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Sample records for alamar blue biofilm

  1. Antimicrobial susceptibility of standard strains of nontuberculous mycobacteria by microplate Alamar Blue assay.

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    Guilian Li

    Full Text Available In this study, 24 standard nontuberculous mycobacteria (NTM species strains including 12 slowly growing mycobacteria strains and 12 rapidly growing mycobacteria strains were subjected to drug susceptibility testing using microplate Alamar Blue assay-based 7H9 broth. The most active antimicrobial agents against the 24 NTM strains were streptomycin, amikacin, the fluoroquinolones, and the tetracyclines. Mycobacterium chelonae, Mycobacterium abscessus, Mycobacterium bolletii, and Mycobacterium simiae are resistant to most antimicrobial agents. The susceptibility results of this study from 24 NTM standard strains can be referenced by clinicians before susceptibility testing for clinical isolates is performed or when conditions do not allow for susceptibility testing. The application of broth-based methods is recommended by the Clinical and Laboratory Standards Institute, and the documentation of the susceptibility patterns of standard strains of mycobacteria can improve the international standardization of susceptibility testing methods.

  2. Multiple Applications of Alamar Blue as an Indicator of Metabolic Function and Cellular Health in Cell Viability Bioassays

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    Sephra N. Rampersad

    2012-09-01

    Full Text Available Accurate prediction of the adverse effects of test compounds on living systems, detection of toxic thresholds, and expansion of experimental data sets to include multiple toxicity end-point analysis are required for any robust screening regime. Alamar Blue is an important redox indicator that is used to evaluate metabolic function and cellular health. The Alamar Blue bioassay has been utilized over the past 50 years to assess cell viability and cytotoxicity in a range of biological and environmental systems and in a number of cell types including bacteria, yeast, fungi, protozoa and cultured mammalian and piscine cells. It offers several advantages over other metabolic indicators and other cytotoxicity assays. However, as with any bioassay, suitability must be determined for each application and cell model. This review seeks to highlight many of the important considerations involved in assay use and design in addition to the potential pitfalls.

  3. Comparison of microscopy and Alamar blue reduction in a larval based assay for schistosome drug screening.

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    Nuha R Mansour

    Full Text Available BACKGROUND: In view of the current widespread use of and reliance on a single schistosomicide, praziquantel, there is a pressing need to discover and develop alternative drugs for schistosomiasis. One approach to this is to develop High Throughput in vitro whole organism screens (HTS to identify hits amongst large compound libraries. METHODOLOGY/PRINCIPAL FINDINGS: We have been carrying out low throughput (24-well plate in vitro testing based on microscopic evaluation of killing of ex-vivo adult S. mansoni worms using selected compound collections mainly provided through the WHO-TDR Helminth Drug Initiative. To increase throughput, we introduced a similar but higher throughput 96-well primary in vitro assay using the schistosomula stage which can be readily produced in vitro in large quantities. In addition to morphological readout of viability we have investigated using fluorometric determination of the reduction of Alamar blue (AB, a redox indicator of enzyme activity widely used in whole organism screening. A panel of 7 known schistosome active compounds including praziquantel, produced diverse effects on larval morphology within 3 days of culture although only two induced marked larval death within 7 days. The AB assay was very effective in detecting these lethal compounds but proved more inconsistent in detecting compounds which damaged but did not kill. The utility of the AB assay in detecting compounds which cause severe morbidity and/or death of schistosomula was confirmed in testing a panel of compounds previously selected in library screening as having activity against the adult worms. Furthermore, in prospective library screening, the AB assay was able to detect all compounds which induced killing and also the majority of compounds designated as hits based on morphological changes. CONCLUSION: We conclude that an HTS combining AB readout and image-based analysis would provide an efficient and stringent primary assay for schistosome

  4. 改良Alamar Blue法检测结直肠微小组织块的活力%Viability of tissue fragments in colon and rectum detected using modified Alamar Blue assay

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    甘嘉亮; 高枫; 曹云飞; 廖存; 黄家豪; 唐双意

    2012-01-01

    BACKGROUND: Alamar Blue assay is one of the common methods to evaluate histic or cellular viability. It is widely used to detect cell viability at present. However, using Alamar Blue assay to detect the viability of tissue fragments has not been reported. OBJECTIVE: To detect the viability of the regular tissue fragments and cancer tissue fragments in the mucous membrane of colon and rectum using modified Alamar Blue assay. METHODS: Based on cell viability detect assay of Alamar Blue, the viability of the regular tissue fragments and cancer tissue fragments in the mucous membrane of colon and rectum was assessed using absorbance per unit mass. The detecting time was chosen at 0, 6, 12, 18, 24 , 30 and 36 hours according to the specification of the Alamar Blue assay and the pre-experiment results. Every specimen was divided into seven groups and the blank control hole was established. RESULTS AND CONCLUSIONS: Absorbance per unit mass reflected the change tendency of proliferation activity in tissue fragments as the culture time went on. Both regular tissue fragments and cancer tissue fragments in the mucous membrane of colon and rectum reached the best proliferative state at 12-24 hours after culture. It confirms that the modified Alamar Blue assay is a sensitive and effective way to evaluate the viability of colorectal tissue fragments.%背景:Alamar Blue法是测定组织细胞活性的方法之一,目前多数应用在细胞系活力测定方面,尚未见应用于微小组织块活力的评价.目的:采用改良Alamar Blue法评价结直肠正常黏膜组织块和癌组织块的活力.方法:以细胞活力测定的Alamar Blue法为基础,应用单位质量吸光度来评价结直肠正常黏膜组织块和癌组织块的活力.根据检测试剂盒说明书和预实验结果,实验选择0,6,12,18,24,30,36 h作为检测时间点,每一例标本分为7组,设空白对照孔.结果与结论:单位质量吸光度能够随培养时间的推移,很好地反映组织

  5. Screening of Central and South American plant extracts for antimycobacterial activity by the Alamar Blue test Triagem de extratos de plantas das Américas Central e do Sul para atividade antimicobacteriana pelo teste do Alamar Blue

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    Suzana G. Leitão

    2006-03-01

    Full Text Available Forty eight ethanolic crude extracts and fractions (hexane, dichloromethane, ethyl acetate and n-butanol from ten Brazilian plants (Leguminosae, Monimiaceae and Verbenaceae, 1 from Costa Rica (Verbenaceae and 1 from Argentina (Verbenaceae were screened for anti-mycobacterium activity against Mycobacterium tuberculosis (ATCC-27294H37Rv, by the Alamar Blue test, at a fixed concentration of 100 µg/mL. Out of the forty eight, seven were active at this concentration, corresponding to Lantana trifolia (hexane and dichloromethane extracts from leaves, Vitex cooperi (methanol:water, 1:1 extract from barks, Lippia lacunosa (hexane and dichloromethane extracts from leaves and Lippia rotundifolia (hexane and dichloromethane extracts from leaves, all from the Verbenaceae family.Quarenta e oito extratos brutos etanólicos e frações (em hexano, diclorometano, acetato de etila e n-butanol de dez plantas brasileiras pertencentes às famílias Leguminosae, Monimiaceae e Verbenaceae; uma da Costa Rica (Verbenaceae e uma da Argentina (Verbenaceae foram ensaiados para verificação da atividade anti-micobacteriana contra Mycobacterium tuberculosis (ATCC-27294H37Rv, pelo teste do Alamar Blue, a uma concentração fixa de 100 µg/mL. Dentre os quarenta e oito extratos e frações estudados, sete mostraram-se ativos na concentração ensaiada - frações em hexano e diclorometano de folhas de Lantana trifolia, extrato em metanol:água, 1:1 de cascas de Vitex cooperi, frações em hexano e diclorometano de folhas de Lippia lacunosa e de Lippia rotundifolia, sendoque todas essas plantas pertencem à família Verbenaceae.

  6. Susceptibility profiles of Nocardia spp. to antimicrobial and antituberculotic agents detected by a microplate Alamar Blue assay

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    Zhao, Pan; Zhang, Xiujuan; Du, Pengcheng; Li, Guilian; Li, Luxi; Li, Zhenjun

    2017-01-01

    Nocardia species are ubiquitous in natural environments and can cause nocardiosis. Trimethoprim-sulfamethoxazole has long been the monotherapy treatment of choice, but resistance to this treatment has recently emerged. In this study, we used microplate Alamar Blue assays to determine the antimicrobial susceptibility patterns of 65 standard Nocardia isolates, including 28 type strains and 20 clinical Nocardia isolates, to 32 antimicrobial agents, including 13 little studied drugs. Susceptibility to the most commonly used drug, trimethoprim-sulfamethoxazole, was observed in 98% of the isolates. Linezolid, meropenem, and amikacin were also highly effective, with 98%, 95%, and 90% susceptibility, respectively, among the isolates. The isolates showed a high percentage of resistance or nonsusceptibility to isoniazid, rifampicin, and ethambutol. For the remaining antimicrobials, resistance was species-specific among isolates and was observed in traditional drug pattern types. In addition, the antimicrobial susceptibility profiles of a variety of rarely encountered standard Nocardia species are reported, as are the results for rarely reported clinical antibiotics. We also provide a timely update of antimicrobial susceptibility patterns that includes three new drug pattern types. The data from this study provide information on antimicrobial activity against specific Nocardia species and yield important clues for the optimization of species-specific Nocardia therapies. PMID:28252662

  7. Influence of methylene blue-mediated photodynamic therapy on the resistance to detachment of streptococcus mutans biofilms from titanium substrata

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    Sharab, Lina Y.

    In dental settings, as well as in other natural systems, plaque-forming microorganisms develop biofilms in which the microbes become protected via their own phenotypic changes and their polymeric exudates from disinfection by washes and antibiotics. Photodynamic Therapy (PDT) is variably effective against these microorganisms, depending on such factors as whether the bacteria are Gram positive or Gram negative, plaque age and thickness, and internal biofilm oxygen concentration. This investigation applied a novel combination of PDT and water-jet impingement techniques to Streptococcus mutans (ATCC strain 27351)-formed biofilms on commercially pure titanium (cpTi) starting with three different phases (ages) of the bacteria, to examine whether the detachment shear stress --as a signature for the work required for removal of the biofilms- would be affected by prior PDT treatment independently from microbial viability. Biofilms were grown with sucrose addition to Brain Heart Infusion media, producing visible thick films and nearly invisible thin films (within the same piece) having the same numbers of culturable microorganisms, the thicker films having greater susceptibility to detachment by water--jet impingement. Colony-forming-unit (CFU) counts routinely correlated well with results from a spectrophotometric Alamar Blue (AB) assay. Use of Methylene Blue (MB) as a photosensitizer (PS) for PDT of biofilms did not interfere with the AB assay, but did mask AB reduction spectral changes when employed with planktonic organisms. It was discovered in this work that PD-treated microbial biofilms, independently from starting or PS-influenced microorganism viability, were significantly (p<0.05) and differentially more easily delaminated and ultimately removed from their substrata biomaterials by the hydrodynamic forces of water-jet impingement. Control biofilms of varying thickness, not receiving PDT treatment, required between 144 and 228 dynes/cm2 of shear stress to

  8. Photo Inactivation of Streptococcus mutans Biofilm by Violet-Blue light.

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    Gomez, Grace F; Huang, Ruijie; MacPherson, Meoghan; Ferreira Zandona, Andrea G; Gregory, Richard L

    2016-09-01

    Among various preventive approaches, non-invasive phototherapy/photodynamic therapy is one of the methods used to control oral biofilm. Studies indicate that light at specific wavelengths has a potent antibacterial effect. The objective of this study was to determine the effectiveness of violet-blue light at 380-440 nm to inhibit biofilm formation of Streptococcus mutans or kill S. mutans. S. mutans UA159 biofilm cells were grown for 12-16 h in 96-well flat-bottom microtiter plates using tryptic soy broth (TSB) or TSB with 1 % sucrose (TSBS). Biofilm was irradiated with violet-blue light for 5 min. After exposure, plates were re-incubated at 37 °C for either 2 or 6 h to allow the bacteria to recover. A crystal violet biofilm assay was used to determine relative densities of the biofilm cells grown in TSB, but not in TSBS, exposed to violet-blue light. The results indicated a statistically significant (P < 0.05) decrease compared to the non-treated groups after the 2 or 6 h recovery period. Growth rates of planktonic and biofilm cells indicated a significant reduction in the growth rate of the violet-blue light-treated groups grown in TSB and TSBS. Biofilm viability assays confirmed a statistically significant difference between violet-blue light-treated and non-treated groups in TSB and TSBS. Visible violet-blue light of the electromagnetic spectrum has the ability to inhibit S. mutans growth and reduce the formation of S. mutans biofilm. This in vitro study demonstrated that violet-blue light has the capacity to inhibit S. mutans biofilm formation. Potential clinical applications of light therapy in the future remain bright in preventing the development and progression of dental caries.

  9. The effect of blue light on periodontal biofilm growth in vitro.

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    Fontana, Carla R; Song, Xiaoqing; Polymeri, Angeliki; Goodson, J Max; Wang, Xiaoshan; Soukos, Nikolaos S

    2015-11-01

    We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p biofilms, respectively, (p biofilms. The cumulative blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases.

  10. Papain gel containing methylene blue for simultaneous caries removal and antimicrobial photoinactivation against Streptococcus mutans biofilms

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    Silva Jr., Zenildo Santos; Huang, Ying-Ying; de Freitas, Lucas Freitas; França, Cristiane Miranda; Botta, Sergio Brossi; Ana, Patrícia Aparecida; Mesquita-Ferrari, Raquel Agnelli; Santos Fernandes, Kristianne Porta; Deana, Alessandro; Lima Leal, Cintia Raquel; Prates, Renato Araujo; Hamblin, Michael R.; Bussadori, Sandra Kalil

    2016-01-01

    This study intended to evaluate the effects of a papain-gel with a red-light absorbing pigment (methylene blue – MB) to mediate photodynamic therapy (PDT) against Streptococcus mutans biofilms. The PapaMBlue was compared with free MB to generate reactive oxygen species using fluorescence probes (SOSG and HPF). PDT (660-nm light) was carried out against S. mutans biofilms grown on either plastic dishes or on collagen membrane and assayed by CFU, live-dead staining using confocal microscopy, transmission electron microscopy and H&E staining for collagen films. Cytotoxicity and subcellular localization was studied in human fibroblasts. Sponges of bioabsorbable type I collagen membrane were exposed to papain based gel, irradiated with laser and analyzed about their integrity by ATR-FTIR. The PapaMBlue produced higher amounts of singlet oxygen and hydroxyl radicals than free MB, possibly due to better disaggregation of the dye in solution. The PapaMBlue antimicrobial effects on biofilms proved to be capable of reducing the S. mutans. Both MTT and PrestoBlue assays showed higher cell viability and metabolism scores in fibroblasts treated with PapaMBlue and MB, possibly due to stimulation of mitochondrial activity and that collagen triple helix is unaffected. The PapaMBlue is equally effective as MB in destroying S. mutans biofilms growing on plastic or collagen without affecting fibroblasts. PMID:27641507

  11. Distribution and Inhibition of Liposomes on Staphylococcus aureus and Pseudomonas aeruginosa Biofilm.

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    Dong Dong

    Full Text Available Staphylococcus aureus and Pseudomonas aeruginosa are major pathogens in chronic rhinosinusitis (CRS and their biofilms have been associated with poorer postsurgical outcomes. This study investigated the distribution and anti-biofilm effect of cationic (+ and anionic (- phospholipid liposomes with different sizes (unilamellar and multilamellar vesicle, ULV and MLV respectively on S. aureus and P. aeruginosa biofilms.Specific biofilm models for S. aureus ATCC 25923 and P. aeruginosa ATCC 15692 were established. Liposomal distribution was determined by observing SYTO9 stained biofilm exposed to DiI labeled liposomes using confocal scanning laser microscopy, followed by quantitative image analysis. The anti-biofilm efficacy study was carried out by using the alamarBlue assay to test the relative viability of biofilm treated with various liposomes for 24 hours and five minutes.The smaller ULVs penetrated better than larger MLVs in both S. aureus and P. aeruginosa biofilm. Except that +ULV and -ULV displayed similar distribution in S. aureus biofilm, the cationic liposomes adhered better than their anionic counterparts. Biofilm growth was inhibited at 24-hour and five-minute exposure time, although the decrease of viability for P. aeruginosa biofilm after liposomal treatment did not reach statistical significance.The distribution and anti-biofilm effects of cationic and anionic liposomes of different sizes differed in S. aureus and P. aeruginosa biofilms. Reducing the liposome size and formulating liposomes as positively charged enhanced the penetration and inhibition of S. aureus and P. aeruginosa biofilms.

  12. Gold nanoparticles enhance methylene blue-induced photodynamic therapy: a novel therapeutic approach to inhibit Candida albicans biofilm.

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    Khan, Shakir; Alam, Fahad; Azam, Ameer; Khan, Asad U

    2012-01-01

    This article explores the novel gold nanoparticle-enhanced photodynamic therapy of methylene blue against recalcitrant pathogenic Candida albicans biofilm. Physiochemical (X-ray diffraction, ultraviolet-visible absorption, photon cross-correlation, FTIR, and fluorescence spectroscopy) and electron microscopy techniques were used to characterize gold nanoparticles as well as gold nanoparticle-methylene blue conjugate. A 38.2-J/cm(2) energy density of 660-nm diode laser was applied for activation of gold nanoparticle-methylene blue conjugate and methylene blue against C. albicans biofilm and cells. Antibiofilm assays, confocal laser scanning, and electron microscopy were used to investigate the effects of the conjugate. Physical characteristics of the gold nanoparticles (21 ± 2.5 nm and 0.2 mg/mL) and methylene blue (20 μg/mL) conjugation were confirmed by physicochemical and electron microscopy techniques. Antibiofilm assays and microscopic studies showed significant reduction of biofilm and adverse effect against Candida cells in the presence of conjugate. Fluorescence spectroscopic study confirmed type I photo toxicity against biofilm. Gold nanoparticle conjugate-mediated photodynamic therapy may be used against nosocomially acquired refractory Candida albicans biofilm.

  13. Delmopinol-induced matrix removal facilitates photodynamic therapy and chlorhexidine methods for disinfecting mixed oral biofilms

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    Rogers, Stephen Christopher

    It is often observed that the slimy matrixes of various bacterial-formed biofilms can limit their disinfection. This investigation demonstrated that disinfection effectiveness by either photodynamic therapy (PDT) or chlorhexidine irrigation is significantly improved by collapse of that matrix using the non-bactericidal reagent delmopinol as part of the treatment sequence. Cyclic shear-producing conditions were used to grow 4-day, whole salivary and growth media biofilms on glow-discharge-treated polystyrene (N=46) and mini-germanium internal reflection prisms to serve in a periodontal crypt model of disinfection by either methylene-blue-mediated PDT or by chlorhexidine irrigation. Assays for bacterial viability, with and without treatments, were performed by alamarBlueRTM fluorescent methods, statistically applied (ANOVA, Tukey's HSD). Multiple Attenuated Internal Reflection Infrared (MAIR-IR) assays confirmed selective removal of the predominantly polysaccharide matrix materials by the delmopinol treatment, but not by equivalent water or chlorhexidine methods. Confocal-IR microscopy showed that the delmopinol reagent, alone, caused about one-third of each wet biofilm to be removed, while bacterial re-growth was confirmed by alamarBlueRTM assay. Chlorhexidine and PDT suppression of bacterial activity without regrowth was significantly improved with the added delmopinol treatment, and is likely to provide similarly beneficial results in the effective disinfection of diverse biofilms in many settings.

  14. Effects of low-level laser therapy combined with toluidine blue on polysaccharides and biofilm of Streptococcus mutans.

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    de Sousa Farias, S S; Nemezio, M A; Corona, S A M; Aires, C P; Borsatto, M C

    2016-07-01

    The aim of this study was to evaluate the effect of a low-level laser therapy in combination with toluidine blue on polysaccharides and biofilm of Streptococcus mutans. S. mutans biofilms were formed on acrylic resin blocks. These biofilms were exposed eight times/day to 10 % sucrose, and two times/day, they were subjected to one of the following treatments: G1, 0.9 % NaCl as a negative control; G2, 0.12 % chlorhexidine digluconate (CHX) as a positive antibacterial control; and G3 and G4 antimicrobial photodynamic therapy (aPDT) combined with toluidine blue using dosages of 320 and 640 J/cm(2), respectively. The experiment was performed in triplicate. The biofilm formed on each block was collected for determination of the viable bacteria and concentration of insoluble extracellular polysaccharides (IEPS) and intracellular polysaccharides (IPS). CHX and aPDT treatments were able to inhibit bacterial growth in comparison with negative control (p  0.05). The results suggest that low-level laser therapy presents effects on biofilm bacteria viability and in polysaccharides concentration.

  15. Phenylethanol promotes adhesion and biofilm formation of the antagonistic yeast Kloeckera apiculata for the control of blue mold on citrus.

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    Pu, Liu; Jingfan, Fang; Kai, Chen; Chao-an, Long; Yunjiang, Cheng

    2014-06-01

    The yeast Kloeckera apiculata strain 34-9 is an antagonist with biological control activity against postharvest diseases of citrus fruit. In a previous study it was demonstrated that K. apiculata produced the aromatic alcohol phenylethanol. In the present study, we found that K. apiculata was able to form biofilm on citrus fruit and embed in an extracellular matrix, which created a mechanical barrier interposed between the wound surface and pathogen. As a quorum-sensing molecule, phenylethanol can promote the formation of filaments by K. apiculata in potato dextrose agar medium, whereas on the citrus fruit, the antagonist remains as yeast after being treated with the same concentration of phenylethanol. It only induced K. apiculata to adhere and form biofilm. Following genome-wide computational and experimental identification of the possible genes associated with K. apiculata adhesion, we identified nine genes possibly involved in triggering yeast adhesion. Six of these genes were significantly induced after phenylethanol stress treatment. This study provides a new model system of the biology of the antagonist-pathogen interactions that occur in the antagonistic yeast K. apiculata for the control of blue mold on citrus caused by Penicillium italicum.

  16. In vitro effectiveness of 455-nm blue LED to reduce the load of Staphylococcus aureus and Candida albicans biofilms in compact bone tissue.

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    Rosa, Luciano Pereira; da Silva, Francine Cristina; Viana, Magda Souza; Meira, Giselle Andrade

    2016-01-01

    The aim of this study was to evaluate the effectiveness of a 455-nm blue light-emitting diode (LED), at different application times, to reduce the load of Staphylococcus aureus and Candida albicans biofilms applied to compact bone tissue. The microorganisms S. aureus (ATCC 25923) and C. albicans (ATCC 18804) were used to form biofilms on 160 specimens of compact bones that had been divided into eight experimental groups (n = 10) for each microorganism, according to the times of application of the 455-nm blue LED (1, 2, 3, 4, 5, 7, and 10 min) with an irradiance of 75 mW/cm2. After LED application, decimal dilutions of microorganisms were performed, plated on BHI or Sabouraud agar and incubated for 24 h/35 °C to obtain CFU/mL counts. The findings were statistically analyzed using a ANOVA 5 %. For the group of S. aureus biofilms, all groups of 455-nm LED application differ compared with the control group (p albicans biofilms, only those samples receiving 3, 7, and 10 min of LED application presented a significant difference compared with the control group (p albicans biofilms, especially during 10 min of application.

