nonwoven nanocomposite membranes are truly nanostructured and exhibit a nanoporous network structure with high specific surface area, as analyzed by nitrogen adsorption and FE-SEM. Mechanical properties evaluated by tensile tests show high strength combined with remarkably high strain to failure of up to 55%. XRD analysis revealed significant fibril realignment during tensile stretching. After postdrawing of the random mats, the modulus and strength are strongly increased. The present preparation route uses components from renewable resources, is environmentally friendly, and results in permeable membranes of exceptional mechanical performance.

  17. Nitrogen-Doped Carbon Nanofiber/Molybdenum Disulfide Nanocomposites Derived from Bacterial Cellulose for High-Efficiency Electrocatalytic Hydrogen Evolution Reaction.

    Science.gov (United States)

    Lai, Feili; Miao, Yue-E; Huang, Yunpeng; Zhang, Youfang; Liu, Tianxi

    2016-02-17

    To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS2) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS2 nanosheets. The obtained hierarchical pBC-N/MoS2 nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm(-2) at η = 200 mV, low Tafel slope of 61 mV dec(-1), and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS2 nanosheets, the intimate connection between MoS2 nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS2-based nanocomposites as cost-effective HER eletrocatalysts.

  18. Statistical optimization of medium composition for bacterial cellulose production by Gluconacetobacter hansenii UAC09 using coffee cherry husk extract--an agro-industry waste.

    Science.gov (United States)

    Rani, Mahadevaswamy Usha; Rastogi, Navin K; Appaiah, K A Anu

    2011-07-01

    During the production of grape wine, the formation of thick leathery pellicle/bacterial cellulose (BC) at the airliquid interface was due to the bacterium, which was isolated and identified as Gluconacetobacter hansenii UAC09. Cultural conditions for bacterial cellulose production from G. hansenii UAC09 were optimized by central composite rotatable experimental design. To economize the BC production, coffee cherry husk (CCH) extract and corn steep liquor (CSL) were used as less expensive sources of carbon and nitrogen, respectively. CCH and CSL are byproducts from the coffee processing and starch processing industry, respectively. The interactions between pH (4.5- 8.5), CSL (2-10%), alcohol (0.5-2%), acetic acid (0.5- 2%), and water dilution rate to CCH ratio (1:1 to 1:5) were studied using response surface methodology. The optimum conditions for maximum BC production were pH (6.64), CSL (10%), alcohol (0.5%), acetic acid (1.13%), and water to CCH ratio (1:1). After 2 weeks of fermentation, the amount of BC produced was 6.24 g/l. This yield was comparable to the predicted value of 6.09 g/l. This is the first report on the optimization of the fermentation medium by RSM using CCH extract as the carbon source for BC production by G. hansenii UAC09.

  19. Fermentation Tecniques and Applications of Bacterial Cellulose: a Review Técnicas de fermentación y aplicaciones de la celulosa bacteriana: una revisión

    Directory of Open Access Journals (Sweden)

    Luz Dary Carreño Pineda

    2012-12-01

    Full Text Available Bacterial cellulose is a polymer obtained by fermentation with microorganismsfrom Acetobacter, Rhizobium, Agrobacterium and Sarcina genera. Amongthem, Acetobacter xylinum is the most efficient specie. This polymer hasthe same chemical composition of plant cellulose, but its conformation andphysicochemical properties are different, making it attractive for several applications, especially in the areas of food, separation processes, catalysis andhealth, due to its biocompatibility. However, the main problem is the production in mass that is constrained by low yield. It is therefore necessaryto develop some alternatives. This paper presents a review about synthesis,production, properties and principal applications of bacterial cellulose, as wellas some alternatives to reduce the difficulties for process scaling.La celulosa bacteriana es un polímero obtenido por fermentación con microrganismosde los géneros Acetobacter, Rhizobium, Agrobacterium y Sarcina, delas cuales la especie más eficiente es la Acetobacter Xylinum. Este polímero presenta la misma estructura química de la celulosa de origen vegetal, pero difiereen su conformación y propiedades fisicoquímicas, lo que lo hace atractivo para diversas aplicaciones, especialmente en las áreas de alimentos, procesosde separación, catálisis y en medicina, gracias a su biocompatibilidad. Sin embargo, el principal problema es la producción a gran escala limitada por losbajos rendimientos, lo que genera la necesidad de desarrollar alternativas que permitan disminuir o eliminar las causas de esta limitación. En este artículo se hace una revisión acerca de la síntesis, producción, propiedades y principales aplicaciones de la celulosa bacteriana, así como de algunas alternativas estudiadas para disminuir los inconvenientes en el escalamiento del proceso.

  20. Rapid determination of bacterial aminoglycoside resistance in environmental samples using membrane electrospray ionization mass spectrometry.

    Science.gov (United States)

    Fan, Liusheng; Ke, Ming; Yuan, Min; Pu, Ji; Li, Juan; Lu, Jinxing; Xu, Jianguo; Zhang, Mei; Xu, Wei

    2016-08-01

    Antibiotic resistance in pathogenic bacteria is becoming a global public health problem, such as aminoglycoside resistance encoded by the armA gene. Although many methods have been reported, rapid analysis of environmental samples is still challenging. A rapid analytical method was developed in this study to determine bacterial aminoglycoside resistance using membrane electrospray ionization mass spectrometry (MESI-MS). Precursor/product-ion pairs of ArmA unique peptides were detected with minimal sample preparation. Standard peptides were synthesized and used for developing and validating the methodology, and then the method was verified by both ArmA positive and ArmA negative simulated environmental samples. A rapid method for determination of bacterial aminoglycoside resistance was developed using MESI-MS/MS. The bacterial cultural time was optimized to 2 hours, and the precision, accuracy and recovery of this method were investigated. The peptide IHSSTNER (IR-8) unique to ArmA in simulated environmental samples can be successfully identified within 3 hours. The novel assay offered a rapid method to determine bacterial aminoglycoside resistance with high sensitivity, accuracy and precision in simulated environmental samples. This method could also be applied to identify other drug-resistance proteins in clinical/environmental samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Identification of a novel bacterial outer membrane interleukin-1Β-binding protein from Aggregatibacter actinomycetemcomitans.

    Directory of Open Access Journals (Sweden)

    Annamari Paino

    Full Text Available Aggregatibacter actinomycetemcomitans is a gram-negative opportunistic oral pathogen. It is frequently associated with subgingival biofilms of both chronic and aggressive periodontitis, and the diseased sites of the periodontium exhibit increased levels of the proinflammatory mediator interleukin (IL-1β. Some bacterial species can alter their physiological properties as a result of sensing IL-1β. We have recently shown that this cytokine localizes to the cytoplasm of A. actinomycetemcomitans in co-cultures with organotypic gingival mucosa. However, current knowledge about the mechanism underlying bacterial IL-1β sensing is still limited. In this study, we characterized the interaction of A. actinomycetemcomitans total membrane protein with IL-1β through electrophoretic mobility shift assays. The interacting protein, which we have designated bacterial interleukin receptor I (BilRI, was identified through mass spectrometry and was found to be Pasteurellaceae specific. Based on the results obtained using protein function prediction tools, this protein localizes to the outer membrane and contains a typical lipoprotein signal sequence. All six tested biofilm cultures of clinical A. actinomycetemcomitans strains expressed the protein according to phage display-derived antibody detection. Moreover, proteinase K treatment of whole A. actinomycetemcomitans cells eliminated BilRI forms that were outer membrane specific, as determined through immunoblotting. The protein was overexpressed in Escherichia coli in both the outer membrane-associated form and a soluble cytoplasmic form. When assessed using flow cytometry, the BilRI-overexpressing E. coli cells were observed to bind 2.5 times more biotinylated-IL-1β than the control cells, as detected with avidin-FITC. Overexpression of BilRI did not cause binding of a biotinylated negative control protein. In a microplate assay, soluble BilRI bound to IL-1β, but this binding was not specific, as a control

  2. Conjugation of silica nanoparticles with cellulose acetate/polyethylene glycol 300 membrane for reverse osmosis using MgSO4 solution.

    Science.gov (United States)

    Sabir, Aneela; Shafiq, Muhammad; Islam, Atif; Jabeen, Faiza; Shafeeq, Amir; Ahmad, Adnan; Zahid Butt, Muhammad Taqi; Jacob, Karl I; Jamil, Tahir

    2016-01-20

    Thermally-induced phase separation (TIPS) method was used to synthesize polymer matrix (PM) membranes for reverse osmosis from cellulose acetate/polyethylene glycol (CA/PEG300) conjugated with silica nanoparticles (SNPs). Experimental data showed that the conjugation of SNPs changed the surface properties as dense and asymmetric composite structure. The results were explicitly determined by the permeability flux and salt rejection efficiency of the PM-SNPs membranes. The effect of SNPs conjugation on MgSO4 salt rejection was more significant in magnitude than on permeation flux i.e. 2.38 L/m(2)h. FTIR verified that SNPs were successfully conjugated on the surface of PM membrane. DSC of PM-SNPs shows an improved Tg from 76.2 to 101.8 °C for PM and PM-S4 respectively. Thermal stability of the PM-SNPs membranes was observed by TGA which was significantly enhanced with the conjugation of SNPs. The micrographs of SEM and AFM showed the morphological changes and increase in the valley and ridges on membrane surface. Experimental data showed that the PM-S4 (0.4 wt% SNPs) membrane has maximum salt rejection capacity and was selected as an optimal membrane. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Influence of pore structure and architecture of photo-grafted functional layers on separation performance of cellulose-based macroporous membrane adsorbers.

    Science.gov (United States)

    Wang, Jun; Faber, Rene; Ulbricht, Mathias

    2009-09-11

    New weak cation-exchange membrane adsorbers were prepared via UV-initiated heterogeneous graft copolymerization on Hydrosart macroporous regenerated cellulose membranes. The dynamic performance was investigated in detail with respect to the pore size and pore size distribution of the base membranes, ion-exchange capacity and architecture of the grafted functional layers as well as binding of target proteins. Main characterization methods were pore analysis (BET and permporometry), titration, analysis of protein binding under static conditions including visualization by confocal laser scanning microscopy and chromatographic analysis of dynamic protein binding and system dispersion. The trade-off between static binding capacity of the membrane adsorber and its permeability has partially been overcome by adapted architecture of the grafted functional layer achieved via the introduction of uncharged moieties as spacers and via stabilization of the binding layer by chemical cross-linking. The resulting membranes show only negligible effects of flow rate on dynamic binding capacity. There is no considerable size exclusion effect for large proteins due to mesh size of functional cross-linked layers. Investigation of system dispersion based on breakthrough curves confirms that the adapted grafted layer architecture has drastically reduced the contribution of the membrane to total system dispersion. The optimum pore structure of base membranes in combination with the best suited architecture of functional layers was identified in this study.

  4. Conformation of protein secreted across bacterial outer membranes: a study of enterotoxin translocation from Vibrio cholerae

    International Nuclear Information System (INIS)

    Hirst, T.R.; Holmgren, J.

    1987-01-01

    The secretion of enterotoxin by Vibrio cholerae is punctuated by the transient entry of the toxin subunits into the periplasm. In this paper, the authors show that the subunits oligomerize into an assembled holotoxin within the periplasm prior to their secretion across the outer membrane. The rate of toxin assembly was studied by pulse-labeling cells with [ 35 S]-methionine and then monitoring the turnover of radiolabeled subunits as they assembled within the periplasm. The subunits entered the periplasm as monomers and assembled into oligomers with a half-time of ≅ 1 min. Since assembly was a rapid event compared to the rate of toxin efflux from the periplasm, which had a half-time of ≅ 13 min, they conclude that all of the subunits that pass through the periplasm assemble before they traverse the outer membrane. The average concentration of subunit monomers and assembled holotoxin within the periplasm was calculated to be ≅ 20 and ≅ 260 μg/ml, respectively. This indicates that the periplasm is a suitably concentrated milieu where spontaneous toxin assembly can occur. These findings suggest that protein movement across bacterial outer membranes, in apparent contrast to export across other biological membranes, involves translocation of polypeptides that have already folded into tertiary and even quaternary conformations

  5. A quantitative assessment of the membrane-integral sub-proteome of a bacterial magnetic organelle.

    Science.gov (United States)

    Raschdorf, Oliver; Bonn, Florian; Zeytuni, Natalie; Zarivach, Raz; Becher, Dörte; Schüler, Dirk

    2018-02-10

    Magnetotactic bacteria produce chains of complex membrane-bound organelles that direct the biomineralization of magnetic nanoparticles and serve for magnetic field navigation. These magnetosome compartments have recently emerged as a model for studying the subcellular organization of prokaryotic organelles. Previous studies indicated the presence of specific proteins with various functions in magnetosome biosynthesis. However, the exact composition and stoichiometry of the magnetosome subproteome have remained unknown. In order to quantify and unambiguously identify all proteins specifically targeted to the magnetosome membrane of the Alphaproteobacterium Magnetospirillum gryphiswaldense, we analyzed the protein composition of several cellular fractions by semi-quantitative mass spectrometry. We found that nearly all genuine magnetosome membrane-integral proteins belong to a well-defined set of previously identified proteins encoded by gene clusters within a genomic island, indicating a highly controlled protein composition. Magnetosome proteins were present in different quantities with up to 120 copies per particle as estimated by correlating our results with available quantitative Western blot data. This high abundance suggests an unusually crowded protein composition of the membrane and a tight packing with transmembrane domains of integral proteins. Our findings will help to further define the structure of the organelle and contribute to the elucidation of magnetosome biogenesis. Magnetosomes are one of the most complex bacterial organelles and consist of membrane-bounded crystals of magnetic minerals. The exact composition and stoichiometry of the associated membrane integral proteins are of major interest for a deeper understanding of prokaryotic organelle assembly; however, previous proteomic studies failed to reveal meaningful estimations due to the lack of precise and quantitative data, and the inherently high degree of accumulated protein contaminants in

  6. Electrochemical Properties of LLTO/Fluoropolymer-Shell Cellulose-Core Fibrous Membrane for Separator of High Performance Lithium-Ion Battery

    Directory of Open Access Journals (Sweden)

    Fenglin Huang

    2016-01-01

    Full Text Available A superfine Li0.33La0.557TiO3 (LLTO, 69.4 nm was successfully synthesized by a facile solvent-thermal method to enhance the electrochemical properties of the lithium-ion battery separator. Co-axial nanofiber of cellulose and Poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP was prepared by a co-axial electrospinning technique, in which the shell material was PVDF-HFP and the core was cellulose. LLTO superfine nanoparticles were incorporated into the shell of the PVDF-HFP. The core–shell composite nanofibrous membrane showed good wettability (16.5°, contact angle, high porosity (69.77%, and super electrolyte compatibility (497%, electrolyte uptake. It had a higher ionic conductivity (13.897 mS·cm−1 than those of pure polymer fibrous membrane and commercial separator. In addition, the rate capability (155.56 mAh·g−1 was also superior to the compared separator. These excellent performances endowed LLTO composite nanofibrous membrane as a promising separator for high-performance lithium-ion batteries.

  7. Gypsum (CaSO4·2H2O Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    Directory of Open Access Journals (Sweden)

    Tai-Shung Chung

    2013-11-01

    Full Text Available We have examined the gypsum (CaSO4·2H2O scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO processes. Three hollow fiber membranes made of (1 cellulose acetate (CA, (2 polybenzimidazole (PBI/polyethersulfone (PES and (3 PBI-polyhedral oligomeric silsesquioxane (POSS/polyacrylonitrile (PAN were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

  8. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis.

    Science.gov (United States)

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-11-08

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

  9. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    Science.gov (United States)

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-01-01

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. PMID:24957062

  10. Bacterial membrane activity of a-peptide/b-peptoid chimeras: Influence of amino acid composition and chain length on the activity against different bacterial strains

    DEFF Research Database (Denmark)

    Hein-Kristensen, Line; Knapp, Kolja M; Franzyk, Henrik

    2011-01-01

    acid only had a minor effect on MIC values, whereas chain length had a profound influence on activity. All chimeras were less active against Serratia marcescens (MICs above 46 μM). The chimeras were bactericidal and induced leakage of ATP from Staphylococcus aureus and S. marcescens with similar time......BACKGROUND: Characterization and use of antimicrobial peptides (AMPs) requires that their mode of action is determined. The interaction of membrane-active peptides with their target is often established using model membranes, however, the actual permeabilization of live bacterial cells...... and subsequent killing is usually not tested. In this report, six α-peptide/β-peptoid chimeras were examined for the effect of amino acid/peptoid substitutions and chain length on the membrane perturbation and subsequent killing of food-borne and clinical bacterial isolates. RESULTS: All six AMP analogues...

  11. Bacterial membrane vesicles, an overlooked environmental colloid: Biology, environmental perspectives and applications.

    Science.gov (United States)

    Toyofuku, Masanori; Tashiro, Yosuke; Hasegawa, Yusuke; Kurosawa, Masaharu; Nomura, Nobuhiko

    2015-12-01

    Phospholipid vesicles play important roles in biological systems. Bacteria are one of the most abundant organisms on Earth, and bacterial membrane vesicles (MVs) were first observed 50 years ago. Many bacteria release MVs to the environment that mainly consist of the cell membrane and typically range from 20 to 400 nm in size. Bacterial MVs are involved in several biological functions, such as delivery of cargo, virulence and gene transfer. MVs can be isolated from laboratory culture and directly from the environment, indicating their high abundance in and impact on ecosystems. Many colloidal particles in the environment ranging in size from 1 nm to 1 μm have been reported but not characterized at the molecular level, and MVs remain to be explored. Hence, MVs can be considered terra incognita in environmental colloid research. Although MV biogenesis and biological roles are yet to be fully understood, the accumulation of knowledge has opened new avenues for their applications. Via genetic engineering, the MV yield can be greatly increased, and the components of MVs can be tailored. Recent studies have demonstrated that MVs have promising potential for applications such as drug delivery systems and nanobiocatalysts. For instance, MV vaccines have been extensively studied and have already been approved in Europe. Recent MV studies have evoked great interest in the fields of biology and biotechnology, but fundamental questions, such as their transport in the environment or physicochemical features of MVs, remain to be addressed. In this review, we present the current understanding of bacterial MVs and environmental perspectives and further introduce their applications. Copyright © 2015. Published by Elsevier B.V.

  12. Toxic metal ion separation by cellulose acetate/sulfonated poly(ether imide) blend membranes: effect of polymer composition and additive.

    Science.gov (United States)

    Nagendran, A; Vijayalakshmi, A; Arockiasamy, D Lawrence; Shobana, K H; Mohan, D

    2008-07-15

    Toxic heavy metal ion removal from industrial effluents are gaining increased visibility owing to environmental concern and saving precious materials. In this work, an attempt has been made to remove the valuable metal ions using modified ultrafiltration (UF) blend membranes based on cellulose acetate (CA) and sulfonated poly(ether imide) (SPEI) were prepared in the presence and absence of additive, poly(ethylene glycol) 600 (PEG600) in various compositions. Prepared membranes were characterized in terms of pure water flux (PWF), water content and membrane hydraulic resistance. High flux UF membranes were obtained in the range of 15-25 wt% SPEI and 2.5-10 wt% PEG600 in the polymer blend. The molecular weight cut-off (MWCO) of the blend membranes were determined using protein separation studies found to vary from 20 to greater than 69 kDa. Surface morphology of the blend membranes were analysed with scanning electron microscopy. Studies were carried out to find the rejection and permeate flux of metal ions such as Cu(II), Ni(II), Zn(II) and Cd(II) using polyethyleneimine as the chelating ligand. On increasing the composition of SPEI and PEG600, the rejection of metal ions is decreasing while the permeate flux has an increasing trend. These effects are due to the increased pore formation in the CA/SPEI blend membranes because of the hydrophilic SPEI and polymeric additive PEG600. In general, it was found that CA/SPEI blend membranes displayed higher permeate flux and lower rejection compared to pure CA membranes. The extent of separation of metal ions depends on the affinity of metal ions to polyethyleneimine to form macromolecular complexes and the stability of the formed complexes.

  13. Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems.

    Science.gov (United States)

    Duedu, Kwabena O; French, Christopher E

    2017-04-01

    Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris. Colony counting enumerates live cells but the process is laborious and not suitable for large numbers of samples. Enumeration of live bacteria by flow cytometry is a more suitable rapid method with the use of dual staining with SYBR I Green nucleic acid gel stain and Propidium Iodide (SYBR-I/PI). Flow cytometry equipment and maintenance costs however are relatively high and this technique is unavailable in many laboratories that may require a rapid method for evaluating bacteria growth. We therefore sought to adapt and evaluate the SYBR-I/PI technique of enumerating live bacterial cells for a cheaper platform, a fluorimeter. The fluorimetry adapted SYBR-I/PI enumeration of bacteria in turbid growth media had direct correlations with OD600 (p>0.001). To enable comparison of fluorescence results across labs and instruments, a fluorescence intensity standard unit, the equivalent fluorescent DNA (EFD) was proposed, evaluated and found useful. The technique was further evaluated for its usefulness in enumerating bacteria in turbid media containing insoluble particles. Reproducible results were obtained which OD600 could not give. An alternative method based on the assessment of total protein using the Pierce Coomassie Plus (Bradford) Assay was also evaluated and compared. In all, the SYBR-I/PI method was found to be the quickest and most reliable. The protocol is potentially useful for high-throughput applications such as

  14. The Membrane Steps of Bacterial Cell Wall Synthesis as Antibiotic Targets

    Directory of Open Access Journals (Sweden)

    Yao Liu

    2016-08-01

    Full Text Available Peptidoglycan is the major component of the cell envelope of virtually all bacteria. It has structural roles and acts as a selective sieve for molecules from the outer environment. Peptidoglycan synthesis is therefore one of the most important biogenesis pathways in bacteria and has been studied extensively over the last twenty years. The pathway starts in the cytoplasm, continues in the cytoplasmic membrane and finishes in the periplasmic space, where the precursor is polymerized into the peptidoglycan layer. A number of proteins involved in this pathway, such as the Mur enzymes and the penicillin binding proteins (PBPs, have been studied and regarded as good targets for antibiotics. The present review focuses on the membrane steps of peptidoglycan synthesis that involve two enzymes, MraY and MurG, the inhibitors of these enzymes and the inhibition mechanisms. We also discuss the challenges of targeting these two cytoplasmic membrane (associated proteins in bacterial cells and the perspectives on how to overcome the issues.