  17. Data in support of Gallium (Ga3+) antibacterial activities to counteract E. coli and S. epidermidis biofilm formation onto pro-osteointegrative titanium surfaces

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    Cochis, A.; Azzimonti, B.; Sorrentino, R.; Della Valle, C.; De Giglio, E.; Bloise, N.; Visai, L.; Bruni, G.; Cometa, S.; Pezzoli, D.; Candiani, G.; Rimondini, L.; Chiesa, R.

    2016-01-01

    This paper contains original data supporting the antibacterial activities of Gallium (Ga3+)-doped pro-osteointegrative titanium alloys, obtained via Anodic Spark Deposition (ASD), as described in “The effect of silver or gallium doped titanium against the multidrug resistant Acinetobacter baumannii” (Cochis et al. 2016) [1]. In this article we included an indirect cytocompatibility evaluation towards Saos2 human osteoblasts and extended the microbial evaluation of the Ga3+ enriched titanium surfaces against the biofilm former Escherichia coli and Staphylococcus epidermidis strains. Cell viability was assayed by the Alamar Blue test, while bacterial viability was evaluated by the metabolic colorimetric 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Finally biofilm morphology was analyzed by Scanning Electron Microscopy (SEM). Data regarding Ga3+ activity were compared to Silver. PMID:26909385

  18. A blue fluorescent labeling technique utilizing micro- and nanoparticles for tracking in LIVE/DEAD® stained pathogenic biofilms of Staphylococcus aureus and Burkholderia cepacia

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    Klinger-Strobel M

    2016-02-01

    Full Text Available Mareike Klinger-Strobel,1,2,* Julia Ernst,3,* Christian Lautenschläger,4 Mathias W Pletz,1,2 Dagmar Fischer,3,5 Oliwia Makarewicz1,2 1Center for Infectious Diseases and Infection’s Control, 2Center for Sepsis Control and Care, Jena University Hospital, 3Department of Pharmaceutical Technology, Friedrich Schiller University Jena, 4Department of Internal Medicine IV, Jena University Hospital, 5Jena Center for Soft Matter (JCSM, Friedrich Schiller University Jena, Jena, Germany*These authors contributed equally to this work Abstract: Strategies that target and treat biofilms are widely applied to bacterial cultures using popular live/dead staining techniques with mostly red or green fluorescent markers (eg, with SYTO® 9, propidium iodide, fluorescein. Therefore, visualizing drugs or micro- and nanoparticulate delivery systems to analyze their distribution and effects in biofilms requires a third fluorescent dye that does not interfere with the properties of the live/dead markers. The present study establishes and evaluates a model for tracking polymeric particles in fluorescently stained biological material. To this end, poly(D,L-lactide-co-glycolide (PLGA-based micro- and nanoparticles were used as well-established model systems, which, because of their favorable safety profiles, are expected to play important future roles with regard to drug delivery via inhalation. PLGA was covalently and stably labeled with 7-amino-4-methyl-3-coumarinylacetic acid (AMCA, after which blue fluorescent poly(ethylene glycol-block-PLGA (PEG-PLGA particles were prepared using a mixture of fluorescent AMCA-PLGA and PEG-PLGA. Because chitosan is known to reduce negative surface charge, blue fluorescent PEG-PLGA-particles with chitosan were also prepared. These micro- and nanoparticles were physicochemically characterized and could be clearly distinguished from live/dead stained bacteria in biofilms using confocal laser scanning microscopy. Keywords: 7-amino-4

  19. Riesgo de contaminación del acuífero arroyo Alamar en Tijuana, Baja California

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    Marnie González Estévez; Vicente Sánchez Munguía

    2013-01-01

    El acuífero del arroyo Alamar, en Tijuana, Baja California, es uno de los escasos suministros de agua con que cuenta esta ciudad. En el área que recorre el Alamar se realizan actividades que, aunadas a la falta de medidas de control y vigilancia, inciden en la contaminación del lugar. De acuerdo con las fuentes contaminantes examinadas en el presente estudio, aquí se presentan resultados de un ejercicio de evaluación del riesgo de contaminación al que está expuesto el acuífero, mediante la in...

  20. The prediction of human skin responses by using the combined in vitro fluorescein leakage/Alamar Blue (resazurin) assay.

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    Clothier, Richard; Starzec, Gemma; Pradel, Lionel; Baxter, Victoria; Jones, Melanie; Cox, Helen; Noble, Linda

    2002-01-01

    A range of cosmetics formulations with human patch-test data were supplied in a coded form, for the examination of the use of a combined in vitro permeability barrier assay and cell viability assay to generate, and then test, a prediction model for assessing potential human skin patch-test results. The target cells employed were of the Madin Darby canine kidney cell line, which establish tight junctions and adherens junctions able to restrict the permeability of sodium fluorescein across the barrier of the confluent cell layer. The prediction model for interpretation of the in vitro assay results included initial effects and the recovery profile over 72 hours. A set of the hand-wash, surfactant-based formulations were tested to generate the prediction model, and then six others were evaluated. The model system was then also evaluated with powder laundry detergents and hand moisturisers: their effects were predicted by the in vitro test system. The model was under-predictive for two of the ten hand-wash products. It was over-predictive for the moisturisers, (two out of six) and eight out of ten laundry powders. However, the in vivo human patch test data were variable, and 19 of the 26 predictions were correct or within 0.5 on the 0-4.0 scale used for the in vivo scores, i.e. within the same variable range reported for the repeat-test hand-wash in vivo data.

  1. Riesgo de contaminación del acuífero arroyo Alamar en Tijuana, Baja California

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    Marnie González Estévez

    2013-01-01

    Full Text Available El acuífero del arroyo Alamar, en Tijuana, Baja California, es uno de los escasos suministros de agua con que cuenta esta ciudad. En el área que recorre el Alamar se realizan actividades que, aunadas a la falta de medidas de control y vigilancia, inciden en la contaminación del lugar. De acuerdo con las fuentes contaminantes examinadas en el presente estudio, aquí se presentan resultados de un ejercicio de evaluación del riesgo de contaminación al que está expuesto el acuífero, mediante la interacción entre la vulnerabilidad intrínseca y la carga contaminante a la que está siendo sometido; dicha carga se encontró en aproximadamente la mitad de su área.

  2. Biofilm Risks

    DEFF Research Database (Denmark)

    Wirtanen, Gun Linnea; Salo, Satu

    2016-01-01

    This chapter on biofilm risks deals with biofilm formation of pathogenic microbes, sampling and detection methods, biofilm removal, and prevention of biofilm formation. Several common pathogens produce sticky and/or slimy structures in which the cells are embedded, that is, biofilms, on various s...

  3. Combating biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong;

    2012-01-01

    Biofilms are complex microbial communities consisting of microcolonies embedded in a matrix of self-produced polymer substances. Biofilm cells show much greater resistance to environmental challenges including antimicrobial agents than their free-living counterparts. The biofilm mode of life...... is believed to significantly contribute to successful microbial survival in hostile environments. Conventional treatment, disinfection and cleaning strategies do not proficiently deal with biofilm-related problems, such as persistent infections and contamination of food production facilities. In this review......, strategies to control biofilms are discussed, including those of inhibition of microbial attachment, interference of biofilm structure development and differentiation, killing of biofilm cells and induction of biofilm dispersion....

  4. Permeabilizing biofilms

    Science.gov (United States)

    Soukos, Nikolaos S.; Lee, Shun; Doukas,; Apostolos G.

    2008-02-19

    Methods for permeabilizing biofilms using stress waves are described. The methods involve applying one or more stress waves to a biofilm, e.g., on a surface of a device or food item, or on a tissue surface in a patient, and then inducing stress waves to create transient increases in the permeability of the biofilm. The increased permeability facilitates delivery of compounds, such as antimicrobial or therapeutic agents into and through the biofilm.

  5. Beneficial biofilms

    Directory of Open Access Journals (Sweden)

    Sara R Robertson

    2015-10-01

    Full Text Available Surface-adherent biofilm growth is a common trait of bacteria and other microorganisms in nature. Within biofilms, organisms are present in high density and are enmeshed in an organic matrix containing polysaccharides and other molecules. The close proximity of organisms within biofilms facilitates microbial interactions and signaling, including many metabolic processes in which consortia rather than individual organisms participate. Biofilm growth also enables microorganisms to withstand chemical and biological stresses. Here, we review some current literature and document representative beneficial aspects of biofilms using examples from wastewater treatment, microbial fuel cells, biological repair (biocementation of stonework, and biofilm protection against Candida albicans infections. Finally, we address a chemical ecology strategy whereby desired microbial succession and beneficial biofilm formation can be encouraged via manipulation of culture conditions and bacterial signaling.

  6. Reconstructing the growth of a fracture set using fluid inclusion microthermometry, El Alamar Formation (Triassic), NE Mexico

    Science.gov (United States)

    Hooker, J. N.; Eichhubl, P.; Laubach, S.

    2012-12-01

    Aperture-frequency data collected by scanline surveys of natural fractures in tight-gas sandstones and their outcrop analogs commonly follow a power-law aperture size scaling distribution that spans the aperture range from the microscale (apertures power-law equation represents the fracture intensity whereas the exponent reflects the relative abundance of large to small fractures. Comparing data sets collected in rock units from different tectonic regimes and burial settings, and from different structural positions within mesoscopic structures in the same rock unit, we find that the coefficient increases with increasing fracture strain but the exponent stays relatively constant. This suggests that microscopic fractures (microfractures) grow along with macroscopically visible fractures (macrofractures) throughout the evolution of the fracture set. To test this interpretation, we modeled the development of a power-law set of fractures consistent with the observation of incremental fracture opening through the crack-seal mechanism of repeated cycles of fracture opening and cementation. The simulation is an Excel routine that randomly distributes fracture opening increments among a set of active fractures. We compared the modeled sequence of cement increments and the resulting aperture size distribution against fracture scaling and cement timing data collected from the Triassic El Alamar Formation in NE Mexico. Cement timing was inferred through crosscutting relationships and comparison with fluid inclusion microthermometric data from other fracture sets that indicate that the fracture set used for this field validation formed during uplift and ambient cooling. Thus, opening temperature for this fracture set, serves as a proxy for fracture timing. The field scaling and fluid inclusion data are broadly consistent with the numerical simulation. New microfractures appear to have formed throughout the period of active fracture growth. Some microfractures grew to large

  7. Biofilm Infections

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Jensen, Peter Østrup; Moser, Claus Ernst

    A still increasing interest and emphasis on the sessile bacterial lifestyle biofilms has been seen since it was realized that the vast majority of the total microbial biomass exists as biofilms. Aggregation of bacteria was first described by Leeuwenhoek in 1677, but only recently recognized...... as being important in chronic infection. In 1993 the American Society for Microbiology (ASM) recognized that the biofilm mode of growth was relevant to microbiology. This book covers both the evidence for biofilms in many chronic bacterial infections as well as the problems facing these infections...... such as diagnostics, pathogenesis, treatment regimes and in vitro and in vivo models for studying biofilms. This is the first scientific book on biofilm infections, chapters written by the world leading scientist and clinicians. The intended audience of this book is scientists, teachers at university level as well...

  8. Validation of the AlamarBlue® assay as a fast screening method to determine the antimicrobial activity of botanical extracts

    NARCIS (Netherlands)

    Tyc, O.; Tomás-Menor, L.; Garbeva, P.V.; Barrajón-Catalán, E.; Micol, V.

    2016-01-01

    Plant compounds are a potential source of new antimicrobial molecules against a variety of infections. Plant extracts suppose complex phytochemical libraries that may be used for the first stages of the screening process for antimicrobials. However, their large variability and complexity require fas

  9. Salmonella biofilms

    NARCIS (Netherlands)

    Castelijn, G.A.A.

    2013-01-01

    Biofilm formation by Salmonellaspp. is a problem in the food industry, since biofilms may act as a persistent source of product contamination. Therefore the aim of this study was to obtain more insight in the processes involved and the factors contributing to Salmonellabiofilm formation. A collectio

  10. Biofilm development

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2015-01-01

    During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction or terminat......During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction...... or termination of biofilm matrix production via the second messenger molecule c-di-GMP. In between initiation and termination of biofilm formation we have defined specific biofilm stages, but the currently available evidence suggests that these transitions are mainly governed by adaptive responses......, and not by specific genetic programs. It appears that biofilm formation can occur through multiple pathways and that the spatial structure of the biofilms is species dependent as well as dependent on environmental conditions. Bacterial subpopulations, e.g., motile and nonmotile subpopulations, can develop...

  11. Red and Green Fluorescence from Oral Biofilms

    Science.gov (United States)

    Hoogenkamp, Michel A.; Krom, Bastiaan P.; Janus, Marleen M.; ten Cate, Jacob M.; de Soet, Johannes J.; Crielaard, Wim; van der Veen, Monique H.

    2016-01-01

    Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent green and red fluorescence, with higher red and green fluorescence intensities from biofilms grown in the presence of serum (gingivitis simulation) as compared to the sucrose grown biofilms (cariogenic simulation). Remarkably, cocci with long chain lengths, presumably streptococci, were observed in the biofilms. Green and red fluorescence were not found homogeneously distributed within the biofilms: highly fluorescent spots (both green and red) were visible throughout the biomass. An increase in red fluorescence from the in vitro biofilms appeared to be related to the clinical inflammatory response of the respective saliva donors, which was previously assessed during an in vivo period of performing no-oral hygiene. The BioFlux model proved to be a reliable model to assess biofilm fluorescence. With this model, a prediction can be made whether a patient will be prone to the development of gingivitis or caries. PMID:27997567

  12. Viability Reagent, PrestoBlue, in Comparison with Other Available Reagents, Utilized in Cytotoxicity and Antimicrobial Assays

    Directory of Open Access Journals (Sweden)

    Namrita Lall

    2013-01-01

    Full Text Available This study compared different commercially available viability reagents. The growth indicator reagents include p-iodonitrotetrazolium violet (INT, PrestoBlue, and Alamar Blue which were used for antimicrobial analysis against Streptococcus mutans, Prevotella intermedia, Propionibacterium acnes, and Mycobacterium tuberculosis. PrestoBlue and Alamar Blue are resazurin based reagents that resulted in a quick and easily distinguishable colour change that allowed for visual readings. INT and Sodium 3′-[1-(phenyl amino-carbonyl-3,4-tetrazolium]-bis-[4-methoxy-6-nitro] benzene sulfonic acid hydrate (XTT are tetrazolium based reagents which are converted to a formazan dye in the presence of metabolically active mitochondria enzyme. For cell viability analysis, reagents XTT and PrestoBlue were compared. PrestoBlue was able to clearly indicate the minimum inhibitory concentration (MIC of various positive drug controls on various microbial strains. PrestoBlue was also a good indicator of the 50% inhibitory concentration (IC50 of positive drug controls on various cell lines.

  13. Wound biofilms: lessons learned from oral biofilms.

    Science.gov (United States)

    Mancl, Kimberly A; Kirsner, Robert S; Ajdic, Dragana

    2013-01-01

    Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque, are a primary cause of oral diseases including caries, gingivitis, and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible; thus, biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well elucidated. In contrast, wound research has relatively recently directed attention to the role biofilms have in chronic wounds. This review discusses the biofilms in periodontal disease and chronic wounds with comparisons focusing on biofilm detection, biofilm formation, the immune response to biofilms, bacterial interaction, and quorum sensing. Current treatment modalities used by both fields and future therapies are also discussed.

  14. Kind of Blue - Europa Blues

    DEFF Research Database (Denmark)

    Mortensen, Tore; Kirkegaard, Peter

    2009-01-01

    Bidraget reflekterer over sammenhænge mellem to værker fra det musikalske og litterære område. Det drejer sig om Miles Davis' Kind of Blue fra 1959 og Arne Dahls krimi, Europa Blues fra 2001. Den grundlæggende indfaldsvinkel er det performative, den frie, men samtidigt disciplinerede musikalske...

  15. Blue Laser.

    Science.gov (United States)

    1985-12-01

    HOLLOW CATHODE LASER FABRICATION 13 4. EXPERIENCE WITH THE BLUE LASER 18 4.1 Operational and Processing Experience 18 4.2 Performance Testing 20 5...34 -. - . •. SECTION 3 BLUE HOLLOW CATHODE LASER FABRICATION This section presents an overview of the steps taken in creating a HCL. There is...to the laser assembly. These steps can actually be considered as the final steps in laser fabrication because some of them involve adding various

  16. The in vivo biofilm

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Alhede, Maria; Alhede, Morten

    2013-01-01

    Bacteria can grow and proliferate either as single, independent cells or organized in aggregates commonly referred to as biofilms. When bacteria succeed in forming a biofilm within the human host, the infection often becomes very resistant to treatment and can develop into a chronic state. Biofilms...... have been studied for decades using various in vitro models, but it remains debatable whether such in vitro biofilms actually resemble in vivo biofilms in chronic infections. In vivo biofilms share several structural characteristics that differ from most in vitro biofilms. Additionally, the in vivo...... experimental time span and presence of host defenses differ from chronic infections and the chemical microenvironment of both in vivo and in vitro biofilms is seldom taken into account. In this review, we discuss why the current in vitro models of biofilms might be limited for describing infectious biofilms...

  17. Biofilm Fixed Film Systems

    Directory of Open Access Journals (Sweden)

    Dipesh Das

    2011-09-01

    Full Text Available The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment.

  18. Pseudomonas aeruginosa Biofilm Infections

    DEFF Research Database (Denmark)

    Rybtke, Morten; Hultqvist, Louise Dahl; Givskov, Michael

    2015-01-01

    Studies of biopsies from infectious sites, explanted tissue and medical devises have provided evidence that biofilms are the underlying cause of a variety of tissue-associated and implant-associated recalcitrant human infections. With a need for novel anti-biofilm treatment strategies, research...... in biofilm infection microbiology, biofilm formation mechanisms and biofilm-associated antimicrobial tolerance has become an important area in microbiology. Substantial knowledge about biofilm formation mechanisms, biofilm-associated antimicrobial tolerance and immune evasion mechanisms has been obtained...... through work with biofilms grown in in vitro experimental setups, and the relevance of this information in the context of chronic infections is being investigated by the use of animal models of infection. Because our current in vitro experimental setups and animal models have limitations, new advanced...

  19. Biofilms: A microbial home

    Science.gov (United States)

    Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

    2011-01-01

    Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms. PMID:21976832

  20. Biofilms: A microbial home

    OpenAIRE

    Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

    2011-01-01

    Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms.

  1. The Biofilm Challenge

    DEFF Research Database (Denmark)

    Alhede, Maria; Alhede, Morten

    2014-01-01

    The concept of biofilms has emerged in the clinical setting during the last decade. Infections involving biofilms have been documented in all parts of the human body, and it is currently believed that the presence of biofilm-forming bacteria is equivalent to chronic infection. A quick Pubmed search...

  2. Posthuman blues

    CERN Document Server

    Tonnies, Mac

    2013-01-01

    Posthuman Blues, Vol. I is first volume of the edited version of the popular weblog maintained by author Mac Tonnies from 2003 until his tragic death in 2009. Tonnies' blog was a pastiche of his original fiction, reflections on his day-to-day life, trenchant observations of current events, and thoughts on an eclectic range of material he culled from the Internet. What resulted was a remarkably broad portrait of a thoughtful man and the complex times in which he lived, rendered with intellige...

  3. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    Bacteria in natural, industrial and clinical settings predominantly live in biofilms, i.e., sessile structured microbial communities encased in self-produced extracellular matrix material. One of the most important characteristics of microbial biofilms is that the resident bacteria display...... a remarkable increased tolerance toward antimicrobial attack. Biofilms formed by opportunistic pathogenic bacteria are involved in devastating persistent medical device-associated infections, and chronic infections in individuals who are immune-compromised or otherwise impaired in the host defense. Because...... the use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  4. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...... at the microscale of complex communities, including biofilms.Studies of multispecies biofilms and the interactions shaping these are conducted in traditional approaches used for single-species biofilms with some adjustments; but a crucial point for consideration is which strains to combine and where these should...

  5. Color vision: retinal blues.

    Science.gov (United States)

    Johnston, Jamie; Esposti, Federico; Lagnado, Leon

    2012-08-21

    Two complementary studies have resolved the circuitry underlying green-blue color discrimination in the retina. A blue-sensitive interneuron provides the inhibitory signal required for computing green-blue color opponency.

  6. Hydraulic resistance of biofilms

    KAUST Repository

    Dreszer, C.

    2013-02-01

    Biofilms may interfere with membrane performance in at least three ways: (i) increase of the transmembrane pressure drop, (ii) increase of feed channel (feed-concentrate) pressure drop, and (iii) increase of transmembrane passage. Given the relevance of biofouling, it is surprising how few data exist about the hydraulic resistance of biofilms that may affect the transmembrane pressure drop and membrane passage. In this study, biofilms were generated in a lab scale cross flow microfiltration system at two fluxes (20 and 100Lm-2h-1) and constant cross flow (0.1ms-1). As a nutrient source, acetate was added (1.0mgL-1 acetate C) besides a control without nutrient supply. A microfiltration (MF) membrane was chosen because the MF membrane resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric substances (EPS) were determined, it was demonstrated that no internal membrane fouling occurred and that the fouling layer actually consisted of a grown biofilm and was not a filter cake of accumulated bacterial cells. At 20Lm-2h-1 flux with a nutrient dosage of 1mgL-1 acetate C, the resistance after 4 days reached a value of 6×1012m-1. At 100Lm-2h-1 flux under the same conditions, the resistance was 5×1013m-1. No correlation of biofilm resistance to biofilm thickness was found; Biofilms with similar thickness could have different resistance depending on the applied flux. The cell number in biofilms was between 4×107 and 5×108 cellscm-2. At this number, bacterial cells make up less than a half percent of the overall biofilm volume and therefore did not hamper the water flow through the biofilm significantly. A flux of 100Lm-2h-1 with nutrient supply caused higher cell numbers, more biomass, and higher biofilm resistance than a flux of 20Lm-2h-1. However, the biofilm thickness

  7. Meningococcal biofilm formation

    DEFF Research Database (Denmark)

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation......X alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  8. Surface modification of materials to encourage beneficial biofilm formation

    Directory of Open Access Journals (Sweden)

    Amreeta Sarjit

    2015-10-01

    Full Text Available Biofilms are communities of sessile microorganisms that grow and produce extrapolymeric substances on an abiotic or biotic surface. Although biofilms are often associated with negative impacts, the role of beneficial biofilms is wide and include applications in bioremediation, wastewater treatment and microbial fuel cells. Microbial adhesion to a surface, which is highly dependent on the physicochemical properties of the cells and surfaces, is an essential step in biofilm formation. Surface modification therefore represents an important way to modulate microbial attachment and ultimately biofilm formation by microorganisms. In this review different surface modification processes such as organosilane surface modification, plasma treatment, and chemical modification of carbon nanotubes, electro-oxidation and covalent-immobilization with neutral red and methylene blue molecules are outlined. The effectiveness of these modifications and their industrial applications are also discussed. There is inadequate literature on surface modification as a process to enhance beneficial biofilm formation. These methods need to be safe, economically viable, scalable and environmental friendly and their potential to fulfil these criteria for many applications has yet to be determined.