  15. Energetics and molecular biology of active transport in bacterial membrane vesicles.

    Science.gov (United States)

    Kaback, H R; Ramos, S; Robertson, D E; Stroobant, P; Tokuda, H

    1977-01-01

    Bacterial membrane vesicles retain the same sidedness as the membrane in the intact cell and catalyze active transport of many solutes by a respiration-dependent mechanism that does not involve the generation of utilization of ATP or other high-energy phosphate compounds. In E. coli vesicles, most of these transport systems are coupled to an electrochemical gradient of protons (deltamuH+, interior negative and alkaline) generated primarily by the oxidation of D-lactate or reduced phenazine methosulfate via a membrane-bound respiratory chain. Oxygen or, under appropriate conditions, fumarate or nitrate can function as terminal electron acceptors, and the site at which deltamuH+ is generated is located before cytochrome b1 in the respiratory chain. Certain (N-dansyl)aminoalkyl-beta-D-galactopyranosides (Dns-gal) and N(2-nitro-4-azidophenyl)aminoalkyl 1-thio-beta-D-galactopyranosides (APG) are competitive inhibitors of lactose transport but are not transported themselves. Various fluorescence techniques, direct binding assays, and photoinactivation studies demonstrate that the great bulk of the lac carrier protein (ca. 95%) does not bind ligand in the absence of energy-coupling. Upon generation of a deltamuH+ (interior negative and alkaline), binding of Dns-gal and APG-dependent photoinactivation are observed. The data indicate that energy is coupled to the initial step in the transport process, and suggest that the lac carrier protein may be negatively charged.

  16. Flexible, highly graphitized carbon aerogels based on bacterial cellulose/lignin: Catalyst-free synthesis and its application in energy storage devices

    KAUST Repository

    Xu, Xuezhu

    2015-04-15

    Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst-assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol-formaldehyde (RF) or lignin-resorcinol-formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst-free and cost-effective. The toughened carbon aerogels, consisting of blackberry-like, core-shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid-state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Removal of chromium (VI) ions from aqueous solutions using amine-impregnated TiO2 nanoparticles modified cellulose acetate membranes.

    Science.gov (United States)

    Gebru, Kibrom Alebel; Das, Chandan

    2018-01-01

    In this work, TiO 2 nanoparticles (NPs) were modified using tetraethylenepentamine (TEPA), ethylenediamine (EDA), and hexamethylenetetramine (HMTA) amines using impregnation process. The prepared amine modified TiO 2 samples were explored as an additive to fabricate ultrafiltration membranes with enhanced capacity towards the removal of chromium ions from aqueous solution. Modified membranes were prepared from cellulose acetate (CA) polymer blended with polyethylene glycol (PEG) additive, and amine modified TiO 2 by using phase inversion technique. Fourier transform infrared spectroscopy (FTIR), zeta potential (ζ), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), water contact angle (WCA), and atomic absorption spectrophotometer (AAS) studies were done to characterize the membranes in terms of chemical structure, electric charge, thermal stability, morphology, hydrophilicity, and removal performance. The pure water permeability and Cr (VI) ion removal efficiency of the unmodified (i.e. CA/U-Ti) and the amine modified (CA/Ti-HMTA, CA/Ti-EDA, and CA/Ti-TEPA) membranes were dependent on pH and metal ion concentration. Incorporation of amine modified TiO 2 composite to the CA polymer was found to improve the fouling and removal characteristics of the membranes during the chromium ultrafiltration process. The maximum removal efficiency result of Cr (VI) ions at pH of 3.5 using CA/Ti-TEPA membrane was 99.8%. The washing/regeneration cycle results in this study described as an essential part for prospect industrial applications of the prepared membranes. The maximum Cr (VI) removal results by using CA/Ti-TEPA membrane for four washing/regeneration cycles are 99.6%, 99.5%, 98.6% and, 96.6%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Response Mechanisms of Bacterial Degraders to Environmental Contaminants on the Level of Cell Walls and Cytoplasmic Membrane

    Directory of Open Access Journals (Sweden)

    Slavomíra Murínová

    2014-01-01

    Full Text Available Bacterial strains living in the environment must cope with the toxic compounds originating from humans production. Surface bacterial structures, cell wall and cytoplasmic membrane, surround each bacterial cell and create selective barriers between the cell interior and the outside world. They are a first site of contact between the cell and toxic compounds. Organic pollutants are able to penetrate into cytoplasmic membrane and affect membrane physiological functions. Bacteria had to evolve adaptation mechanisms to counteract the damage originated from toxic contaminants and to prevent their accumulation in cell. This review deals with various adaptation mechanisms of bacterial cell concerning primarily the changes in cytoplasmic membrane and cell wall. Cell adaptation maintains the membrane fluidity status and ratio between bilayer/nonbilayer phospholipids as well as the efflux of toxic compounds, protein repair mechanisms, and degradation of contaminants. Low energy consumption of cell adaptation is required to provide other physiological functions. Bacteria able to survive in toxic environment could help us to clean contaminated areas when they are used in bioremediation technologies.

  19. Response mechanisms of bacterial degraders to environmental contaminants on the level of cell walls and cytoplasmic membrane.

    Science.gov (United States)

    Murínová, Slavomíra; Dercová, Katarína

    2014-01-01

    Bacterial strains living in the environment must cope with the toxic compounds originating from humans production. Surface bacterial structures, cell wall and cytoplasmic membrane, surround each bacterial cell and create selective barriers between the cell interior and the outside world. They are a first site of contact between the cell and toxic compounds. Organic pollutants are able to penetrate into cytoplasmic membrane and affect membrane physiological functions. Bacteria had to evolve adaptation mechanisms to counteract the damage originated from toxic contaminants and to prevent their accumulation in cell. This review deals with various adaptation mechanisms of bacterial cell concerning primarily the changes in cytoplasmic membrane and cell wall. Cell adaptation maintains the membrane fluidity status and ratio between bilayer/nonbilayer phospholipids as well as the efflux of toxic compounds, protein repair mechanisms, and degradation of contaminants. Low energy consumption of cell adaptation is required to provide other physiological functions. Bacteria able to survive in toxic environment could help us to clean contaminated areas when they are used in bioremediation technologies.

  20. Identifying the components in eggshell membrane responsible for reducing the heat resistance of bacterial pathogens.

    Science.gov (United States)

    Ahlborn, Gene; Sheldon, Brian W

    2006-04-01

    combination of these proteins and perhaps other ESM components interferes with interactions between bacterial lipopolysaccharides, sensitizing the outer bacterial membrane to the lethal affects of heat and possibly pressure and osmotic stressors.

  1. Application of photodynamic therapy, laser therapy, and a cellulose membrane for calcaneal pressure ulcer treatment in a diabetic patient: A case report.

    Science.gov (United States)

    Rosa, Luciano Pereira; da Silva, Francine Cristina; Vieira, Regiane Lima; Tanajura, Beatriz Rocha; da Silva Gusmão, Alana Gonçalves; de Oliveira, Janeide Muritiba; Dos Santos, Nathalia Aparecida Campanário; Bagnato, Vanderlei Salvador

    2017-09-01

    Diabetes mellitus is a metabolic disorder in which a person has high blood glucose levels due to inadequate insulin production by the pancreas. Wounds in these individuals cannot heal properly over time due to circulatory changes that hinder and stagnate the healing process. We report the case of an 82-year-old female type 2 diabetes mellitus carrier, presenting to clinical-dermatological examination pressure ulcer (PU) in the right calcaneus region. The patient was treated with photodynamic therapy using curcumin and blue light-emitting diodes (LEDs), laser therapy, and the application of a cellulose membrane in order to promote ulcer decontamination by local action, accelerate wound healing, and maintain favorable conditions of asepsis and moisture, respectively. The ulcer healing occurred after 30days of treatment and total epithelialization was observed. From the results obtained in this case report, we conclude that the combination of photodynamic therapy, laser therapy, and coating with a cellulose membrane is a promising treatment for the healing of PU in diabetic patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Cellulose microfibril structure: inspirations from plant diversity

    Science.gov (United States)

    Roberts, A. W.

    2018-03-01

    Cellulose microfibrils are synthesized at the plasma membrane by cellulose synthase catalytic subunits that associate to form cellulose synthesis complexes. Variation in the organization of these complexes underlies the variation in cellulose microfibril structure among diverse organisms. However, little is known about how the catalytic subunits interact to form complexes with different morphologies. We are using an evolutionary approach to investigate the roles of different catalytic subunit isoforms in organisms that have rosette-type cellulose synthesis complexes.

  3. [Bacterial outer membrane vesicles as nano carriers to study immunological activities].

    Science.gov (United States)

    Qi, Chen; Min, W U; Hongzhen, Bai; Zeling, Guo; Jun, Zhou; Qingqing, Wang; Guping, Tang

    2017-03-25

    Objective: To prepare a nano-carrier based on combining bacterial outer membrane vesicles (OMV) with three block polymer pluronic F127 (PEO 100 -PPO 65 -PEO 100 ) (OMV-F127) and to investigate its immunological activity. Methods: Attenuated salmonella (sal) was cultivated. OMV were separated by centrifugal ultrafiltration or ultrasonication, and OMV-F127 was prepared by mechanical extrudation method. The protein contents and compositions were tested with BCA and SDS-PAGE; the morphology of OMV, F127 and OMV-F127 were observed with FM and TEM; the particle sizes and their zeta potential were determined with DLS. Mouse macrophage RAW246.7 cells were treated with OMV-F127 (50 μg/mL, 100 μg/mL) in vitro, and the concentrations of IL-12, TNF-α and IFN-γ in culture supernatant were measured with ELISA kits. Results: The contents of protein in separated OMV by centrifugal ultrafiltration and ultrasonication were 2.8 mg/mL and 2.7 mg/mL, respectively. SDS-PAGE showed the marker protein OmpF/C in OMV. Under the FM and TEM, ball-like structure of F127 and OMV-F127 was observed. Size analysis revealed that the diameters of OMV, F127 and OMV-F127 were 72±2 nm, 90±3 nm and 92±2 nm, respectively. ELISA tests revealed that OMV-F127 significantly stimulated the secretion of IL-12, TNF-α and IFN-γ in RAW246.7 cells. Conclusion: A nano-carrier based on bacterial outer membrane vesicles has been prepared, which can stimulate the secretion of cytokines and may have immunomodulatory effects.

  4. Legionella pneumophila-Derived Outer Membrane Vesicles Promote Bacterial Replication in Macrophages.

    Directory of Open Access Journals (Sweden)

    Anna Lena Jung

    2016-04-01

    Full Text Available The formation and release of outer membrane vesicles (OMVs is a phenomenon of Gram-negative bacteria. This includes Legionella pneumophila (L. pneumophila, a causative agent of severe pneumonia. Upon its transmission into the lung, L. pneumophila primarily infects and replicates within macrophages. Here, we analyzed the influence of L. pneumophila OMVs on macrophages. To this end, differentiated THP-1 cells were incubated with increasing doses of Legionella OMVs, leading to a TLR2-dependent classical activation of macrophages with the release of pro-inflammatory cytokines. Inhibition of TLR2 and NF-κB signaling reduced the induction of pro-inflammatory cytokines. Furthermore, treatment of THP-1 cells with OMVs prior to infection reduced replication of L. pneumophila in THP-1 cells. Blocking of TLR2 activation or heat denaturation of OMVs restored bacterial replication in the first 24 h of infection. With prolonged infection-time, OMV pre-treated macrophages became more permissive for bacterial replication than untreated cells and showed increased numbers of Legionella-containing vacuoles and reduced pro-inflammatory cytokine induction. Additionally, miRNA-146a was found to be transcriptionally induced by OMVs and to facilitate bacterial replication. Accordingly, IRAK-1, one of miRNA-146a's targets, showed prolonged activation-dependent degradation, which rendered THP-1 cells more permissive for Legionella replication. In conclusion, L. pneumophila OMVs are initially potent pro-inflammatory stimulators of macrophages, acting via TLR2, IRAK-1, and NF-κB, while at later time points, OMVs facilitate L. pneumophila replication by miR-146a-dependent IRAK-1 suppression. OMVs might thereby promote spreading of L. pneumophila in the host.

  5. Interaction of antimicrobial peptide Plantaricin149a and four analogs with lipid bilayers and bacterial membranes

    Directory of Open Access Journals (Sweden)

    José Luiz de Souza Lopes

    2013-12-01

    Full Text Available The amidated analog of Plantaricin149, an antimicrobial peptide from Lactobacillus plantarum NRIC 149, directly interacts with negatively charged liposomes and bacterial membranes, leading to their lysis. In this study, four Pln149-analogs were synthesized with different hydrophobic groups at their N-terminus with the goal of evaluating the effect of the modifications at this region in the peptide's antimicrobial properties. The interaction of these peptides with membrane models, surface activity, their hemolytic effect on red blood cells, and antibacterial activity against microorganisms were evaluated. The analogs presented similar action of Plantaricin149a; three of them with no hemolytic effect (< 5% until 0.5 mM, in addition to the induction of a helical element when binding to negative liposomes. The N-terminus difference between the analogs and Plantaricin149a retained the antibacterial effect on S. aureus and P. aeruginosa for all peptides (MIC50 of 19 µM and 155 µM to Plantaricin149a, respectively but resulted in a different mechanism of action against the microorganisms, that was bactericidal for Plantaricin149a and bacteriostatic for the analogs. This difference was confirmed by a reduction in leakage action for the analogs. The lytic activity of Plantaricin149a is suggested to be a result of the peptide-lipid interactions from the amphipathic helix and the hydrophobic residues at the N-terminus of the antimicrobial peptide.

  6. A membrane basis for bacterial identification and discrimination using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rehse, Steven J.; Jeyasingham, Narmatha; Diedrich, Jonathan; Palchaudhuri, Sunil

    2009-05-01

    Nanosecond single-pulse laser-induced breakdown spectroscopy (LIBS) has been used to discriminate between two different genera of Gram-negative bacteria and between several strains of the Escherichia coli bacterium based on the relative concentration of trace inorganic elements in the bacteria. Of particular importance in all such studies to date has been the role of divalent cations, specifically Ca2+ and Mg2+, which are present in the membranes of Gram-negative bacteria and act to aggregate the highly polar lipopolysaccharide molecules. We have demonstrated that the source of emission from Ca and Mg atoms observed in LIBS plasmas from bacteria is at least partially located at the outer membrane by intentionally altering membrane biochemistry and correlating these changes with the observed changes in the LIBS spectra. The definitive assignment of some fraction of the LIBS emission to the outer membrane composition establishes a potential serological, or surface-antigen, basis for the laser-based identification. E. coli and Pseudomonas aeruginosa were cultured in three nutrient media: trypticase soy agar as a control, a MacConkey agar with a 0.01% concentration of bile salts including sodium deoxycholate, and a trypticase soy agar with a 0.4% deoxycholate concentration. The higher concentration of deoxycholate is known to disrupt bacterial outer membrane integrity and was expected to induce changes in the observed LIBS spectra. Altered LIBS emission was observed for bacteria cultured in this 0.4% medium and laser ablated in an all-argon environment. These spectra evidenced a reduced calcium emission and in the case of one species, a reduced magnesium emission. Culturing on the lower (0.01%) concentration of bile salts altered the LIBS spectra for both the P. aeruginosa and two strains of E. coli in a highly reproducible way, although not nearly as significantly as culturing in the higher concentration of deoxycholate did. This was possibly due to the accumulation

  7. Antimicrobial Peptide Potency is Facilitated by Greater Conformational Flexibility when Binding to Gram-negative Bacterial Inner Membranes

    Science.gov (United States)

    Amos, Sarah-Beth T. A.; Vermeer, Louic S.; Ferguson, Philip M.; Kozlowska, Justyna; Davy, Matthew; Bui, Tam T.; Drake, Alex F.; Lorenz, Christian D.; Mason, A. James

    2016-11-01

    The interaction of antimicrobial peptides (AMPs) with the inner membrane of Gram-negative bacteria is a key determinant of their abilities to exert diverse bactericidal effects. Here we present a molecular level understanding of the initial target membrane interaction for two cationic α-helical AMPs that share structural similarities but have a ten-fold difference in antibacterial potency towards Gram-negative bacteria. The binding and insertion from solution of pleurocidin or magainin 2 to membranes representing the inner membrane of Gram-negative bacteria, comprising a mixture of 128 anionic and 384 zwitterionic lipids, is monitored over 100 ns in all atom molecular dynamics simulations. The effects of the membrane interaction on both the peptide and lipid constituents are considered and compared with new and published experimental data obtained in the steady state. While both magainin 2 and pleurocidin are capable of disrupting bacterial membranes, the greater potency of pleurocidin is linked to its ability to penetrate within the bacterial cell. We show that pleurocidin displays much greater conformational flexibility when compared with magainin 2, resists self-association at the membrane surface and penetrates further into the hydrophobic core of the lipid bilayer. Conformational flexibility is therefore revealed as a key feature required of apparently α-helical cationic AMPs for enhanced antibacterial potency.

  8. Structure of the Cellulose Synthase Complex of Gluconacetobacter hansenii at 23.4 Å Resolution.

    Directory of Open Access Journals (Sweden)

    Juan Du

    Full Text Available Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsD in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 Å for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. The results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation components, and

  9. Effect of Structure on the Interactions between Five Natural Antimicrobial Compounds and Phospholipids of Bacterial Cell Membrane on Model Monolayers

    Directory of Open Access Journals (Sweden)

    Stella W. Nowotarska

    2014-06-01

    Full Text Available Monolayers composed of bacterial phospholipids were used as model membranes to study interactions of the naturally occurring phenolic compounds 2,5-dihydroxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde, and the plant essential oil compounds carvacrol, cinnamaldehyde, and geraniol, previously found to be active against both Gram-positive and Gram-negative pathogenic microorganisms. The lipid monolayers consist of 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE, 1,2-dihexa- decanoyl-sn-glycero-3-phospho-(1'-rac-glycerol (DPPG, and 1,1',2,2'-tetratetradecanoyl cardiolipin (cardiolipin. Surface pressure–area (π-A and surface potential–area (Δψ-A isotherms were measured to monitor changes in the thermodynamic and physical properties of the lipid monolayers. Results of the study indicated that the five compounds modified the three lipid monolayer structures by integrating into the monolayer, forming aggregates of antimicrobial –lipid complexes, reducing the packing effectiveness of the lipids, increasing the membrane fluidity, and altering the total dipole moment in the monolayer membrane model. The interactions of the five antimicrobial compounds with bacterial phospholipids depended on both the structure of the antimicrobials and the composition of the monolayers. The observed experimental results provide insight into the mechanism of the molecular interactions between naturally-occurring antimicrobial compounds and phospholipids of the bacterial cell membrane that govern activities.

  10. Vaginal epithelial cells regulate membrane adhesiveness to co-ordinate bacterial adhesion

    NARCIS (Netherlands)

    Younes, Jessica A.; Klappe, Karin; Kok, Jan Willem; Busscher, Henk J.; Reid, Gregor; van der Mei, Henny C.

    Vaginal epithelium is colonized by different bacterial strains and species. The bacterial composition of vaginal biofilms controls the balance between health and disease. Little is known about the relative contribution of the epithelial and bacterial cell surfaces to bacterial adhesion and whether

  11. Incorporation of citrus essential oils into bacterial cellulose-based edible films and assessment of their physical properties

    Science.gov (United States)

    Indrarti, L.; Indriyati

    2017-03-01

    The use of edible films in food protection and preservation has recently gained more interest since they offer several advantages over synthetic packaging materials. Biocellulose (BC) offers great opportunity as edible film due to their unique physical and mechanical properties. In this study, biocellulose films were prepared by solution casting with addition of 30% carboxymethyl cellulose (CMC) and 30% glycerol as the homogenizer and plasticizer, respectively. Furthermore, various citrus essential oils (EOs) including lemon, lime, and sweet orange were added at 50% w/w of BC dried weight. The solutions were then cast on the tray and allowed to dry in the air convection oven at 40°C overnight. The films were characterized for water solubility, tensile strength (TS), elongation at break (EB), water vapour transmission rate (WVTR), and color. Those characteristics may influence consumer acceptability of the packaged products. Results revealed that addition of lemon and sweet orange EOs into BC-based edible film decreased water solubility and TS, but improved EB, as these oils acted as plasticizers in the film. However, different trend was observed for BC-based film incorporated with lime oil, which had higher solubility and TS, but lower EB and WVTR compared with that of control film. Addition of citrus EOs into BC-based films did not have much effect on color properties as stated in L*, a*, and b* values.

  12. Mechanism of Action of a Membrane-Active Quinoline-Based Antimicrobial on Natural and Model Bacterial Membranes.

    Science.gov (United States)

    Hubbard, Alasdair T M; Barker, Robert; Rehal, Reg; Vandera, Kalliopi-Kelli A; Harvey, Richard D; Coates, Anthony R M

    2017-02-28

    HT61 is a quinoline-derived antimicrobial, which exhibits bactericidal potency against both multiplying and quiescent methicillin resistant and sensitive Staphylococcus aureus, and has been proposed as an adjunct for other antimicrobials to extend their usefulness in the face of increasing antimicrobial resistance. In this study, we have examined HT61's effect on the permeability of S. aureus membranes and whether this putative activity can be attributed to an interaction with lipid bilayers. Using membrane potential and ATP release assays, we have shown that HT61 disrupts the membrane enough to result in depolarization of the membrane and release of intercellular constituents at concentrations above and below the minimum inhibitory concentration of the drug. Utilizing both monolayer subphase injection and neutron reflectometry, we have shown that increasing the anionic lipid content of the membrane leads to a more marked effect of the drug. In bilayers containing 25 mol % phosphatidylglycerol, neutron reflectometry data suggest that exposure to HT61 increases the level of solvent in the hydrophobic region of the membrane, which is indicative of gross structural damage. Increasing the proportion of PG elicits a concomitant level of membrane damage, resulting in almost total destruction when 75 mol % phosphatidylglycerol is present. We therefore propose that HT61's primary action is directed toward the cytoplasmic membrane of Gram-positive bacteria.

  13. Novel electrospun polyvinylidene fluoride-graphene oxide-silver nanocomposite membranes with protein and bacterial antifouling characteristics

    Directory of Open Access Journals (Sweden)

    C. Liu

    2018-04-01

    Full Text Available We developed and fabricated novel polyvinylidene fluoride (PVDF-(0.5–2%Ag and PVDF-(0.5–2%Ag-1% graphene oxide (GO nanocomposite membranes with antifouling properties through electrospinning. Silver nanoparticles (AgNPs were in situ synthesized from silver nitrate precursor directly. The tensile properties, wetting, antifouling characteristics of pristine PVDF and its nanocomposite membranes were studied. Tensile tests showed that the addition of 0.5–2% AgNPs to PVDF improves its elastic modulus and tensile strength markedly. A further increase in both tensile modulus and strength of PVDF were obtained by hybridizing AgNPs with 1% GO. Water contact angle measurements revealed that the incorporation of AgNPs or AgNPs/GO nanofillers into PVDF decreases its degree of hydrophobicity. This led to the nanocomposite membranes having higher water flux permeation. In addition, AgNPs and AgNPs/GO fillers played a crucial role against protein and bacterial fouling of the resulting composite membranes. The antibacterial activities of electrospun nanocomposite membranes were assessed against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. On the basis of water contact angle, water permeation flux and antifouling results, electrospun PVDF-2% Ag-GO composite membrane was found to exhibit excellent filtration performance, protein antifouling and bactericidal activities. Thus such a fibrous nanocomposite is considered as a high-potential membrane for water purification and disinfection applications.

  14. Fabrication of novel nanohybrids by impregnation of CuO nanoparticles into bacterial cellulose and chitosan nanofibers: Characterization, antimicrobial and release properties.

    Science.gov (United States)

    Almasi, Hadi; Jafarzadeh, Paria; Mehryar, Laleh

    2018-04-15

    The efficiency of bacterial cellulose nanofibers (BCNF) and chitosan nanofibers (CHNF) were compared, aiming at fabricating novel organic-inorganic nanohybrids containing copper oxide (CuO) nanoparticles (NPs). FT-IR spectra confirmed the formation of real nanohybrids through occurring new interactions between CuO NPs and nanofibers. XRD results indicated that both the crystallite size and the crystallinity index of nanofibers decreased after nanohybrid formation. Noticeably, these morphological changes for CHNF were more than those for BCNF. Strong attachment of CuO-NPs to the BCNF and CHNF nanofibrils was observed in FE-SEM images. After 72 h, CuO releasing for CuO-BCNF and CuO-CHNF nanohybrids was recorded as 65.5% and 47.7%, respectively. The antibacterial activity of CuO NPs against both Gram-positive and Gram-negative bacteria decreased after attachment to BCNF. However, a synergistic effect was observed between CuO and CHNF on the antimicrobial activity of CuO-CHNF nanohybrid. This study demonstrated the potential of fabricated nanohybrids in water purification and food packaging applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. A new method to prepare no-binder, integral electrodes-separator, asymmetric all-solid-state flexible supercapacitor derived from bacterial cellulose

    Science.gov (United States)

    Lv, Xvdan; Li, Guohui; Li, Dawei; Huang, Fenglin; Liu, Wenting; Wei, Qufu

    2017-11-01

    Bacterial cellulose (BC) with unique three dimensional multilayer network structure and excellent mechanical strength is used for the substrate of the all-solid-state flexible supercapacitor. The technique was realized by in-situ depositing conductive polymer polyaniline (PANI) on BC, through both peeling off one side of the multilayer PANI/BC composition film and filtrating KOH activated pyrolysis PANI/BC (KPBC) obtained N- and O-enriched carbon powders on the peeling side. The flexible integral electrode-separator supercapacitor device was about 15 μm, which exhibited the well bending and stretching performance. The film supercapacitor also showed excellent cycle life with maximum 28.3 F cm-3 volumetric capacitance, and retains 100% over 2500 charge/discharge cycles at the 0.1 A g-1 current density. In addition, the flexible supercapacitor only indicated 2.48 Ω solution resistances (Rs) at 1 mol PVA/H2SO4 electrolyte. This flexible film supercapacitor has great potential in wearable devices.

  16. Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

    Science.gov (United States)

    Hao, Xiaodong; Wang, Jie; Ding, Bing; Wang, Ya; Chang, Zhi; Dou, Hui; Zhang, Xiaogang

    2017-06-01

    Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g-1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g-1 at a current density of 0.5 A g-1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

  17. Electrospun regenerated cellulose nanofibrous membranes surface-grafted with polymer chains/brushes via the atom transfer radical polymerization method for catalase immobilization.

    Science.gov (United States)

    Feng, Quan; Hou, Dayin; Zhao, Yong; Xu, Tao; Menkhaus, Todd J; Fong, Hao

    2014-12-10

    In this study, an electrospun regenerated cellulose (RC) nanofibrous membrane with fiber diameters of ∼200-400 nm was prepared first; subsequently, 2-hydroxyethyl methacrylate (HEMA), 2-dimethylaminoethyl methacrylate (DMAEMA), and acrylic acid (AA) were selected as the monomers for surface grafting of polymer chains/brushes via the atom transfer radical polymerization (ATRP) method. Thereafter, four nanofibrous membranes (i.e., RC, RC-poly(HEMA), RC-poly(DMAEMA), and RC-poly(AA)) were explored as innovative supports for immobilization of an enzyme of bovine liver catalase (CAT). The amount/capacity, activity, stability, and reusability of immobilized catalase were evaluated, and the kinetic parameters (Vmax and Km) for immobilized and free catalase were determined. The results indicated that the respective amounts/capacities of immobilized catalase on RC-poly(HEMA) and RC-poly(DMAEMA) nanofibrous membranes reached 78 ± 3.5 and 67 ± 2.7 mg g(-1), which were considerably higher than the previously reported values. Meanwhile, compared to that of free CAT (i.e., 18 days), the half-life periods of RC-CAT, RC-poly(HEMA)-CAT, RC-poly(DMAEMA)-CAT, and RC-poly(AA)-CAT were 49, 58, 56, and 60 days, respectively, indicating that the storage stability of immobilized catalase was also significantly improved. Furthermore, the immobilized catalase exhibited substantially higher resistance to temperature variation (tested from 5 to 70 °C) and lower degree of sensitivity to pH value (tested from 4.0 and 10.0) than the free catalase. In particular, according to the kinetic parameters of Vmax and Km, the nanofibrous membranes of RC-poly(HEMA) (i.e., 5102 μmol mg(-1) min(-1) and 44.89 mM) and RC-poly(DMAEMA) (i.e., 4651 μmol mg(-1) min(-1) and 46.98 mM) had the most satisfactory biocompatibility with immobilized catalase. It was therefore concluded that the electrospun RC nanofibrous membranes surface-grafted with 3-dimensional nanolayers of polymer chains/brushes would be

  18. Enhancing Properties and Performance of Cellulose Acetate/Polyethylene Glycol (CA/PEG Membrane with the addition of Titanium Dioxide (TiO2 by Using Surface Coating Method

    Directory of Open Access Journals (Sweden)

    Nurkhamidah Siti

    2018-01-01

    Full Text Available In this study, cellulose acetate/polyethylene glycol (CA/PEG membrane with composition 80/20 was prepared by phase inversion method. Titanium dioxide with different number has been added by using surface coating. Hydrophilicity, morphology, flux permeate and salt rejection of membranes has been studied. The hydrophilicity is determined by Fourier-Transformed Infra-Red (FTIR spectra and contact angle analysis. Surface and fractured morphology are identified by using Scanning Electron Microscopy (SEM. The experiment results show that hydrophilicity of CA/PEG membrane increases with the addition and the increasing of TiO2 contents. However, with further increasing of TiO2, hydrophilicity of CPT membrane decreases. The optimum membrane is CA/PEG/TiO2 80/20/1,25 g/L solvent (CPT 3 with flux permeate of 111,82 L.m-2h-1 and salt rejection of 48,30%.

  19. Detergent disruption of bacterial inner membranes and recovery of protein translocation activity

    International Nuclear Information System (INIS)

    Cunningham, K.; Wickner, W.T.

    1989-01-01

    Isolation of the integral membrane components of protein translocation requires methods for fractionation and functional reconstitution. The authors treated inner-membrane vesicles of Escherichia coli with mixtures of octyl β-D-glucoside, phospholipids, and an integral membrane carrier protein under conditions that extract most of the membrane proteins into micellar solution. Upon dialysis, proteoliposomes were reconstituted that supported translocation of radiochemically pure [ 35 S]pro-OmpA (the precursor of outer membrane protein A). Translocation into these proteoliposomes required ATP hydrolysis and membrane proteins, indicating that the reaction is that of the inner membrane. The suspension of membranes in detergent was separated into supernatant and pellet fractions by ultracentrifugation. After reconstitution, translocation activity was observed in both fractions, but processing by leader peptidase of translocated pro-OmpA to OmpA was not detectable in the reconstituted pellet fraction. Processing activity was restored by addition of pure leader peptidase as long as this enzyme was added before detergent removal, indicating that the translocation activity is not associated with detergent-resistant membrane vesicles. These results show that protein translocation activity can be recovered from detergent-disrupted membrane vesicles, providing a first step towards the goal of isolating the solubilized components

  20. Cellulose nanocrystal properties and their applications

    Directory of Open Access Journals (Sweden)

    mahdi jonoobi

    2015-05-01

    Full Text Available The main purpose of this work is to provide an overview of recent research in the area of cellulose nonmaterials production from different sources. Due to their abundance, their renewability, high strength and stiffness, being eco-friendly, and low weight; numerous studies have been reported on the isolation of cellulose nanomaterials from different cellulosic sources and their use in high performance applications. This work covers an introduction into the nano cellulose definition as well as used methods for isolation of nanomaterials (nanocrystals from various sources. The rod-like cellulose nanocrystals (CNC can be isolated from sources like wood, plant fibers, agriculture and industrial bio residues, tunicates, and bacterial cellulose using acid hydrolysis process. Following this, the paper focused on characterization methods, materials properties and structure. The current review is a comprehensive literature regarding the nano cellulose isolation and demonstrates the potential of cellulose nanomaterials to be used in a wide range of high-tech applications.

  1. A novel membrane sensor controls the localization and ArfGEF activity of bacterial RalF.

    Directory of Open Access Journals (Sweden)

    Marcia Folly-Klan

    Full Text Available The intracellular bacterial pathogen Legionella pneumophila (Lp evades destruction in macrophages by camouflaging in a specialized organelle, the Legionella-containing vacuole (LCV, where it replicates. The LCV maturates by incorporating ER vesicles, which are diverted by effectors that Lp injects to take control of host cell membrane transport processes. One of these effectors, RalF, recruits the trafficking small GTPase Arf1 to the LCV. LpRalF has a Sec7 domain related to host ArfGEFs, followed by a capping domain that intimately associates with the Sec7 domain to inhibit GEF activity. How RalF is activated to function as a LCV-specific ArfGEF is unknown. We combined the reconstitution of Arf activation on artificial membranes with cellular expression and Lp infection assays, to analyze how auto-inhibition is relieved for LpRalF to function in vivo. We find that membranes activate LpRalF by about 1000 fold, and identify the membrane-binding region as the region that inhibits the Sec7 active site. It is enriched in aromatic and positively charged residues, which establish a membrane sensor to control the GEF activity in accordance with specific lipid environments. A similar mechanism of activation is found in RalF from Rickettsia prowazekii (Rp, with a different aromatic/charged residues ratio that results in divergent membrane preferences. The membrane sensor is the primary determinant of the localization of LpRalF on the LCV, and drives the timing of Arf activation during infection. Finally, we identify a conserved motif in the capping domain, remote from the membrane sensor, which is critical for RalF activity presumably by organizing its active conformation. These data demonstrate that RalF proteins are regulated by a membrane sensor that functions as a binary switch to derepress ArfGEF activity when RalF encounters a favorable lipid environment, thus establishing a regulatory paradigm to ensure that Arf GTPases are efficiently activated at

  2. Polyvinyl alcohol–cellulose composite

    Indian Academy of Sciences (India)

    We have made an attempt to prepare taste sensor material by using functionalized polymer without any lipid. PVA–cellulose composite has been modified to use as the sensor material. The research work covers polymer membrane preparation, morphology study and structural characterization of the membrane and study of ...

  3. Effect of DS Concentration on the PRO Performance Using a 5-Inch Scale Cellulose Triacetate-Based Hollow Fiber Membrane Module

    Directory of Open Access Journals (Sweden)

    Masahiro Yasukawa

    2018-05-01

    Full Text Available In this study, pressure-retarded osmosis (PRO performance of a 5-inch scale cellulose triacetate (CTA-based hollow fiber (HF membrane module was evaluated under a wide range of operating conditions (0.0–6.0 MPa of applied pressure, 0.5–2.0 L/min feed solution (FS inlet flow rate, 1.0–6.0 L/min DS inlet flow rate and 0.1–0.9 M draw solution (DS concentration by using a PRO/reverse osmosis (RO hybrid system. The subsequent RO system for DS regeneration enabled the evaluation of the steady-stated module performance. In the case of pilot-scale module operation, since the DS dilution and the feed solution (FS up-concentration had occurred and was not negligible, unlike the lab-scale experiment, PRO performance strongly depended on operating conditions such as inlet flow rates of both the DS and FS concentration. To compare the module performance with different configurations, we proposed a converted parameter in which a difference of the packing density between the spiral wound (SW and the HF module was fairly considered. In the case of HF configuration, because of high packing density, volumetric-based performance was higher than that of SW module, that is, the required number of the module would be less than that of SW module in a full-scale PRO plant.

  4. Characterization of Cellulose Synthesis in Plant Cells

    Science.gov (United States)

    Maleki, Samaneh Sadat; Mohammadi, Kourosh; Ji, Kong-shu

    2016-01-01

    Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4) D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC) from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA) proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family. PMID:27314060

  5. Characterization of Cellulose Synthesis in Plant Cells

    Directory of Open Access Journals (Sweden)

    Samaneh Sadat Maleki

    2016-01-01

    Full Text Available Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4 D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family.

  6. Bacterial adhesion to antibiotic-loaded guided tissue regeneration membranes – A scanning electron microscopy study

    Directory of Open Access Journals (Sweden)

    Chi-Fang Cheng

    2015-01-01

    Conclusion: Incorporation of tetracycline or amoxicillin greatly reduced adhesion of S. mutans or A. actinomycetemcomitans on the ePTFE, glycolide fiber, or collagen membranes. This finding indicates that it is valuable and effective to use the antibiotic-loaded GTR membranes for periodontal regeneration therapy.

  7. Cellulose synthase complex organization and cellulose microfibril structure.

    Science.gov (United States)

    Turner, Simon; Kumar, Manoj

    2018-02-13

    Cellulose consists of linear chains of β-1,4-linked glucose units, which are synthesized by the cellulose synthase complex (CSC). In plants, these chains associate in an ordered manner to form the cellulose microfibrils. Both the CSC and the local environment in which the individual chains coalesce to form the cellulose microfibril determine the structure and the unique physical properties of the microfibril. There are several recent reviews that cover many aspects of cellulose biosynthesis, which include trafficking of the complex to the plasma membrane and the relationship between the movement of the CSC and the underlying cortical microtubules (Bringmann et al. 2012 Trends Plant Sci. 17 , 666-674 (doi:10.1016/j.tplants.2012.06.003); Kumar & Turner 2015 Phytochemistry 112 , 91-99 (doi:10.1016/j.phytochem.2014.07.009); Schneider et al. 2016 Curr. Opin. Plant Biol. 34 , 9-16 (doi:10.1016/j.pbi.2016.07.007)). In this review, we will focus on recent advances in cellulose biosynthesis in plants, with an emphasis on our current understanding of the structure of individual catalytic subunits together with the local membrane environment where cellulose synthesis occurs. We will attempt to relate this information to our current knowledge of the structure of the cellulose microfibril and propose a model in which variations in the structure of the CSC have important implications for the structure of the cellulose microfibril produced.This article is part of a discussion meeting issue 'New horizons for cellulose nanotechnology'. © 2017 The Author(s).

  8. Cellulose Synthesis in Agrobacterium tumefaciens

    Energy Technology Data Exchange (ETDEWEB)

    Alan R. White; Ann G. Matthysse

    2004-07-31

    We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants including CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried out one

  9. Bistable Bacterial Growth Rate in Response to Antibiotics with Low Membrane Permeability

    Science.gov (United States)

    Elf, Johan; Nilsson, Karin; Tenson, Tanel; Ehrenberg, Måns

    2006-12-01

    We demonstrate that growth rate bistability for bacterial cells growing exponentially at a fixed external antibiotic concentration can emerge when the cell wall permeability for the drug is low and the growth rate sensitivity to the intracellular drug concentration is high. Under such conditions, an initially high growth rate can remain high, due to dilution of the intracellular drug concentration by rapid cell volume increase, while an initially low growth rate can remain low, due to slow cell volume increase and insignificant drug dilution. Our findings have implications for the testing of novel antibiotics on growing bacterial strains.

  10. Cellulose is not just cellulose

    DEFF Research Database (Denmark)

    Hidayat, Budi Juliman; Felby, Claus; Johansen, Katja Salomon

    2012-01-01

    Most secondary plant cell walls contain irregular regions known as dislocations or slip planes. Under industrial biorefining conditions dislocations have recently been shown to play a key role during the initial phase of the enzymatic hydrolysis of cellulose in plant cell walls. In this review we...... chart previous publications that have discussed the structure of dislocations and their susceptibility to hydrolysis. The supramolecular structure of cellulose in dislocations is still unknown. However, it has been shown that cellulose microfibrils continue through dislocations, i.e. dislocations...... are not regions where free cellulose ends are more abundant than in the bulk cell wall. In more severe cases cracks between fibrils form at dislocations and it is possible that the increased accessibility that these cracks give is the reason why hydrolysis of cellulose starts at these locations. If acid...

  11. Cellulose nanomaterials in water treatment technologies.

    Science.gov (United States)

    Carpenter, Alexis Wells; de Lannoy, Charles-François; Wiesner, Mark R

    2015-05-05

    Cellulose nanomaterials are naturally occurring with unique structural, mechanical and optical properties. While the paper and packaging, automotive, personal care, construction, and textiles industries have recognized cellulose nanomaterials' potential, we suggest cellulose nanomaterials have great untapped potential in water treatment technologies. In this review, we gather evidence of cellulose nanomaterials' beneficial role in environmental remediation and membranes for water filtration, including their high surface area-to-volume ratio, low environmental impact, high strength, functionalizability, and sustainability. We make direct comparison between cellulose nanomaterials and carbon nanotubes (CNTs) in terms of physical and chemical properties, production costs, use and disposal in order to show the potential of cellulose nanomaterials as a sustainable replacement for CNTs in water treatment technologies. Finally, we comment on the need for improved communication and collaboration across the myriad industries invested in cellulose nanomaterials production and development to achieve an efficient means to commercialization.

  12. Cellulose Nanomaterials in Water Treatment Technologies

    Science.gov (United States)

    Carpenter, Alexis Wells; de Lannoy, Charles François; Wiesner, Mark R.

    2015-01-01

    Cellulose nanomaterials are naturally occurring with unique structural, mechanical and optical properties. While the paper and packaging, automotive, personal care, construction, and textiles industries have recognized cellulose nanomaterials’ potential, we suggest cellulose nanomaterials have great untapped potential in water treatment technologies. In this review, we gather evidence of cellulose nanomaterials’ beneficial role in environmental remediation and membranes for water filtration, including their high surface area-to-volume ratio, low environmental impact, high strength, functionalizability, and sustainability. We make direct comparison between cellulose nanomaterials and carbon nanotubes (CNTs) in terms of physical and chemical properties, production costs, use and disposal in order to show the potential of cellulose nanomaterials as a sustainable replacement for CNTs in water treatment technologies. Finally, we comment on the need for improved communication and collaboration across the myriad industries invested in cellulose nanomaterials production and development to achieve an efficient means to commercialization. PMID:25837659

  13. Atomic Force Microscopy of bacterial photosynthetic systems: A new model for Native Membrane Organization

    NARCIS (Netherlands)

    Bahatyrova, S.

    2005-01-01

    The main goal of this thesis was to investigate the supramolecular architecture of a photosynthetic membrane from Rhodobacter sphaeroides purple bacteria cells. This is extremely timely, since we now know all of the structures of photosynthetic pigment-protein LH and RC complexes, ATP-synthase and

  14. The Motion of a Single Molecule, the Lambda-Receptor, in the Bacterial Outer Membrane

    DEFF Research Database (Denmark)

    Oddershede, Lene; Dreyer, Jakob Kisbye; Grego, Sonia

    2002-01-01

    Using optical tweezers and single particle tracking, we have revealed the motion of a single protein, the lambda-receptor, in the outer membrane of living Escherichia coli bacteria. We genetically modified the lambda-receptor placing a biotin on an extracellular site of the receptor in vivo...

  15. Interaction of phospholipase A of the E. coli outer membrane with the inhibitors of eucaryotic phospholipases A₂ and their effect on the Ca²⁺-induced permeabilization of the bacterial membrane.

    Science.gov (United States)

    Belosludtsev, Konstantin N; Belosludtseva, Natalia V; Kondratyev, Maxim S; Agafonov, Alexey V; Purtov, Yuriy A

    2014-03-01

    Phospholipase A of the bacterial outer membrane (OMPLA) is a β-barrel membrane protein which is activated under various stress conditions. The current study examines interaction of inhibitors of eucaryotic phospholipases A₂--palmitoyl trifluoromethyl ketone (PACOCF₃) and aristolochic acid (AA)--with OMPLA and considers a possible involvement of the enzyme in the Ca²⁺-dependent permeabilization of the outer membrane of Escherichia coli. Using the method of molecular docking, it has been predicted that PACOCF₃ and AA bind to OMPLA at the same site and with the same affinity as the OMPLA inhibitors, hexadecanesulfonylfluoride and bromophenacyl bromide, and the substrate of the enzyme palmitoyl oleoyl phosphatidylethanolamine. It has also been shown that PACOCF₃, AA, and bromophenacyl bromide inhibit the Ca²⁺-induced temperature-dependent changes in the permeability of the bacterial membrane for the fluorescent probe propidium iodide and suppressed the transformation of E. coli cells with plasmid DNA induced by Ca²⁺ and heat shock. The cell viability was not affected by the eucaryotic phospholipases A₂ inhibitors. The study discusses a possible involvement of OMPLA in the mechanisms of bacterial transmembrane transport based on the permeabilization of the bacterial outer membrane.

  16. Real-time examination of aminoglycoside activity towards bacterial mimetic membranes using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D).

    Science.gov (United States)

    Joshi, Tanmaya; Voo, Zhi Xiang; Graham, Bim; Spiccia, Leone; Martin, Lisandra L

    2015-02-01

    The rapid increase in multi-drug resistant bacteria has resulted in previously discontinued treatments being revisited. Aminoglycosides are effective "old" antibacterial agents that fall within this category. Despite extensive usage and understanding of their intracellular targets, there is limited mechanistic knowledge regarding how aminoglycosides penetrate bacterial membranes. Thus, the activity of two well-known aminoglycosides, kanamycin A and neomycin B, towards a bacterial mimetic membrane (DMPC:DMPG (4:1)) was examined using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The macroscopic effect of increasing the aminoglycoside concentration showed that kanamycin A exerts a threshold response, switching from binding to the membrane to disruption of the surface. Neomycin B, however, disrupted the membrane at all concentrations examined. At concentrations above the threshold value observed for kanamycin A, both aminoglycosides revealed similar mechanistic details. That is, they both inserted into the bacterial mimetic lipid bilayer, prior to disruption via loss of materials, presumably aminoglycoside-membrane composites. Depth profile analysis of this membrane interaction was achieved using the overtones of the quartz crystal sensor. The measured data is consistent with a two-stage process in which insertion of the aminoglycoside precedes the 'detergent-like' removal of membranes from the sensor. The results of this study contribute to the insight required for aminoglycosides to be reconsidered as active antimicrobial agents/co-agents by providing details of activity at the bacterial membrane. Kanamycin and neomycin still offer potential as antimicrobial therapeutics for the future and the QCM-D method illustrates great promise for screening new antibacterial or antiviral drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Radiosensitization of hypoxic bacterial cells and animal tumours by membrane active drugs and hyperthermia

    International Nuclear Information System (INIS)

    Singh, B.B.; Srinivasan, V.T.; Shenoy, M.A.; George, K.C.; Maniar, H.S.; Rawat, K.P.