  9. Biofilm Cohesive Strength as a Basis for Biofilm Recalcitrance: Are Bacterial Biofilms Overdesigned?

    Science.gov (United States)

    Aggarwal, Srijan; Stewart, Philip S; Hozalski, Raymond M

    2015-01-01

    Bacterial biofilms are highly resistant to common antibacterial treatments, and several physiological explanations have been offered to explain the recalcitrant nature of bacterial biofilms. Herein, a biophysical aspect of biofilm recalcitrance is being reported on. While engineering structures are often overdesigned with a factor of safety (FOS) usually under 10, experimental measurements of biofilm cohesive strength suggest that the FOS is on the order of thousands. In other words, bacterial biofilms appear to be designed to withstand extreme forces rather than typical or average loads. In scenarios requiring the removal or control of unwanted biofilms, this emphasizes the importance of considering strategies for structurally weakening the biofilms in conjunction with bacterial inactivation.

  10. Relevance of Biofilms in the Pathogenesis of Shiga-Toxin-Producing Escherichia coli Infection

    OpenAIRE

    2013-01-01

    The present study was designed to determine the relationships among biofilm formation, cellular stress and release of Shiga toxin (Stx) by three different clinical Shiga toxin-producing Escherichia coli (STEC) strains. The biofilm formation was determined using crystal violet stain in tryptic soy broth or thioglycollate medium with the addition of sugars (glucose or mannose) or hydrogen peroxide. The reactive oxygen species (ROSs) were detected by the reduction of nitro blue tetrazolium an...

  11. Biofilm in wound care.

    Science.gov (United States)

    Rajpaul, Kumal

    2015-03-01

    A biofilm can be described as a microbial colony encased in a polysaccharide matrix which can become attached to a wound surface. This can affect the healing potential of chronic wounds due to the production of destructive enzymes and toxins which can promote a chronic inflammatory state within the wound. Biofilms can be polymicrobial and can result in delayed wound healing and chronic wound infection resistant to antibiotics, leading to prolonged hospitalisation for some patients. There appears to be a correlation between biofilms and non-healing in chronic wounds. It is suggested that biofilms are a major player in the chronicity of wounds. They are a complex concept to diagnose and management needs to be multifactorial.

  12. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.

    2015-06-18

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies. The objective of this study was to determine the occurrence, extent and timescale of biofilm compaction and relaxation (decompaction), caused by permeate flux variations. The impact of permeate flux changes on biofilm thickness, structure and stiffness was investigated in situ and non-destructively with optical coherence tomography using membrane fouling monitors operated at a constant crossflow velocity of 0.1 m s−1 with permeate production. The permeate flux was varied sequentially from 20 to 60 and back to 20 L m−2 h−1. The study showed that the average biofilm thickness on the membrane decreased after elevating the permeate flux from 20 to 60 L m−2 h−1 while the biofilm thickness increased again after restoring the original flux of 20 L m−2 h−1, indicating the occurrence of biofilm compaction and relaxation. Within a few seconds after the flux change, the biofilm thickness was changed and stabilized, biofilm compaction occurred faster than the relaxation after restoring the original permeate flux. The initial biofilm parameters were not fully reinstated: the biofilm thickness was reduced by 21%, biofilm stiffness had increased and the hydraulic biofilm resistance was elevated by 16%. Biofilm thickness was related to the hydraulic biofilm resistance. Membrane performance losses are related to the biofilm thickness, density and morphology, which are influenced by (variations in) hydraulic conditions. A (temporarily) permeate flux increase caused biofilm compaction, together with membrane performance losses. The impact of biofilms on membrane performance can be influenced (increased and reduced) by operational parameters. The article shows that a (temporary) pressure increase leads to more

  13. Interactions in multispecies biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Ren, Dawei; Bjarnsholt, Thomas;

    2014-01-01

    The recent focus on complex bacterial communities has led to the recognition of interactions across species boundaries. This is particularly pronounced in multispecies biofilms, where synergistic interactions impact the bacterial distribution and overall biomass produced. Importantly, in a number...... of settings, the interactions in a multispecies biofilm affect its overall function, physiology, or surroundings, by resulting in enhanced resistance, virulence, or degradation of pollutants, which is of significant importance to human health and activities. The underlying mechanisms causing these synergistic...

  14. Biofilms in chronic wounds.

    Science.gov (United States)

    James, Garth A; Swogger, Ellen; Wolcott, Randall; Pulcini, Elinor deLancey; Secor, Patrick; Sestrich, Jennifer; Costerton, John W; Stewart, Philip S

    2008-01-01

    Chronic wounds including diabetic foot ulcers, pressure ulcers, and venous leg ulcers are a worldwide health problem. It has been speculated that bacteria colonizing chronic wounds exist as highly persistent biofilm communities. This research examined chronic and acute wounds for biofilms and characterized microorganisms inhabiting these wounds. Chronic wound specimens were obtained from 77 subjects and acute wound specimens were obtained from 16 subjects. Culture data were collected using standard clinical techniques. Light and scanning electron microscopy techniques were used to analyze 50 of the chronic wound specimens and the 16 acute wound specimens. Molecular analyses were performed on the remaining 27 chronic wound specimens using denaturing gradient gel electrophoresis and sequence analysis. Of the 50 chronic wound specimens evaluated by microscopy, 30 were characterized as containing biofilm (60%), whereas only one of the 16 acute wound specimens was characterized as containing biofilm (6%). This was a statistically significant difference (p<0.001). Molecular analyses of chronic wound specimens revealed diverse polymicrobial communities and the presence of bacteria, including strictly anaerobic bacteria, not revealed by culture. Bacterial biofilm prevalence in specimens from chronic wounds relative to acute wounds observed in this study provides evidence that biofilms may be abundant in chronic wounds.

  15. Bacteriophages and Biofilms

    Directory of Open Access Journals (Sweden)

    David R. Harper

    2014-06-01

    Full Text Available Biofilms are an extremely common adaptation, allowing bacteria to colonize hostile environments. They present unique problems for antibiotics and biocides, both due to the nature of the extracellular matrix and to the presence within the biofilm of metabolically inactive persister cells. Such chemicals can be highly effective against planktonic bacterial cells, while being essentially ineffective against biofilms. By contrast, bacteriophages seem to have a greater ability to target this common form of bacterial growth. The high numbers of bacteria present within biofilms actually facilitate the action of bacteriophages by allowing rapid and efficient infection of the host and consequent amplification of the bacteriophage. Bacteriophages also have a number of properties that make biofilms susceptible to their action. They are known to produce (or to be able to induce enzymes that degrade the extracellular matrix. They are also able to infect persister cells, remaining dormant within them, but re-activating when they become metabolically active. Some cultured biofilms also seem better able to support the replication of bacteriophages than comparable planktonic systems. It is perhaps unsurprising that bacteriophages, as the natural predators of bacteria, have the ability to target this common form of bacterial life.

  16. Blue cures blue but be cautious

    Directory of Open Access Journals (Sweden)

    Pranav Sikka

    2011-01-01

    Full Text Available Methemoglobinemia is a disorder characterized by the presence of >1% methemoglobin (metHb in the blood. Spontaneous formation of methemoglobin is normally counteracted by protective enzyme systems, for example, nicotinamide adenine dinucleotide phosphate (NADPH methemoglobin reductase. Methemoglobinemia is treated with supplemental oxygen and methylene blue (1-2 mg/kg administered slow intravenously, which acts by providing an artificial electron acceptor for NADPH methemoglobin reductase. But known or suspected glucose-6-phosphate dehydrogenase (G6PD deficiency is a relative contraindication to the use of methylene blue because G6PD is the key enzyme in the formation of NADPH through pentose phosphate pathway and G6PD-deficient individuals generate insufficient NADPH to efficiently reduce methylene blue to leukomethylene blue, which is necessary for the activation of the NADPH-dependent methemoglobin reductase system. So, we should be careful using methylene blue in methemoglobinemia patient before G6PD levels.

  17. Biofilms and the food industry

    Directory of Open Access Journals (Sweden)

    Nathanon Trachoo

    2003-11-01

    Full Text Available In the past, interest in biofilms was limited to research related to water distribution systems, waste water treatment and dental plaques. Biofilm has become a more popular research topic in many other areas in recent years including food safety. Biofilm formation can compromise the sanitation of food surfaces and environmental surfaces by spreading detached organisms to other areas of processing plants. Unfortunately, these detached organisms are not similar to normal microorganisms suspended in an aquatic environment but are more resistant to several stresses or microbial inactivation including some food preservation methods. Microstructures of biofilms as revealed by different types of microscopic techniques showed that biofilms are highly complex and consist of many symbiotic organisms, some of which are human pathogens. This article reviewed the process of biofilm formation, the significance of biofilms on food or food contact surfaces, their ability to protect foodborne pathogens from environmental stresses and recent methods for the study of biofilms on food contact surfaces.

  18. Blue light-mediated inactivation of Enterococcus faecalis in vitro.

    Science.gov (United States)

    Pileggi, Giorgio; Wataha, John C; Girard, Myriam; Grad, Iwona; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2013-05-01

    In dentistry, residual infection remains a major cause of failure after endodontic treatment; many of these infections involve Enterococcus faecalis. In the current study, we explored the possibility that blue light activated photosensitizers could be used, in principle, to inactivate this microbe as an adjunct disinfection strategy for endodontic therapy. Three blue light absorbing photosensitizers, eosin-Y, rose bengal, and curcumin, were tested on E. faecalis grown in planktonic suspensions or biofilms. Photosensitizers were incubated for 30 min with bacteria then exposed to blue light (450-500 nm) for 240 s. Sodium hypochlorite (3%) was used as a control. After 48 h, the viability of E. faecalis was estimated by measuring colony-forming units post-exposure vs. untreated controls (CFU/mL). Blue light irradiation alone did not alter E. faecalis viability. For planktonic cultures, blue light activated eosin-Y (5 μM), rose bengal (1 μM), or curcumin (5 μM) significantly (pfaecalis viability compared to exposure to the unirradiated photochemicals. For biofilm cultures, concentrations of light-activated eosin-Y, rose bengal, and curcumin of 100, 10, and 10 μM respectively, completely suppressed E. faecalis viability (pendodontic treatment.

  19. Portable hyperspectral fluorescence imaging system for detection of biofilms on stainless steel surfaces

    Science.gov (United States)

    Jun, Won; Lee, Kangjin; Millner, Patricia; Sharma, Manan; Chao, Kuanglin; Kim, Moon S.

    2008-04-01

    A rapid nondestructive technology is needed to detect bacterial contamination on the surfaces of food processing equipment to reduce public health risks. A portable hyperspectral fluorescence imaging system was used to evaluate potential detection of microbial biofilm on stainless steel typically used in the manufacture of food processing equipment. Stainless steel coupons were immersed in bacterium cultures, such as E. coli, Pseudomonas pertucinogena, Erwinia chrysanthemi, and Listeria innocula. Following a 1-week exposure, biofilm formations were assessed using fluorescence imaging. In addition, the effects on biofilm formation from both tryptic soy broth (TSB) and M9 medium with casamino acids (M9C) were examined. TSB grown cells enhance biofilm production compared with M9C-grown cells. Hyperspectral fluorescence images of the biofilm samples, in response to ultraviolet-A (320 to 400 nm) excitation, were acquired from approximately 416 to 700 nm. Visual evaluation of individual images at emission peak wavelengths in the blue revealed the most contrast between biofilms and stainless steel coupons. Two-band ratios compared with the single-band images increased the contrast between the biofilm forming area and stainless steel coupon surfaces. The 444/588 nm ratio images exhibited the greatest contrast between the biofilm formations and stainless coupon surfaces.

  20. Biofilm formation on abiotic surfaces

    DEFF Research Database (Denmark)

    Tang, Lone

    2011-01-01

    Bacteria can attach to any surface in contact with water and proliferate into complex communities enclosed in an adhesive matrix, these communities are called biofilms. The matrix makes the biofilm difficult to remove by physical means, and bacteria in biofilm can survive treatment with many...... to changing the surface hydrophobicity. The influence of surface topography in the biomolecule of great importance for bacterial adhesion...

  1. Comparison of RNA extraction methods from biofilm samples of Staphylococcus epidermidis

    Directory of Open Access Journals (Sweden)

    França Angela

    2011-12-01

    Full Text Available Abstract Background Microbial biofilms are communities of bacteria adhered to a surface and surrounded by an extracellular polymeric matrix. Biofilms have been associated with increased antibiotic resistance and tolerance to the immune system. Staphylococcus epidermidis is the major bacterial species found in biofilm-related infections on indwelling medical devices. Obtaining high quality mRNA from biofilms is crucial to validate the transcriptional measurements associated with the switching to the biofilm mode of growth. Therefore, we selected three commercially available RNA extraction kits with distinct characteristics, including those using silica membrane or organic extraction methods, and enzymatic or mechanical cell lysis, and evaluated the RNA quality obtained from two distinct S. epidermidis bacterial biofilms. Results RNA extracted using the different kits was evaluated for quantity, purity, integrity, and functionally. All kits were able to extract intact and functional total RNA from the biofilms generated from each S. epidermidis strain. The results demonstrated that the kit based on mechanical lysis and organic extraction (FastRNA® Pro Blue was the only one that was able to isolate pure and large quantities of RNA. Normalized expression of the icaA virulence gene showed that RNA extracted with PureLink™ had a significant lower concentration of icaA mRNA transcripts than the other kits tested. Conclusions When working with complex samples, such as biofilms, that contain a high content extracellular polysaccharide and proteins, special care should be taken when selecting the appropriate RNA extraction system, in order to obtain accurate, reproducible, and biologically significant results. Among the RNA extraction kits tested, FastRNA® Pro Blue was the best option for both S. epidermidis biofilms used.

  2. Preliminary study on total protein extraction methods from Enterococcus faecalis biofilm.

    Science.gov (United States)

    Chen, W; Liang, J; He, Z; Jiang, W

    2016-08-30

    Enterococcus faecalis is the major pathogen of post-endodontic disease and refractory periapical periodontitis, and recent research on this species has focused on its pathogenicity. E. faecalis most often causes disease in the form of a biofilm, and total protein expression shows a strong association with its virulence. Therefore, the purpose of our study was to explore different methods of extracting the total proteins of the E. faecalis (ATCC 33186 standard strain) biofilm. The total proteins in the biofilm were extracted using an ultrasonication method with varied parameters, including duration, amplitude setting, period, and duty cycle. After the optimal conditions of ultrasonication were determined based on the protein profile from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the total protein content in the biofilm was detected using the bicinchoninic acid assay, Bradford Coomassie brilliant blue assay, and Lowry assay, and the results were compared and analyzed. The parameters for the optimal conditions of ultrasonication were as follows: a processing duration of 2 min, amplitude setting of 20%, and ultrasonication period of 4 s at a 50% duty cycle. The total protein content was 2299.1 mg/dish when measured by the bicinchoninic assay, 3793.8 mg/dish when measured by the Bradford Coomassie brilliant blue assay, and 1858.0 mg/dish when measured by the Lowry assay. These results demonstrate that the Bradford Coomassie brilliant blue assay is a simple and feasible method for use in detecting the total protein content in a bacterial biofilm.

  3. Occurrence and purification on microcystis species. Biodegradation of micropollutant producing from blue-green algae using effective microorganism in bio-film; Aoko/sono hassei to joka taisaku. Seibutsumaku no yuyo biseibutsu ni yoru aoko no bunkai to kodo joka

    Energy Technology Data Exchange (ETDEWEB)

    Inamori, Y. [National Inst. for Environmental Studies, Tsukuba (Japan); Akimoto, S. [Tsukuba Univ., (Japan). Graduate School

    1994-09-10

    The bio-film method is to utilize the purification force of a bio-film consisted of the microorganisms such as the bacteria, fungi, protozoa, micrometazoa and so forth, which are formed on the surface of the gravels at a bottom part of the river, for a polluted water purification. This bio-film method was developed for a purpose of to make its activity proceed artificially and efficiently insides the tank. If these protozoa and metazoa occur as a substantial quantity in the bio-film treatment method of the polluted lake water, as they exhibit a large force to decompose and make inorganic the algae, their mass colonization is extremely important. In actual site practice, because the bio-film quantity and the bio-phase fluctuate substantially depending on the inflowing pollution load quantity and the temperature, an investigation of the manipulation method, by which the bio-phase corresponding to an inflow condition can be dominant, is necessary. In addition, in order to effectively decompose and remove the 2-MTB, microcystin RR and so forth, because securing the colonization field for the useful microorganisms is essential, a development of the adhesion carrier in which the useful microorganisms are easy to live, is also needed. 9 refs., 5 figs., 2 tabs.

  4. Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Alhede, Maria; Bjarnsholt, Thomas; Givskov, Michael Christian;

    2014-01-01

    biofilms, which protect the aggregated, biopolymer-embedded bacteria from the detrimental actions of antibiotic treatments and host immunity. A key component in the protection against innate immunity is rhamnolipid, which is a quorum sensing (QS)-regulated virulence factor. QS is a cell-to-cell signaling...... mechanism used to coordinate expression of virulence and protection of aggregated biofilm cells. Rhamnolipids are known for their ability to cause hemolysis and have been shown to cause lysis of several cellular components of the human immune system, for example, macrophages and polymorphonuclear leukocytes...

  5. Manipulation of Biofilm Microbial Ecology

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C.; Palmer, R.J., Jr.; Zinn, M.; Smith, C.A.; Burkhalter, R.; Macnaughton, S.J.; Whitaker, K.W.; Kirkegaard, R.D.

    1998-08-15

    The biofilm mode of growth provides such significant advantages to the members of the consortium that most organisms in important habitats are found in biofilms. The study of factors that allow manipulation of biofilm microbes in the biofilm growth state requires that reproducible biofilms be generated. The most effective monitoring of biofilm formation, succession and desaturation is with on-line monitoring of microbial biofilms with flowcell for direct observation. The biofilm growth state incorporates a second important factor, the heterogeneity in distribution in time and space of the component members of the biofilm consortium. This heterogeneity is reflected not only in the cellular distribution but in the metabolic activity within a population of cells. Activity and cellular distribution can be mapped in four dimensions with confocal microscopy, and function can be ascertained by genetically manipulated reporter functions for specific genes or by vital stains. The methodology for understanding the microbial ecology of biofilms is now much more readily available and the capacity to manipulate biofilms is becoming an important feature of biotechnology.

  6. Critical review on biofilm methods.

    Science.gov (United States)

    Azeredo, Joana; Azevedo, Nuno F; Briandet, Romain; Cerca, Nuno; Coenye, Tom; Costa, Ana Rita; Desvaux, Mickaël; Di Bonaventura, Giovanni; Hébraud, Michel; Jaglic, Zoran; Kačániová, Miroslava; Knøchel, Susanne; Lourenço, Anália; Mergulhão, Filipe; Meyer, Rikke Louise; Nychas, George; Simões, Manuel; Tresse, Odile; Sternberg, Claus

    2017-05-01

    Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms.

  7. Microbial Biofilms and Chronic Wounds

    Science.gov (United States)

    Omar, Amin; Wright, J. Barry; Schultz, Gregory; Burrell, Robert; Nadworny, Patricia

    2017-01-01

    Background is provided on biofilms, including their formation, tolerance mechanisms, structure, and morphology within the context of chronic wounds. The features of biofilms in chronic wounds are discussed in detail, as is the impact of biofilm on wound chronicity. Difficulties associated with the use of standard susceptibility tests (minimum inhibitory concentrations or MICs) to determine appropriate treatment regimens for, or develop new treatments for use in, chronic wounds are discussed, with alternate test methods specific to biofilms being recommended. Animal models appropriate for evaluating biofilm treatments are also described. Current and potential future therapies for treatment of biofilm-containing chronic wounds, including probiotic therapy, virulence attenuation, biofilm phenotype expression attenuation, immune response suppression, and aggressive debridement combined with antimicrobial dressings, are described. PMID:28272369

  8. Biofilm roughness determines Cryptosporidium parvum retention in environmental biofilms.

    Science.gov (United States)

    DiCesare, E A Wolyniak; Hargreaves, B R; Jellison, K L

    2012-06-01

    The genus Cryptosporidium is a group of waterborne protozoan parasites that have been implicated in significant outbreaks of gastrointestinal infections throughout the world. Biofilms trap these pathogens and can contaminate water supplies through subsequent release. Biofilm microbial assemblages were collected seasonally from three streams in eastern Pennsylvania and used to grow biofilms in laboratory microcosms. Daily oocyst counts in the influx and efflux flow allowed the calculation of daily oocyst retention in the biofilm. Following the removal of oocysts from the influx water, oocyst attachment to the biofilm declined to an equilibrium state within 5 days that was sustained for at least 25 days. Varying the oocyst loading rate for the system showed that biofilm retention could be saturated, suggesting that discrete binding sites determined the maximum number of oocysts retained. Oocyst retention varied seasonally but was consistent across all three sites; however, seasonal oocyst retention was not consistent across years at the same site. No correlation between oocyst attachment and any measured water quality parameter was found. However, oocyst retention was strongly correlated with biofilm surface roughness and roughness varied among seasons and across years. We hypothesize that biofilm roughness and oocyst retention are dependent on environmentally driven changes in the biofilm community rather than directly on water quality conditions. It is important to understand oocyst transport dynamics to reduce risks of human infection. Better understanding of factors controlling biofilm retention of oocysts should improve our understanding of oocyst transport at different scales.

  9. Blue and White Pot

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    Many recent archaeological studies have proven that the earliest blue and white porcelain was produced from the kiln in Gongxian County, Henan Province in the Tang Dynasty (618-907). It was an important variety of porcelain available for export then. The early blue and white porcelain in the Yuan Dynasty appeared dark and gray. During the reign of Zhizheng, clear blue and white porcelain was produced, indicating

  10. The Root Canal Biofilm

    NARCIS (Netherlands)

    Sluis, van der L.W.M.; Boutsioukis, C.; Jiang, L.M.; Macedo, R.; Verhaagen, B.; Versluis, M.; Chávez de Paz, E.; Sedgley, C.M.; Kishen, A.

    2015-01-01

    The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm), and their products from the root canal wall, their removal out of the root cana

  11. Cellular blue naevus

    Directory of Open Access Journals (Sweden)

    Mittal R

    2001-01-01

    Full Text Available A 31-year-old man had asymptomatic, stationary, 1.5X2 cm, shiny, smooth, dark blue nodule on dorsum of right hand since 12-14 years. In addition he had developed extensive eruption of yellow to orange papulonodular lesions on extensors of limbs and buttocks since one and half months. Investigations confirmed that yellow papules were xanthomatosis and he had associated diabetes mellitus and hyperlipidaemia. Biopsy of blue nodule confirmed the clinical diagnosis of cellular blue naevus. Cellular blue naevus is rare and its association with xanthomatosis and diabetes mellitus were interesting features of above patients which is being reported for its rarity.