    1987-01-01

    The present report deals with the results on phenothiazine derivatives such as promethazine (PMZ), trimeprazine (TMZ), trifluoperazine (TFP) and prochlorperazine (PCP) and their comparison with that of chlorpromazine (CPZ). Their efficiency in combination with hyperthermia, radiation and other anti-cancer drugs in treating murine tumors has also been presented herein. In addition, results on bacterial cells dealing with their mechanistic aspects are also included. (author). 57 refs., 27 figures, 13 tables

  18. Mitigation of membrane biofouling by d-amino acids: Effect of bacterial cell-wall property and d-amino acid type.

    Science.gov (United States)

    Wang, Si-Yu; Sun, Xue-Fei; Gao, Wen-Jing; Wang, Yi-Fu; Jiang, Bei-Bei; Afzal, Muhammad Zaheer; Song, Chao; Wang, Shu-Guang

    2018-04-01

    Development of novel approaches for biofouling mitigation is of crucial importance for membrane-based technologies. d-amino acids (d-AAs) have been proposed as a potential strategy to mitigate biofouling. However, the effect of bacterial cell-wall properties and d-AAs type on biofouling mitigation remains unclear. This study assesses the effect of d-AAs type on membrane biofouling control, towards Gram positive (G+) and Gram negative (G-) bacteria. Three kinds of d-AAs were found to inhibit both G+ and G- bacterial attachment in short-term attachment and dead-end filtration experiments. The existence of d-AAs reduces extracellular polysaccharides and proteins on the membrane, which may decrease membrane biofouling. Cross-flow filtration tests further indicated that d-AAs could effectively reduce membrane biofouling. The permeate flux recovery post chemical cleaning, improved for both P. aeruginosa and B. subtilis treated with d-AAs. The results obtained from this study enable better understanding of the role of d-AAs species on bacterial adhesion and biofilm formation. This may provide a new way to regulate biofilm formation by manipulating the species of d-AAs membrane systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Staphylococcus aureus Infection of Human Gestational Membranes Induces Bacterial Biofilm Formation and Host Production of Cytokines.

    Science.gov (United States)

    Doster, Ryan S; Kirk, Leslie A; Tetz, Lauren M; Rogers, Lisa M; Aronoff, David M; Gaddy, Jennifer A

    2017-02-15

    Staphylococcus aureus, a metabolically flexible gram-positive pathogen, causes infections in a variety of tissues. Recent evidence implicates S. aureus as an emerging cause of chorioamnionitis and premature rupture of membranes, which are associated with preterm birth and neonatal disease. We demonstrate here that S. aureus infects and forms biofilms on the choriodecidual surface of explanted human gestational membranes. Concomitantly, S. aureus elicits the production of proinflammatory cytokines, which could ultimately perturb maternal-fetal tolerance during pregnancy. Therefore, targeting the immunological response to S. aureus infection during pregnancy could attenuate disease among infected individuals, especially in the context of antibiotic resistance. Published by Oxford University Press for the Infectious Diseases Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  20. Control of biofouling by xanthine oxidase on seawater reverse osmosis membranes from a desalination plant: enzyme production and screening of bacterial isolates from the full-scale plant.

    Science.gov (United States)

    Nagaraj, V; Skillman, L; Li, D; Xie, Z; Ho, G

    2017-07-01

    Control of biofouling on seawater reverse osmosis (SWRO) membranes is a major challenge as treatments can be expensive, damage the membrane material and often biocides do not remove the polymers in which bacteria are embedded. Biological control has been largely ignored for biofouling control. The objective of this study was to demonstrate the effectiveness of xanthine oxidase enzyme against complex fouling communities and then identify naturally occurring bacterial strains that produce the free radical generating enzyme. Initially, 64 bacterial strains were isolated from different locations of the Perth Seawater Desalination Plant. In our preceding study, 25/64 isolates were selected from the culture collection as models for biofouling studies, based on their prevalence in comparison to the genomic bacterial community. In this study, screening of these model strains was performed using a nitroblue tetrazolium assay in the presence of hypoxanthine as substrate. Enzyme activity was measured by absorbance. Nine of 25 strains tested positive for xanthine oxidase production, of which Exiguobacterium from sand filters and Microbacterium from RO membranes exhibited significant levels of enzyme production. Other genera that produced xanthine oxidase were Marinomonas, Pseudomonas, Bacillus, Pseudoalteromonas and Staphylococcus. Strain variations were observed between members of the genera Microbacterium and Bacillus. Xanthine oxidase, an oxidoreductase enzyme that generates reactive oxygen species, is endogenously produced by many bacterial species. In this study, production of the enzyme by bacterial isolates from a full-scale desalination plant was investigated for potential use as biological control of membrane fouling in seawater desalination. We have previously demonstrated that free radicals generated by a commercially available xanthine oxidase in the presence of a hypoxanthine substrate, effectively dispersed biofilm polysaccharides on industrially fouled membranes

  1. Kinetics of membrane damage to high (HNA) and low (LNA) nucleic acid bacterial clusters in drinking water by ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate.

    Science.gov (United States)

    Ramseier, Maaike K; von Gunten, Urs; Freihofer, Pietro; Hammes, Frederik

    2011-01-01

    Drinking water was treated with ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate to investigate the kinetics of membrane damage of native drinking water bacterial cells. Membrane damage was measured by flow cytometry using a combination of SYBR Green I and propidium iodide (SGI+PI) staining as indicator for cells with permeabilized membranes and SGI alone to measure total cell concentration. SGI+PI staining revealed that the cells were permeabilized upon relatively low oxidant exposures of all tested oxidants without a detectable lag phase. However, only ozonation resulted in a decrease of the total cell concentrations for the investigated reaction times. Rate constants for the membrane damage reaction varied over seven orders of magnitude in the following order: ozone > chlorine > chlorine dioxide ≈ ferrate > permanganate > chloramine. The rate constants were compared to literature data and were in general smaller than previously measured rate constants. This confirmed that membrane integrity is a conservative and therefore safe parameter for disinfection control. Interestingly, the cell membranes of high nucleic acid (HNA) content bacteria were damaged much faster than those of low nucleic acid (LNA) content bacteria during treatment with chlorine dioxide and permanganate. However, only small differences were observed during treatment with chlorine and chloramine, and no difference was observed for ferrate treatment. Based on the different reactivity of these oxidants it was suggested that HNA and LNA bacterial cell membranes have a different chemical constitution. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Entrapped cells-based-anaerobic membrane bioreactor treating domestic wastewater: Performances, fouling, and bacterial community structure.

    Science.gov (United States)

    Juntawang, Chaipon; Rongsayamanont, Chaiwat; Khan, Eakalak

    2017-11-01

    A laboratory scale study on treatment performances and fouling of entrapped cells-based-anaerobic membrane bioreactor (E-AnMBR) in comparison with suspended cells-based-bioreactor (S-AnMBR) treating domestic wastewater was conducted. The difference between E-AnMBR and S-AnMBR was the uses of cells entrapped in phosphorylated polyvinyl alcohol versus planktonic cells. Bulk organic removal efficiencies by the two AnMBRs were comparable. Lower concentrations of suspended biomass, bound extracellular polymeric substances and soluble microbial products in E-AnMBR resulted in less fouling compared to S-AnMBR. S-AnMBR provided 7 days of operation time versus 11 days for E-AnMBR before chemical cleaning was required. The less frequent chemical cleaning potentially leads to a longer membrane life-span for E-AnMBR compared to S-AnMBR. Phyla Proteobacteria, Chloroflexi, Bacteroidetes and Acidobacteria were dominant in cake sludge from both AnMBRs but their abundances were different between the two AnMBRs, suggesting influence of cell entrapment on the bacteria community. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Structural and thermodynamic characterization of doxycycline/β-cyclodextrin supramolecular complex and its bacterial membrane interactions.

    Science.gov (United States)

    Suárez, Diego F; Consuegra, Jessika; Trajano, Vivianne C; Gontijo, Sávio M L; Guimarães, Pedro P G; Cortés, Maria E; Denadai, Ângelo L; Sinisterra, Rubén D

    2014-06-01

    Doxycycline is a semi-synthetic antibiotic commonly used for the treatment of many aerobic and anaerobic bacteria. It inhibits the activity of matrix metalloproteinases (MMPs) and affects cell proliferation. In this study, the structural and thermodynamic parameters of free DOX and a DOX/βCD complex were investigated, as well as their interactions and effects on Staphylococcus aureus cells and cellular cytotoxicity. Complexation of DOX and βCD was confirmed to be an enthalpy- and entropy-driven process, and a low equilibrium constant was obtained. Treatment of S. aureus with higher concentrations of DOX or DOX/βCD resulted in an exponential decrease in S. aureus cell size, as well as a gradual neutralization of zeta potential. These thermodynamic profiles suggest that ion-pairing and hydrogen bonding interactions occur between DOX and the membrane of S. aureus. In addition, the adhesion of βCD to the cell membrane via hydrogen bonding is hypothesized to mediate a synergistic effect which accounts for the higher activity of DOX/βCD against S. aureus compared to pure DOX. Lower cytotoxicity and induction of osteoblast proliferation was also associated with DOX/βCD compared with free DOX. These promising findings demonstrate the potential for DOX/βCD to mediate antimicrobial activity at lower concentrations, and provides a strategy for the development of other antimicrobial formulations. Copyright © 2014. Published by Elsevier B.V.

  4. A census of membrane-bound and intracellular signal transduction proteins in bacteria: Bacterial IQ, extroverts and introverts

    Directory of Open Access Journals (Sweden)

    Galperin Michael Y

    2005-06-01

    highest IQ, including the current leader Wolinella succinogenes, are found among the poorly studied beta-, delta- and epsilon-proteobacteria. Among all bacterial phyla, only cyanobacteria appear to be true introverts, probably due to their capacity to conduct oxygenic photosynthesis, using a complex system of intracellular membranes. The census data, available at http://www.ncbi.nlm.nih.gov/Complete_Genomes/SignalCensus.html, can be used to get an insight into metabolic and behavioral propensities of each given organism and improve prediction of the organism's properties based solely on its genome sequence.

  5. A census of membrane-bound and intracellular signal transduction proteins in bacteria: bacterial IQ, extroverts and introverts.

    Science.gov (United States)

    Galperin, Michael Y

    2005-06-14

    , are found among the poorly studied beta-, delta- and epsilon-proteobacteria. Among all bacterial phyla, only cyanobacteria appear to be true introverts, probably due to their capacity to conduct oxygenic photosynthesis, using a complex system of intracellular membranes. The census data, available at http://www.ncbi.nlm.nih.gov/Complete_Genomes/SignalCensus.html, can be used to get an insight into metabolic and behavioral propensities of each given organism and improve prediction of the organism's properties based solely on its genome sequence.

  6. Membrane Lipids as Indicators for Viable Bacterial Communities Inhabiting Petroleum Systems.

    Science.gov (United States)

    Gruner, Andrea; Mangelsdorf, Kai; Vieth-Hillebrand, Andrea; Horsfield, Brian; van der Kraan, Geert M; Köhler, Thomas; Janka, Christoph; Morris, Brandon E L; Wilkes, Heinz

    2017-08-01

    Microbial activity in petroleum reservoirs has been implicated in a suite of detrimental effects including deterioration of petroleum quality, increases in oil sulfur content, biofouling of steel pipelines and other infrastructures, and well plugging. Here, we present a biogeochemical approach, using phospholipid fatty acids (PLFAs), for detecting viable bacteria in petroleum systems. Variations within the bacterial community along water flow paths (producing well, topside facilities, and injection well) can be elucidated in the field using the same technique, as shown here within oil production plants in the Molasse Basin of Upper Austria. The abundance of PLFAs is compared to total cellular numbers, as detected by qPCR of the 16S rDNA gene, to give an overall comparison between the resolutions of both methods in a true field setting. Additionally, the influence of biocide applications on lipid- and DNA-based quantification was investigated. The first oil field, Trattnach, showed significant PLFA abundances and cell numbers within the reservoir and topside facilities. In contrast, the second field (Engenfeld) showed very low PLFA levels overall, likely due to continuous treatment of the topside facilities with a glutaraldehyde-based antimicrobial. In comparison, Trattnach is dosed once per week in a batch fashion. Changes within PLFA compositions across the flow path, throughout the petroleum production plants, point to cellular adaptation within the system and may be linked to shifts in the dominance of certain bacterial types in oil reservoirs versus topside facilities. Overall, PLFA-based monitoring provides a useful tool to assess the abundance and high-level taxonomic diversity of viable microbial populations in oil production wells, topside infrastructure, pipelines, and other related facilities.

  7. Polyvinyl alcohol–cellulose composite: a taste sensing material

    Indian Academy of Sciences (India)

    Unknown

    cellulose composite membrane was converted to phosphate ester by phosphorylation, phosphorus content of the membrane was estimated by Heraeus Schöniger Combustion Appa- ratus, Germany, following the method of Schöniger (1955).

  8. Is the C-terminal insertional signal in Gram-negative bacterial outer membrane proteins species-specific or not?

    Directory of Open Access Journals (Sweden)

    Paramasivam Nagarajan

    2012-09-01

    Full Text Available Abstract Background In Gram-negative bacteria, the outer membrane is composed of an asymmetric lipid bilayer of phopspholipids and lipopolysaccharides, and the transmembrane proteins that reside in this membrane are almost exclusively β-barrel proteins. These proteins are inserted into the membrane by a highly conserved and essential machinery, the BAM complex. It recognizes its substrates, unfolded outer membrane proteins (OMPs, through a C-terminal motif that has been speculated to be species-specific, based on theoretical and experimental results from only two species, Escherichia coli and Neisseria meningitidis, where it was shown on the basis of individual sequences and motifs that OMPs from the one cannot easily be over expressed in the other, unless the C-terminal motif was adapted. In order to determine whether this species specificity is a general phenomenon, we undertook a large-scale bioinformatics study on all predicted OMPs from 437 fully sequenced proteobacterial strains. Results We were able to verify the incompatibility reported between Escherichia coli and Neisseria meningitidis, using clustering techniques based on the pairwise Hellinger distance between sequence spaces for the C-terminal motifs of individual organisms. We noticed that the amino acid position reported to be responsible for this incompatibility between Escherichia coli and Neisseria meningitidis does not play a major role for determining species specificity of OMP recognition by the BAM complex. Instead, we found that the signal is more diffuse, and that for most organism pairs, the difference between the signals is hard to detect. Notable exceptions are the Neisseriales, and Helicobacter spp. For both of these organism groups, we describe the specific sequence requirements that are at the basis of the observed difference. Conclusions Based on the finding that the differences between the recognition motifs of almost all organisms are small, we assume that

  9. Model of mouth-to-mouth transfer of bacterial lipoproteins through inner membrane LolC, periplasmic LolA, and outer membrane LolB

    OpenAIRE

    Okuda, Suguru; Tokuda, Hajime

    2009-01-01

    Outer membrane-specific lipoproteins in Escherichia coli are released from the inner membrane by an ATP-binding cassette transporter, the LolCDE complex, which causes the formation of a soluble complex with a periplasmic molecular chaperone, LolA. LolA then transports lipoproteins to the outer membrane where an outer membrane receptor, LolB, incorporates lipoproteins into the outer membrane. The molecular mechanisms underlying the Lol-dependent lipoprotein sorting have been clarified in detai...

  10. Electromotive force and impedance studies of cellulose acetate membranes: Evidence for two binding sites for divalent cations and for an alveolar structure of the skin layer

    DEFF Research Database (Denmark)

    Smith Sørensen, T.; Jensen, J.B.; Malmgren-Hansen, B.

    1991-01-01

    from the lamellar wall is of some significance only at low salt concentrations. Measured Nernst distribution coefficients in dense CA-membranes agree roughly with calculated values. We also focus on new results for the binding of divalent cations to the glucuronic acid groups of the CA-chains, which...... asymmetic membranes. The skin layer in asymmetric membranes is assumed to have properties similar to dense membranes. The EMF measurements were interpreted by means of a Donnan-Nernst-Planck (Teorell-Meyer-Sievers) model, which functions quite well due to the low fixed charge in the membrane. The membrane...... may temporarily transform the membranes from weak cationic exchange membranes to weak anionic exchange membranes. The divalent cations may be washed out, but the rate of dissociation is very low. There seems to be two relaxations, the slower being of the order of weeks, the faster being of the order...

  11. Porous rod-like MgO complex membrane with good anti-bacterial activity directed by conjugated linolenic acid polymer

    Science.gov (United States)

    Wang, Hua-Jie; Chen, Meng; Mi, Li-Wei; Shi, Li-Hua; Cao, Ying

    2016-02-01

    The problem of infection in the tissue engineering substitutes is driving us to seek new coating materials. We previously found that conjugated linolenic acid (CLnA) has well biocompatibility and excellent membrane-forming property. The objective of this study is to endow the anti-bacterial activity to CLnA membra ne by linking with MgO. The results showed that the CLnA polymer membrane can be loaded with porous rod-like MgO and such complex membrane showed anti-bacterial sensitivity against gram-positive bacteria ( Staphylococcus aureus) even at the low concentration (0.15 μg/mm2). In the present study, the best zone of inhibition got to 18.2 ± 0.8 mm when the amount of MgO reach 2.42 ± 0.58 μg/mm2. It was deduced that the porous rod-like structure of MgO was directed by CLnA in its polymerization process. Such CLnA/MgO complex membrane can be helpful in the tissue engineering, medicine, food engineering, food preservation, etc. on the basis of its good anti-bacterial activity.

  12. Porous rod-like MgO complex membrane with good anti-bacterial activity directed by conjugated linolenic acid polymer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua-Jie, E-mail: wanghuajie972001@163.com; Chen, Meng [Henan Normal University, College of Chemistry and Chemical Engineering (China); Mi, Li-Wei, E-mail: mlwzzu@163.com [Zhongyuan University of Technology, Center for Advanced Materials Research (China); Shi, Li-Hua [Anyang 101 Education Center (China); Cao, Ying, E-mail: caoying1130@sina.com [Zhongyuan University of Technology, Center for Advanced Materials Research (China)

    2016-02-15

    The problem of infection in the tissue engineering substitutes is driving us to seek new coating materials. We previously found that conjugated linolenic acid (CLnA) has well biocompatibility and excellent membrane-forming property. The objective of this study is to endow the anti-bacterial activity to CLnA membra ne by linking with MgO. The results showed that the CLnA polymer membrane can be loaded with porous rod-like MgO and such complex membrane showed anti-bacterial sensitivity against gram-positive bacteria (Staphylococcus aureus) even at the low concentration (0.15 μg/mm{sup 2}). In the present study, the best zone of inhibition got to 18.2 ± 0.8 mm when the amount of MgO reach 2.42 ± 0.58 μg/mm{sup 2}. It was deduced that the porous rod-like structure of MgO was directed by CLnA in its polymerization process. Such CLnA/MgO complex membrane can be helpful in the tissue engineering, medicine, food engineering, food preservation, etc. on the basis of its good anti-bacterial activity.

  13. High-strength cellulose/poly(ethylene glycol) gels.

    Science.gov (United States)

    Liang, Songmiao; Wu, Junjie; Tian, Huafeng; Zhang, Lina; Xu, Jian

    2008-01-01

    Cellulose gel membranes have been prepared by a pre-gelation method employing cellulose solutions in aqueous NaOH-thiourea obtained at low temperature. The cellulose gels were then swollen by low-molecular-weight polyethylene glycol (PEG; MWcellulose/PEG gels were studied by various techniques. The gels exhibit high mechanical performance, and the tensile strength of the gel membranes increases sharply with an increase in the molecular weight of PEG from 200 to 800 g mol(-1). Moreover, their elongation at break remains stable at 100 %. PEG800 efficiently improves the optical transmittance of the gel membranes at ambient temperature, which is about five times greater than that of a normal cellulose hydrogel membrane. A strong hydrogen-bonding interaction occurs between PEG and cellulose leading to a homogeneous structure, high mechanical strength and good transparency of the gel membranes.

  14. Bacterial production of short-chain organic acids and trehalose from levulinic acid: a potential cellulose-derived building block as a feedstock for microbial production.

    Science.gov (United States)

    Habe, Hiroshi; Sato, Shun; Morita, Tomotake; Fukuoka, Tokuma; Kirimura, Kohtaro; Kitamoto, Dai

    2015-02-01

    Levulinic acid (LA) is a platform chemical derived from cellulosic biomass, and the expansion of LA utilization as a feedstock is important for production of a wide variety of chemicals. To investigate the potential of LA as a substrate for microbial conversion to chemicals, we isolated and identified LA-utilizing bacteria. Among the six isolated strains, Pseudomonas sp. LA18T and Rhodococcus hoagie LA6W degraded up to 70 g/L LA in a high-cell-density system. The maximal accumulation of acetic acid by strain LA18T and propionic acid by strain LA6W was 13.6 g/L and 9.1 g/L, respectively, after a 4-day incubation. Another isolate, Burkholderia stabilis LA20W, produced trehalose extracellularly in the presence of 40 g/L LA to approximately 2 g/L. These abilities to produce useful compounds supported the potential of microbial LA conversion for future development and cellulosic biomass utilization. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Structure of the Neisserial outer membrane protein Opa₆₀: loop flexibility essential to receptor recognition and bacterial engulfment.

    Science.gov (United States)

    Fox, Daniel A; Larsson, Per; Lo, Ryan H; Kroncke, Brett M; Kasson, Peter M; Columbus, Linda

    2014-07-16

    The structure and dynamics of Opa proteins, which we report herein, are responsible for the receptor-mediated engulfment of Neisseria gonorrheae or Neisseria meningitidis by human cells and can offer deep understanding into the molecular recognition of pathogen-host receptor interactions. Such interactions are vital to understanding bacterial pathogenesis as well as the mechanism of foreign body entry to a human cell, which may provide insights for the development of targeted pharmaceutical delivery systems. The size and dynamics of the extracellular loops of Opa60 required a hybrid refinement approach wherein membrane and distance restraints were used to generate an initial NMR structural ensemble, which was then further refined using molecular dynamics in a DMPC bilayer. The resulting ensemble revealed that the extracellular loops, which bind host receptors, occupy compact conformations, interact with each other weakly, and are dynamic on the nanosecond time scale. We predict that this conformational sampling is critical for enabling diverse Opa loop sequences to engage a common set of receptors.

  16. Insights into the Antimicrobial Mechanism of Action of Human RNase6: Structural Determinants for Bacterial Cell Agglutination and Membrane Permeation

    Science.gov (United States)

    Pulido, David; Arranz-Trullén, Javier; Prats-Ejarque, Guillem; Velázquez, Diego; Torrent, Marc; Moussaoui, Mohammed; Boix, Ester

    2016-01-01

    Human Ribonuclease 6 is a secreted protein belonging to the ribonuclease A (RNaseA) superfamily, a vertebrate specific family suggested to arise with an ancestral host defense role. Tissue distribution analysis revealed its expression in innate cell types, showing abundance in monocytes and neutrophils. Recent evidence of induction of the protein expression by bacterial infection suggested an antipathogen function in vivo. In our laboratory, the antimicrobial properties of the protein have been evaluated against Gram-negative and Gram-positive species and its mechanism of action was characterized using a membrane model. Interestingly, our results indicate that RNase6, as previously reported for RNase3, is able to specifically agglutinate Gram-negative bacteria as a main trait of its antimicrobial activity. Moreover, a side by side comparative analysis with the RN6(1–45) derived peptide highlights that the antimicrobial activity is mostly retained at the protein N-terminus. Further work by site directed mutagenesis and structural analysis has identified two residues involved in the protein antimicrobial action (Trp1 and Ile13) that are essential for the cell agglutination properties. This is the first structure-functional characterization of RNase6 antimicrobial properties, supporting its contribution to the infection focus clearance. PMID:27089320

  17. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins.

    Directory of Open Access Journals (Sweden)

    Felix Dempwolff

    2016-06-01

    Full Text Available Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro-and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds.

  18. A Versatile Strategy for Production of Membrane Proteins with Diverse Topologies: Application to Investigation of Bacterial Homologues of Human Divalent Metal Ion and Nucleoside Transporters.

    Science.gov (United States)

    Ma, Cheng; Hao, Zhenyu; Huysmans, Gerard; Lesiuk, Amelia; Bullough, Per; Wang, Yingying; Bartlam, Mark; Phillips, Simon E; Young, James D; Goldman, Adrian; Baldwin, Stephen A; Postis, Vincent L G

    2015-01-01

    Membrane proteins play key roles in many biological processes, from acquisition of nutrients to neurotransmission, and are targets for more than 50% of current therapeutic drugs. However, their investigation is hampered by difficulties in their production and purification on a scale suitable for structural studies. In particular, the nature and location of affinity tags introduced for the purification of recombinant membrane proteins can greatly influence their expression levels by affecting their membrane insertion. The extent of such effects typically depends on the transmembrane topologies of the proteins, which for proteins of unknown structure are usually uncertain. For example, attachment of oligohistidine tags to the periplasmic termini of membrane proteins often interferes with folding and drastically impairs expression in Escherichia coli. To circumvent this problem we have employed a novel strategy to enable the rapid production of constructs bearing a range of different affinity tags compatible with either cytoplasmic or periplasmic attachment. Tags include conventional oligohistidine tags compatible with cytoplasmic attachment and, for attachment to proteins with a periplasmic terminus, either tandem Strep-tag II sequences or oligohistidine tags fused to maltose binding protein and a signal sequence. Inclusion of cleavage sites for TEV or HRV-3C protease enables tag removal prior to crystallisation trials or a second step of purification. Together with the use of bioinformatic approaches to identify members of membrane protein families with topologies favourable to cytoplasmic tagging, this has enabled us to express and purify multiple bacterial membrane transporters. To illustrate this strategy, we describe here its use to purify bacterial homologues of human membrane proteins from the Nramp and ZIP families of divalent metal cation transporters and from the concentrative nucleoside transporter family. The proteins are expressed in E. coli in a

  19. Fine structure of bacterial adhesion to the epithelial cell membranes of the filiform papillae of tongue and palatine mucosa of rodents: a morphometric, TEM, and HRSEM study.

    Science.gov (United States)

    Watanabe, Ii-Sei; Ogawa, Koichi; Cury, Diego Pulzatto; Dias, Fernando José; Sosthenes, Marcia Consentino Kronka; Issa, João Paulo Mardegan; Iyomasa, Mamie Mizusaki

    2013-12-01

    The palatine mucosa and filiform papillae of the dorsal tongue mucosae of rodents were examined using transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HRSEM). In the HRSEM method, the samples were fixed in 2% osmium tetroxide, dehydrated in alcohol, critical point-dried, and coated with gold-palladium. In addition, the HRSEM technique was used for morphometric analysis (length, width, and length/width ratio of cocci and bacilli). For the TEM method, the tissues were fixed in modified Karnovsky solution (2.5% glutaraldehyde, 2% formalin in 0.1M sodium phosphate buffer, pH 7.4) and embedded in Spurr resin. The results demonstrated that there are thick polygonal keratinized epithelial cells where groups of bacteria are revealed in three-dimensional images on the surface of filiform papillae in these animals. The bacterial membranes are randomly attached to the microplicae surface of epithelial cells. Morphometrics showed higher values of length and width of cocci in newborn (0 day) as compared to newborn (7 days) and adults animals, the bacilli showed no differences in these measurements. At high magnification, the TEM images revealed the presence of glycocalyx microfilaments that constitute a fine adhesion area between bacterial membranes and the membranes of epithelial microplicae cells. In conclusion, the present data revealed the fine fibrillar structures of bacteria that facilitate adhesion to the epithelial cell membranes of the oral cavity and morphometric changes in newborn (0 day) rats as compared with other periods. Copyright © 2013 Wiley Periodicals, Inc.

  20. A novel approach to recycle bacterial culture waste for fermentation reuse via a microbial fuel cell-membrane bioreactor system.

    Science.gov (United States)

    Li, Jian; Zhu, Yuan; Zhuang, Liangpeng; Otsuka, Yuichiro; Nakamura, Masaya; Goodell, Barry; Sonoki, Tomonori; He, Zhen

    2015-09-01

    Biochemical production processes require water and nutrient resources for culture media preparation, but aqueous waste is generated after the target products are extracted. In this study, culture waste (including cells) produced from a lab-scale fermenter was fed into a microbial fuel cell-membrane bioreactor (MFC-MBR) system. Electrical energy was generated via the interaction between the microbial consortia and the solid electrode in the MFC. The treated wastewater was reclaimed in this process which was reused as a solvent and a nutrient source in subsequent fermentation. Polarization testing showed that the MFC produced a maximum current density of 37.53 A m(-3) with a maximum power density of 5.49 W m(-3). The MFC was able to generate 0.04 kWh of energy per cubic meter of culture waste treated. The lab-scale fermenters containing pure cultures of an engineered Pseudomonas spp. were used to generate 2-pyrone-4,6-dicarboxylic acid (PDC), a high value platform chemical. When the MFC-MBR-treated wastewater was used for the fermenter culture medium, a specific bacterial growth rate of 1.00 ± 0.05 h(-1) was obtained with a PDC production rate of 708.11 ± 64.70 mg PDC L(-1) h(-1). Comparable values for controls using pure water were 0.95 ± 0.06 h(-1) and 621.01 ± 22.09 mg PDC L(-1) h(-1) (P > 0.05), respectively. The results provide insight on a new approach for more sustainable bio-material production while at the same time generating energy, and suggest that the treated wastewater can be used as a solvent and a nutrient source for the fermentation production of high value platform chemicals.

  1. The effect of a beta-lactamase inhibitor peptide on bacterial membrane structure and integrity: a comparative study.

    Science.gov (United States)

    Alaybeyoglu, Begum; Uluocak, Bilge Gedik; Akbulut, Berna Sariyar; Ozkirimli, Elif

    2017-05-01

    Co-administration of beta-lactam antibiotics and beta-lactamase inhibitors has been a favored treatment strategy against beta-lactamase-mediated bacterial antibiotic resistance, but the emergence of beta-lactamases resistant to current inhibitors necessitates the discovery of novel non-beta-lactam inhibitors. Peptides derived from the Ala46-Tyr51 region of the beta-lactamase inhibitor protein are considered as potent inhibitors of beta-lactamase; unfortunately, peptide delivery into the cell limits their potential. The properties of cell-penetrating peptides could guide the design of beta-lactamase inhibitory peptides. Here, our goal is to modify the peptide with the sequence RRGHYY that possesses beta-lactamase inhibitory activity under in vitro conditions. Inspired by the work on the cell-penetrating peptide pVEC, our approach involved the addition of the N-terminal hydrophobic residues, LLIIL, from pVEC to the inhibitor peptide to build a chimera. These residues have been reported to be critical in the uptake of pVEC. We tested the potential of RRGHYY and its chimeric derivative as a beta-lactamase inhibitory peptide on Escherichia coli cells and compared the results with the action of the antimicrobial peptide melittin, the beta-lactam antibiotic ampicillin, and the beta-lactamase inhibitor potassium clavulanate to get mechanistic details on their action. Our results show that the addition of LLIIL to the N-terminus of the beta-lactamase inhibitory peptide RRGHYY increases its membrane permeabilizing potential. Interestingly, the addition of this short stretch of hydrophobic residues also modified the inhibitory peptide such that it acquired antimicrobial property. We propose that addition of the hydrophobic LLIIL residues to the peptide N-terminus offers a promising strategy to design novel antimicrobial peptides in the battle against antibiotic resistance. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2017 European

  2. Method of forming an electrically conductive cellulose composite

    Science.gov (United States)

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Woodward, Jonathan [Ashtead, GB

    2011-11-22

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  3. Dissecting the role of conformational change and membrane binding by the bacterial cell division regulator MinE in the stimulation of MinD ATPase activity.

    Science.gov (United States)

    Ayed, Saud H; Cloutier, Adam D; McLeod, Laura J; Foo, Alexander C Y; Damry, Adam M; Goto, Natalie K

    2017-12-15

    The bacterial cell division regulators MinD and MinE together with the division inhibitor MinC localize to the membrane in concentrated zones undergoing coordinated pole-to-pole oscillation to help ensure that the cytokinetic division septum forms only at the mid-cell position. This dynamic localization is driven by MinD-catalyzed ATP hydrolysis, stimulated by interactions with MinE's anti-MinCD domain. This domain is buried in the 6-β-stranded MinE "closed" structure, but is liberated for interactions with MinD, giving rise to a 4-β-stranded "open" structure through an unknown mechanism. Here we show that MinE-membrane interactions induce a structural change into a state resembling the open conformation. However, MinE mutants lacking the MinE membrane-targeting sequence stimulated higher ATP hydrolysis rates than the full-length protein, indicating that binding to MinD is sufficient to trigger this conformational transition in MinE. In contrast, conformational change between the open and closed states did not affect stimulation of ATP hydrolysis rates in the absence of membrane binding, although the MinD-binding residue Ile-25 is critical for this conformational transition. We therefore propose an updated model where MinE is brought to the membrane through interactions with MinD. After stimulation of ATP hydrolysis, MinE remains bound to the membrane in a state that does not catalyze additional rounds of ATP hydrolysis. Although the molecular basis for this inhibited state is unknown, previous observations of higher-order MinE self-association may explain this inhibition. Overall, our findings have general implications for Min protein oscillation cycles, including those that regulate cell division in bacterial pathogens. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Effect of combination dope composition and evaporation time on the separation performance of cellulose acetate membrane for demak brackish water treatment

    Directory of Open Access Journals (Sweden)

    Kusworo Tutuk Djoko

    2017-01-01

    Full Text Available The coastal areas in Indonesia often have a problem of clean water lack, because the water is classified as brackish water. Therefore, this research investigated the fabrication of CA membranes using phase inversion method for brackish water treatment. Investigation was conducted to study the effect of combination dope composition and evaporation time on separation performance and morphology of the memrbane. Membrane was fabricated by dry-wet phase inversion technique with variation of polymer concentration 17, 18 and 20 wt% in the total solid and evaporation time of 5, 10 and 15 seconds, respectively. The asymmetric membranes were characterized by permeability test through rejection and flux measurements using brackish water as feed. The experimental results from SEM images analysis showed that all the membranes have a thin small porous layer and thicker sub-structure of larger porous layer formed asymmetric membrane. Moreover, the greater polymer concentration is resulting smaller pore size and smaller membrane porosity. The longer evaporation time was also resulted in denser membrane active layer. The best membrane performance was observed at the composition of 20 wt% CA polymer, 1 wt % polyethylene glycol with the solvent evaporation time of 15 seconds.

  5. Cellulose Insulation

    Science.gov (United States)

    1980-01-01

    Fire retardant cellulose insulation is produced by shredding old newspapers and treating them with a combination of chemicals. Insulating material is blown into walls and attics to form a fiber layer which blocks the flow of air. All-Weather Insulation's founders asked NASA/UK-TAP to help. They wanted to know what chemicals added to newspaper would produce an insulating material capable of meeting federal specifications. TAP researched the query and furnished extensive information. The information contributed to successful development of the product and helped launch a small business enterprise which is now growing rapidly.

  6. A comparison of bacterial populations in enhanced biological phosphorus removal processes using membrane filtration or gravity sedimentation for solids-liquid separation.

    Science.gov (United States)

    Hall, Eric R; Monti, Alessandro; Mohn, William W

    2010-05-01

    In an earlier phase of this study, we compared the performances of pilot scale treatment systems operated in either a conventional enhanced biological phosphorus removal (CEBPR) mode, or a membrane enhanced biological phosphorus removal (MEBPR) mode. In the present investigation, we characterized the bacterial community populations in these processes during parallel operation with the same municipal wastewater feed. The objectives of the study were (1) to assess the similarity of the bacterial communities supported in the two systems over time, (2) to determine if distinct bacterial populations are associated with the MEBPR and CEBPR processes, and (3) to relate the dynamics of the community composition to changes in treatment process configuration and to treatment process performance. The characteristics of the bacterial populations were first investigated with ribosomal intergenic spacer analysis, or RISA. To further understand the bacterial population dynamics, important RISA phylotypes were isolated and identified through 16S RNA gene sequencing. The parallel MEBPR and CEBPR systems developed bacterial communities that were distinct. The CEBPR community appeared to exhibit greater diversity, and this may have been the primary reason why the CEBPR treatment train demonstrated superior functional stability relative to the MEBPR counterpart. Moreover, the more diverse bacterial population apparent in the CEBPR system was observed to be more dynamic than that of the MEBPR process. Several RISA bands were found to be characteristic of either the membrane or conventional biological system. In particular, the MEBPR configuration appeared to be selective for the slow-growing organism Magnospira bakii and for the foam-associated Microthrix parvicella and Gordonia sp., while gravity separation led to the washout of M. parvicella. In both pilot trains, sequence analysis confirmed the presence of EBPR-related organisms such as Accumulibacter phosphatis. The survey of the

  7. Production by Tobacco Transplastomic Plants of Recombinant Fungal and Bacterial Cell-Wall Degrading Enzymes to Be Used for Cellulosic Biomass Saccharification

    Directory of Open Access Journals (Sweden)

    Paolo Longoni

    2015-01-01

    Full Text Available Biofuels from renewable plant biomass are gaining momentum due to climate change related to atmospheric CO2 increase. However, the production cost of enzymes required for cellulosic biomass saccharification is a major limiting step in this process. Low-cost production of large amounts of recombinant enzymes by transgenic plants was proposed as an alternative to the conventional microbial based fermentation. A number of studies have shown that chloroplast-based gene expression offers several advantages over nuclear transformation due to efficient transcription and translation systems and high copy number of the transgene. In this study, we expressed in tobacco chloroplasts microbial genes encoding five cellulases and a polygalacturonase. Leaf extracts containing the recombinant enzymes showed the ability to degrade various cell-wall components under different conditions, singly and in combinations. In addition, our group also tested a previously described thermostable xylanase in combination with a cellulase and a polygalacturonase to study the cumulative effect on the depolymerization of a complex plant substrate. Our results demonstrate the feasibility of using transplastomic tobacco leaf extracts to convert cell-wall polysaccharides into reducing sugars, fulfilling a major prerequisite of large scale availability of a variety of cell-wall degrading enzymes for biofuel industry.

  8. Production by Tobacco Transplastomic Plants of Recombinant Fungal and Bacterial Cell-Wall Degrading Enzymes to Be Used for Cellulosic Biomass Saccharification.

    Science.gov (United States)

    Longoni, Paolo; Leelavathi, Sadhu; Doria, Enrico; Reddy, Vanga Siva; Cella, Rino

    2015-01-01

    Biofuels from renewable plant biomass are gaining momentum due to climate change related to atmospheric CO2 increase. However, the production cost of enzymes required for cellulosic biomass saccharification is a major limiting step in this process. Low-cost production of large amounts of recombinant enzymes by transgenic plants was proposed as an alternative to the conventional microbial based fermentation. A number of studies have shown that chloroplast-based gene expression offers several advantages over nuclear transformation due to efficient transcription and translation systems and high copy number of the transgene. In this study, we expressed in tobacco chloroplasts microbial genes encoding five cellulases and a polygalacturonase. Leaf extracts containing the recombinant enzymes showed the ability to degrade various cell-wall components under different conditions, singly and in combinations. In addition, our group also tested a previously described thermostable xylanase in combination with a cellulase and a polygalacturonase to study the cumulative effect on the depolymerization of a complex plant substrate. Our results demonstrate the feasibility of using transplastomic tobacco leaf extracts to convert cell-wall polysaccharides into reducing sugars, fulfilling a major prerequisite of large scale availability of a variety of cell-wall degrading enzymes for biofuel industry.

  9. Absence of phosphatidylcholine in bacterial membranes facilitates translocation of Sec-dependent β-lactamase AmpC from cytoplasm to periplasm in two Pseudomonas strains.

    Science.gov (United States)

    Liu, Xin; Sun, Yufang; Cao, Fang; Xiong, Min; Yang, Sheng; Li, Yang; Yu, Xuejing; Li, Yadong; Wang, Xingguo

    2017-05-01

    Phosphatidylcholine (PC) is a rare membrane lipid in bacteria but crucial for virulence of various plant and animal pathogens. The pcs- mutant lacking PC in bacterial membranes of Pseudomonas syringae pv. syringae van Hall 1336 displayed more ampicillin resistance. Ampicillin susceptibility tests gave an IC50 (half maximal inhibitory concentration) of 52 mg/ml for Pseudomonas syringae pv. syringae van Hall 1336, 53 mg/ml for the complemented strain 1336 RM (pcs-/+) and 90 mg/ml for the 1336 pcs- mutant. Activity assay of β-lactamase in periplasmic extracts gave 0.050 U/mg for the 1336 wild type, 0.052 U/mg for the 1336RM (pcs-/+), 0.086 U/mg for the 1336 pcs- mutant. Analysis by western blotting showed that the content of AmpC enzyme was markedly different in periplasmic extracts between the wild-type and pcs- mutant strains. Reverse transcriptase PCR also showed that the presence or absence of PC in bacterial membranes did not affect the transcription of ampC gene. The phenotype of the pcs- mutant was able to be recovered to the wild type by introducing a wild-type pcs gene into the pcs- mutant. Similar results were also obtained from the soil-dwelling bacterium Pseudomonas sp. 593. Our results demonstrate that the absence of PC in bacterial membranes facilitates the translocation of Sec-dependent β-lactamase AmpC from cytoplasm to periplasm, and the enhanced ampicillin-resistance in the pcs- strains mainly comes from effective translocation of AmpC via Sec-pathway. Copyright © 2016. Published by Elsevier Ltd.

  10. Cellulose Perversions

    Directory of Open Access Journals (Sweden)

    Maria H. Godinho

    2013-03-01

    Full Text Available Cellulose micro/nano-fibers can be produced by electrospinning from liquid crystalline solutions. Scanning electron microscopy (SEM, as well as atomic force microscopy (AFM and polarizing optical microscopy (POM measurements showed that cellulose-based electrospun fibers can curl and twist, due to the presence of an off-core line defect disclination, which was present when the fibers were prepared. This permits the mimicking of the shapes found in many systems in the living world, e.g., the tendrils of climbing plants, three to four orders of magnitude larger. In this work, we address the mechanism that is behind the spirals’ and helices’ appearance by recording the trajectories of the fibers toward diverse electrospinning targets. The intrinsic curvature of the system occurs via asymmetric contraction of an internal disclination line, which generates different shrinkages of the material along the fiber. The completely different instabilities observed for isotropic and anisotropic electrospun solutions at the exit of the needle seem to corroborate the hypothesis that the intrinsic curvature of the material is acquired during liquid crystalline sample processing inside the needle. The existence of perversions, which joins left and right helices, is also investigated by using suspended, as well as flat, targets. Possible routes of application inspired from the living world are addressed.

  11. Mitigation of Membrane Biofouling in MBR Using a Cellulolytic Bacterium, Undibacterium sp. DM-1, Isolated from Activated Sludge.

    Science.gov (United States)

    Nahm, Chang Hyun; Lee, Seonki; Lee, Sang Hyun; Lee, Kibaek; Lee, Jaewoo; Kwon, Hyeokpil; Choo, Kwang-Ho; Lee, Jung-Kee; Jang, Jae Young; Lee, Chung-Hak; Park, Pyung-Kyu

    2017-03-28

    Biofilm formation on the membrane surface results in the loss of permeability in membrane bioreactors (MBRs) for wastewater treatment. Studies have revealed that cellulose is not only produced by a number of bacterial species but also plays a key role during formation of their biofilm. Hence, in this study, cellulase was introduced to a MBR as a cellulose-induced biofilm control strategy. For practical application of cellulase to MBR, a cellulolytic ( i.e ., cellulase-producing) bacterium, Undibacterium sp. DM-1, was isolated from a lab-scale MBR for wastewater treatment. Prior to its application to MBR, it was confirmed that the cell-free supernatant of DM-1 was capable of inhibiting biofilm formation and of detaching the mature biofilm of activated sludge and cellulose-producing bacteria. This suggested that cellulase could be an effective anti-biofouling agent for MBRs used in wastewater treatment. Undibacterium sp. DM-1-entrapping beads ( i.e ., cellulolytic-beads) were applied to a continuous MBR to mitigate membrane biofouling 2.2-fold, compared with an MBR with vacant-beads as a control. Subsequent analysis of the cellulose content in the biofilm formed on the membrane surface revealed that this mitigation was associated with an approximately 30% reduction in cellulose by cellulolytic-beads in MBR.

  12. Dual layer hollow fiber PVDF ultra-filtration membranes containing Ag nano-particle loaded zeolite with longer term anti-bacterial capacity in salt water.

    Science.gov (United States)

    Shi, Huyan; Xue, Lixin; Gao, Ailin; Zhou, Qingbo

    2016-01-01

    Dual layer polyvinylidene fluoride (PVDF), antibacterial, hollow fiber, ultra-filtration composite membranes with antibacterial particles (silver (Ag) nano-particles loaded zeolite (Z-Ag)) in the outer layer were prepared with high water flux and desired pore sizes. The amounts of Ag(+) released from the composite membranes, freshly made and stored in water and salt solution, were measured. The result indicated that dual layer PVDF antibacterial hollow fiber containing Z-Ag (M-1-Ag) still possessed the ability of continuous release of Ag(+) even after exposure to water with high ionic content, showing a longer term resistance to bacterial adhesion and antibacterial activity than membrane doped with Z-Ag(+) (M-1). Results from an anti-adhesion and bacteria killing test with Escherichia coli supported that the antibacterial efficiency of dual hollow fiber PVDF membranes with Z-Ag was much higher than those with Z-Ag(+) after long time storage in water or exposure to phosphate buffered saline (PBS) solution. This novel hollow fiber membrane may find applications in constructing sea water pretreatment devices with long term antifouling capability for the desalination processes.