  12. Photodynamic therapy for inactivating endodontic bacterial biofilms and effect of tissue inhibitors on antibacterial efficacy

    Science.gov (United States)

    Shrestha, Annie; Kishen, Anil

    Complex nature of bacterial cell membrane and structure of biofilm has challenged the efficacy of antimicrobial photodynamic therapy (APDT) to achieve effective disinfection of infected root canals. In addition, tissue-inhibitors present inside the root canals are known to affect APDT activity. This study was aimed to assess the effect of APDT on bacterial biofilms and evaluate the effect of tissue-inhibitors on the APDT. Rose-bengal (RB) and methylene-blue (MB) were tested on Enterococcus faecalis (gram-positive) and Pseudomonas aeruginosa (gram-negative) biofilms. In vitro 7- day old biofilms were sensitized with RB and MB, and photodynamically activated with 20-60 J/cm2. Photosensitizers were pre-treated with different tissue-inhibitors (dentin, dentin-matrix, pulp tissue, bacterial lipopolysaccharides (LPS), and bovine serum albumin (BSA)) and tested for antibacterial effect of APDT. Microbiological culture based analysis was used to analyze the cell viability, while Laser Scanning Confocal Microscopy (LSCM) was used to examine the structure of biofilm. Photoactivation resulted in significant reduction of bacterial biofilms with RB and MB. The structure of biofilm under LSCM was found to be disrupted with reduced biofilm thickness. Complete biofilm elimination could not be achieved with both tested photosensitizers. APDT effect using MB and RB was inhibited in a decreasing order by dentin-matrix, BSA, pulp, dentin and LPS (P< 0.05). Both strains of bacterial biofilms resisted complete elimination after APDT and the tissue inhibitors existing within the root canal reduced the antibacterial activity at varying degrees. Further research is required to enhance the antibacterial efficacy of APDT in an endodontic environment.

  13. Feeling blue? Blue phosphors for OLEDs

    Directory of Open Access Journals (Sweden)

    Hungshin Fu

    2011-10-01

    Full Text Available Research on organic light emitting diodes (OLEDs has been revitalized, partly due to the debut of the OLED TV by SONY in 2008. While there is still plenty of room for improvement in efficiency, cost-effectiveness and longevity, it is timely to report on the advances of light emitting materials, the core of OLEDs, and their future perspectives. The focus of this account is primarily to chronicle the blue phosphors developed in our laboratory. Special attention is paid to the design strategy, synthetic novelty, and their OLED performance. The report also underscores the importance of the interplay between chemistry and photophysics en route to true-blue phosphors.

  14. Blue Ocean Thinking

    Science.gov (United States)

    Orem, Donna

    2016-01-01

    This article describes a concept called the "blue ocean thinking strategy," developed by W. Chan Kim and Renée Mauborgne, professors at INSEAD, an international graduate school of business in France. The "blue ocean" thinking strategy considers opportunities to create new markets for services, rather than focusing solely on…

  15. Blue Willow Story Plates

    Science.gov (United States)

    Fontes, Kris

    2009-01-01

    In the December 1997 issue of "SchoolArts" is a lesson titled "Blue Willow Story Plates" by Susan Striker. In this article, the author shares how she used this lesson with her middle-school students many times over the years. Here, she describes a Blue Willow plate painting project that her students made.

  16. Biofilm susceptibility to metal toxicity.

    Science.gov (United States)

    Harrison, Joe J; Ceri, Howard; Stremick, Carol A; Turner, Raymond J

    2004-12-01

    This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.

  17. Critical review on biofilm methods

    DEFF Research Database (Denmark)

    Azeredo, Joana; F. Azevedo, Nuno; Briandet, Romain;

    2017-01-01

    Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research...... into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods...... to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages...

  18. Critical review on biofilm methods

    DEFF Research Database (Denmark)

    Azeredo, Joana; F. Azevedo, Nuno; Briandet, Romain;

    2017-01-01

    into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods...... to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages...... and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms....

  19. Biofilms: a developing microscopic community

    Directory of Open Access Journals (Sweden)

    Rivera Sandra Patricia

    2004-09-01

    Full Text Available Biofilms are microbial communities composed by different microbiota embebbed in a special adaptive environment. These communities show different characteristics such as heterogeneity, diversity in microenvironments, capacity to resist antimicrobial therapy and ability to allow bacterial communication. These characteristics convert them in complex organizations that are difficult to eradicate in their own environment. In the man, biofilms are associated to a great number of slow-development infectious processes which greatly difficulties their eradication. In the industry and environment, biofilms are centered in processes known as biofouling and bioremediation. The former is the contamination of a system due to the microbial activity of a biofilm. The latter uses biofilms to improve the conditions of a contaminated system. The study of biofilms is a new and exciting field which is constantly evolving and whose implications in medicine and industry would have important repercussions for the humankind.

  20. Electrochemical biofilm control: a review.

    Science.gov (United States)

    Sultana, Sujala T; Babauta, Jerome T; Beyenal, Haluk

    2015-01-01

    One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are: (1) to present the current status of knowledge regarding electrochemical biofilm control; (2) to establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it; (3) to discuss current proposed mechanisms; and (4) to introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing datasets across the literature and generating comparable datasets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use.

  1. From blue jeans to blue genes.

    Science.gov (United States)

    Boon, Laurence M; Vikkula, Miikka

    2009-03-01

    Cutaneous venous anomalies are common. They are blue and vary in size, number, and location and account for most consultations at specialized interdisciplinary clinics for vascular anomalies. Venous lesions are clinically important because they cause pain, dysfunction, destruction of adjacent tissues, and esthetic concern. Only resection and sclerotherapy are helpful, although not always curative. Understanding etiopathogenesis could help design animal models and develop novel therapeutic approaches. John B. Mulliken, MD, envisioned a project to uncover the genetic basis of an inherited form of venous malformation in a large New England family. Recruitment of 2 young fellows resulted in a collaborative project that unraveled the searched-for gene and its mutation. This was an opening for a new era in vascular anomalies. Two blue genes' mutations were discovered, which account for most, if not all, of the inherited forms of venous anomalies, but other genes as well, for rheologically diverse lesions. Differential diagnosis and management has improved, and animal models are being made. This was achieved through the help of Dr Mulliken, who inspired 2 young investigators in blue jeans to find 2 blue genes.

  2. Understanding Biofilms in Chronic Sinusitis.

    Science.gov (United States)

    Tajudeen, Bobby A; Schwartz, Joseph S; Palmer, James N

    2016-02-01

    Chronic sinusitis is a burdensome disease that has substantial individual and societal impact. Although great advances in medical and surgical therapies have been made, some patients continue to have recalcitrant infections. Microbial biofilms have been implicated as a cause of recalcitrant chronic sinusitis, and recent studies have tried to better understand the pathogenesis of chronic sinusitis as it relates to microbial biofilms. Here, we provide an overview of biofilms in chronic sinusitis with emphasis on pathogenesis, treatment, and future directions. In addition, recent evidence is presented, elucidating the role of bitter taste receptors as a possible key factor leading to biofilm formation.

  3. Biofilm and Dental Biomaterials

    Directory of Open Access Journals (Sweden)

    Marit Øilo

    2015-05-01

    Full Text Available All treatment involving the use of biomaterials in the body can affect the host in positive or negative ways. The microbiological environment in the oral cavity is affected by the composition and shape of the biomaterials used for oral restorations. This may impair the patients’ oral health and sometimes their general health as well. Many factors determine the composition of the microbiota and the formation of biofilm in relation to biomaterials such as, surface roughness, surface energy and chemical composition, This paper aims to give an overview of the scientific literature regarding the association between the chemical, mechanical and physical properties of dental biomaterials and oral biofilm formation, with emphasis on current research and future perspectives.

  4. Antimicrobial Photoinactivation Using Visible Light Plus Water-Filtered Infrared-A (VIS + wIRA) Alters In Situ Oral Biofilms.

    Science.gov (United States)

    Al-Ahmad, A; Bucher, M; Anderson, A C; Tennert, C; Hellwig, E; Wittmer, A; Vach, K; Karygianni, L

    2015-01-01

    Recently, growing attention has been paid to antimicrobial photodynamic therapy (aPDT) in dentistry. Changing the microbial composition of initial and mature oral biofilm by aPDT using visible light plus water-filtered infrared-A wavelengths (VIS + wIRA) has not yet been investigated. Moreover, most aPDT studies have been conducted on planktonic bacterial cultures. Therefore, in the present clinical study we cultivated initial and mature oral biofilms in six healthy volunteers for 2 hours or 3 days, respectively. The biofilms were treated with aPDT using VIS+wIRA (200 mW cm(-2)), toluidine blue (TB) and chlorine e6 (Ce6) for 5 minutes. Chlorhexidine treated biofilm samples served as positive controls, while untreated biofilms served as negative controls. After aPDT treatment the colony forming units (CFU) of the biofilm samples were quantified, and the surviving bacteria were isolated in pure cultures and identified using MALDI-TOF, biochemical tests and 16S rDNA-sequencing. aPDT killed more than 99.9% of the initial viable bacterial count and 95% of the mature oral biofilm in situ, independent of the photosensitizer. The number of surviving bacterial species was highly reduced to 6 (TB) and 4 (Ce6) in the treated initial oral biofilm compared to the 20 different species of the untreated biofilm. The proportions of surviving bacterial species were also changed after TB- and Ce6-mediated aPDT of the mature oral biofilm, resulting in a shift in the microbial composition of the treated biofilm compared to that of the control biofilm. In conclusion, aPDT using VIS + wIRA showed a remarkable potential to eradicate both initial and mature oral biofilms, and also to markedly alter the remaining biofilm. This encourages the clinical use of aPDT with VIS + wIRA for the treatment of periimplantitis and periodontitis.

  5. Blue ocean strategy.

    Science.gov (United States)

    Kim, W Chan; Mauborgne, Renée

    2004-10-01

    Despite a long-term decline in the circus industry, Cirque du Soleil profitably increased revenue 22-fold over the last ten years by reinventing the circus. Rather than competing within the confines of the existing industry or trying to steal customers from rivals, Cirque developed uncontested market space that made the competition irrelevant. Cirque created what the authors call a blue ocean, a previously unknown market space. In blue oceans, demand is created rather than fought over. There is ample opportunity for growth that is both profitable and rapid. In red oceans--that is, in all the industries already existing--companies compete by grabbing for a greater share of limited demand. As the market space gets more crowded, prospects for profits and growth decline. Products turn into commodities, and increasing competition turns the water bloody. There are two ways to create blue oceans. One is to launch completely new industries, as eBay did with online auctions. But it's much more common for a blue ocean to be created from within a red ocean when a company expands the boundaries of an existing industry. In studying more than 150 blue ocean creations in over 30 industries, the authors observed that the traditional units of strategic analysis--company and industry--are of limited use in explaining how and why blue oceans are created. The most appropriate unit of analysis is the strategic move, the set of managerial actions and decisions involved in making a major market-creating business offering. Creating blue oceans builds brands. So powerful is blue ocean strategy, in fact, that a blue ocean strategic move can create brand equity that lasts for decades.

  6. Biofilm architecture in a novel pressurized biofilm reactor.

    Science.gov (United States)

    Jiang, Wei; Xia, Siqing; Duan, Liang; Hermanowicz, Slawomir W

    2015-01-01

    A novel pure-oxygen pressurized biofilm reactor was operated at different organic loading, mechanical shear and hydrodynamic conditions to understand the relationships between biofilm architecture and its operation. The ultimate goal was to improve the performance of the biofilm reactor. The biofilm was labeled with seven stains and observed with confocal laser scanning microscopy. Unusual biofilm architecture of a ribbon embedded between two surfaces with very few points of attachment was observed. As organic loading increased, the biofilm morphology changed from a moderately rough layer into a locally smoother biomass with significant bulging protuberances, although the chemical oxygen demand (COD) removal efficiency remained unchanged at about 75%. At higher organic loadings, biofilms contained a larger fraction of active cells distributed uniformly within a proteinaceous matrix with decreasing polysaccharide content. Higher hydrodynamic shear in combination with high organic loading resulted in the collapse of biofilm structure and a substantial decrease in reactor performance (a COD removal of 16%). Moreover, the important role of proteins for the spatial distribution of active cells was demonstrated quantitatively.

  7. Le blue-jean

    OpenAIRE

    Miller, Daniel

    2012-01-01

    Le Blue-jean: pourquoi la technologie vient en dernier. La plupart des personnes pensent que la technique (ou la technologie) correspond à ce qui vient en amont du produit. Dans cet article, Daniel Miller s’intéresse plutôt à des cas dans lesquels l’ordre de la séquence est renversé et où le produit précède, ou initie, en quelque sorte, la technique. L’auteur commence par décrire les techniques d’usure artificielle des blue jeans  : une technique qui vise à copier les effets du port des blue ...

  8. Cytotoxic effects of 109 reference compounds on rat H4IIE and human HepG2 hepatocytes. III: Mechanistic assays on oxygen consumption with MitoXpress and NAD(P)H production with Alamar Blue™.

    Science.gov (United States)

    Schoonen, Willem G E J; Stevenson, Joe C R; Westerink, Walter M A; Horbach, G Jean

    2012-04-01

    In vitro toxicity screening can reduce the attrition rate of drug candidates in the pharmaceutical industry in the early development process. The focus in this study is to compare the sensitivity for cytotoxicity of a time-resolved fluoro metric oxygen probe with that of a fluoro metric Alamar Blue™ (AB) assay. Both assays measure mitochondrial activity by either oxygen consumption (LUX-A65N-1 (MitoXpress, Luxcel) probe) or NADH/FADH conversion (AB). Both assays were carried out with increasing concentrations of 109 reference compounds using rat H4IIE and human HepG2 hepatocytes at incubation periods of 24, 48 and 72 h. Prior to this study, the influence on medium with either glucose or galactose was studied to analyze the rate of glycolysis and oxygen consumption, which latter process may be impaired in hepatoma cells. Inhibitors of oxygen consumption in combination with a glucose up-take inhibitor showed the largest consumption rate differences in the presence of 5mM of glucose. The choice for the 109 reference compounds was based on the so-called Multicentre Evaluation for In vitro Cytotoxicity (MEIC) and on diverse drug categories. For 59 toxic reference compounds, an evaluation for both assays was carried up to 10(-3)M. Toxicity was demonstrated with MitoXpress for 23 (39%) and 36 (61%) compounds in H4IIE and HepG2 cells, respectively, and with AB for 44 (75%) and 40 (68%) compounds. For 50 more pharmaceutical drugs more physiological concentrations were used up to 3.16×10(-5)M, and only 19 (38%) of these compounds appeared to be toxic in both assays. In conclusion, overall 63 (58%) and 60 (55%) compounds showed toxic effects with the MitoXpress and AB assays on rat H4IIE and human HepG2 hepatocytes, respectively. AB assays were more sensitive with respect to H4IIE cells and MitoXpress assays with respect to HepG2 cells. At all tested time intervals, MitoXpress showed its sensitivity, while AB is more sensitive at 48 and 72 h. With AB more toxic compounds

  9. Staphylococcus aureus biofilms: recent developments in biofilm dispersal.

    Science.gov (United States)

    Lister, Jessica L; Horswill, Alexander R

    2014-01-01

    Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.

  10. FROM BLUE JEANS TO BLUE GENES

    OpenAIRE

    Boon, Laurence M.; Vikkula, Miikka

    2009-01-01

    Cutaneous venous anomalies are common. They are blue in color and vary in size, number and location, and account for the majority of consultations at specialized interdisciplinary clinics for vascular anomalies. Venous lesions are clinically important as they cause pain, dysfunction, destruction of adjacent tissues and esthetic concern. Only resection and sclerotherapy are helpful, although not always curative. Understanding etiopathogenesis could help design animal models and develop novel t...

  11. Experimental evolution in biofilm populations.

    Science.gov (United States)

    Steenackers, Hans P; Parijs, Ilse; Foster, Kevin R; Vanderleyden, Jozef

    2016-05-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques.

  12. Interaction of Nanoparticles with Biofilms

    Science.gov (United States)

    In this work we have studied the interaction and adsorption of engineered nanoparticles such as TiO2, ZnO, CeO2 , and carbon nanotubes with biofilms. Biofilm is an extracellular polymeric substance coating comprised of living material and it is an aggregation of bacteria, algae, ...

  13. Experimental evolution in biofilm populations

    Science.gov (United States)

    Steenackers, Hans P.; Parijs, Ilse; Foster, Kevin R.; Vanderleyden, Jozef

    2016-01-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques. PMID:26895713

  14. Microalgal biofilms for wastewater treatment

    NARCIS (Netherlands)

    Boelee, N.C.

    2013-01-01

    The objective of this thesis was to explore the possibilities of using microalgal biofilms for the treatment of municipal wastewater, with a focus on the post-treatment of municipal wastewater effluent. The potential of microalgal biofilms for wastewater treatment was first investigated using a scen

  15. Microbial ecology of phototrophic biofilms

    NARCIS (Netherlands)

    Roeselers, G.

    2007-01-01

    Biofilms are layered structures of microbial cells and an extracellular matrix of polymeric substances, associated with surfaces and interfaces. Biofilms trap nutrients for growth of the enclosed microbial community and help prevent detachment of cells from surfaces in flowing systems. Phototrophic

  16. Blue Ribbon Panel Report

    Science.gov (United States)

    An NCI Cancer Currents blog by the NCI acting director thanking the cancer community for contributing to the Cancer Moonshot Blue Ribbon Panel report, which was presented to the National Cancer Advisory Board on September 7.

  17. New York Blue

    Data.gov (United States)

    Federal Laboratory Consortium — New York Blue is used cooperatively by the Laboratory and Stony Brook University as part of the New York Center for Computation Sciences. Ranked as the 28th fastest...

  18. Methylene blue test

    Science.gov (United States)

    Methemoglobinemia - methylene blue test ... No special preparation is required for this test. ... which are genetic (problem with your genes). This test is used to tell the difference between methemoglobinemia ...

  19. Susceptibility of Candida albicans, Staphylococcus aureus, and Streptococcus mutans biofilms to photodynamic inactivation: an in vitro study.

    Science.gov (United States)

    Pereira, Cristiane Aparecida; Romeiro, Rogério Lima; Costa, Anna Carolina Borges Pereira; Machado, Ana Karina Silva; Junqueira, Juliana Campos; Jorge, Antonio Olavo Cardoso

    2011-05-01

    The purpose of this study was to evaluate specific effects of photodynamic inactivation (PDI) using methylene blue as photosensitizer and low-power laser irradiation on the viability of single-, dual-, and three-species biofilms formed by C. albicans, S. aureus, and S. mutans. Biofilms were grown in acrylic discs immersed in sterile brain heart infusion broth (BHI) containing 5% sucrose, inoculated with microbial suspension (10(6) cells/ml) and incubated for 5 days. On the fifth day, the effects of the methylene blue (MB) photosensitizer at a concentration of 0.1 mg/ml for 5 min and InGaAlP laser (660 nm) for 98 s, alone and conjugated were evaluated. Next, the discs were placed in tubes with sterile physiological solution [0.9% sodium chloride (NaCl)] and sonicated for to disperse the biofilms. Ten-fold serial dilutions were carried and aliquots seeded in selective agar, which were then incubated for 48 h. Then the numbers CFU/ml (log(10)) were counted and analyzed statistically (ANOVA, Tukey test, p biofilms groups was performed. Significant decreases in the viability of all microorganisms were observed for biofilms exposed to PDI mediated by MB dye. Reductions (log(10)) of single-species biofilms were greater (2.32-3.29) than the association of biofilms (1.00-2.44). Scanning electron microscopy micrographs suggested that lethal photosensitization occurred predominantly in the outermost layers of the biofilms. The results showed that PDI mediated by MB dye, might be a useful approach for the control of oral biofilms.

  20. Antibiotic tolerance and microbial biofilms

    DEFF Research Database (Denmark)

    Folkesson, Anders

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We study the dynamics of antibiotic action within hydrodynamic flow chamber biofilms of Escherichia coli and Pseudomonas aeruginosa using isogenic mutants and fluorescent gene...... expression reporters and we address the question of how biofilm organization affects antibiotic susceptibility. The dynamics of microbial killing is monitored by viable count determination, and confocal laser microscopy. Our work shows that the apparent increased antibiotic tolerance is due to the formation...... of antibiotic tolerant subpopulations within the biofilm. The formation of these subpopulations is highly variable and dependent on the antibiotic used, the biofilm structural organization and the induction of specific tolerance mechanisms....

  1. Silver against Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Kirketerp-Møller, K.; Kristiansen, S.

    2007-01-01

    Silver has been recognized for its antimicrobial properties for centuries. Most studies on the antibacterial efficacy of silver, with particular emphasis on wound healing, have been performed on planktonic bacteria. Our recent studies, however, strongly suggest that colonization of wounds involves...... bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa......, but that the silver concentration is important. A concentration of 5-10 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...

  2. Bacterial interactions in dental biofilm.

    Science.gov (United States)

    Huang, Ruijie; Li, Mingyun; Gregory, Richard L

    2011-01-01

    Biofilms are masses of microorganisms that bind to and multiply on a solid surface, typically with a fluid bathing the microbes. The microorganisms that are not attached but are free floating in an aqueous environment are termed planktonic cells. Traditionally, microbiology research has addressed results from planktonic bacterial cells. However, many recent studies have indicated that biofilms are the preferred form of growth of most microbes and particularly those of a pathogenic nature. Biofilms on animal hosts have significantly increased resistance to various antimicrobials compared to planktonic cells. These microbial communities form microcolonies that interact with each other using very sophisticated communication methods (i.e., quorum-sensing). The development of unique microbiological tools to detect and assess the various biofilms around us is a tremendously important focus of research in many laboratories. In the present review, we discuss the major biofilm mechanisms and the interactions among oral bacteria.

  3. Repeated applications of photodynamic therapy on Candida glabrata biofilms formed in acrylic resin polymerized.

    Science.gov (United States)

    de Figueiredo Freitas, Lírian Silva; Rossoni, Rodnei Dennis; Jorge, Antonio Olavo Cardoso; Junqueira, Juliana Campos

    2017-04-01

    Previous studies have been suggested that photodynamic therapy (PDT) can be used as an adjuvant treatment for denture stomatitis. In this study, we evaluated the effects of multiple sessions of PDT on Candida glabrata biofilms in specimens of polymerized acrylic resin formed after 5 days. Subsequently, four applications of PDT were performed on biofilms in 24-h intervals (days 6-9). Also, we evaluated two types of PDT, including application of laser and methylene blue or light-emitting diode (LED) and erythrosine. The control groups were treated with physiological solution. The effects of PDT on biofilm were evaluated after the first and fourth application of PDT. The biofilm analysis was performed by counting the colony-forming units. The results showed that between the days 6 and 9, the biofilms not treated by PDT had an increase of 5.53 to 6.05 log (p = 0.0271). Regarding the treatments, after one application of PDT, the biofilms decreased from 5.53 to 0.89 log. When it was done four applications, the microbial reduction ranged from 6.05 log to 0.11 log. We observed that one application of PDT with laser or LED caused a reduction of 3.36 and 4.64 compared to the control groups, respectively (p = 0.1708). When it was done four applications of PDT, the reductions achieved were 1.57 for laser and 5.94 for LED (p = 0.0001). It was concluded that repeated applications of PDT on C. glabrata biofilms showed higher antimicrobial activity compared to single application. PDT mediated by LED and erythrosine was more efficient than the PDT mediated by laser and methylene blue.