  13. Characterisation of cellulose-binding proteins that are involved in the adhesion mechanism of Fibrobacter intestinalis DR7.

    Science.gov (United States)

    Miron, J; Forsberg, C W

    1999-04-01

    Cellulose-binding proteins (CBP) isolated from cell envelopes of the cellulolytic bacterium Fibrobacter intestinalis strain DR7 were studied in order to investigate the adhesion mechanism. The proteins were examined for their reaction with antibodies that specifically block bacterial adhesion, response to glycosylation staining and monosaccharide composition. To this end, the effect of some monosaccharides (CBP components) on blocking of DR7 adhesion to cellulose was determined. Previous study had shown the occurrence of 16 CBP in the outer membrane and periplasm of DR7, of which 6 had endoglucanase activity (Miron and Forsberg 1998). Data from the present study show that most of the 16 CBP of DR7, except for the 38-, 90- and 180-kDa proteins, are glycosylated. Rabbit antibodies that specifically block DR7 adhesion were prepared by affinity preabsorption of antiserum against wild-type DR7 with bacterial cells of its adherence-defective mutant (DR7-M). The preabsorbed antibodies reacted positively in Western blotting with glycosylated CBP of 225, 200, 150, 70, 45 and block the adhesion of DR7 cells to cellulose. It is suggested that some glycosylated residues of CBP may have a predominant role in the adhesion of DR7 to cellulose.

  14. Characterization of cellulose extracted from oil palm empty fruit bunch

    Science.gov (United States)

    Sisak, Muhammad Asri Abdul; Daik, Rusli; Ramli, Suria

    2015-09-01

    Recently, cellulose has been studied by many researchers due to its promising properties such as biodegradability, biocompatibility, hydrophilicity and robustness. Due to that it is applied in many fields such as paper, film, drug delivery, membranes, etc. Cellulose can be extracted from various plants while oil palm empty fruit bunch (OPEFB) is the one of its sources. In this study, cellulose was extracted by chemical treatments which involved the use of formic acid and hydrogen peroxide to remove hemicellulose and lignin components. Maximum yield was 43.22%. Based on the FT-IR spectra, the peak of wax (1735 cm-1), hemicellulose (1375 cm-1) and lignin (1248 cm-1 and 1037 cm-1) were not observed in extracted cellulose. TGA analysis showed that the extracted cellulose starts to thermally degrade at 340 °C. The SEM analysis suggested that the cellulose extracted from OPEFB was not much different from commercial cellulose.

  15. Does chlorination of seawater reverse osmosis membranes control biofouling?

    Science.gov (United States)

    Khan, Muhammad Tariq; Hong, Pei-Ying; Nada, Nabil; Croue, Jean Philippe

    2015-07-01

    Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full-scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Does Chlorination of Seawater Reverse Osmosis Membranes Control Biofouling?

    KAUST Repository

    Khan, Muhammad Tariq

    2015-04-01

    Biofouling is the major problem of reverse osmosis (RO) membranes used for desalting seawater (SW). The use of chlorine is a conventional and common practice to control/prevent biofouling. Unlike polyamide RO membranes, cellulose triacetate (CTA) RO membranes display a high chlorine tolerance. Due to this characteristic, CTA membranes are used in most of the RO plants located in the Middle East region where the elevated seawater temperature and water quality promote the risk of membrane biofouling. However, there is no detailed study on the investigation/characterization of CTA-RO membrane fouling. In this investigation, the fouling profile of a full–scale SWRO desalination plant operating with not only continuous chlorination of raw seawater but also intermittent chlorination of CTA-RO membranes was studied. Detailed water quality and membrane fouling analyses were conducted. Profiles of microbiological, inorganic, and organic constituents of analysed fouling layers were extensively discussed. Our results clearly identified biofilm development on these membranes. The incapability of chlorination on preventing biofilm formation on SWRO membranes could be assigned to its failure in effectively reaching throughout the different regions of the permeators. This failure could have occurred due to three main factors: plugging of membrane fibers, chlorine consumption by organics accumulated on the front side fibers, or chlorine adaptation of certain bacterial populations.

  17. Model of mouth-to-mouth transfer of bacterial lipoproteins through inner membrane LolC, periplasmic LolA, and outer membrane LolB.

    Science.gov (United States)

    Okuda, Suguru; Tokuda, Hajime

    2009-04-07

    Outer membrane-specific lipoproteins in Escherichia coli are released from the inner membrane by an ATP-binding cassette transporter, the LolCDE complex, which causes the formation of a soluble complex with a periplasmic molecular chaperone, LolA. LolA then transports lipoproteins to the outer membrane where an outer membrane receptor, LolB, incorporates lipoproteins into the outer membrane. The molecular mechanisms underlying the Lol-dependent lipoprotein sorting have been clarified in detail. However, it remained unclear how Lol factors interact with each other to conduct very efficient lipoprotein transfer in the periplasm where ATP is not available. To address this issue, a photo-reactive phenylalanine analogue, p-benzoyl-phenylalanine, was introduced at various positions of LolA and LolB, of which the overall structures are very similar and comprise an incomplete beta-barrel with a hydrophobic cavity inside. Cells expressing LolA or LolB derivatives containing the above analogue were irradiated with UV for in vivo photo-cross-linking. These analyses revealed a hot area in the same region of LolA and LolB, through which LolA and LolB interact with each other. This area is located at the entrance of the hydrophobic cavity. Moreover, this area in LolA is involved in the interaction with a membrane subunit, LolC, whereas no cross-linking occurs between LolA and the other membrane subunit, LolE, or ATP-binding subunit LolD, despite the structural similarity between LolC and LolE. The hydrophobic cavities of LolA and LolB were both found to bind lipoproteins inside. These results indicate that the transfer of lipoproteins through Lol proteins occurs in a mouth-to-mouth manner.

  18. Characterization of genes in the cellulose-synthesizing operon (acs operon) of Acetobacter xylinum: implications for cellulose crystallization.

    OpenAIRE

    Saxena, I M; Kudlicka, K; Okuda, K; Brown, R M

    1994-01-01

    The synthesis of an extracellular ribbon of cellulose in the bacterium Acetobacter xylinum takes place from linearly arranged, membrane-localized, cellulose-synthesizing and extrusion complexes that direct the coupled steps of polymerization and crystallization. To identify the different components involved in this process, we isolated an Acetobacter cellulose-synthesizing (acs) operon from this bacterium. Analysis of DNA sequence shows the presence of three genes in the acs operon, in which ...

  19. Reactions with 1.3 propane sultone for the synthesis of cation-exchange membranes

    NARCIS (Netherlands)

    van der Velden, P.M.; Rupkema, B.; Smolders, C.A.; Bantjes, A.

    1977-01-01

    For several reasons it is interesting for membrane technology to introduce strongly anionic groups in membranes. Therefore the possibilities of 1.3 propane sultone were studied to modify cellulose, cellulose acetate and polyacrylonitrile. The results showed that cellulose and cellulose acetate could

  20. On the Spatial Organization of mRNA, Plasmids, and Ribosomes in a Bacterial Host Overexpressing Membrane Proteins.

    Directory of Open Access Journals (Sweden)

    Lieke A van Gijtenbeek

    2016-12-01

    Full Text Available By using fluorescence imaging, we provide a time-resolved single-cell view on coupled defects in transcription, translation, and growth during expression of heterologous membrane proteins in Lactococcus lactis. Transcripts encoding poorly produced membrane proteins accumulate in mRNA-dense bodies at the cell poles, whereas transcripts of a well-expressed homologous membrane protein show membrane-proximal localization in a translation-dependent fashion. The presence of the aberrant polar mRNA foci correlates with cessation of cell division, which is restored once these bodies are cleared. In addition, activation of the heat-shock response and a loss of nucleoid-occluded ribosomes are observed. We show that the presence of a native-like N-terminal domain is key to SRP-dependent membrane localization and successful production of membrane proteins. The work presented gives new insights and detailed understanding of aberrant membrane protein biogenesis, which can be used for strategies to optimize membrane protein production.

  1. Biophysical studies of the interaction of squalamine and other cationic amphiphilic molecules with bacterial and eukaryotic membranes: importance of the distribution coefficient in membrane selectivity.

    Science.gov (United States)

    Di Pasquale, Eric; Salmi-Smail, Chanaz; Brunel, Jean-Michel; Sanchez, Patrick; Fantini, Jacques; Maresca, Marc

    2010-02-01

    The interaction of squalamine (SQ) with eukaryotic and prokaryotic membranes was studied and compared with the interaction of two other cationic amphipathic antimicrobials (CAAs), i.e. the antibiotic polymyxin B (PMB) and the detergent hexadecyltrimethylammonium bromide (CTAB). Whole cell experiments showed that the three CAA have in common the ability to interact with lipopolysaccharide-containing membranes through a divalent cation sensitive process. Differences were found regarding their kinetics of membrane permeabilisation and their selectivity for bacteria, with a preferential permeabilisation of bacteria by PMB>SQ and no selectivity for CTAB. Experiments with lipid monolayers and bilayers showed that this selectivity did not correlate with a preferential interaction of the CAAs with lipids but rather relies on differences in their ability to penetrate lipid bilayers and to cause electrically active lesions. Incidentally, our results also suggest that the distribution coefficient of CAAs could be used to predict their selectivity for bacteria.

  2. PENGARUH MEDIUM PERENDAM TERHADAP SIFAT MEKANIK, MORFOLOGI, DAN KINERJA MEMBRAN NATA DE COCO

    Directory of Open Access Journals (Sweden)

    Senny Widyaningsih

    2008-05-01

    Full Text Available Nata de coco is bacterial cellulose which is produced by Acetobacter xylinum in fermentation process of coconut water. Based on its properties, nata de coco can be used as a membrane. Soaking medium in purification of nata de coco gel can influence structure, morphology, and performance of nata de coco membrane. First medium was NaOCl 0.05% and NaOH 5%, Second medium was ultrasonic. Third medium was NaOH 1% and CH3COOH 1%. Mechanical property were analysized based on its tensile strength. Morphology of membrane was analysized using SEM. Performance of membrane was determined based on its permeability. The result showed that nata de coco membrane which had the best value on mechanical properties, morphology, and performance was membrane in third medium.

  3. Experimental lamellar keratoplasty in rabbits using microfibrilar cellulose membrane: clinical, morphological and immunohistochemical findings Ceratoplastia lamelar experimental em coelhos usando membrana microfibrilar de celulose: achados clínicos, morfológicos e imunoistoquímicos

    Directory of Open Access Journals (Sweden)

    Luciana Riacciardi Macedo

    2010-02-01

    Full Text Available The clinical, histopathological and immunohistochemical features of the cornea were investigated in adult male New Zealand rabbits submitted to lamellar keratoplasty with microfibrillar cellulose membrane. Thirty animals were divided into five groups (n=6 and evaluated up to 60 days after surgery. Clinical examination revealed moderate manifestations of edema, blepharospasm and photophobia on the second day, which became mild or disappeared after the seventh day. This period was characterized clinically by repair of the corneal defect. Histopathological analysis showed the presence of a thin layer of squamous cells covering the damaged area as early as 7th day, accompanied by a mild infiltrate of polymorphonuclear cells. Blood vessels were observed in the epithelium after the 15th day, which had regressed by day 48. Ki67 antibody labeling showed an increase of proliferating cells in the epithelium by the 15th day and in the stroma by day 30. Remodeling and epithelial adhesion were observed during this period. Microfibrillar cellulose membrane (Bionext® used for lamellar keratoplasty was found to yield good results considering the good integration of the implant.Avaliaram-se aspectos clínicos, histopatógicos e imunoistoquímicos da córnes de coelhos da raça Nova Zelândia adultos e machos em ceratoplastias lamelares com membrana de celulose microfibrilar. Trinta animais distribuídos em cinco grupos (n=6 foram estudados por até 60 dias de pós-operatório. A avaliação clínica revelou manifestações moderadas de edema, blefaroespasmo e fotofobia ao segundo dia, evoluindo para formas discretas ou ausentes a partir do sétimo dia, período em que se observou, clinicamente, reparo do defeito corneal. A histopatologia revelou uma fina camada de células escamosas, recobrindo a área lesada já aos sete dias, com discreto infiltrado de células polimorfonucleares. Observaram-se vasos no epitélio a partir do 15o dia, com regressão ao 48o dia

  4. Water absorption and maintenance of nanofiber cellulose ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-05-17

    May 17, 2012 ... Department of Food Science and Nutrition, Catholic University of Daegu, Gyeongsan 712-702, Korea. Accepted 13 ... culture. Bacterial cellulose acts as a floatation device supplying the bacteria to the oxygen rich air-media inter- face and also act as protecting device from UV light. (Ross et al., 1996).

  5. ExsB Is Required for Correct Assembly of the Pseudomonas aeruginosa Type III Secretion Apparatus in the Bacterial Membrane and Full Virulence In Vivo

    Science.gov (United States)

    Perdu, Caroline; Huber, Philippe; Bouillot, Stéphanie; Blocker, Ariel; Elsen, Sylvie; Attrée, Ina

    2015-01-01

    Pseudomonas aeruginosa is responsible for high-morbidity infections of cystic fibrosis patients and is a major agent of nosocomial infections. One of its most potent virulence factors is a type III secretion system (T3SS) that injects toxins directly into the host cell cytoplasm. ExsB, a lipoprotein localized in the bacterial outer membrane, is one of the components of this machinery, of which the function remained elusive until now. The localization of the exsB gene within the exsCEBA regulatory gene operon suggested an implication in the T3SS regulation, while its similarity with yscW from Yersinia spp. argued in favor of a role in machinery assembly. The present work shows that ExsB is necessary for full in vivo virulence of P. aeruginosa. Furthermore, the requirement of ExsB for optimal T3SS assembly and activity is demonstrated using eukaryotic cell infection and in vitro assays. In particular, ExsB promotes the assembly of the T3SS secretin in the bacterial outer membrane, highlighting the molecular role of ExsB as a pilotin. This involvement in the regulation of the T3S apparatus assembly may explain the localization of the ExsB-encoding gene within the regulatory gene operon. PMID:25690097

  6. Komagataeibacter rhaeticus as an alternative bacteria for cellulose production.

    Science.gov (United States)

    Machado, Rachel T A; Gutierrez, Junkal; Tercjak, Agnieszka; Trovatti, Eliane; Uahib, Fernanda G M; Moreno, Gabriela de Padua; Nascimento, Andresa P; Berreta, Andresa A; Ribeiro, Sidney J L; Barud, Hernane S

    2016-11-05

    A strain isolated from Kombucha tea was isolated and used as an alternative bacterium for the biosynthesis of bacterial cellulose (BC). In this study, BC generated by this novel bacterium was compared to Gluconacetobacter xylinus biosynthesized BC. Kinetic studies reveal that Komagataeibacter rhaeticus was a viable bacterium to produce BC according to yield, thickness and water holding capacity data. Physicochemical properties of BC membranes were investigated by UV-vis and Fourier transform infrared spectroscopies (FTIR), thermogravimetrical analysis (TGA) and X-ray diffraction (XRD). Additionally, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used for morphological characterization. Mechanical properties at nano and macroscale were studied employing PeakForce quantitative nanomechanical property mapping (QNM) and dynamic mechanical analyzer (DMA), respectively. Results confirmed that BC membrane biosynthesized by Komagataeibacter rhaeticus had similar physicochemical, morphological and mechanical properties than BC membrane produced by Gluconacetobacter xylinus and can be widely used for the same applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Preliminary study on biosynthesis and characterization of bacteria cellulose films from coconut water

    Science.gov (United States)

    Indrianingsih, A. W.; Rosyida, V. T.; Jatmiko, T. H.; Prasetyo, D. J.; Poeloengasih, C. D.; Apriyana, W.; Nisa, K.; Nurhayati, S.; Hernawan; Darsih, C.; Pratiwi, D.; Suwanto, A.; Ratih, D.

    2017-12-01

    Bacterial cellulose produced by Acetobacter xylinum is a unique type of bacterial cellulose. It contains more than 90% of water. A preliminary study had shown that bacterial cellulose films has remarkable mechanical properties. The aim of this study was to investigate the optimum condition such as percentage of carbon source, time of cultivation, and pH to produce bacterial cellulose films from local coconut water, and its characterization on morphology, swelling ability and tensile strength of dried bacterial cellulose. A. xylinum was grown on coconut water culture medium with addition of 3%, 5%, and 7% of sugar, while the cultivation time was vary from 3 days, 5 days and 7 days. pH condition was conducted in pH 3, pH 5 and pH 7. Bacterial cellulose samples were dried using oven with temperature of 100°C until the moisture content reached 4-5%. This study showed that several parameters for optimum condition to produce bacterial cellulose films from local waste of coconut water had been obtained (5% of carbon source; pH 5; and 7 day of incubation period). The electron microscopy also showed that dried bacterial cellulose films had pores covered by fibrils on the surface. Therefore, the present work proposes the optimum formula and condition that can be used based on properties of end product needed.

  8. Membrane and core periplasmic Agrobacterium tumefaciens virulence Type IV secretion system components localize to multiple sites around the bacterial perimeter during lateral attachment to plant cells.

    Science.gov (United States)

    Aguilar, Julieta; Cameron, Todd A; Zupan, John; Zambryski, Patricia

    2011-01-01

    Type IV secretion systems (T4SS) transfer DNA and/or proteins into recipient cells. Here we performed immunofluorescence deconvolution microscopy to localize the assembled T4SS by detection of its native components VirB1, VirB2, VirB4, VirB5, VirB7, VirB8, VirB9, VirB10, and VirB11 in the C58 nopaline strain of Agrobacterium tumefaciens, following induction of virulence (vir) gene expression. These different proteins represent T4SS components spanning the inner membrane, periplasm, or outer membrane. Native VirB2, VirB5, VirB7, and VirB8 were also localized in the A. tumefaciens octopine strain A348. Quantitative analyses of the localization of all the above Vir proteins in nopaline and octopine strains revealed multiple foci in single optical sections in over 80% and 70% of the bacterial cells, respectively. Green fluorescent protein (GFP)-VirB8 expression following vir induction was used to monitor bacterial binding to live host plant cells; bacteria bind predominantly along their lengths, with few bacteria binding via their poles or subpoles. vir-induced attachment-defective bacteria or bacteria without the Ti plasmid do not bind to plant cells. These data support a model where multiple vir-T4SS around the perimeter of the bacterium maximize effective contact with the host to facilitate efficient transfer of DNA and protein substrates. Transfer of DNA and/or proteins to host cells through multiprotein type IV secretion system (T4SS) complexes that span the bacterial cell envelope is critical to bacterial pathogenesis. Early reports suggested that T4SS components localized at the cell poles. Now, higher-resolution deconvolution fluorescence microscopy reveals that all structural components of the Agrobacterium tumefaciens vir-T4SS, as well as its transported protein substrates, localize to multiple foci around the cell perimeter. These results lead to a new model of A. tumefaciens attachment to a plant cell, where A. tumefaciens takes advantage of the multiple

  9. Topical application of zinc oxide nanoparticles reduces bacterial skin infection in mice and exhibits antibacterial activity by inducing oxidative stress response and cell membrane disintegration in macrophages.

    Science.gov (United States)

    Pati, Rashmirekha; Mehta, Ranjit Kumar; Mohanty, Soumitra; Padhi, Avinash; Sengupta, Mitali; Vaseeharan, Baskarlingam; Goswami, Chandan; Sonawane, Avinash

    2014-08-01

    Here we studied immunological and antibacterial mechanisms of zinc oxide nanoparticles (ZnO-NPs) against human pathogens. ZnO-NPs showed more activity against Staphylococcus aureus and least against Mycobacterium bovis-BCG. However, BCG killing was significantly increased in synergy with antituberculous-drug rifampicin. Antibacterial mechanistic studies showed that ZnO-NPs disrupt bacterial cell membrane integrity, reduce cell surface hydrophobicity and down-regulate the transcription of oxidative stress-resistance genes in bacteria. ZnO-NP treatment also augmented the intracellular bacterial killing by inducing reactive oxygen species production and co-localization with Mycobacterium smegmatis-GFP in macrophages. Moreover, ZnO-NPs disrupted biofilm formation and inhibited hemolysis by hemolysin toxin producing S. aureus. Intradermal administration of ZnO-NPs significantly reduced the skin infection, bacterial load and inflammation in mice, and also improved infected skin architecture. We envision that this study offers novel insights into antimicrobial actions of ZnO-NPs and also demonstrates ZnO-NPs as a novel class of topical anti-infective agent for the treatment of skin infections. This in-depth study demonstrates properties of ZnO nanoparticles in infection prevention and treatment in several skin infection models, dissecting the potential mechanisms of action of these nanoparticles and paving the way to human applications. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Construction of nerve guide conduits from cellulose/soy protein composite membranes combined with Schwann cells and pyrroloquinoline quinone for the repair of peripheral nerve defect.

    Science.gov (United States)

    Luo, Lihua; Gan, Li; Liu, Yongming; Tian, Weiqun; Tong, Zan; Wang, Xiong; Huselstein, Celine; Chen, Yun

    2015-02-20

    Regeneration and functional reconstruction of peripheral nerve defects remained a significant clinical challenge. Nerve guide conduits, with seed cells or neurotrophic factors (NTFs), had been widely used to improve the repair and regeneration of injured peripheral nerve. Pyrroloquinoline quinone (PQQ) was an antioxidant that can stimulate nerve growth factors (NGFs) synthesis and accelerate the Schwann cells (SCs) proliferation and growth. In present study, three kinds of nerve guide conduits were constructed: one from cellulose/SPI hollow tube (CSC), another from CSC combined with SCs (CSSC), and the third one from CSSC combined with PQQ (CSSPC), respectively. And then they were applied to bridge and repair the sciatic nerve defect in rats, using autograft as control. Effects of different nerve guide conduits on the nerve regeneration were comparatively evaluated by general analysis, sciatic function index (SFI) and histological analysis (HE and TEM). Newly-formed regenerative nerve fibers were observed and running through the transparent nerve guide conduits 12 weeks after surgery. SFI results indicated that the reconstruction of motor function in CSSPC group was better than that in CSSC and CSC groups. HE images from the cross-sections and longitudinal-sections of the harvested regenerative nerve indicated that regenerative nerve fibers had been formed and accompanied with new blood vessels and matrix materials in the conduits. TEM images also showed that lots of fresh myelinated and non-myelinated nerve fibers had been formed. Parts of vacuolar, swollen and abnormal axons occurred in CSC and CSSC groups, while the vacuolization and swell of axons was the least serious in CSSPC group. These results indicated that CSSPC group had the most ability to repair and reconstruct the nerve structure and functions due to the comprehensive contributions from hollow CSC tube, SCs and PQQ. As a result, the CSSPC may have the potential for the applications as nerve guide

  11. Antibiotic Resistance and Regulation of the Gram-Negative Bacterial Outer Membrane Barrier by Host Innate Immune Molecules

    Directory of Open Access Journals (Sweden)

    Samuel I. Miller

    2016-09-01

    Full Text Available The Gram-negative outer membrane is an important barrier that provides protection against toxic compounds, which include antibiotics and host innate immune molecules such as cationic antimicrobial peptides. Recently, significant research progress has been made in understanding the biogenesis, regulation, and functioning of the outer membrane, including a recent paper from the laboratory of Dr. Brett Finlay at the University of British Columbia (J. van der Heijden et al., mBio 7:e01238-16, 2016, http://dx.doi.org/10.1128/mBio.01541-16. These investigators demonstrate that toxic oxygen radicals, such as those found in host tissues, regulate outer membrane permeability by altering the outer membrane porin protein channels to regulate the influx of oxygen radicals as well as β-lactam antibiotics. This commentary provides context about this interesting paper and discusses the prospects of utilizing increased knowledge of outer membrane biology to develop new antibiotics for antibiotic-resistant Gram-negative bacteria.

  12. Extracorporeal Membrane Oxygenation and Modern Detoxification Techniques in a Puerpera with Viral and Bacterial Pneumonia Caused by Flu A(H1N1 Virus

    Directory of Open Access Journals (Sweden)

    R. A. Kornelyuk

    2017-01-01

    Full Text Available Outbreaks of viral infections have become a global healthcare challenge over the last decade. The 2009—2010 flu A (H1N1 outbreak resulted in global pandemia, associated with high morbidity and mortality reaching 31%. Another flu A (H1N1 outbreak occurred in 2015—2016. There is a strong probability that it may be repeated in the future. This infection is associated with its high incidence among pregnant women. There are some published reports describing the efficacy and safety of veno%venous extracorporeal membrane oxygenation (ECMO in patients with severe acute respiratory distress syndrome that is refractory to standard therapeutic options. The article presents a clinical case of a successful use of extracorporeal membrane oxygenation and intermittent renal replacement therapy in a puerpera with acute respiratory distress syndrome caused by flu A (H1N1-related severe viral and bacterial pneumonia. The positive effects of the combination of veno%venous extracorporeal membrane oxygenation and modern detoxification techniques have been demonstrated. Revealed organizational problemswere related to selection criteria for prescription of extracorporeal gas exchange, as well as to carrying out the procedure in an institution in the deficiency of the experienced staff and corresponding equipment.

  13. Development of a novel pH sensor based upon Janus Green B immobilized on triacetyl cellulose membrane: Experimental design and optimization

    Science.gov (United States)

    Chamkouri, Narges; Niazi, Ali; Zare-Shahabadi, Vali

    2016-03-01

    A novel pH optical sensor was prepared by immobilizing an azo dye called Janus Green B on the triacetylcellulose membrane. Condition of the dye solution used in the immobilization step, including concentration of the dye, pH, and duration were considered and optimized using the Box-Behnken design. The proposed sensor showed good behavior and precision (RSD < 5%) in the pH range of 2.0-10.0. Advantages of this optical sensor include on-line applicability, no leakage, long-term stability (more than 6 months), fast response time (less than 1 min), high selectivity and sensitivity as well as good reversibility and reproducibility.

  14. Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling

    Directory of Open Access Journals (Sweden)

    Ashish A. Malik

    2015-04-01

    Full Text Available Using a pulse-chase 13CO2 plant labeling experiment we compared the flow of plant carbon into macromolecular fractions of root-associated soil microorganisms. Time dependent 13C dilution patterns in microbial cellular fractions were used to calculate their turnover time. The turnover times of microbial biomolecules were found to vary: microbial RNA (19 h and DNA (30 h turned over fastest followed by chloroform fumigation extraction-derived soluble cell lysis products (14 d, while phospholipid fatty acids (PLFAs had the slowest turnover (42 d. PLFA/NLFA 13C analyses suggest that both mutualistic arbuscular mycorrhizal and saprophytic fungi are dominant in initial plant carbon uptake. In contrast, high initial 13C enrichment in RNA hints at bacterial importance in initial C uptake due to the dominance of bacterial derived RNA in total extracts of soil RNA. To explain this discrepancy, we observed low renewal rate of bacterial lipids, which may therefore bias lipid fatty acid based interpretations of the role of bacteria in soil microbial food webs. Based on our findings, we question current assumptions regarding plant-microbe carbon flux and suggest that the rhizosphere bacterial contribution to plant assimilate uptake could be higher. This highlights the need for more detailed quantitative investigations with nucleic acid biomarkers to further validate these findings.

  15. High-resolution phylogenetic analysis of residual bacterial species of fouled membranes after NaOCl cleaning.

    Science.gov (United States)

    Navarro, Ronald R; Hori, Tomoyuki; Inaba, Tomohiro; Matsuo, Kazuyuki; Habe, Hiroshi; Ogata, Atsushi

    2016-05-01

    Biofouling is one of the major problems during wastewater treatment using membrane bioreactors (MBRs). In this regard, sodium hypochlorite (NaOCl) has been widely used to wash fouled membranes for maintenance and recovery purposes. Advanced chemical and biological characterization was conducted in this work to evaluate the performance of aqueous NaOCl solutions during washing of polyacrylonitrile membranes. Fouled membranes from MBR operations supplemented with artificial wastewater were washed with 0.1% and 0.5% aqueous NaOCl solutions for 5, 10 and 30 min. The changes in organics composition on the membrane surface were directly monitored by an attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectrometer. In addition, high-throughput Illumina sequencing of 16S rRNA genes was applied to detect any residual microorganisms. Results from ATR-FT-IR analysis indicated the complete disappearance of functional groups representing different fouling compounds after at least 30 min of treatment with 0.1% NaOCl. However, the biomolecular survey revealed the presence of residual bacteria even after 30 min of treatment with 0.5% NaOCl solution. Evaluation of microbial diversity of treated samples using Chao1, Shannon and Simpson reciprocal indices showed an increase in evenness while no significant decline in richness was observed. These implied that only the population of dominant species was mainly affected. The high-resolution phylogenetic analysis revealed the presence of numerous operational taxonomic units (OTUs) whose close relatives exhibit halotolerance. Some OTUs related to thermophilic and acid-resistant strains were also identified. Finally, the taxonomic analysis of recycled membranes that were previously washed with NaOCl also showed the presence of numerous halotolerant-related OTUs in the early stage of fouling. This further suggested the possible contribution of such chemical tolerance on their survival against NaOCl washing, which in turn

  16. Ubiquitination of the bacterial inositol phosphatase, SopB, regulates its biological activity at the plasma membrane.

    LENUS (Irish Health Repository)

    Knodler, Leigh A

    2009-11-01

    The Salmonella type III effector, SopB, is an inositol polyphosphate phosphatase that modulates host cell phospholipids at the plasma membrane and the nascent Salmonella-containing vacuole (SCV). Translocated SopB persists for many hours after infection and is ubiquitinated but the significance of this covalent modification has not been investigated. Here we identify by mass spectrometry six lysine residues of SopB that are mono-ubiquitinated. Substitution of these six lysine residues with arginine, SopB-K(6)R, almost completely eliminated SopB ubiquitination. We found that ubiquitination does not affect SopB stability or membrane association, or SopB-dependent events in SCV biogenesis. However, two spatially and temporally distinct events are dependent on ubiquitination, downregulation of SopB activity at the plasma membrane and prolonged retention of SopB on the SCV. Activation of the mammalian pro-survival kinase Akt\\/PKB, a downstream target of SopB, was intensified and prolonged after infection with the SopB-K(6)R mutant. At later times, fewer SCV were decorated with SopB-K(6)R compared with SopB. Instead SopB-K(6)R was present as discrete vesicles spread diffusely throughout the cell. Altogether, our data show that ubiquitination of SopB is not related to its intracellular stability but rather regulates its enzymatic activity at the plasma membrane and intracellular localization.

  17. Environmental controls on the distribution of bacterial tetraether membrane lipids: constraints on the MBT-CBT paleothermometer

    NARCIS (Netherlands)

    Peterse, F.

    2011-01-01

    Over the past years, a new proxy for the reconstruction of continental paleotemperature and past soil pH has been developed based on branched glycerol dialkyl glycerol tetraethers (GDGTs). Branched GDGTs are membrane lipids of as of yet unknown bacteria that thrive in peat and soils. Their molecular

  18. Characterization of cellulose nanowhiskers

    International Nuclear Information System (INIS)

    Nascimento, Nayra R.; Pinheiro, Ivanei F.; Morales, Ana R.; Ravagnani, Sergio P.; Mei, Lucia

    2015-01-01

    Cellulose is the most abundant polymer earth. The cellulose nanowhiskers can be extracted from the cellulose. These have attracted attention for its use in nanostructured materials for various applications, such as nanocomposites, because they have peculiar characteristics, among them, high aspect ratio, biodegradability and excellent mechanical properties. This work aims to characterize cellulose nanowhiskers from microcrystalline cellulose. Therefore, these materials were characterized by X-ray diffraction (XRD) to assess the degree of crystallinity, infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) to the morphology of nanowhiskers and thermal stability was evaluated by Thermogravimetric Analysis (TGA). (author)

  19. Acoustic Properties of Cellulose

    Science.gov (United States)

    Trematerra, Amelia; Lombardi, Ilaria

    2017-08-01

    Cellulose is the oldest material for thermal insulation in construction field. Thomas Jefferson was the first architect that used the cellulose in his project of the Monticello house (1800). But only after 1945 that the cellulose from newsprint was used across America and northern Europe. In the 70s with the energy crisis it Austria, Czech Republic, Switzerland and Germany began the production of cellulose derived from paper newspapers. It used for both winter and summer thermal insulation, while respecting the environment. In this paper are reported acoustic measurements carried out with the tube of Kundt, with the cellulose melted and with glue with different thicknesses.

  20. Constants of the Alper and Howard-Flanders oxygen equation for damage to bacterial membrane, deduced from observations on the radiation-induced penicillin-sensitive lesion.

    Science.gov (United States)

    Obioha, F I; Gillies, N E; Cullen, B M; Walker, H C; Alper, T

    1984-05-01

    Energy deposited in the bacterial envelope of E. coli B/r induces lesions which are lethally attacked by penicillin in concentration insufficient to affect unirradiated bacteria. The critical lesions are probably in the membrane moiety. Bacteria were irradiated in the presence of 100 per cent oxygen, oxygen-free nitrogen and mixtures of 1.01, 0.59, 0.3, 0.1 and 0.06 per cent oxygen in nitrogen. Changes in sensitivity with pO2 conformed with the Alper and Howard-Flanders equation, for bacteria treated after irradiation by penicillin as well as for the untreated ones. The values of m were respectively 4.8 and 3.3; the values of K were identical, within experimental error, i.e. 4.4 mmHg. Sensitivity to induction of the penicillin-sensitive lesion was calculated from the difference in the reciprocals of D0 values proper to untreated and treated bacteria, for every gas used. The value of m could not be directly calculated because the effect of penicillin on anoxically irradiated bacteria was not detectable. For that reason, a transformation of the oxygen equation was used which allowed estimates to be made of both m and K, provided the results conformed with the equation. Within experimental error they did so conform. The calculated values of m and K for induction of the penicillin-sensitive lesion were respectively 8 and 5.9 mmHg, but it is shown that the oxygen enhancement ratio was probably underestimated and the K value overestimated. On the assumptions that these values of m and K are specific for radiation damage to bacterial membrane, and that radiation-induced killing is attributable to lethal lesions in the membrane as well as the DNA, the results demonstrate that any interaction of oxygen with sites of energy deposition in the DNA must play a very much smaller role in radiosensitization than does interaction with sites of energy deposition in the membrane.

  1. Influence of cytokine gene polymorphisms and of the Helicobacter pylori outer membrane protein Hp0638 on bacterial pathogenesis

    OpenAIRE

    Dossumbekova, Anar

    2006-01-01

    Infection with H. pylori leads to persistent colonisation and chronic inflammation of the gastric mucosa, thereby increasing the risk for the developing peptic ulceration, distal gastric adenocarcinoma and gastric lymphoma. In the current study we showed that cytokine gene polymorphisms influence mucosal cytokine expression, gastric inflammation and the long-term development of precancerous lesions in H. pylori infection. Host polymorphisms are associated with certain bacterial strain types, ...

  2. Evolving Microbial Communities in Cellulose-Fed Microbial Fuel Cell

    Directory of Open Access Journals (Sweden)

    Renata Toczyłowska-Mamińska

    2018-01-01

    Full Text Available The abundance of cellulosic wastes make them attractive source of energy for producing electricity in microbial fuel cells (MFCs. However, electricity production from cellulose requires obligate anaerobes that can degrade cellulose and transfer electrons to the electrode (exoelectrogens, and thus most previous MFC studies have been conducted using two-chamber systems to avoid oxygen contamination of the anode. Single-chamber, air-cathode MFCs typically produce higher power densities than aqueous catholyte MFCs and avoid energy input for the cathodic reaction. To better understand the bacterial communities that evolve in single-chamber air-cathode MFCs fed cellulose, we examined the changes in the bacterial consortium in an MFC fed cellulose over time. The most predominant bacteria shown to be capable electron generation was Firmicutes, with the fermenters decomposing cellulose Bacteroidetes. The main genera developed after extended operation of the cellulose-fed MFC were cellulolytic strains, fermenters and electrogens that included: Parabacteroides, Proteiniphilum, Catonella and Clostridium. These results demonstrate that different communities evolve in air-cathode MFCs fed cellulose than the previous two-chamber reactors.

  3. Analysis for the presence of determinants involved in the transport of mercury across bacterial membrane from polluted water bodies of India.

    Science.gov (United States)

    Jan, Arif Tasleem; Azam, Mudsser; Choi, Inho; Ali, Arif; Haq, Qazi Mohd Rizwanul

    2016-01-01

    Mercury, which is ubiquitous and recalcitrant to biodegradation processes, threatens human health by escaping to the environment via various natural and anthropogenic activities. Non-biodegradability of mercury pollutants has necessitated the development and implementation of economic alternatives with promising potential to remove metals from the environment. Enhancement of microbial based remediation strategies through genetic engineering approaches provides one such alternative with a promising future. In this study, bacterial isolates inhabiting polluted sites were screened for tolerance to varying concentrations of mercuric chloride. Following identification, several Pseudomonas and Klebsiella species were found to exhibit the highest tolerance to both organic and inorganic mercury. Screened bacterial isolates were examined for their genetic make-up in terms of the presence of genes (merP and merT) involved in the transport of mercury across the membrane either alone or in combination to deal with the toxic mercury. Gene sequence analysis revealed that the merP gene showed 86-99% homology, while the merT gene showed >98% homology with previously reported sequences. By exploring the genes involved in imparting metal resistance to bacteria, this study will serve to highlight the credentials that are particularly advantageous for their practical application to remediation of mercury from the environment. Copyright © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  4. Characterization of bacterial communities in hybrid upflow anaerobic sludge blanket (UASB)-membrane bioreactor (MBR) process for berberine antibiotic wastewater treatment.

    Science.gov (United States)

    Qiu, Guanglei; Song, Yong-Hui; Zeng, Ping; Duan, Liang; Xiao, Shuhu

    2013-08-01

    Biodegradation of berberine antibiotic was investigated in upflow anaerobic sludge blanket (UASB)-membrane bioreactor (MBR) process. After 118days of operation, 99.0%, 98.0% and 98.0% overall removals of berberine, COD and NH4(+)-N were achieved, respectively. The detailed composition of the established bacterial communities was studied by using 16S rDNA clone library. Totally, 400 clones were retrieved and grouped into 186 operational taxonomic units (OTUs). UASB was dominated by Firmicutes and Bacteroidetes, while Proteobacteria, especially Alpha- and Beta-proteobacteria were prevalent in the MBRs. Clostridium, Eubacterium and Synergistes in the UASB, as well as Hydrogenophaga, Azoarcus, Sphingomonas, Stenotrophomonas, Shinella and Alcaligenes in the MBRs were identified as potential functional species in biodegradation of berberine and/or its metabolites. The bacterial community compositions in two MBRs were significantly discrepant. However, the identical functions of the functional species ensured the comparable pollutant removal performances in two bioreactors. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Combination of upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR) for berberine reduction from wastewater and the effects of berberine on bacterial community dynamics.

    Science.gov (United States)

    Qiu, Guanglei; Song, Yonghui; Zeng, Ping; Duan, Liang; Xiao, Shuhu

    2013-02-15

    Berberine is a broad-spectrum antibiotic extensively used in personal medication. The production of berberine results in the generation of wastewater containing concentrated residual berberine. However, few related studies up to date focus on berberine removal from wastewaters. In this study, a lab-scale upflow anaerobic sludge blanket (UASB)-membrane bioreactor (MBR) process was developed for berberine removal from synthetic wastewater. The performance of the UASB-MBR system on berberine, COD and NH(4)(+)--N removal was investigated at different berberine loadings. And the effects of berberine on bacterial communities were evaluated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Results showed that, as the increase of berberine loadings, UASB performance was affected remarkably, whereas, efficient and stable performance of MBR ensured the overall removal rates of berberine, COD and NH(4)(+)--N consistently reached up to 99%, 98% and 98%, respectively. Significant shifts of bacterial community structures were detected in both UASB and MBR, especially in the initial operations. Along with the increase of berberine loadings, high antibiotic resisting species and some functional species, i.e. Acinetobacter sp., Clostridium sp., Propionibacterium sp., and Sphingomonas sp. in UASB, as well as Sphingomonas sp., Methylocystis sp., Hydrogenophaga sp. and Flavobacterium sp. in MBR were enriched in succession. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Cyclic Cystine-Bridged Peptides from the Marine Sponge Clathria basilana Induce Apoptosis in Tumor Cells and Depolarize the Bacterial Cytoplasmic Membrane.

    Science.gov (United States)

    Mokhlesi, Amin; Stuhldreier, Fabian; Wex, Katharina W; Berscheid, Anne; Hartmann, Rudolf; Rehberg, Nidja; Sureechatchaiyan, Parichat; Chaidir, Chaidir; Kassack, Matthias U; Kalscheuer, Rainer; Brötz-Oesterhelt, Heike; Wesselborg, Sebastian; Stork, Björn; Daletos, Georgios; Proksch, Peter

    2017-11-22

    Investigation of the sponge Clathria basilana collected in Indonesia afforded five new peptides, including microcionamides C (1) and D (2), gombamides B (4), C (5), and D (6), and an unusual amide, (E)-2-amino-3-methyl-N-styrylbutanamide (7), along with 11 known compounds, among them microcionamide A (3). The structures of the new compounds were elucidated by one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of the constituent amino acid residues in 1-7 were determined by Marfey's analysis. Microcionamides A, C, and D (1-3) showed in vitro cytotoxicity against lymphoma (Ramos) and leukemia cell lines (HL-60, Nomo-1, Jurkat J16), as well as against a human ovarian carcinoma cell line (A2780) with IC 50 values ranging from 0.45 to 28 μM. Mechanistic studies showed that compounds 1-3 rapidly induce apoptotic cell death in Jurkat J16 and Ramos cells and that 1 and 2 potently block autophagy upon starvation conditions, thereby impairing pro-survival signaling of cancer cells. In addition, microcionamides C and A (1 and 3) inhibited bacterial growth of Staphylococcus aureus and Enterococcus faecium with minimal inhibitory concentrations between 6.2 and 12 μM. Mechanistic studies indicate dissipation of the bacterial membrane potential.

  7. Role of Gamma Radiation and Some Natural Products in Alteration of Bacterial Outer Membrane Porins Permeability for Uptake of Certain Antibiotics

    International Nuclear Information System (INIS)

    El-Bastawisy, H.S.

    2015-01-01

    Membrane permeability is the first step involved in resistance of bacteria to an antibiotic. The bacterial outer membrane proteins (OMPs) that constitute porins play role in the definition of intrinsic resistance in Gram negative bacilli that is altered under antibiotic pressure. It has been noted that the response to prolonged exposure to increasing levels of antibiotic cause major changes in the permeability of the bacterium due to down regulation of porins and over expression of efflux pumps. In this study a total of 92 bacterial isolates of different species were isolated from different sites of cancer and non cancer patients; the microorganisms were identified using API system. The susceptibility test was carried out for all the isolates to detect the multidrug resistant isolates; from this test eleven strains were selected for further studies. Antimicrobial susceptibility of the eleven strains against some selected antibiotics acting on the inhibition of cell wall synthesis before and after in vitro gamma irradiation was carried out. The obtained results showed a clear increase in the number of resistant isolates after irradiation as compared to those before irradiation. The efficacy of the citrus fruits (Citrus limon, Citrus paradise, Citrus reticulate and Citrus sinensis) was tested to improve the performance of the tested antibiotics by increasing its permeability through the porin channels. The dried crushed citrus fruits peels were decontaminated by gamma irradiation at 700 Gray; then the aqueous extract of the citrus fruits were prepared to test its antimicrobial activity against the selected bacterial strains. The obtained results revealed that the aqueous extracts of different citrus fruits peels did not show any antibacterial activities against six bacterial isolates (Acinetobacter calcoaceticus 44, Enterbacter cloacae 51, Escherichia coli 52, Pseudomonas fluorescens 64, Klebsiella pneumoniae 78 and Pseudomonas aeruginosa 90). Therefore, these six

  8. The absence of protein Y4yS affects negatively the abundance of T3SS Mesorhizobium loti secretin, RhcC2, in bacterial membranes.

    Science.gov (United States)

    Mercante, Virginia; Duarte, Cecilia M; Sánchez, Cintia M; Zalguizuri, Andrés; Caetano-Anollés, Gustavo; Lepek, Viviana C

    2015-01-01

    Mesorhizobium loti MAFF303099 has a functional type III secretion system (T3SS) that is involved in the determination of nodulation competitiveness on Lotus. The M. loti T3SS cluster contains gene y4yS (mlr8765) that codes for a protein of unknown function (Y4yS). A mutation in the y4yS gene favors the M. loti symbiotic competitive ability on Lotus tenuis cv. Esmeralda and affects negatively the secretion of proteins through T3SS. Here we localize Y4yS in the bacterial membrane using a translational reporter peptide fusion. In silico analysis indicated that this protein presents a tetratricopeptide repeat (TPR) domain, a signal peptide and a canonical lipobox LGCC in the N-terminal sequence. These features that are shared with proteins required for the formation of the secretin complex in type IV secretion systems and in the Tad system, together with its localization, suggest that the y4yS-encoded protein is required for the formation of the M. loti T3SS secretin (RhcC2) complex. Remarkably, analysis of RhcC2 in the wild-type and M. loti y4yS mutant strains indicated that the absence of Y4yS affects negatively the accumulation of normal levels of RhcC2 in the membrane.