  4. Oral biofilm models for mechanical plaque removal

    NARCIS (Netherlands)

    Verkaik, Martinus J.; Busscher, Henk J.; Rustema-Abbing, Minie; Slomp, Anje M.; Abbas, Frank; van der Mei, Henny C.

    2010-01-01

    In vitro plaque removal studies require biofilm models that resemble in vivo dental plaque. Here, we compare contact and non-contact removal of single and dual-species biofilms as well as of biofilms grown from human whole saliva in vitro using different biofilm models. Bacteria were adhered to a sa

  5. Bacterial biofilms: prokaryotic adventures in multicellularity

    DEFF Research Database (Denmark)

    Webb, J.S.; Givskov, Michael Christian; Kjelleberg, S.

    2003-01-01

    The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight...... into differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity....

  6. Impact of Hydrodynamics on Oral Biofilm Strength

    NARCIS (Netherlands)

    Paramonova, E.; Kalmykowa, O. J.; van der Mei, H. C.; Busscher, H. J.; Sharma, P. K.

    2009-01-01

    Mechanical removal of oral biofilms is ubiquitously accepted as the best way to prevent caries and periodontal diseases. Removal effectiveness strongly depends on biofilm strength. To investigate the influence of hydrodynamics on oral biofilm strength, we grew single- and multi-species biofilms of S

  7. Oral Biofilm Architecture on Natural Teeth

    NARCIS (Netherlands)

    Zijnge, Vincent; van Leeuwen, M. Barbara M.; Degener, John E.; Abbas, Frank; Thurnheer, Thomas; Gmuer, Rudolf; Harmsen, Hermie J. M.

    2010-01-01

    Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and acces

  8. Environmental factors that shape biofilm formation.

    Science.gov (United States)

    Toyofuku, Masanori; Inaba, Tomohiro; Kiyokawa, Tatsunori; Obana, Nozomu; Yawata, Yutaka; Nomura, Nobuhiko

    2015-01-01

    Cells respond to the environment and alter gene expression. Recent studies have revealed the social aspects of bacterial life, such as biofilm formation. Biofilm formation is largely affected by the environment, and the mechanisms by which the gene expression of individual cells affects biofilm development have attracted interest. Environmental factors determine the cell's decision to form or leave a biofilm. In addition, the biofilm structure largely depends on the environment, implying that biofilms are shaped to adapt to local conditions. Second messengers such as cAMP and c-di-GMP are key factors that link environmental factors with gene regulation. Cell-to-cell communication is also an important factor in shaping the biofilm. In this short review, we will introduce the basics of biofilm formation and further discuss environmental factors that shape biofilm formation. Finally, the state-of-the-art tools that allow us investigate biofilms under various conditions are discussed.

  9. Holographic microrheology of biofilms

    Science.gov (United States)

    Chiong Cheong, Fook; Duarte, Simone; Grier, David

    2008-03-01

    We present microrheological measurements of polymeric matrices, including the extra-cellular polysaccharide gel synthesized by the dental pathogen S. mutans. As part of this study, we introduce the use of precision three-dimensional particle tracking based on video holographic microscopy. This technique offers nanometer-scale resolution at video rates, thereby providing detailed information on the gels' complex viscoelastic moduli, including insights into their heterogeneity. The particular application to dental biofilms complements previous studies based on macroscopic rheology, and demonstrates the utility of holographic microrheology for soft-matter physics and biomedical research.

  10. Detection of microbial biofilms on food processing surfaces: hyperspectral fluorescence imaging study

    Science.gov (United States)

    Jun, Won; Kim, Moon S.; Chao, Kaunglin; Lefcourt, Alan M.; Roberts, Michael S.; McNaughton, James L.

    2009-05-01

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this investigation was to determine a minimal number of spectral bands suitable to differentiate microbial biofilm formation from the four background materials typically used during food processing. Ultimately, the resultant spectral information will be used in development of handheld portable imaging devices that can be used as visual aid tools for sanitation and safety inspection (microbial contamination) of the food processing surfaces. Pathogenic E. coli O157:H7 and Salmonella cells were grown in low strength M9 minimal medium on various surfaces at 22 +/- 2 °C for 2 days for biofilm formation. Biofilm autofluorescence under UV excitation (320 to 400 nm) obtained by hyperspectral fluorescence imaging system showed broad emissions in the blue-green regions of the spectrum with emission maxima at approximately 480 nm for both E. coli O157:H7 and Salmonella biofilms. Fluorescence images at 480 nm revealed that for background materials with near-uniform fluorescence responses such as stainless steel and formica cutting board, regardless of the background intensity, biofilm formation can be distinguished. This suggested that a broad spectral band in the blue-green regions can be used for handheld imaging devices for sanitation inspection of stainless, cutting board, and formica surfaces. The non-uniform fluorescence responses of granite make distinctions between biofilm and background difficult. To further investigate potential detection of the biofilm formations on granite surfaces with multispectral approaches, principal component analysis (PCA) was performed using the hyperspectral fluorescence image data. The resultant PCA score images revealed distinct contrast between

  11. Significance of biofilms in dentistry.

    Science.gov (United States)

    Wróblewska, Marta; Strużycka, Izabela; Mierzwińska-Nastalska, Elżbieta

    2015-01-01

    In the past decades significant scientific progress has taken place in the knowledge about biofilms. They constitute multilayer conglomerates of bacteria and fungi, surrounded by carbohydrates which they produce, as well as substances derived from saliva and gingival fluid. Modern techniques showed significant diversity of the biofilm environment and a system of microbial communication (quorum sensing), enhancing their survival. At present it is believed that the majority of infections, particularly chronic with exacerbations, are a result of biofilm formation, particularly in the presence of biomaterials. It should be emphasised that penetration of antibiotics and other antimicrobial agents into deeper layers of a biofilm is poor, causing therapeutic problems and necessitating sometimes removal of the implant or prosthesis. Biofilms play an increasing role in dentistry as a result of more and more broad use in dental practice of plastic and implantable materials. Biofilms are produced on the surfaces of teeth as dental plaque, in the para-nasal sinuses, on prostheses, dental implants, as well as in waterlines of a dental unit, constituting a particular risk for severely immunocompromised patients. New methods of therapy and prevention of infections linked to biofilms are under development.

  12. Atypical cellular blue nevus or malignant blue nevus?*

    Science.gov (United States)

    Daltro, Luise Ribeiro; Yaegashi, Lygia Bertalha; Freitas, Rodrigo Abdalah; Fantini, Bruno de Carvalho; Souza, Cacilda da Silva

    2017-01-01

    Blue nevus is a benign melanocytic lesion whose most frequent variants are dendritic (common) blue nevus and cellular blue nevus. Atypical cellular blue nevus presents an intermediate histopathology between the typical and a rare variant of malignant blue nevus/melanoma arising in a cellular blue nevus. An 8-year-old child presented a pigmented lesion in the buttock since birth, but with progressive growth in the last two years. After surgical excision, histopathological examination revealed atypical cellular blue nevus. Presence of mitoses, ulceration, infiltration, cytological atypia or necrosis may occur in atypical cellular blue nevus, making it difficult to differentiate it from melanoma. The growth of blue nevus is unusual and considered of high-risk for malignancy, being an indicator for complete resection and periodic follow-up of these patients. PMID:28225968

  13. Biofilm models for the practitioner

    DEFF Research Database (Denmark)

    Morgenroth, Eberhard Friedrich; van Loosdrecht, M. C. M.; Wanner, O.

    2000-01-01

    Even though mathematical biofilm models are extensively used in biofilm research, there has been very little application of these models in the engineering practice so far. However, practitioners would be interested in models that can be used as tools to control plant operation under dynamic...... conditions or to help them handle complex interactions between particle removal, carbon oxidation, nitrification, denitrification and biological phosphorus removal. But even though there is a whole range of biofilm models available, it is difficult for the practitioner to select the appropriate modeling...

  14. Antibiotic resistance of bacterial biofilms

    DEFF Research Database (Denmark)

    Hoiby, N.; Bjarnsholt, T.; Givskov, M.

    2010-01-01

    and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains...... to antibiotics. Biofilm growth is associated with an increased level of mutations as well as with quorum-sensing-regulated mechanisms. Conventional resistance mechanisms such as chromosomal beta-lactamase, upregulated efflux pumps and mutations in antibiotic target molecules in bacteria also contribute...

  15. The Blue Collar Brain

    Directory of Open Access Journals (Sweden)

    Guy eVan Orden

    2012-06-01

    Full Text Available Much effort has gone into elucidating control of the body by the brain, less so the role of the body in controlling the brain. This essay develops the idea that the brain does a great deal of work in the service of behavior that is controlled by the body, a blue collar role compared to the white collar control exercised by the body. The argument that supports a blue collar role for the brain is also consistent with recent discoveries clarifying the white collar role of synergies across the body's tensegrity structure, and the evidence of critical phenomena in brain and behavior.

  16. A Blue Lagoon Function

    DEFF Research Database (Denmark)

    Markvorsen, Steen

    2007-01-01

    We consider a specific function of two variables whose graph surface resembles a blue lagoon. The function has a saddle point $p$, but when the function is restricted to any given straight line through $p$ it has a {\\em{strict local minimum}} along that line at $p$.......We consider a specific function of two variables whose graph surface resembles a blue lagoon. The function has a saddle point $p$, but when the function is restricted to any given straight line through $p$ it has a {\\em{strict local minimum}} along that line at $p$....

  17. Metabolism links bacterial biofilms and colon carcinogenesis.

    Science.gov (United States)

    Johnson, Caroline H; Dejea, Christine M; Edler, David; Hoang, Linh T; Santidrian, Antonio F; Felding, Brunhilde H; Ivanisevic, Julijana; Cho, Kevin; Wick, Elizabeth C; Hechenbleikner, Elizabeth M; Uritboonthai, Winnie; Goetz, Laura; Casero, Robert A; Pardoll, Drew M; White, James R; Patti, Gary J; Sears, Cynthia L; Siuzdak, Gary

    2015-06-02

    Bacterial biofilms in the colon alter the host tissue microenvironment. A role for biofilms in colon cancer metabolism has been suggested but to date has not been evaluated. Using metabolomics, we investigated the metabolic influence that microbial biofilms have on colon tissues and the related occurrence of cancer. Patient-matched colon cancers and histologically normal tissues, with or without biofilms, were examined. We show the upregulation of polyamine metabolites in tissues from cancer hosts with significant enhancement of N(1), N(12)-diacetylspermine in both biofilm-positive cancer and normal tissues. Antibiotic treatment, which cleared biofilms, decreased N(1), N(12)-diacetylspermine levels to those seen in biofilm-negative tissues, indicating that host cancer and bacterial biofilm structures contribute to the polyamine metabolite pool. These results show that colonic mucosal biofilms alter the cancer metabolome to produce a regulator of cellular proliferation and colon cancer growth potentially affecting cancer development and progression.

  18. Metabolism links bacterial biofilms and colon carcinogenesis

    Science.gov (United States)

    Johnson, Caroline H.; Dejea, Christine M.; Edler, David; Hoang, Linh T.; Santidrian, Antonio F.; Felding, Brunhilde H.; Cho, Kevin; Wick, Elizabeth C.; Hechenbleikner, Elizabeth M.; Uritboonthai, Winnie; Goetz, Laura; Casero, Robert A.; Pardoll, Drew M.; White, James R.; Patti, Gary J.; Sears, Cynthia L.; Siuzdak, Gary

    2015-01-01

    SUMMARY Bacterial biofilms in the colon alter the host tissue microenvironment. A role for biofilms in colon cancer metabolism has been suggested but to date has not been evaluated. Using metabolomics, we investigated the metabolic influence that microbial biofilms have on colon tissues and the related occurrence of cancer. Patient-matched colon cancers and histologically normal tissues, with or without biofilms, were examined. We show the upregulation of polyamine metabolites in tissues from cancer hosts with significant enhancement of N1, N12-diacetylspermine in both biofilm positive cancer and normal tissues. Antibiotic treatment, which cleared biofilms, decreased N1, N12-diacetylspermine levels to those seen in biofilm negative tissues, indicating that host cancer and bacterial biofilm structures contribute to the polyamine metabolite pool. These results show that colonic mucosal biofilms alter the cancer metabolome, to produce a regulator of cellular proliferation and colon cancer growth potentially affecting cancer development and progression. PMID:25959674

  19. The ``Swiss cheese'' instability of bacterial biofilms

    Science.gov (United States)

    Jang, Hongchul; Rusconi, Roberto; Stocker, Roman

    2012-11-01

    Bacteria often adhere to surfaces, where they develop polymer-encased communities (biofilms) that display dramatic resistance to antibiotic treatment. A better understanding of cell detachment from biofilms may lead to novel strategies for biofilm disruption. Here we describe a new detachment mode, whereby a biofilm develops a nearly regular array of ~50-100 μm holes. Using surface-treated microfluidic devices, we create biofilms of controlled shape and size. After the passage of an air plug, the break-up of the residual thin liquid film scrapes and rearranges bacteria on the surface, such that a ``Swiss cheese'' pattern is left in the residual biofilm. Fluorescent staining of the polymeric matrix (EPS) reveals that resistance to cell dislodgement correlates with local biofilm age, early settlers having had more time to hunker down. Because few survivors suffice to regrow a biofilm, these results point at the importance of considering microscale heterogeneity in assessing the effectiveness of biofilm removal strategies.

  20. Effect of calcium on moving-bed biofilm reactor biofilms.

    Science.gov (United States)

    Goode, C; Allen, D G

    2011-03-01

    The effect of calcium concentration on the biofilm structure, microbiology, and treatment performance was evaluated in a moving-bed biofilm reactor. Three experiments were conducted in replicate laboratory-scale reactors to determine if wastewater calcium is an important variable for the design and optimization of these reactors. Biofilm structural properties, such as thickness, oxygen microprofiles, and the composition of extracellular polymeric substances (EPS) were affected by increasing calcium concentrations. Above a threshold concentration of calcium between 1 and 50 mg/L, biofilms became thicker and denser, with a shift toward increasingly proteinaceous EPS at higher calcium concentrations up to 200 mgCa2+/L. At 300 mgCa2+/L, biofilms were found to become primarily composed of inorganic calcium precipitates. Microbiology was assessed through microscopy, denaturing grade gel electrophoresis, and enumeration of higher organisms. Higher calcium concentrations were found to change the bacterial community and promote the abundant growth of filamentous organisms and various protazoa and metazoan populations. The chemical oxygen demand removal efficiency was improved for reactors at calcium concentrations of 50 mg/L and above. Reactor effluents for the lowest calcium concentration (1 mgCa2+/L) were found to be turbid (>50 NTU), as a result of the detachment of small and poorly settling planktonic biomass, whereas higher concentrations promoted settling of the suspended phase. In general, calcium was found to be an important variable causing significant changes in biofilm structure and reactor function.

  1. Differential growth of wrinkled biofilms

    CERN Document Server

    Espeso, D R; Einarsson, B

    2015-01-01

    Biofilms are antibiotic-resistant bacterial aggregates that grow on moist surfaces and can trigger hospital-acquired infections. They provide a classical example in biology where the dynamics of cellular communities may be observed and studied. Gene expression regulates cell division and differentiation, which affect the biofilm architecture. Mechanical and chemical processes shape the resulting structure. We gain insight into the interplay between cellular and mechanical processes during biofilm development on air-agar interfaces by means of a hybrid model. Cellular behavior is governed by stochastic rules informed by a cascade of concentration fields for nutrients, waste and autoinducers. Cellular differentiation and death alter the structure and the mechanical properties of the biofilm, which is deformed according to Foppl-Von Karman equations informed by cellular processes and the interaction with the substratum. Stiffness gradients due to growth and swelling produce wrinkle branching. We are able to repr...

  2. Nanotechnology: Role in dental biofilms

    Directory of Open Access Journals (Sweden)

    Bhardwaj Sonia

    2009-01-01

    Full Text Available Biofilms are surface- adherent populations of microorganisms consisting of cells, water and extracellular matrix material Nanotechnology is promising field of science which can guide our understanding of the role of interspecies interaction in the development of biofilm. Streptococcus mutans with other species of bacteria has been known to form dental biofilm. The correlation between genetically modified bacteria Streptococcus mutans and nanoscale morphology has been assessed using AFMi.e atomic force microscopy. Nanotechnology application includes 16 O/ 18 O reverse proteolytic labeling,use of quantum dots for labeling of bacterial cells, selective removal of cariogenic bacteria while preserving the normal oral flora and silver antimicrobial nanotechnology against pathogens associated with biofilms. The future comprises a mouthwash full of smart nanomachines which can allow the harmless flora of mouth to flourish in a healthy ecosystem

  3. Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Ren, Dawei

    between plasmid host range and composition of the recipient community was investigated in Manuscript 5 by comparing plasmid permissiveness in single populations and in a microbial community composed of 15 soil strains. By use of flow cytometry (FCM) and 16S rRNA gene sequencing, the IncP1 plasmid, pKJK10...... bacterial species, the study to elucidate the impact of interaction networks on the multispecies biofilms in natural ecosystems, especially in soil, is still at an early stage. The diverse patterns of interactions within the mixed communities as well as the predatorprey relationship between protozoa...... interactions in this four-species biofilm model community. Manuscript 2 presents the further application of this developed approach on evaluating the synergistic/antagonistic interactions in multispecies biofilms composed of seven soil isolates. 63% of the four-species biofilms were found to interact...

  4. After Stroke, 'Blue' Light May Help Beat the Blues

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_163731.html After Stroke, 'Blue' Light May Help Beat the Blues Akin ... a danger for people recovering from a debilitating stroke. But new research suggests that tweaking a rehabilitation ...

  5. Hydrodynamics of catheter biofilm formation

    CERN Document Server

    Sotolongo-Costa, Oscar; Rodriguez-Perez, Daniel; Martinez-Escobar, Sergio; Fernandez-Barbero, Antonio

    2009-01-01

    A hydrodynamic model is proposed to describe one of the most critical problems in intensive medical care units: the formation of biofilms inside central venous catheters. The incorporation of approximate solutions for the flow-limited diffusion equation leads to the conclusion that biofilms grow on the internal catheter wall due to the counter-stream diffusion of blood through a very thin layer close to the wall. This biological deposition is the first necessary step for the subsequent bacteria colonization.

  6. Critical review on biofilm methods

    DEFF Research Database (Denmark)

    Azeredo, Joana; F. Azevedo, Nuno; Briandet, Romain

    2017-01-01

    Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research in...... and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms....

  7. Plaque Type Blue Naevus

    Directory of Open Access Journals (Sweden)

    Sentamilselvi G

    1997-01-01

    Full Text Available A case of plaque type blue naevus was encountered in a Dermatology Clinic in Madras. The various clinical differential diagnoses are discussed, the hitopathological features described and the benign nature of the tumour stressed. The case is reported for its rarity and to create an awareness of this entity.

  8. Blue rubber bleb naevus

    Directory of Open Access Journals (Sweden)

    Mittal R

    1995-01-01

    Full Text Available A 35 year old female had multiple progressive painful, tender, soft, bluish compressible nodules with the feel of rubber nipples. There was no evidence of gastrointestinal haemangiomas or other systemic abnormalities. Histopathologically, cavernous haemangioma with prominent smooth muscle outline proved the clinical diagnosis of blue rubber bleb naevus. Only cutaneous lesions were seen in the patient.

  9. The "Blue Banana" Revisited

    NARCIS (Netherlands)

    Faludi, A.K.F.

    2015-01-01

    This essay is about the “Blue Banana”. Banana is the name given subsequently by others to a Dorsale européenne (European backbone) identified empirically by Roger Brunet. In a background study to the Communication of the European Commission ‘Europe 2000’, Klaus Kunzmann and Michael Wegener put forwa

  10. The Blue Denmark

    DEFF Research Database (Denmark)

    Hansen, Carsten Ørts; Sornn-Friese, Henrik

    This paper makes an important contribution to the discussion about knowledge based localised externalities in the context of shipping and the maritime sector in Denmark. In the paper we ask if there is a national, knowledge‐based maritime cluster configured around the shipowners in Denmark. This ...... talk about The Blue Denmark....

  11. Blue spectral inflation

    CERN Document Server

    Schunck, Franz E

    2008-01-01

    We reconsider the nonlinear second order Abel equation of Stewart and Lyth, which follows from a nonlinear second order slow-roll approximation. We find a new eigenvalue spectrum in the blue regime. Some of the discrete values of the spectral index n_s have consistent fits to the cumulative COBE data as well as to recent ground-base CMB experiments.

  12. Dark Blue II

    OpenAIRE

    2013-01-01

    Dark Blue II, high fired porcelain, decorated with cobalt chloride, woodfired with salt. 10,5 x 10,5 x 19 cm. Ferdigstilt: 2012. Innkjøpt til Collection of The American Museum of Ceramic Art, Pomona, California, USA.

  13. Biofilm-specific antibiotic tolerance and resistance.

    Science.gov (United States)

    Olsen, I

    2015-05-01

    Biofilms are heterogeneous structures composed of bacterial cells surrounded by a matrix and attached to solid surfaces. The bacteria here are 100 to 1,000 times more tolerant to antimicrobials than corresponding planktonic cells. Biofilms can be difficult to eradicate when they cause biofilm-related diseases, e.g., implant infections, cystic fibrosis, urinary tract infections, and periodontal diseases. A number of phenotypic features of the biofilm can be involved in biofilm-specific tolerance and resistance. Little is known about the molecular mechanisms involved. The current review deals with both phenotypic and molecular mechanisms of biofilm-specific antibiotic tolerance and resistance.