  9. Antimicrobial properties of arginine- and lysine-rich histones and involvement of bacterial outer membrane protease T in their differential mode of actions.

    Science.gov (United States)

    Tagai, Chihiro; Morita, Shuu; Shiraishi, Takayuki; Miyaji, Kazuyuki; Iwamuro, Shawichi

    2011-10-01

    There is growing evidence of the antimicrobial properties of histones and histone-derived peptides; however, most of them are specific to lysine (Lys)-rich histones (H1, H2A, and H2B). In the present study, we focused on arginine (Arg)-rich histones (H3 and H4) and investigated their antimicrobial properties in comparison with those of histone H2B. In a standard microdilution assay, calf thymus histones H2B, H3, and H4 showed growth inhibitory activity against the bacterial outer membrane protease T (OmpT) gene-expressing Escherichia coli strain JCM5491 with calculated 50% growth inhibitory concentrations of 3.8, 10, and 12.7 μM, respectively. A lysate prepared from the JCM5491 cells was capable of strongly, moderately, and slightly fragmenting histones H2B, H3, and H4, respectively. While the lysate prepared from the cells of the ompT-deleted E. coli strain BL21(DE3) did not digest these histones, the ompT-transformed BL21(DE3), termed BL21/OmpT(+), cell lysate digested the histones more strongly than the JCM5491 cell lysate. Laser confocal and scanning electron microscopic analyses demonstrated that while histone H2B penetrated the cell membrane of JCM5491 or BL21/OmpT(+) cells, histones H3 and H4 remained on the cell surface and subsequently disrupted the cell membrane structure with bleb formation in a manner similar to general antimicrobial peptides. The BL21(DE3) cells treated with each histone showed no bleb formation, but cell integrity was affected and the cell surface was corrugated. Consequently, it is suggested that OmpT is involved in the antimicrobial properties of Arg- and Lys-rich histones and that the modes of antimicrobial action of these histones are different. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Synthesis and characterization of amorphous cellulose from triacetate of cellulose

    International Nuclear Information System (INIS)

    Vega-Baudrit, Jose; Sibaja, Maria; Nikolaeva, Svetlana; Rivera A, Andrea

    2014-01-01

    It was carried-out a study for the synthesis and characterization of amorphous cellulose starting from cellulose triacetate. X-rays diffraction was used in order to obtain the cellulose crystallinity degree, also infrared spectroscopy FTIR was used. (author)

  11. Cellulose-silica aerogels.

    Science.gov (United States)

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Polyvinyl alcohol–cellulose composite: a taste sensing material

    Indian Academy of Sciences (India)

    We have made an attempt to prepare taste sensor material by using functionalized polymer without any lipid. PVA–cellulose composite has been modified to use as the sensor material. The research work covers polymer membrane preparation, morphology study and structural characterization of the membrane and study of ...

  13. Internally plasticised cellulose polymers

    International Nuclear Information System (INIS)

    Burnup, M.; Hayes, G.F.; Fydelor, P.J.

    1981-01-01

    Plasticised cellulose polymers comprise base polymer having a chain of β-anhydroglucose units joined by ether linkages, with at least one of said units carrying at least one chemically unreactive side chain derived from an allylic monomer or a vinyl substituted derivative of ferrocene. The side chains are normally formed by radiation grafting. These internally plasticised celluloses are useful in particular as inhibitor coatings for rocket motor propellants and in general wherever cellulose polymers are employed. (author)

  14. A comparison of the performance of aromatic polyamide and cellulose acetate reverse osmosis membrane on the regeneration of secondary effluents; Comparacion del funcionamiento de membranas de osmosis inversa de poliamida aromatica y acetato de celulosa en la regeneracion de efluentes secundarios

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Ramirez, J. A.; Carrasco Vega, M.; Sales Marquez, D.; Quiroga Alonso, J. M.

    2002-07-01

    The application of reverse osmosis in regenerating waste waters has aroused a great deal of interest, although relatively few experiments using this technique have so far been carried out in Spain. In 1994, an experimental pilot plant was built at the La Barrosa waste water treatment plant in Chiclana de la Frontera in the province of Cadiz. This pilot plant with a capacity of 100 m''3/day, was equipped with various advanced treatments, most notably reverse osmosis, for treating urban waste waters for re-use. Since this pilot plant was built, various experiments have been carried out employing cellulose acetate (Hydranautics) and different types of Spanish-made aromatic polyamide membranes (Pridesa). Each type of membrane proposed different operating characteristics and feed-water requirements making each one suitable for a particular purpose. In this study, the secondary effluents was subjected to different kinds of treatment-called intense treatment, moderate treatment and minimum treatment-before reaching the reverse osmosis unit, which influenced the conditions in which the membranes operated. Following each type of treatment, the waters entering and leaving the installation were analysed to evaluate the quality of the final effluent and the effectiveness of the treatment carried out. The quality was extremely good in all the permeate samples analysed, almost irrespective of the type of treatment applied. It was also found that the cellulose acetate membranes tended to become less dirty than the aromatic polyamide membranes,due to their surface morphology. Nevertheless, the polyamide membranes have various advantages allowing them to be used in a wide range of applications at a lower energy cost. (Author) 8 refs.

  15. Determination of the size and phase composition of silver nanoparticles in a gel film of bacterial cellulose by small-angle X-ray scattering, electron diffraction, and electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V. V.; Klechkovskaya, V. V., E-mail: klechvv@ns.crys.ras.ru; Shtykova, E. V.; Dembo, K. A.; Arkharova, N. A.; Ivakin, G. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Smyslov, R. Yu. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation)

    2009-03-15

    The nanoscale structural features in a composite (gel film of Acetobacter Xylinum cellulose with adsorbed silver nanoparticles, stabilized by N-polyvinylpyrrolidone) have been investigated by small-angle X-ray scattering. The size distributions of inhomogeneities in the porous structure of the cellulose matrix and the size distributions of silver nanoparticles in the composite have been determined. It is shown that the sizes of synthesized nanoparticles correlate with the sizes of inhomogeneities in the gel film. Particles of larger size (with radii up to 100 nm) have also been found. Electron microscopy of thin cross sections of a dried composite layer showed that large particles are located on the cellulose layer surface. Electron diffraction revealed a crystal structure of silver nanoparticles in the composite.

  16. Protein and DNA technologies for functional expression of membrane-associated cytochromes P450 in bacterial cell factories

    DEFF Research Database (Denmark)

    Vazquez Albacete, Dario

    The heavy dependence and massive consumption of fossil fuels by humans is changing our environment very rapidly. Some of the side effects of industrial activity include the pollution of the natural resources we rely on, and the reduction of biodiversity. Some chemicals found in nature exhibit great....... In most of biosynthetic pathways leading to these chemicals the cytochrome P450 enzyme family (P450s) is responsible for their final functionalization. However, the membrane-bound nature of P450s, makes their expression in microbial hosts a challenge. In order to meet the global demand for these natural......450 engineering guidelines and serves as platform to improve performance of microbial cells, thereby boosting recombinant production of complex plant P450-derived biochemicals. The knowledge generated, could guide future reconstruction of functional plant metabolic pathways leading to high valuable...

  17. Direct observation of the effects of cellulose synthesis inhibitors using live cell imaging of Cellulose Synthase (CESA) in Physcomitrella patens.

    Science.gov (United States)

    Tran, Mai L; McCarthy, Thomas W; Sun, Hao; Wu, Shu-Zon; Norris, Joanna H; Bezanilla, Magdalena; Vidali, Luis; Anderson, Charles T; Roberts, Alison W

    2018-01-15

    Results from live cell imaging of fluorescently tagged Cellulose Synthase (CESA) proteins in Cellulose Synthesis Complexes (CSCs) have enhanced our understanding of cellulose biosynthesis, including the mechanisms of action of cellulose synthesis inhibitors. However, this method has been applied only in Arabidopsis thaliana and Brachypodium distachyon thus far. Results from freeze fracture electron microscopy of protonemal filaments of the moss Funaria hygrometrica indicate that a cellulose synthesis inhibitor, 2,6-dichlorobenzonitrile (DCB), fragments CSCs and clears them from the plasma membrane. This differs from Arabidopsis, in which DCB causes CSC accumulation in the plasma membrane and a different cellulose synthesis inhibitor, isoxaben, clears CSCs from the plasma membrane. In this study, live cell imaging of the moss Physcomitrella patens indicated that DCB and isoxaben have little effect on protonemal growth rates, and that only DCB causes tip rupture. Live cell imaging of mEGFP-PpCESA5 and mEGFP-PpCESA8 showed that DCB and isoxaben substantially reduced CSC movement, but had no measureable effect on CSC density in the plasma membrane. These results suggest that DCB and isoxaben have similar effects on CSC movement in P. patens and Arabidopsis, but have different effects on CSC intracellular trafficking, cell growth and cell integrity in these divergent plant lineages.

  18. Regulation of cellulose synthesis in response to stress.

    Science.gov (United States)

    Kesten, Christopher; Menna, Alexandra; Sánchez-Rodríguez, Clara

    2017-12-01

    The cell wall is a complex polysaccharide network that provides stability and protection to the plant and is one of the first layers of biotic and abiotic stimuli perception. A controlled remodeling of the primary cell wall is essential for the plant to adapt its growth to environmental stresses. Cellulose, the main component of plant cell walls is synthesized by plasma membrane-localized cellulose synthases moving along cortical microtubule tracks. Recent advancements demonstrate a tight regulation of cellulose synthesis at the primary cell wall by phytohormone networks. Stress-induced perturbations at the cell wall that modify cellulose synthesis and microtubule arrangement activate similar phytohormone-based stress response pathways. The integration of stress perception at the primary cell wall and downstream responses are likely to be tightly regulated by phytohormone signaling pathways in the context of cellulose synthesis and microtubule arrangement. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Cellulose Degradation by Cellulose-Clearing and Non-Cellulose-Clearing Brown-Rot Fungi

    OpenAIRE

    Highley, Terry L.

    1980-01-01

    Cellulose degradation by four cellulose-clearing brown-rot fungi in the Coniophoraceae—Coniophora prasinoides, C. puteana, Leucogyrophana arizonica, and L. olivascens—is compared with that of a non-cellulose-clearing brown-rot fungus, Poria placenta. The cellulose- and the non-cellulose-clearing brown-rot fungi apparently employ similar mechanisms to depolymerize cellulose; most likely a nonenzymatic mechanism is involved.

  20. Cellulose nanomaterials as green nanoreinforcements for polymer nanocomposites

    Science.gov (United States)

    Dufresne, Alain

    2017-12-01

    Unexpected and attractive properties can be observed when decreasing the size of a material down to the nanoscale. Cellulose is no exception to the rule. In addition, the highly reactive surface of cellulose resulting from the high density of hydroxyl groups is exacerbated at this scale. Different forms of cellulose nanomaterials, resulting from a top-down deconstruction strategy (cellulose nanocrystals, cellulose nanofibrils) or bottom-up strategy (bacterial cellulose), are potentially useful for a large number of industrial applications. These include the paper and cardboard industry, use as reinforcing filler in polymer nanocomposites, the basis for low-density foams, additives in adhesives and paints, as well as a wide variety of filtration, electronic, food, hygiene, cosmetic and medical products. This paper focuses on the use of cellulose nanomaterials as a filler for the preparation of polymer nanocomposites. Impressive mechanical properties can be obtained for these materials. They obviously depend on the type of nanomaterial used, but the crucial point is the processing technique. The emphasis is on the melt processing of such nanocomposite materials, which has not yet been properly resolved and remains a challenge. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

  1. Outer membrane vesicles from Brucella abortus promote bacterial internalization by human monocytes and modulate their innate immune response.

    Directory of Open Access Journals (Sweden)

    Cora N Pollak

    Full Text Available Outer membrane vesicles (OMVs released by some gram-negative bacteria have been shown to exert immunomodulatory effects that favor the establishment of the infection. The aim of the present study was to assess the interaction of OMVs from Brucella abortus with human epithelial cells (HeLa and monocytes (THP-1, and the potential immunomodulatory effects they may exert. Using confocal microscopy and flow cytometry, FITC-labeled OMVs were shown to be internalized by both cell types. Internalization was shown to be partially mediated by clathrin-mediated endocytosis. Pretreatment of THP-1 cells with Brucella OMVs inhibited some cytokine responses (TNF-α and IL-8 to E. coli LPS, Pam3Cys or flagellin (TLR4, TLR2 and TLR5 agonists, respectively. Similarly, pretreatment with Brucella OMVs inhibited the cytokine response of THP-1 cells to B. abortus infection. Treatment of THP-1 cells with OMVs during IFN-γ stimulation reduced significantly the inducing effect of this cytokine on MHC-II expression. OMVs induced a dose-dependent increase of ICAM-1 expression on THP-1 cells and an increased adhesion of these cells to human endothelial cells. The addition of OMVs to THP-1 cultures before the incubation with live B. abortus resulted in increased numbers of adhered and internalized bacteria as compared to cells not treated with OMVs. Overall, these results suggest that OMVs from B. abortus exert cellular effects that promote the internalization of these bacteria by human monocytes, but also downregulate the innate immune response of these cells to Brucella infection. These effects may favor the persistence of Brucella within host cells.

  2. A Bioinformatics Analysis Reveals a Group of MocR Bacterial Transcriptional Regulators Linked to a Family of Genes Coding for Membrane Proteins

    Directory of Open Access Journals (Sweden)

    Teresa Milano

    2016-01-01

    Full Text Available The MocR bacterial transcriptional regulators are characterized by an N-terminal domain, 60 residues long on average, possessing the winged-helix-turn-helix (wHTH architecture responsible for DNA recognition and binding, linked to a large C-terminal domain (350 residues on average that is homologous to fold type-I pyridoxal 5′-phosphate (PLP dependent enzymes like aspartate aminotransferase (AAT. These regulators are involved in the expression of genes taking part in several metabolic pathways directly or indirectly connected to PLP chemistry, many of which are still uncharacterized. A bioinformatics analysis is here reported that studied the features of a distinct group of MocR regulators predicted to be functionally linked to a family of homologous genes coding for integral membrane proteins of unknown function. This group occurs mainly in the Actinobacteria and Gammaproteobacteria phyla. An analysis of the multiple sequence alignments of their wHTH and AAT domains suggested the presence of specificity-determining positions (SDPs. Mapping of SDPs onto a homology model of the AAT domain hinted at possible structural/functional roles in effector recognition. Likewise, SDPs in wHTH domain suggested the basis of specificity of Transcription Factor Binding Site recognition. The results reported represent a framework for rational design of experiments and for bioinformatics analysis of other MocR subgroups.

  3. Constants of the Alper and Howard-Flanders oxygen equation for damage to bacterial membrane, deduced from observations on the radiation-induced penicillin-sensitive lesion

    International Nuclear Information System (INIS)

    Obioha, F.I.; Gillies, N.E.; Cullen, B.M.; Walker, H.C.; Alper, T.

    1984-01-01

    E. coli were irradiated in the presence of 100% oxygen, oxygen-free nitrogen and mixtures of 1.01, 0.59, 0.3, 0.1 and 0.06% oxygen in nitrogen. Changes in sensitivity with pO 2 conformed with the Alper and Howard-Flanders equation for bacteria treated after irradiation by penicillin as well as for the untreated ones. Values of m were respectively 4.8 and 3.3; values of K were identical, within experimental error, (4.4 mmHg). Sensitivity to induction of the bacterial membrane penicillin-sensitive lesion was calculated from the difference in the reciprocals of D 0 values proper to untreated and treated bacteria, for every gas used. The value of m could not be directly calculated because the effect of penicillin on anoxically irradiated bacteria was not detectable. For that reason, a transformation of the oxygen equation was used, allowing estimates to be made of both m and K, provided the results conformed with the equation. Within experimental error they did. Calculated values of m and K for induction of the penicillin-sensitive lesion were respectively 8 and 5.9 mmHg, but it is shown that the oxygen enhancement ratio was probably underestimated and the value overestimated. (author)

  4. Cellulose acetate electrospun nanofibrous membrane: fabrication ...

    Indian Academy of Sciences (India)

    In recent times, research on developing biodegradable, bio- functional and biocompatible nanosized materials has gained much interest. Nanometre length is the ..... comparison to control (tissue culture plastic, without mem- brane). It was observed that the cell viability was more than 90% of control after the nanofibres were ...

  5. Gas separation membranes

    Science.gov (United States)

    Schell, William J.

    1979-01-01

    A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

  6. Solid residues from Ruminococcus cellulose fermentations as components of wood adhesive formulations

    Science.gov (United States)

    P.J. Weimer; A.H. Conner; L.F. Lorenz

    2003-01-01

    Residues from the fermentation of cellulose by the anaerobic bacteria Ruminococcus albus (strain 7) or Ruminococcus flavefaciens (strains FD-1 or B34b) containing residual cellulose, bacterial cells and their associated adhesins, were examined for their ability to serve as components of adhesives for plywood fabrication. The residues contained differing amounts of...

  7. Membranes and Films from Polymers.

    Science.gov (United States)

    Blumberg, Avrom A.

    1986-01-01

    Provides background information on polymeric films and membranes including production methods, special industrial and medical applications, laboratory preparation, and an experimental investigation of a porous cellulose acetate membrane. Presents a demonstration to distinguish between high- and low-density polyethylene. (JM)

  8. Fulton Cellulosic Ethanol Biorefinery

    Energy Technology Data Exchange (ETDEWEB)

    Sumait, Necy [BlueFire Ethanol, Irvine, CA (United States); Cuzens, John [BlueFire Ethanol, Irvine, CA (United States); Klann, Richard [BlueFire Ethanol, Irvine, CA (United States)

    2015-07-24

    Final report on work performed by BlueFire on the deployment of acid hydrolysis technology to convert cellulosic waste materials into renewable fuels, power and chemicals in a production facility to be located in Fulton, Mississippi.

  9. A novel antibacterial peptide derived from Crocodylus siamensis haemoglobin hydrolysate induces membrane permeabilization causing iron dysregulation, oxidative stress and bacterial death.

    Science.gov (United States)

    Lueangsakulthai, J; Jangpromma, N; Temsiripong, T; McKendrick, J E; Khunkitti, W; Maddocks, S E; Klaynongsruang, S

    2017-10-01

    A novel antibacterial peptide from Crocodylus siamensis haemoglobin hydrolysate (CHH) was characterized for antimicrobial activity. CHHs were hydrolysed for 2 h (2 h-CHH), 4 h (4h-CHH), 6 h (6 h-CHH) and 8 h (8 h-CHH). The 8 h-CHH showed antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa at concentrations of 20, 20, 20 and 10 mg ml -1 (w/v) respectively. Fluorescent microscopy revealed that the 8 h-CHH had bactericidal activity against E. coli and P. aeruginosa. β-galactosidase assay supported by RT-qPCR demonstrated that the 8 h-CHH resulted in differential expression of genes involved in iron homeostasis (ftnA and bfd) and oxidative stress (sodA, soxR and oxyR). Siderophore assay indicated that the 8 h-CHH also impaired siderophore production with diminished expression of pvdF. This pattern of gene expression suggests that the 8 h-CHH triggers the release of free ferric ions in the cytoplasm. However, decreased expression of genes associated with the SOS response (recA and lexA) in combination with neutral comet revealed that no DNA damage was caused by 8 h-CHH. Membrane permeabilization assay indicated that 8 h-CHH caused membrane leakage thought to mediate the antibacterial and iron-stress responses observed, due to loss of regulated iron transport. The novel active peptide from 8 h-CHH was determined as QAIIHNEKVQAHGKKVL (QL17), with 41% hydrophobicity and +2 net charge. The QAIIHNEKVQAHGKKVL fragment of C. siamensis haemoglobin is antibacterial via a mechanism that likely relies on iron dysregulation and oxidative stress which results in bacterial death. We have described for the first time, a novel peptide derived from C. siamensis haemoglobin hydrolysate that has the potential to be developed as a novel antimicrobial peptide. © 2017 The Society for Applied Microbiology.

  10. Occurrence of Cellulose-Producing Gluconacetobacter spp. in Fruit Samples and Kombucha Tea, and Production of the Biopolymer.

    Science.gov (United States)

    Neera; Ramana, Karna Venkata; Batra, Harsh Vardhan

    2015-06-01

    Cellulose producing bacteria were isolated from fruit samples and kombucha tea (a fermented beverage) using CuSO4 solution in modified Watanabe and Yamanaka medium to inhibit yeasts and molds. Six bacterial strains showing cellulose production were isolated and identified by 16S rRNA gene sequencing as Gluconacetobacter xylinus strain DFBT, Ga. xylinus strain dfr-1, Gluconobacter oxydans strain dfr-2, G. oxydans strain dfr-3, Acetobacter orientalis strain dfr-4, and Gluconacetobacter intermedius strain dfr-5. All the cellulose-producing bacteria were checked for the cellulose yield. A potent cellulose-producing bacterium, i.e., Ga. xylinus strain DFBT based on yield (cellulose yield 5.6 g/L) was selected for further studies. Cellulose was also produced in non- conventional media such as pineapple juice medium and hydrolysed corn starch medium. A very high yield of 9.1 g/L cellulose was obtained in pineapple juice medium. Fourier transform infrared spectrometer (FT-IR) analysis of the bacterial cellulose showed the characteristic peaks. Soft cellulose with a very high water holding capacity was produced using limited aeration. Scanning electron microscopy (SEM) was used to analyze the surface characteristics of normal bacterial cellulose and soft cellulose. The structural analysis of the polymer was performed using (13)C solid-state nuclear magnetic resonance (NMR). More interfibrillar space was observed in the case of soft cellulose as compared to normal cellulose. This soft cellulose can find potential applications in the food industry as it can be swallowed easily without chewing.

  11. Microfibrillated cellulose and new nanocomposite materials: a review

    DEFF Research Database (Denmark)

    Siró, Istvan; Plackett, David

    2010-01-01

    Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject...... typically required high energy input, chemical and/or enzymatic fiber pre-treatments have been developed to overcome this problem. A challenge associated with using nanocellulose in composites is the lack of compatibility with hydrophobic polymers and various chemical modification methods have been explored...... in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose....

  12. Cellulose Supplementation Early in Life Ameliorates Colitis in Adult Mice

    Science.gov (United States)

    Nagy-Szakal, Dorottya; Hollister, Emily B.; Luna, Ruth Ann; Szigeti, Reka; Tatevian, Nina; Smith, C. Wayne; Versalovic, James; Kellermayer, Richard

    2013-01-01

    Decreased consumption of dietary fibers, such as cellulose, has been proposed to promote the emergence of inflammatory bowel diseases (IBD: Crohn disease [CD] and ulcerative colitis [UC]) where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods may prevent consecutive intestinal inflammation. The incidence of IBD peaks in young adulthood indicating that pediatric environmental exposures may be important in the etiology of this disease gro