  14. Control of Candida albicans metabolism and biofilm formation by Pseudomonas aeruginosa phenazines.

    Science.gov (United States)

    Morales, Diana K; Grahl, Nora; Okegbe, Chinweike; Dietrich, Lars E P; Jacobs, Nicholas J; Hogan, Deborah A

    2013-01-29

    Candida albicans has developmental programs that govern transitions between yeast and filamentous morphologies and between unattached and biofilm lifestyles. Here, we report that filamentation, intercellular adherence, and biofilm development were inhibited during interactions between Candida albicans and Pseudomonas aeruginosa through the action of P. aeruginosa-produced phenazines. While phenazines are toxic to C. albicans at millimolar concentrations, we found that lower concentrations of any of three different phenazines (pyocyanin, phenazine methosulfate, and phenazine-1-carboxylate) allowed growth but affected the development of C. albicans wrinkled colony biofilms and inhibited the fungal yeast-to-filament transition. Phenazines impaired C. albicans growth on nonfermentable carbon sources and led to increased production of fermentation products (ethanol, glycerol, and acetate) in glucose-containing medium, leading us to propose that phenazines specifically inhibited respiration. Methylene blue, another inhibitor of respiration, also prevented the formation of structured colony biofilms. The inhibition of filamentation and colony wrinkling was not solely due to lowered extracellular pH induced by fermentation. Compared to smooth, unstructured colonies, wrinkled colony biofilms had higher oxygen concentrations within the colony, and wrinkled regions of these colonies had higher levels of respiration. Together, our data suggest that the structure of the fungal biofilm promotes access to oxygen and enhances respiratory metabolism and that the perturbation of respiration by bacterial molecules such as phenazines or compounds with similar activities disrupts these pathways. These findings may suggest new ways to limit fungal biofilms in the context of disease. IMPORTANCE Many of the infections caused by Candida albicans, a major human opportunistic fungal pathogen, involve both morphological transitions and the formation of surface-associated biofilms. Through the

  15. Strategies for combating bacterial biofilm infections

    Institute of Scientific and Technical Information of China (English)

    Hong Wu; Claus Moser; Heng-Zhuang Wang; Niels Hiby; Zhi-Jun Song

    2015-01-01

    Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases the difficulties for the clinical treatment of biofilm infections. Clinical and laboratory investigations demonstrated a perspicuous correlation between biofilm infection and medical foreign bodies or indwelling devices. Clinical observations and experimental studies indicated clearly that antibiotic treatment alone is in most cases insufficient to eradicate biofilm infections. Therefore, to effectively treat biofilm infections with currently available antibiotics and evaluate the outcomes become important and urgent for clinicians. The review summarizes the latest progress in treatment of clinical biofilm infections and scientific investigations, discusses the diagnosis and treatment of different biofilm infections and introduces the promising laboratory progress, which may contribute to prevention or cure of biofilm infections. We conclude that, an efficient treatment of biofilm infections needs a well-established multidisciplinary collaboration, which includes removal of the infected foreign bodies, selection of biofilm-active, sensitive and well-penetrating antibiotics, systemic or topical antibiotic administration in high dosage and combinations, and administration of anti-quorum sensing or biofilm dispersal agents.

  16. Anthranilate deteriorates the structure of Pseudomonas aeruginosa biofilms and antagonizes the biofilm-enhancing indole effect.

    Science.gov (United States)

    Kim, Soo-Kyoung; Park, Ha-Young; Lee, Joon-Hee

    2015-04-01

    Anthranilate and indole are alternative degradation products of tryptophan, depending on the bacterial species. While indole enhances the biofilm formation of Pseudomonas aeruginosa, we found that anthranilate, the tryptophan degradation product of P. aeruginosa, had an opposite effect on P. aeruginosa biofilm formation, in which anthranilate deteriorated the mushroom structure of biofilm. The anthranilate effect on biofilm formation was differentially exerted depending on the developmental stage and the presence of shear force. Anthranilate slightly accelerated the initial attachment of P. aeruginosa at the early stage of biofilm development and appeared to build more biofilm without shear force. But anthranilate weakened the biofilm structure in the late stage, deteriorating the mushroom structure of biofilms with shear force to make a flat biofilm. To investigate the interplay of anthranilate with indole in biofilm formation, biofilms were cotreated with anthranilate and indole, and the results showed that anthranilate antagonized the biofilm-enhancing effect of indole. Anthranilate was able to deteriorate the preformed biofilm. The effect of anthranilate and indole on biofilm formation was quorum sensing independent. AntR, a regulator of anthranilate-degrading metabolism was synergistically activated by cotreatment with anthranilate and indole, suggesting that indole might enhance biofilm formation by facilitating the degradation of anthranilate. Anthranilate slightly but significantly affected the cyclic diguaniylate (c-di-GMP) level and transcription of major extracellular polysaccharide (Psl, Pel, and alginate) operons. These results suggest that anthranilate may be a promising antibiofilm agent and antagonize the effect of indole on P. aeruginosa biofilm formation.

  17. Antimicrobial blue light inactivation of Methicillin-resistant Staphylococcus aureus

    Science.gov (United States)

    Wang, Yucheng; Dai, Tianhong; Gu, Ying

    2016-10-01

    Background: With the increasing emergence of multidrug-resistant (MDR) bacterial strains, there is a pressing need for the development of alternative treatment for infections. Antimicrobial blue light (aBL) has provided a simple and effective approach. Methods: We first investigated the effectiveness of aBL (415 nm) inactivation of USA300 LAClux (a communityacquired Methicillin-resistant Staphylococcus aureus strain) both in the planktonic and biofilm forms. The survival of the bacteria in suspensions was determined by serial dilution and that of the biofilm-embedded bacteria was determined by bioluminescence quantification. Using a mouse model of thermal burn infected with USA300 LAClux, we further assessed the effectiveness of aBL for treating localized infections. Bioluminescence imaging was performed to monitor in real time bacterial viability in vivo. Results: In vitro study showed that, for the planktonic counterpart of the bacteria or the 24-h-old biofilms, an irradiance of 55 mW/cm2 for 60 min resulted in a 4.61 log10 or 2.56 log10 inactivation, respectively. In vivo study using infected mouse burns demonstrated that a 2.56-log10 inactivation was achieved after 100-mW/cm2 irradiation for 62 min. Conclusions: aBL is a potential alternative approach for treating Methicillin-resistant Staphylococcus aureus infections.

  18. Strategies for combating bacterial biofilm infections

    DEFF Research Database (Denmark)

    Wu, Hong; Moser, Claus Ernst; Wang, Heng-Zhuang

    2015-01-01

    Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases...... the difficulties for the clinical treatment of biofilm infections. Clinical and laboratory investigations demonstrated a perspicuous correlation between biofilm infection and medical foreign bodies or indwelling devices. Clinical observations and experimental studies indicated clearly that antibiotic treatment...... alone is in most cases insufficient to eradicate biofilm infections. Therefore, to effectively treat biofilm infections with currently available antibiotics and evaluate the outcomes become important and urgent for clinicians. The review summarizes the latest progress in treatment of clinical biofilm...

  19. Enzymatic removal and disinfection of bacterial biofilms

    DEFF Research Database (Denmark)

    Johansen, Charlotte; Falholt, Per; Gram, Lone

    1997-01-01

    Model biofilms of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas fluorescens, and Pseudomonas aeruginosa were made on steel and polypropylene substrata. Plaque-resembling biofilms of Streptococcus mutans, Actinomyces, viscosus, and Fusobacterium nucleatum were made on saliva...

  20. Ciliates as engineers of phototrophic biofilms

    NARCIS (Netherlands)

    Weerman, Ellen J.; van der Geest, Harm G.; van der Meulen, Myra D.; Manders, Erik M. M.; van de Koppel, Johan; Herman, Peter M. J.; Admiraal, Wim

    2011-01-01

    1. Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the 'engineering' effect

  1. Candida Biofilms: Development, Architecture, and Resistance.

    Science.gov (United States)

    Chandra, Jyotsna; Mukherjee, Pranab K

    2015-08-01

    Intravascular device-related infections are often associated with biofilms (microbial communities encased within a polysaccharide-rich extracellular matrix) formed by pathogens on the surfaces of these devices. Candida species are the most common fungi isolated from catheter-, denture-, and voice prosthesis-associated infections and also are commonly isolated from contact lens-related infections (e.g., fungal keratitis). These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Recent technological advances have facilitated the development of novel approaches to investigate the formation of biofilms and identify specific markers for biofilms. These studies have provided extensive knowledge of the effect of different variables, including growth time, nutrients, and physiological conditions, on biofilm formation, morphology, and architecture. In this article, we will focus on fungal biofilms (mainly Candida biofilms) and provide an update on the development, architecture, and resistance mechanisms of biofilms.

  2. THE TRANSATLANTIC BLUE DIPLOMACY

    Directory of Open Access Journals (Sweden)

    Ioana GUTU

    2016-12-01

    Full Text Available The international diplomatic environment has reached to an unprecedented development, involving one of the newly specialized diplomatic types, namely the economic diplomacy. At the core of the fast movements in the diplomatic spheres across the Globe are the international agreements like the Transatlantic Trade and Investment Partnership (TTIP that determined diplomacy to dissolve into new subtypes, evolving from ground to the ocean and implementing new ways of achieving economic and climate sustainability. One of the newly created diplomatic spheres, is the blue ocean diplomacy that acts mainly in accordance with the rules and regulations that are being applied to the transatlantic economy. Even though TTIP encourages the increase of trade flows across the Atlantic, it will also ease the foreign investment procedures that, under the approach of keeping a sustainable environment, will represent one of the most important initiatives in implementing the blue economy concept within the framework of the transatlantic diplomacy.

  3. Faint Blue Galaxies

    CERN Document Server

    Ellis, Richard S

    1997-01-01

    The physical properties of the faint blue galaxy population are reviewed in the context of observational progress made via deep spectroscopic surveys and Hubble Space Telescope imaging of field galaxies at various limits, and theoretical models for the integrated star formation history of the Universe. Notwithstanding uncertainties in the properties of the local population of galaxies, convincing evidence has emerged from several independent studies for a rapid decline in the volume-averaged star formation rate of field galaxies since a redshift z~1. Together with the small angular sizes and modest mean redshift of the faintest detectable sources, these results can be understood in hierarchical models where the bulk of the star formation occurred at redshifts between z~1-2. The physical processes responsible for the subsequent demise of the faint blue galaxy population remains unclear. Considerable progress will be possible when the evolutionary trends can be monitored in the context of independent physical p...

  4. Characterization and fluorescence of yellow biofilms in karst caves, southwest Slovenia

    Directory of Open Access Journals (Sweden)

    Janez Mulec

    2015-05-01

    Full Text Available Biofilms of different colours that colonize surfaces within karst caves represent a source of nutrients. They occur commonly and abundantly at sites with sediments, and close to seepages or underground rivers. Golden-yellow subaerial biofilms are particularly well observed because of their contrast with their surroundings, the characteristics of the pigment and recently, even more, due to the characteristics of light-emitting diode (LED illumination. Yellow microbial biofilms were sampled from three caves in southwestern Slovenia, Dimnice, Križna jama and Sveta jama. The highest concentration of cultivable microbes (2.33×108 CFU/g and the biggest number of identified bacteria (66.0% were retrieved from a sample from Sveta jama. Using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight for bacterial identification showed that different species of Pseudomonas prevailed in all samples. Yellow biofilms showed an absorption peak around 400 nm, and two emission peaks, a major in the blue (~460 nm and a minor in the orange (~600 nm parts of the spectrum when excited at 405 nm. Microbial mats that colonize surfaces are probably frequently overlooked in caves because they are difficult to observe when they have no pigmentation and the contrast with their surroundings is low. Additional studies are needed to aid the understanding of the role of pigmented biofilms and their interactions with underlying substrata in respect of the evolution of substrate micromorphology.

  5. Molecular Analysis of Shower Curtain Biofilm Microbes

    OpenAIRE

    Kelley, Scott T.; Theisen, Ulrike; Angenent, Largus T.; Amand, Allison St.; Pace, Norman R.

    2004-01-01

    Households provide environments that encourage the formation of microbial communities, often as biofilms. Such biofilms constitute potential reservoirs for pathogens, particularly for immune-compromised individuals. One household environment that potentially accumulates microbial biofilms is that provided by vinyl shower curtains. Over time, vinyl shower curtains accumulate films, commonly referred to as “soap scum,” which microscopy reveals are constituted of lush microbial biofilms. To dete...

  6. New Dimensions of Moving Bed Biofilm Carriers

    OpenAIRE

    Piculell, Maria

    2016-01-01

    The moving bed biofilm reactor (MBBR) is a biological wastewater treatment process in which microorganisms grow as biofilms on suspended carriers. Conventionally, MBBRs are mainly designed and optimized based on the carrier surface area, neglecting the dynamic relationship between carrier design, reactor operation and biofilm characteristics, such as biofilm thickness and the composition of the microbial community. The purpose of this research project was to learn more about the roles of the ...

  7. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2011-01-01

    Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actuall...

  8. Extracellular DNA in oral microbial biofilms.

    Science.gov (United States)

    Jakubovics, Nicholas S; Burgess, J Grant

    2015-07-01

    The extracellular matrix of microbial biofilms is critical for surface adhesion and nutrient homeostasis. Evidence is accumulating that extracellular DNA plays a number of important roles in biofilm integrity and formation on hard and soft tissues in the oral cavity. Here, we summarise recent developments in the field and consider the potential of targeting DNA for oral biofilm control.

  9. Targeting quorum sensing in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Jakobsen, Tim Holm; Bjarnsholt, Thomas; Jensen, Peter Østrup;

    2013-01-01

    Bacterial resistance to conventional antibiotics combined with an increasing acknowledgement of the role of biofilms in chronic infections has led to a growing interest in new antimicrobial strategies that target the biofilm mode of growth. In the aggregated biofilm mode, cell-to-cell communication...

  10. Biofilm Induced Tolerance Towards Antimicrobial Peptides

    DEFF Research Database (Denmark)

    Folkesson, Anders; Haagensen, Janus Anders Juul; Zampaloni, Claudia

    2008-01-01

    of microbial killing were monitored by viable count determination, and confocal laser microscopy. Strains forming structurally organized biofilms show an increased bacterial survival when challenged with colistin, compared to strains forming unstructured biofilms. The increased survival is due to genetically......, but the protection is conditional being dependent on the structural organization of the biofilm, and the induction of specific tolerance mechanisms....

  11. Confocal Microscopy Imaging of the Biofilm Matrix

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Meyer, Rikke Louise

    2016-01-01

    The extracellular matrix is an integral part of microbial biofilms and an important field of research. Confocal laser scanning microscopy is a valuable tool for the study of biofilms, and in particular of the biofilm matrix, as it allows real-time visualization of fully hydrated, living specimens...

  12. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de mondzorgpraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  13. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de tandartspraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  14. Presence of extracellular DNA in the Candida albicans biofilm matrix and its contribution to biofilms.

    Science.gov (United States)

    Martins, Margarida; Uppuluri, Priya; Thomas, Derek P; Cleary, Ian A; Henriques, Mariana; Lopez-Ribot, José L; Oliveira, Rosário

    2010-05-01

    DNA has been described as a structural component of the extracellular matrix (ECM) in bacterial biofilms. In Candida albicans, there is a scarce knowledge concerning the contribution of extracellular DNA (eDNA) to biofilm matrix and overall structure. This work examined the presence and quantified the amount of eDNA in C. albicans biofilm ECM and the effect of DNase treatment and the addition of exogenous DNA on C. albicans biofilm development as indicators of a role for eDNA in biofilm development. We were able to detect the accumulation of eDNA in biofilm ECM extracted from C. albicans biofilms formed under conditions of flow, although the quantity of eDNA detected differed according to growth conditions, in particular with regards to the medium used to grow the biofilms. Experiments with C. albicans biofilms formed statically using a microtiter plate model indicated that the addition of exogenous DNA (>160 ng/ml) increases biofilm biomass and, conversely, DNase treatment (>0.03 mg/ml) decreases biofilm biomass at later time points of biofilm development. We present evidence for the role of eDNA in C. albicans biofilm structure and formation, consistent with eDNA being a key element of the ECM in mature C. albicans biofilms and playing a predominant role in biofilm structural integrity and maintenance.

  15. Pattern formation in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Parsek, Matthew R.; Tolker-Nielsen, Tim

    2008-01-01

    Bacteria are capable of forming elaborate multicellular communities called biofilms. Pattern formation in biofilms depends on cell proliferation and cellular migration in response to the available nutrients and other external cues, as well as on self-generated intercellular signal molecules...... and the production of an extracellular matrix that serves as a structural 'scaffolding' for the biofilm cells. Pattern formation in biofilms allows cells to position themselves favorably within nutrient gradients and enables buildup and maintenance of physiologically distinct subpopulations, which facilitates...... survival of one or more subpopulations upon environmental insult, and therefore plays an important role in the innate tolerance displayed by biofilms toward adverse conditions....

  16. The roles of biofilm matrix polysaccharide Psl in mucoid Pseudomonas aeruginosa biofilms.

    Science.gov (United States)

    Ma, Luyan; Wang, Shiwei; Wang, Di; Parsek, Matthew R; Wozniak, Daniel J

    2012-07-01

    The opportunistic pathogen Pseudomonas aeruginosa causes life-threatening, persistent infections in patients with cystic fibrosis (CF). Persistence is attributed to the ability of these bacteria to form structured communities (biofilms). Biofilms rely on an extracellular polymeric substances matrix to maintain structure. Psl exopolysaccharide is a key matrix component of nonmucoid biofilms, yet the role of Psl in mucoid biofilms is unknown. In this report, using a variety of mutants in a mucoid P. aeruginosa background, we found that deletion of Psl-encoding genes dramatically decreased their biofilm formation ability, indicating that Psl is also a critical matrix component of mucoid biofilms. Our data also suggest that the overproduction of alginate leads to mucoid biofilms, which occupy more space, whereas Psl-dependent biofilms are densely packed. These data suggest that Psl polysaccharide may have significant contributions in biofilm persistence in patients with CF and may be helpful for designing therapies for P. aeruginosa CF infection.

  17. Combining Biofilm-Controlling Compounds and Antibiotics as a Promising New Way to Control Biofilm Infections

    Directory of Open Access Journals (Sweden)

    Andréia Bergamo Estrela

    2010-05-01

    Full Text Available Many bacteria grow on surfaces forming biofilms. In this structure, they are well protected and often high dosages of antibiotics cannot clear infectious biofilms. The formation and stabilization of biofilms are mediated by diffusible autoinducers (e.g. N-acyl homoserine lactones, small peptides, furanosyl borate diester. Metabolites interfering with this process have been identified in plants, animals and microbes, and synthetic analogues are known. Additionally, this seems to be not the only way to control biofilms. Enzymes capable of cleaving essential components of the biofilm matrix, e.g. polysaccharides or extracellular DNA, and thus weakening the biofilm architecture have been identified. Bacteria also have mechanisms to dissolve their biofilms and return to planktonic lifestyle. Only a few compounds responsible for the signalling of these processes are known, but they may open a completely novel line of biofilm control. All these approaches lead to the destruction of the biofilm but not the killing of the pathogens. Therefore, a combination of biofilm-destroying compounds and antibiotics to handle biofilm infections is proposed. In this article, different approaches to combine biofilm-controlling compounds and antibiotics to fight biofilm infections are discussed, as well as the balance between biofilm formation and virulence.

  18. Natural Blue Food Colour

    DEFF Research Database (Denmark)

    Roda-Serrat, Maria Cinta

    2017-01-01

    the presence of the chromophore phycocyanobilin (PCB), a covalently attached linear tetrapyrrole. The applications of phycocyanins as food colorants are however limited, as they show poor stability in certain conditions of pH, light and temperature. Cleavage of PCB from the protein followed by careful product...... decreased. PCB was also found to be more sensitive to pH than phycocyanin. Regarding the stability with time, PCB showed a similar stability at pH 3, and worse at pH 5 and pH 7. The change from blue to green colour in acid conditions was attributed to protonation of the chromophore. However, the effect...

  19. Vibrio cholerae Biofilms and Cholera Pathogenesis.

    Directory of Open Access Journals (Sweden)

    Anisia J Silva

    2016-02-01

    Full Text Available Vibrio cholerae can switch between motile and biofilm lifestyles. The last decades have been marked by a remarkable increase in our knowledge of the structure, regulation, and function of biofilms formed under laboratory conditions. Evidence has grown suggesting that V. cholerae can form biofilm-like aggregates during infection that could play a critical role in pathogenesis and disease transmission. However, the structure and regulation of biofilms formed during infection, as well as their role in intestinal colonization and virulence, remains poorly understood. Here, we review (i the evidence for biofilm formation during infection, (ii the coordinate regulation of biofilm and virulence gene expression, and (iii the host signals that favor V. cholerae transitions between alternative lifestyles during intestinal colonization, and (iv we discuss a model for the role of V. cholerae biofilms in pathogenicity.

  20. Role of multicellular aggregates in biofilm formation

    DEFF Research Database (Denmark)

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin;

    2016-01-01

    response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation.IMPORTANCE During the past decades, there has been a consensus around the model of development of a biofilm......In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However......, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm...

  1. Modelling the growth of a methanotrophic biofilm

    DEFF Research Database (Denmark)

    Arcangeli, J.-P.; Arvin, E.

    1999-01-01

    This article discusses the growth of methanotrophic biofilms. Several independent biofilm growths scenarios involving different inocula were examined. Biofilm growth, substrate removal and product formation were monitored throughout the experiments. Based on the oxygen consumption it was concluded...... that heterotrophs and nitrifiers co-existed with methanotrophs in the biofilm. Heterotrophic biomass grew on soluble polymers formed by the hydrolysis of dead biomass entrapped in the biofilm. Nitrifier populations developed because of the presence of ammonia in the mineral medium. Based on these experimental...... was performed on this model. It indicated that the most influential parameters were those related to the biofilm (i.e. density; solid-volume fraction; thickness). This suggests that in order to improve the model, further research regarding the biofilm structure and composition is needed....

  2. Molecular Basis for Saccharomyces cerevisiae Biofilm Development

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz

    of translation of FLO11. In conclusion, I have conducted the first global study of the genetic program for yeast biofilm formation on polystyrene. This work provide several target genes as good basis for further research of biofilm, that I believe can contribute to fields such as cell biology, genetics, system......In this study, I sought to identify genes regulating the global molecular program for development of sessile multicellular communities, also known as biofilm, of the eukaryotic microorganism, Saccharomyces cerevisiae (yeast). Yeast biofilm has a clinical interest, as biofilms can cause chronic......, but only a small subset is previously described as regulators of FLO11. These results reveal that the regulation of biofilm formation and FLO11 is even more complex than what has previously been described. I find that the molecular program for biofilm formation shares many essential components with two...

  3. The immune system vs. Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Jensen, Peter Østrup; Givskov, Michael; Bjarnsholt, Thomas

    2010-01-01

    revealed both innate as well as adaptive immune responses to biofilms. On the other hand, measures launched by biofilm bacteria to achieve protection against the various immune responses have also been demonstrated. Whether particular immune responses to biofilm infections exist remains to be firmly...... established. However, because biofilm infections are often persistent (or chronic), an odd situation appears with the simultaneous activation of both arms of the host immune response, neither of which can eliminate the biofilm pathogen, but instead, in synergy, causes collateral tissue damage. Although...... the present review on the immune system vs. biofilm bacteria is focused on Pseudomonas aeruginosa (mainly because this is the most thoroughly studied), many of the same mechanisms are also seen with biofilm infections generated by other microorganisms....

  4. Biofilm monitoring using complex permittivity.

    Energy Technology Data Exchange (ETDEWEB)

    Altman, Susan Jeanne; McGrath, Lucas K.; Dolan, Patricia L.; Yelton, William Graham

    2008-10-01

    There is strong interest in the detection and monitoring of bio-fouling. Bio-fouling problems are common in numerous water treatments systems, medical and dental apparatus and food processing equipment. Current bio-fouling control protocols are time consuming and costly. New early detection techniques to monitor bio-forming contaminates are means to enhanced efficiency. Understanding the unique dielectric properties of biofilm development, colony forming bacteria and nutrient background will provide a basis to the effectiveness of controlling or preventing biofilm growth. Dielectric spectroscopy measurements provide values of complex permittivity, {var_epsilon}*, of biofilm formation by applying a weak alternating electric field at various frequencies. The dielectric characteristic of the biofilm, {var_epsilon}{prime}, is the real component of {var_epsilon}* and measures the biofilm's unique ability to store energy. Graphically observed dependencies of {var_epsilon}{prime} to frequency indicate dielectric relaxation or dielectric dispersion behaviors that mark the particular stage of progression during the development of biofilms. In contrast, any frequency dependency of the imaginary component, {var_epsilon}{double_prime} the loss factor, is expressed as dielectric losses from the biofilm due to dipole relaxation. The tangent angle of these two component vectors is the ratio of the imaginary component to the real component, {var_epsilon}{double_prime}/{var_epsilon}{prime} and is referred to as the loss angle tangent (tan {delta}) or dielectric loss. Changes in tan {delta} are characteristic of changes in dielectric losses during various developmental stages of the films. Permittivity scans in the above figure are of biofilm growth from P. Fluorescens (10e7 CFU's at the start). Three trends are apparent from these scans, the first being a small drop in the imaginary permittivity over a 7 hours period, best seen in the Cole-Cole plot (a). The second trend

  5. Rapid identification of bacterial biofilms and biofilm wound models using a multichannel nanosensor.

    Science.gov (United States)

    Li, Xiaoning; Kong, Hao; Mout, Rubul; Saha, Krishnendu; Moyano, Daniel F; Robinson, Sandra M; Rana, Subinoy; Zhang, Xinrong; Riley, Margaret A; Rotello, Vincent M

    2014-12-23

    Identification of infectious bacteria responsible for biofilm-associated infections is challenging due to the complex and heterogeneous biofilm matrix. To address this issue and minimize the impact of heterogeneity on biofilm identification, we developed a gold nanoparticle (AuNP)-based multichannel sensor to detect and identify biofilms based on their physicochemical properties. Our results showed that the sensor can discriminate six bacterial biofilms including two composed of uropathogenic bacteria. The capability of the sensor was further demonstrated through discrimination of biofilms in a mixed bacteria/mammalian cell in vitro wound model.

  6. Biofilms in chronic infections - a matter of opportunity - monospecies biofilms in multispecies infections

    DEFF Research Database (Denmark)

    Burmølle, Mette; Thomsen, Trine Rolighed; Fazli, Mustafa

    2010-01-01

    to permanent tissue fillers and chronic wounds) both as to distribution (such as where in the wound bed) and organization (monospecies or multispecies microcolonies). We correlate these biofilm observations to observations of commensal biofilms (dental and intestine) and biofilms in natural ecosystems (soil......). The observations of the chronic biofilm infections point toward a trend of low bacterial diversity and sovereign monospecies biofilm aggregates even though the infection in which they reside are multispecies. In contrast to this, commensal and natural biofilm aggregates contain multiple species that are believed...

  7. Blue ocean leadership.

    Science.gov (United States)

    Kim, W Chan; Mauborgne, Renée

    2014-05-01

    Ten years ago, two INSEAD professors broke ground by introducing "blue ocean strategy," a new model for discovering uncontested markets that are ripe for growth. In this article, they apply their concepts and tools to what is perhaps the greatest challenge of leadership: closing the gulf between the potential and the realized talent and energy of employees. Research indicates that this gulf is vast: According to Gallup, 70% of workers are disengaged from their jobs. If companies could find a way to convert them into engaged employees, the results could be transformative. The trouble is, managers lack a clear understanding of what changes they could make to bring out the best in everyone. Here, Kim and Mauborgne offer a solution to that problem: a systematic approach to uncovering, at each level of the organization, which leadership acts and activities will inspire employees to give their all, and a process for getting managers throughout the company to start doing them. Blue ocean leadership works because the managers' "customers"-that is, the people managers oversee and report to-are involved in identifying what's effective and what isn't. Moreover, the approach doesn't require leaders to alter who they are, just to undertake a different set of tasks. And that kind of change is much easier to implement and track than changes to values and mind-sets.

  8. Postpartum Blues and Postpartum Depression

    Directory of Open Access Journals (Sweden)

    Erdem Ö et al.

    2009-09-01

    Full Text Available Postpartum blues which is seen during the postpartum period is a transient psychological state. Most of the mothers experience maternity blues in postpartum period. It remains usually unrecognized by the others. Some sensitive families can misattribute these feelings as depression. In this article, we tried to review the characteristics of maternity blues and its differences from depression. We defined depression and presented the incidence and diagnostic criteria, of major depression as well as the risk factors and clinic findings of postpartum depression. Thus, especially at primary care we aimed to prevent misdiagnosis of both maternity blues and depression

  9. Electrochemical impedance spectroscopy of biofilms

    Science.gov (United States)

    Microbial activity that leads to the formation of biofilms on process equipment can accelerate corrosion, reduce heat transfer rates, and generally decrease process efficiencies. Additional concerns arise in the food and pharma industries where product quality and safety are a high priority. Pharmac...

  10. Exploiting social evolution in biofilms

    DEFF Research Database (Denmark)

    Boyle, Kerry E; Heilmann, Silja; van Ditmarsch, Dave

    2013-01-01

    and thus, regrettably, select for resistance against their own action. A possible solution lies in targeting the mechanisms by which bacteria interact with each other within biofilms. The emerging field of microbial social evolution combines molecular microbiology with evolutionary theory to dissect...

  11. Biogenesis of Enterococcis faecium biofilms

    NARCIS (Netherlands)

    Paganelli, F.L.

    2015-01-01

    Nosocomial infections caused by Enterococcus faecium have rapidly increased worldwide and treatment options become more limited. The presence of antibiotic resistance genes and virulence factors in pathogenic E. faecium contribute to difficult-to-treat infections, frequently biofilm mediated, such a

  12. Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A.

    Science.gov (United States)

    Karygianni, L; Ruf, S; Follo, M; Hellwig, E; Bucher, M; Anderson, A C; Vach, K; Al-Ahmad, A

    2014-12-01

    Antimicrobial photodynamic therapy (APDT) has gained increased attention as an alternative treatment approach in various medical fields. However, the effect of APDT using visible light plus water-filtered infrared A (VIS + wIRA) on oral biofilms remains unexplored. For this purpose, initial and mature oral biofilms were obtained in situ; six healthy subjects wore individual upper jaw acrylic devices with bovine enamel slabs attached to their proximal sites for 2 h or 3 days. The biofilms were incubated with 100 μg ml(-1) toluidine blue O (TB) or chlorin e6 (Ce6) and irradiated with VIS + wIRA with an energy density of 200 mW cm(-2) for 5 min. After cultivation, the CFU of half of the treated biofilm samples were quantified, whereas following live/dead staining, the other half of the samples were monitored by confocal laser scanning microscopy (CLSM). TB- and Ce6-mediated APDT yielded a significant decrease of up to 3.8 and 5.7 log10 CFU for initial and mature oral biofilms, respectively. Quantification of the stained photoinactivated microorganisms confirmed these results. Overall, CLSM revealed the diffusion of the tested photosensitizers into the deepest biofilm layers after exposure to APDT. In particular, Ce6-aided APDT presented elevated permeability and higher effectiveness in eradicating 89.62% of biofilm bacteria compared to TB-aided APDT (82.25%) after 3 days. In conclusion, antimicrobial photoinactivation using VIS + wIRA proved highly potent in eradicating oral biofilms. Since APDT excludes the development of microbial resistance, it could supplement the pharmaceutical treatment of periodontitis or peri-implantitis.

  13. Hydrodynamic dispersion within porous biofilms

    KAUST Repository

    Davit, Y.

    2013-01-23

    Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher\\'s equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels\\' network; (2) the solute\\'s diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport. © 2013 American Physical Society.

  14. Chemical Biology Strategies for Biofilm Control.

    Science.gov (United States)

    Yang, Liang; Givskov, Michael

    2015-08-01

    Microbes live as densely populated multicellular surface-attached biofilm communities embedded in self-generated, extracellular polymeric substances (EPSs). EPSs serve as a scaffold for cross-linking biofilm cells and support development of biofilm architecture and functions. Biofilms can have a clear negative impact on humans, where biofilms are a common denominator in many chronic diseases in which they prime development of destructive inflammatory conditions and the failure of our immune system to efficiently cope with them. Our current assortment of antimicrobial agents cannot efficiently eradicate biofilms. For industrial applications, the removal of biofilms within production machinery in the paper and hygienic food packaging industry, cooling water circuits, and drinking water manufacturing systems can be critical for the safety and efficacy of those processes. Biofilm formation is a dynamic process that involves microbial cell migration, cell-to-cell signaling and interactions, EPS synthesis, and cell-EPS interactions. Recent progress of fundamental biofilm research has shed light on novel chemical biology strategies for biofilm control. In this article, chemical biology strategies targeting the bacterial intercellular and intracellular signaling pathways will be discussed.

  15. Dynamic interactions of neutrophils and biofilms

    Directory of Open Access Journals (Sweden)

    Josefine Hirschfeld

    2014-12-01

    Full Text Available Background: The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms. Objective/design: In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed. Results/conclusion: Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

  16. Instant BlueStacks

    CERN Document Server

    Judge, Gary

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. A fast-paced, example-based approach guide for learning BlueStacks.This book is for anyone with a Mac or PC who wants to run Android apps on their computer. Whether you want to play games that are freely available for Android but not your computer, or you want to try apps before you install them on a physical device or use it as a development tool, this book will show you how. No previous experience is needed as this is written in plain English

  17. Mycobacterium biofilms: factors involved in development, dispersal, and therapeutic strategies against biofilm-relevant pathogens.

    Science.gov (United States)

    Xiang, Xiaohong; Deng, Wanyan; Liu, Minqiang; Xie, Jianping

    2014-01-01

    Many bacteria can develop biofilm (BF), a multicellular structure largely combining bacteria and their extracellular polymeric substances (EPS). The formation of biofilm results in an alternative existence in which microbes ensure their survival in adverse environments. Biofilm-relevant infections are more persistent, resistant to most antibiotics, and more recalcitrant to host immunity. Mycobacterium tuberculosis, the causative agent of tuberculosis, can develop biofilm, though whether M. tuberculosis can form biofilm within tuberculosis patients has yet to be determined. Here, we summarize the factors involved in the development and dispersal of mycobacterial biofilms, as well as underlying regulatory factors and inhibitors against biofilm to deepen our understanding of their development and to elucidate potential novel modes of action for future antibiotics. Key factors in biofilm formation identified as drug targets represent a novel and promising avenue for developing better antibiotics.

  18. Influence of biofilm thickness on micropollutants removal in nitrifying MBBRs

    DEFF Research Database (Denmark)

    Torresi, Elena; Andersen, Henrik Rasmus; Smets, Barth F.;

    The removal of pharmaceuticals was investigated in nitrifying Moving Bed Biofilm Reactors (MBBRs) containing carriers with different biofilm thicknesses. The biofilm with the thinnest thickness was found to have the highest nitrification and biotransformation rate for some key pharmaceuticals...

  19. Novel metabolic activity indicator in Streptococcus mutans biofilms

    NARCIS (Netherlands)

    Deng, D.M.; Hoogenkamp, M.A.; ten Cate, J.M.; Crielaard, W.

    2009-01-01

    Antimicrobial resistance of micro-organisms in biofilms requires novel strategies to evaluate the efficacy of caries preventive agents in actual biofilms. Hence we investigated fluorescence intensity (FI) in Streptococcus mutans biofilms constitutively expressing green fluorescent protein (GFP). Upo

  20. Inhibition of Biofilm Formation Using Novel Nanostructured Surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Biofilms are ubiquitous in the environment. Few surfaces resist biofilm formation, most promote it. Biofilm formation poses problems in water systems as they can...

  1. The composition and compression of biofilms developed on ultrafiltration membranes determine hydraulic biofilm resistance.

    Science.gov (United States)

    Derlon, Nicolas; Grütter, Alexander; Brandenberger, Fabienne; Sutter, Anja; Kuhlicke, Ute; Neu, Thomas R; Morgenroth, Eberhard

    2016-10-01

    This study aimed at identifying how to improve the level of permeate flux stabilisation during gravity-driven membrane filtration without control of biofilm formation. The focus was therefore on understanding (i) how the different fractions of the biofilms (inorganics particles, bacterial cells, EPS matrix) influence its hydraulic resistance and (ii) how the compression of biofilms impacts its hydraulic resistance, i.e., can water head be increased to increase the level of permeate flux stabilisation. Biofilms were developed on ultrafiltration membranes at 88 and 284 cm water heads with dead-end filtration for around 50 days. A larger water head resulted in a smaller biofilm permeability (150 and 50 L m(-2) h(-1) bar(-1) for biofilms grown at 88 cm and 284 cm water head, respectively). Biofilms were mainly composed of EPS (>90% in volume). The comparison of the hydraulic resistances of biofilms to model fouling layers indicated that most of the hydraulic resistance is due to the EPS matrix. The compressibility of the biofilm was also evaluated by subjecting the biofilms to short-term (few minutes) and long-term variations of transmembrane pressures (TMP). A sudden change of TMP resulted in an instantaneous and reversible change of biofilm hydraulic resistance. A long-term change of TMP induced a slow change in the biofilm hydraulic resistance. Our results demonstrate that the response of biofilms to a TMP change has two components: an immediate variation of resistance (due to compression/relaxation) and a long-term response (linked to biofilm adaptation/growth). Our results provide relevant information about the relationship between the operating conditions in terms of TMP, the biofilm structure and composition and the resulting biofilm hydraulic resistance. These findings have practical implications for a broad range of membrane systems.

  2. How Staphylococcus aureus biofilms develop their characteristic structure

    OpenAIRE

    Periasamy, Saravanan; Joo, Hwang-Soo; Anthony C. Duong; Bach, Thanh-Huy L.; Tan, Vee Y.; Chatterjee, Som S; Cheung, Gordon Y. C.; Otto, Michael

    2012-01-01

    Biofilms cause significant problems in the environment and during the treatment of infections. However, the molecular mechanisms underlying biofilm formation are poorly understood. There is a particular lack of knowledge about biofilm maturation processes, such as biofilm structuring and detachment, which are deemed crucial for the maintenance of biofilm viability and the dissemination of cells from a biofilm. Here, we identify the phenol-soluble modulin (PSM) surfactant peptides as key biofi...

  3. Innovative Strategies to Overcome Biofilm Resistance

    Directory of Open Access Journals (Sweden)

    Aleksandra Taraszkiewicz

    2013-01-01

    Full Text Available We review the recent literature concerning the efficiency of antimicrobial photodynamic inactivation toward various microbial species in planktonic and biofilm cultures. The review is mainly focused on biofilm-growing microrganisms because this form of growth poses a threat to chronically infected or immunocompromised patients and is difficult to eradicate from medical devices. We discuss the biofilm formation process and mechanisms of its increased resistance to various antimicrobials. We present, based on data in the literature, strategies for overcoming the problem of biofilm resistance. Factors that have potential for use in increasing the efficiency of the killing of biofilm-forming bacteria include plant extracts, enzymes that disturb the biofilm structure, and other nonenzymatic molecules. We propose combining antimicrobial photodynamic therapy with various antimicrobial and antibiofilm approaches to obtain a synergistic effect to permit efficient microbial growth control at low photosensitizer doses.

  4. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  5. Mucosal biofilm detection in chronic otitis media

    DEFF Research Database (Denmark)

    Wessman, Marcus; Bjarnsholt, Thomas; Eickhardt-Sørensen, Steffen Robert

    2015-01-01

    The objectives of this study were to examine middle ear biopsies from Greenlandic patients with chronic otitis media (COM) for the presence of mucosal biofilms and the bacteria within the biofilms. Thirty-five middle ear biopsies were obtained from 32 Greenlandic COM patients admitted to ear...... of the patients served as controls. PNA-FISH showed morphological signs of biofilms in 15 out of 35 (43 %) middle ear biopsies. In the control skin biopsies, there were signs of biofilms in eight out of 23 biopsies (30 %), probably representing skin flora. PCR and 16s sequencing detected bacteria in seven out...... of 20 (35 %) usable middle ear biopsies, and in two out of ten (20 %) usable control samples. There was no association between biofilm findings and PCR and 16s sequencing. Staphylococci were the most common bacteria in bacterial culture. We found evidence of bacterial biofilms in 43 % of middle ear...

  6. [Biofilms and their significance in medical microbiology].

    Science.gov (United States)

    Cernohorská, L; Votava, M

    2002-11-01

    Microorganisms are able to adhere to various surfaces and to form there a three-dimensional structure known as biofilm. In biofilms, microbial cells show characteristics and behaviours different from those of plankton cells. Intercellular signalizations of the quorum-sensing type regulate interaction between members of the biofilm. Bacteria embedded in the biofilm can escape and form well known planktonic forms, that are obviously only a part of the bacterial life cycle. Bacteria adhere also to medically important surfaces such as catheters, either urinary or intravenous ones, artificial heart valves, orthopedic implants and so on and contribute to device-related infections like cystitis, catheter-related sepsis, endocarditis etc. Once a biofilm has been established on a surface, the bacteria harboured inside are less exposed to the host's immune response and less susceptible to antibiotics. As an important cause of nosocomial infections the biofilm must remain in the centre of the microbiologist's attention.

  7. Microbial biofilms: biosurfactants as antibiofilm agents.

    Science.gov (United States)

    Banat, Ibrahim M; De Rienzo, Mayri A Díaz; Quinn, Gerry A

    2014-12-01

    Current microbial inhibition strategies based on planktonic bacterial physiology have been known to have limited efficacy on the growth of biofilm communities. This problem can be exacerbated by the emergence of increasingly resistant clinical strains. All aspects of biofilm measurement, monitoring, dispersal, control, and inhibition are becoming issues of increasing importance. Biosurfactants have merited renewed interest in both clinical and hygienic sectors due to their potential to disperse microbial biofilms in addition to many other advantages. The dispersal properties of biosurfactants have been shown to rival those of conventional inhibitory agents against bacterial and yeast biofilms. This makes them suitable candidates for use in new generations of microbial dispersal agents and for use as adjuvants for existing microbial suppression or eradication strategies. In this review, we explore aspects of biofilm characteristics and examine the contribution of biologically derived surface-active agents (biosurfactants) to the disruption or inhibition of microbial biofilms.

  8. Artificial biofilms establish the role of matrix interactions in staphylococcal biofilm assembly and disassembly.

    Science.gov (United States)

    Stewart, Elizabeth J; Ganesan, Mahesh; Younger, John G; Solomon, Michael J

    2015-08-14

    We demonstrate that the microstructural and mechanical properties of bacterial biofilms can be created through colloidal self-assembly of cells and polymers, and thereby link the complex material properties of biofilms to well understood colloidal and polymeric behaviors. This finding is applied to soften and disassemble staphylococcal biofilms through pH changes. Bacterial biofilms are viscoelastic, structured communities of cells encapsulated in an extracellular polymeric substance (EPS) comprised of polysaccharides, proteins, and DNA. Although the identity and abundance of EPS macromolecules are known, how these matrix materials interact with themselves and bacterial cells to generate biofilm morphology and mechanics is not understood. Here, we find that the colloidal self-assembly of Staphylococcus epidermidis RP62A cells and polysaccharides into viscoelastic biofilms is driven by thermodynamic phase instability of EPS. pH conditions that induce phase instability of chitosan produce artificial S. epidermidis biofilms whose mechanics match natural S. epidermidis biofilms. Furthermore, pH-induced solubilization of the matrix triggers disassembly in both artificial and natural S. epidermidis biofilms. This pH-induced disassembly occurs in biofilms formed by five additional staphylococcal strains, including three clinical isolates. Our findings suggest that colloidal self-assembly of cells and matrix polymers produces biofilm viscoelasticity and that biofilm control strategies can exploit this mechanism.

  9. Penetration of erythromycin through Staphylococcus epidermidis biofilm

    Institute of Scientific and Technical Information of China (English)

    LIN Mao-hu; HE Lei; GAO Jie; LIU Yun-xi; SUO Ji-jiang; XING Yu-bin; JIA Ning

    2013-01-01

    Background The catheter related infection caused by Staphylococcus epiderrnidis biofilm is increasing and difficult to treat by antimicrobial chemotherapy.The properties of biofilms that give rise to antibiotic resistance are only partially understood.This study aimed to elucidate the penetration of erythromycin through Staphylococcus epidermidis biofilm.Methods The penetration ratio of erythromycin through Staphylococcus epidermidis biofilms of 1457,1457-msrA,and wild isolate S68 was detected by biofilm penetration model at different time points according to the standard regression curve.The RNNDNA ratio and the cell density within the biofilms were observed by confocal laser microscope and transmission electromicroscope,respectively.Results The penetration ratios of erythromycin through the biofilms of 1457,1457-msrA,and S68 after cultivation for 36 hours were 0.93,0.55 and 0.4,respectively.The erythromycin penetration ratio through 1457 biofilm (0.58 after 8 hours)was higher than that through the other two (0.499 and 0.31 after 24 hours).Lower growth rate of the cells in biofilm was shown,with reduction of RNA/DNA proportion observed by confocal laser microscope through acridine orange stain.Compared with the control group observed by transmission electrmicroscope,the cell density of biofilm air face was lower than that of agar face,with more cell debris.Conclusions Erythromycin could penetrate to the Staphylococcus epidermidis biofilm,but could not kill the cells thoroughly.The lower growth rate of the cells within biofilm could help decreasing the erythromycin susceptibility.

  10. Polymicrobial biofilms by diabetic foot clinical isolates.

    Science.gov (United States)

    Mottola, Carla; Mendes, João J; Cristino, José Melo; Cavaco-Silva, Patrícia; Tavares, Luís; Oliveira, Manuela

    2016-01-01

    Diabetes mellitus is a major chronic disease that continues to increase significantly. One of the most important and costly complications of diabetes is foot ulceration that may be colonized by pathogenic and antimicrobial resistant bacteria, which may express several virulence factors that could impair treatment success. These bacterial communities can be organized in polymicrobial biofilms, which may be responsible for diabetic foot ulcer (DFU) chronicity. We evaluated the influence of polymicrobial communities in the ability of DFU isolates to produce biofilm, using a microtiter plate assay and a multiplex fluorescent in situ hybridization, at three time points (24, 48, 72 h), after evaluating biofilm formation by 95 DFU isolates belonging to several bacterial genera (Staphylococcus, Corynebacterium, Enterococcus, Pseudomonas and Acinetobacter). All isolates were biofilm-positive at 24 h, and the amount of biofilm produced increased with incubation time. Pseudomonas presented the higher biofilm production, followed by Corynebacterium, Acinetobacter, Staphylococcus and Enterococcus. Significant differences were found in biofilm formation between the three time points. Polymicrobial communities produced higher biofilm values than individual species. Pseudomonas + Enterococcus, Acinetobacter + Staphylococcus and Corynebacterium + Staphylococcus produced higher biofilm than the ones formed by E. faecalis + Staphylococcus and E. faecalis + Corynebacterium. Synergy between bacteria present in dual or multispecies biofilms has been described, and this work represents the first report on time course of biofilm formation by polymicrobial communities from DFUs including several species. The biological behavior of different bacterial species in polymicrobial biofilms has important clinical implications for the successful treatment of these infections.

  11. Antibiotic tolerance and resistance in biofilms

    DEFF Research Database (Denmark)

    Ciofu, Oana; Tolker-Nielsen, Tim

    2010-01-01

    One of the most important features of microbial biofilms is their tolerance to antimicrobial agents and components of the host immune system. The difficulty of treating biofilm infections with antibiotics is a major clinical problem. Although antibiotics may decrease the number of bacteria...... in biofilms, they will not completely eradicate the bacteria in vivo which may have important clinical consequences in form of relapses of the infection....

  12. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Science.gov (United States)

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp.

  13. Growing and Analyzing Biofilms in Flow Chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic...... conditions, and the environment can be carefully controlled and easily changed. The protocols in this unit include construction of the flow chamber and the bubble trap, assembly and sterilization of the flow chamber system, inoculation of the flow chambers, running of the system, image capture and analysis...

  14. Focus on the physics of biofilms

    Science.gov (United States)

    Lecuyer, Sigolene; Stocker, Roman; Rusconi, Roberto

    2015-03-01

    Bacteria are the smallest and most abundant form of life. They have traditionally been considered as primarily planktonic organisms, swimming or floating in a liquid medium, and this view has shaped many of the approaches to microbial processes, including for example the design of most antibiotics. However, over the last few decades it has become clear that many bacteria often adopt a sessile, surface-associated lifestyle, forming complex multicellular communities called biofilms. Bacterial biofilms are found in a vast range of environments and have major consequences on human health and industrial processes, from biofouling of surfaces to the spread of diseases. Although the study of biofilms has been biologists’ territory for a long time, a multitude of phenomena in the formation and development of biofilms hinges on physical processes. We are pleased to present a collection of research papers that discuss some of the latest developments in many of the areas to which physicists can contribute a deeper understanding of biofilms, both experimentally and theoretically. The topics covered range from the influence of physical environmental parameters on cell attachment and subsequent biofilm growth, to the use of local probes and imaging techniques to investigate biofilm structure, to the development of biofilms in complex environments and the modeling of colony morphogenesis. The results presented contribute to addressing some of the major challenges in microbiology today, including the prevention of surface contamination, the optimization of biofilm disruption methods and the effectiveness of antibiotic treatments.

  15. In situ rheology of yeast biofilms.

    Science.gov (United States)

    Brugnoni, Lorena I; Tarifa, María C; Lozano, Jorge E; Genovese, Diego

    2014-01-01

    The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p rheology and contribute to a thin body of knowledge about fungal biofilm formation.

  16. Growing and analyzing biofilms in flow chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic...... conditions, and the environment can be carefully controlled and easily changed. The protocols in this unit include construction of the flow chamber and the bubble trap, assembly and sterilization of the flow chamber system, inoculation of the flow chambers, running of the system, image capture and analysis...

  17. Biofilm responses to marine fish farm wastes

    Energy Technology Data Exchange (ETDEWEB)

    Sanz-Lazaro, Carlos, E-mail: carsanz@um.es [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100 Murcia (Spain); Navarrete-Mier, Francisco; Marin, Arnaldo [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100 Murcia (Spain)

    2011-03-15

    The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. - Research highlights: > Biofilms can act as a trophic pathway of fish farm dissolved wastes. > Biofilms are reliable tools for monitoring fish farm dissolved wastes. > The influence of the fish farm dissolved wastes can be detected 120-350 m from farm. - Under the influence of fish farming biofilm accumulates organic carbon, nutrients, selenium and metals, regardless of the structure and trophic niche of the community.

  18. Microbial biofilms: from ecology to molecular genetics.

    Science.gov (United States)

    Davey, M E; O'toole, G A

    2000-12-01

    Biofilms are complex communities of microorganisms attached to surfaces or associated with interfaces. Despite the focus of modern microbiology research on pure culture, planktonic (free-swimming) bacteria, it is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces. Furthermore, these microbial communities are often composed of multiple species that interact with each other and their environment. The determination of biofilm architecture, particularly the spatial arrangement of microcolonies (clusters of cells) relative to one another, has profound implications for the function of these complex communities. Numerous new experimental approaches and methodologies have been developed in order to explore metabolic interactions, phylogenetic groupings, and competition among members of the biofilm. To complement this broad view of biofilm ecology, individual organisms have been studied using molecular genetics in order to identify the genes required for biofilm development and to dissect the regulatory pathways that control the plankton-to-biofilm transition. These molecular genetic studies have led to the emergence of the concept of biofilm formation as a novel system for the study of bacterial development. The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced our understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis of biofilm development.

  19. Electroactive biofilms of sulphate reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cordas, Cristina M.; Guerra, L. Tiago; Xavier, Catarina [Requimte-CQFB, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Moura, Jose J.G. [Requimte-CQFB, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)], E-mail: jose.moura@dq.fct.unl.pt

    2008-12-01

    Biofilms formed from a pure strain of Desulfovibrio desulfuricans 27774 on stainless steel and graphite polarised surfaces were studied. The polarisation conditions applied were -0.4 V vs. SCE for different times. A cathodic current related with the biofilms growth was observed with a maximum intensity of -270 mA m{sup -2} that remained stable for several days using graphite electrodes. These sulphate reducing bacteria biofilms present electrocatalytic activity towards hydrogen and oxygen reduction reactions. Electrode polarisation has a selective effect on the catalytic activity. The biofilms were also observed by scanning electronic microscopy revealing the formation of homogeneous films on the surfaces.

  20. The clinical impact of bacterial biofilms

    DEFF Research Database (Denmark)

    Høiby, Niels; Ciofu, Oana; Johansen, Helle Krogh

    2011-01-01

    . Bacterial biofilms are resistant to antibiotics, disinfectant chemicals and to phagocytosis and other components of the innate and adaptive inflammatory defense system of the body. It is known, for example, that persistence of staphylococcal infections related to foreign bodies is due to biofilm formation...... and increased doubling times. These more or less dormant cells are therefore responsible for some of the tolerance to antibiotics. Biofilm growth is associated with an increased level of mutations. Bacteria in biofilms communicate by means of molecules, which activates certain genes responsible for production...

  1. Biofilm formation in Acinetobacter baumannii.

    Science.gov (United States)

    Longo, Francesca; Vuotto, Claudia; Donelli, Gianfranco

    2014-04-01

    Acinetobacter baumannii has received much attention in recent years because of its increasing involvement in a number of severe infections and outbreaks occurring in clinical settings, and presumably related to its ability to survive and persist in hospital environments. The treatment of infections caused by A. baumannii nosocomial strains has become increasingly problematic, due to their intrinsic and/or acquired resistance to multiple classes of antibiotics. Furthermore, the demonstrated ability of nosocomial strains to grow as biofilm is believed to play a significant role in their persistence and antibiotic resistance. This review summarises current knowledge on A. baumannii biofilm formation and its clinical significance, as well as the related genetic determinants and the regulation of this process.

  2. Antimicrobial and biofilm inhibiting diketopiperazines.

    Science.gov (United States)

    de Carvalho, M P; Abraham, W-R

    2012-01-01

    Diketopiperazines are the smallest cyclic peptides known. 90% of Gram-negative bacteria produce diketopiperazines and they have also been isolated from Gram-positive bacteria, fungi and higher organisms. Biosynthesis of cyclodipeptides can be achieved by dedicated nonribosomal peptide synthetases or by a novel type of synthetases named cyclopeptide synthases. Since the first report in 1924 a large number of bioactive diketopiperazines was discovered spanning activities as antitumor, antiviral, antifungal, antibacterial, antiprion, antihyperglycemic or glycosidase inhibitor agents. As infections are of increasing concern for human health and resistances against existing antibiotics are growing this review focuses on the antimicrobial activities of diketopiperazines. The antibiotic bicyclomycin is a diketopiperazine and structure activity studies revealed the unique nature of this compound which was finally developed for clinical applications. The antimicrobial activities of a number of other diketopiperazines along with structure activity relationships are discussed. Here a special focus is on the activity-toxicity problem of many compounds setting tight limitations to their application as drugs. Not only these classical antimicrobial activities but also proposed action in modulating bacterial communication as a new target to control biofilms will be evaluated. Pathogens organized in biofilms are difficult to eradicate because of the increase of their tolerance for antibiotics for several orders. Diketopiperazines were reported to modulate LuxR-mediated quorum-sensing systems of bacteria, and they are considered to influence cell-cell signaling offering alternative ways of biofilm control by interfering with microbial communication. Concluding the review we will finally discuss the potential of diketopiperazines in the clinic to erase biofilm infections.

  3. Blue moons and Martian sunsets.

    Science.gov (United States)

    Ehlers, Kurt; Chakrabarty, Rajan; Moosmüller, Hans

    2014-03-20

    The familiar yellow or orange disks of the moon and sun, especially when they are low in the sky, and brilliant red sunsets are a result of the selective extinction (scattering plus absorption) of blue light by atmospheric gas molecules and small aerosols, a phenomenon explainable using the Rayleigh scattering approximation. On rare occasions, dust or smoke aerosols can cause the extinction of red light to exceed that for blue, resulting in the disks of the sun and moon to appear as blue. Unlike Earth, the atmosphere of Mars is dominated by micron-size dust aerosols, and the sky during sunset takes on a bluish glow. Here we investigate the role of dust aerosols in the blue Martian sunsets and the occasional blue moons and suns on Earth. We use the Mie theory and the Debye series to calculate the wavelength-dependent optical properties of dust aerosols most commonly found on Mars. Our findings show that while wavelength selective extinction can cause the sun's disk to appear blue, the color of the glow surrounding the sun as observed from Mars is due to the dominance of near-forward scattering of blue light by dust particles and cannot be explained by a simple, Rayleigh-like selective extinction explanation.

  4. Magnetic fields suppress Pseudomonas aeruginosa biofilms and enhance ciprofloxacin activity.

    Science.gov (United States)

    Bandara, H M H N; Nguyen, D; Mogarala, S; Osiñski, M; Smyth, H D C

    2015-01-01

    Due to the refractory nature of pathogenic microbial biofilms, innovative biofilm eradication strategies are constantly being sought. Thus, this study addresses a novel approach to eradicate Pseudomonas aeruginosa biofilms. Magnetic nanoparticles (MNP), ciprofloxacin (Cipro), and magnetic fields were systematically evaluated in vitro for their relative anti-biofilm contributions. Twenty-four-hour biofilms exposed to aerosolized MNPs, Cipro, or a combination of both, were assessed in the presence or absence of magnetic fields (Static one-sided, Static switched, Oscillating, Static + oscillating) using changes in bacterial metabolism, biofilm biomass, and biofilm imaging. The biofilms exposed to magnetic fields alone exhibited significant metabolic and biomass reductions (p biofilms were treated with a MNP/Cipro combination, the most significant metabolic and biomass reductions were observed when exposed to static switched magnetic fields (p biofilms to a static switched magnetic field alone, or co-administration with MNP/Cipro/MNP + Cipro appears to be a promising approach to eradicate biofilms of this bacterium.

  5. Molecular methods for biofilms

    KAUST Repository

    Ferrera, Isabel

    2014-08-30

    at the same time and to compare bacterial communities among different samples or in a single sample after certain treatments. DGGE, T-RFLP and ARISA share similar steps but require different materials and equipment. The three methods involve (i) sampling of the biofilms; (ii) DNA extraction and quantification; and (iii) PCR using specific primers. Metagenomics: This chapter focuses classical and next-generation metagenomics methods. These are limited to bacterial artificial chromosome (BAC) and Fosmid libraries and Sanger and next-generation 454 sequencing, as these methods are currently the most frequently used in research. The chapter discusses the special handling of deoxyribonucleic acid (DNA) needed to construct BAC and Fosmid libraries from marine water samples. It also briefly addresses the related topics of library archiving, databasing, and screening. The chapter provides a high-level overview of the special handling methods required to prepare DNA for BAC library construction. No special handling is needed for Fosmid library construction.

  6. Blue Man袭东京

    Institute of Scientific and Technical Information of China (English)

    Naomi Saeki; 李宝怡

    2008-01-01

    <正>20年前在美国曼克顿风靡一时的Blue Man Group,最近在东京出现,马上成为城中话题。在东京,每年有不少舞台剧演出,但是像Blue Man Group这样备受注目的,近年罕见。Blue Man Group in Tokyo于上年12月开始公演·1个月的门票早在9月中旬

  7. Protein-based biofilm matrices in Staphylococci

    Directory of Open Access Journals (Sweden)

    Pietro eSpeziale

    2014-12-01

    Full Text Available Staphylococcus aureus and Staphylococcus epidermidis are the most important etiological agents of biofilm associated-infections on indwelling medical devices. Biofilm infections may also develop independently of indwelling devices, e.g. in native valve endocarditis, bone tissue and open wounds. After attachment to tissue or indwelling medical devices that have been conditioned with host plasma proteins, staphylococcal biofilms grow and produce a specific environment which provides the conditions for cell-cell interaction and formation of multicellular communities. Bacteria living in biofilms express a variety of macromolecules, including exopolysaccharides, proteins, extracellular eDNA and other polymers. The S. aureus surface protein C and G (SasC and SasG, clumping factor B (ClfB, serine aspartate repeat protein (SdrC, the biofilm-associated protein (Bap and the fibronectin/fibrinogen-binding proteins (FnBPA and FnBPB are individually implicated in biofilm matrix formation. In S. epidermidis, a protein named accumulation-associated protein (Aap contributes to both the primary attachment phase and the establishment of intercellular connections by forming fibrils on the cell surface. In S. epidermidis proteinaceous biofilm formation can also be mediated by the extracellular matrix binding protein (Embp and S. epidermidis surface protein C (SesC. Additionally, multifunctional proteins such as extracellular adherence protein (Eap and extracellular matrix protein binding protein (Emp of S. aureus and the iron-regulated surface determinant protein C (IsdC of S. lugdunensis can promote biofilm formation in iron-depleted conditions. This multitude of proteins intervene at different stages of biofilm formation with certain proteins contributing to biofilm accumulation and others mediating primary attachment to surfaces. This review examines the contribution of proteins to biofilm formation in staphylococci. The potential to develop vaccines to prevent

  8. Resistance of non-typeable Haemophilus influenzae biofilms is independent of biofilm size.

    Science.gov (United States)

    Reimche, Jennifer L; Kirse, Daniel J; Whigham, Amy S; Swords, W Edward

    2017-02-01

    The inflammatory middle ear disease known as otitis media can become chronic or recurrent in some cases due to failure of the antibiotic treatment to clear the bacterial etiological agent. Biofilms are known culprits of antibiotic-resistant infections; however, the mechanisms of resistance for non-typeable Haemophilus influenzae biofilms have not been completely elucidated. In this study, we utilized in vitro static biofilm assays to characterize clinical strain biofilms and addressed the hypothesis that biofilms with greater biomass and/or thickness would be more resistant to antimicrobial-mediated eradication than thinner and/or lower biomass biofilms. Consistent with previous studies, antibiotic concentrations required to eliminate biofilm bacteria tended to be drastically higher than concentrations required to kill planktonic bacteria. The size characterizations of the biofilms formed by the clinical isolates were compared to their minimum biofilm eradication concentrations for four antibiotics. This revealed no correlation between biofilm thickness or biomass and the ability to resist eradication by antibiotics. Therefore, we concluded that biofilm size does not play a role in antibiotic resistance, suggesting that reduction of antibiotic penetration may not be a significant mechanism for antibiotic resistance for this bacterial opportunist.

  9. Subinhibitory concentrations of azithromycin decrease nontypeable Haemophilus influenzae biofilm formation and Diminish established biofilms.

    Science.gov (United States)

    Starner, Timothy D; Shrout, Joshua D; Parsek, Matthew R; Appelbaum, Peter C; Kim, GunHee

    2008-01-01

    Nontypeable Haemophilus influenzae (NTHi) commonly causes otitis media, chronic bronchitis in emphysema, and early airway infections in cystic fibrosis. Long-term, low-dose azithromycin has been shown to improve clinical outcomes in chronic lung diseases, although the mechanism of action remains unclear. The inhibition of bacterial biofilms by azithromycin has been postulated to be one mechanism mediating these effects. We hypothesized that subinhibitory concentrations of azithromycin would affect NTHi biofilm formation. Laboratory strains of NTHi expressing green fluorescent protein and azithromycin-resistant clinical isolates were grown in flow-cell and static-culture biofilm models. Using a range of concentrations of azithromycin and gentamicin, we measured the degree to which these antibiotics inhibited biofilm formation and persistence. Large biofilms formed over 2 to 4 days in a flow cell, displaying complex structures, including towers and channels. Subinhibitory concentrations of azithromycin significantly decreased biomass and maximal thickness in both forming and established NTHi biofilms. In contrast, subinhibitory concentrations of gentamicin had no effect on biofilm formation. Furthermore, established NTHi biofilms became resistant to gentamicin at concentrations far above the MIC. Biofilm formation of highly resistant clinical NTHi isolates (azithromycin MIC of > 64 microg/ml) was similarly decreased at subinhibitory azithromycin concentrations. Clinically obtainable azithromycin concentrations inhibited biofilms in all but the most highly resistant isolates. These data show that subinhibitory concentrations of azithromycin have antibiofilm properties, provide mechanistic insights, and supply an additional rationale for the use of azithromycin in chronic biofilm infections involving H. influenzae.

  10. Reliability of Haemophilus influenzae biofilm measurement via static method, and determinants of in vitro biofilm production.

    Science.gov (United States)

    Obaid, Najla A; Tristram, Stephen; Narkowicz, Christian K; Jacobson, Glenn A

    2016-12-01

    Information is lacking regarding the precision of microtitre plate (MTP) assays used to measure biofilm. This study investigated the precision of an MTP assay to measure biofilm production by nontypeable Haemophilus influenzae (NTHi) and the effects of frozen storage and inoculation technique on biofilm production. The density of bacterial final growth was determined by absorbance after 18-20 h incubation, and biofilm production was then measured by absorbance after crystal violet staining. Biofilm formation was categorised as high and low for each strain. For the high biofilm producing strains of NTHi, interday reproducibility of NTHi biofilm formation measured using the MTP assay was excellent and met the acceptance criteria, but higher variability was observed in low biofilm producers. Method of inoculum preparation was a determinant of biofilm formation with inoculum prepared directly from solid media showing increased biofilm production for at least one of the high producing strains. In general, storage of NTHi cultures at -80 °C for up to 48 weeks did not have any major effect on their ability to produce biofilm.

  11. Physics of biofilms: the initial stages of biofilm formation and dynamics

    Science.gov (United States)

    Lambert, Guillaume; Bergman, Andrew; Zhang, Qiucen; Bortz, David; Austin, Robert

    2014-04-01

    One of the physiological responses of bacteria to external stress is to assemble into a biofilm. The formation of a biofilm greatly increases a bacterial population's resistance to a hostile environment by shielding cells, for example, from antibiotics. In this paper, we describe the conditions necessary for the emergence of biofilms in natural environments and relate them to the emergence of biofilm formation inside microfluidic devices. We show that competing species of Escherichia coli bacteria form biofilms to spatially segregate themselves in response to starvation stress, and use in situ methods to characterize the physical properties of the biofilms. Finally, we develop a microfluidic platform to study the inter-species interactions and show how biofilm-mediated genetic interactions can improve a species’ resistance to external stress.

  12. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.

    2004-01-01

    Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced by Pseudomonas aeruginosa strain PAO1 and its alginate......-overproducing (mucA22) and alginate-defective (algD) variants in order to discern the role of alginate in biofilm formation. These strains, PAO1, Alg(+) PAOmucA22 and Alg(-) PAOalgD, tagged with green fluorescent protein, were grown in a continuous flow cell system to characterize the developmental cycles...... of their biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...

  13. China Mobile: Expanding "Blue Ocean"

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Driving force is crucial for realizing high-speed growth. The strong driving force from "Blue Ocean Strategy" is an important advantage for China Mobile to realize harmonious and leap-forward development.

  14. Karner Blue Butterfly Recovery Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This recovery plan has been prepared by the Karner Blue Butterfly Recovery Team under the leadership of Dr. David Andow, University of Minnesota-St. Paul. Dr. John...

  15. Ecology of blue straggler stars

    CERN Document Server

    Carraro, Giovanni; Beccari, Giacomo

    2015-01-01

    The existence of blue straggler stars, which appear younger, hotter, and more massive than their siblings, is at odds with a simple picture of stellar evolution. Such stars should have exhausted their nuclear fuel and evolved long ago to become cooling white dwarfs. They are found to exist in globular clusters, open clusters, dwarf spheroidal galaxies of the Local Group, OB associations and as field stars. This book summarises the many advances in observational and theoretical work dedicated to blue straggler stars. Carefully edited extended contributions by well-known experts in the field cover all the relevant aspects of blue straggler stars research: Observations of blue straggler stars in their various environments; Binary stars and formation channels; Dynamics of globular clusters; Interpretation of observational data and comparison with models. The book also offers an introductory chapter on stellar evolution written by the editors of the book.

  16. Synergistic effects in mixed Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Reisner, A.; Holler, B.M.; Molin, Søren

    2006-01-01

    the pathways governing development of more complex heterogeneous communities. In this study, we established a laboratory model where biofilm-stimulating effects due to interactions between genetically diverse strains of Escherichia coli were monitored. Synergistic induction of biofilm formation resulting from...

  17. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    In this study we report on a novel structural phenotype in Escherichia coli biofilms: cellular chain formation. Biofilm chaining in E. coli K-12 was found to occur primarily by clonal expansion, but was not due to filamentous growth. Rather, chain formation was the result of intercellular...

  18. The 'Swiss cheese' instability of bacterial biofilms

    CERN Document Server

    Jang, Hongchul; Stocker, Roman

    2012-01-01

    We demonstrate a novel pattern that results in bacterial biofilms as a result of the competition between hydrodynamic forces and adhesion forces. After the passage of an air plug, the break up of the residual thin liquid film scrapes and rearranges bacteria on the surface, such that a Swiss cheese pattern of holes is left in the residual biofilm.

  19. Biofilms: The Stronghold of Legionella pneumophila

    Directory of Open Access Journals (Sweden)

    Mena Abdel-Nour

    2013-10-01

    Full Text Available Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.

  20. Dental diagnostics: molecular analysis of oral biofilms.

    Science.gov (United States)

    Hiyari, Sarah; Bennett, Katie M

    2011-01-01

    Dental biofilms are complex, multi-species bacterial communities that colonize the mouth in the form of plaque and are known to cause dental caries and periodontal disease. Biofilms are unique from planktonic bacteria in that they are mutualistic communities with a 3-dimensional structure and complex nutritional and communication pathways. The homeostasis within the biofilm colony can be disrupted, causing a shift in the bacterial composition of the colony and resulting in proliferation of pathogenic species. Because of this dynamic lifestyle, traditional microbiological techniques are inadequate for the study of biofilms. Many of the bacteria present in the oral cavity are viable but not culturable, which severely limits laboratory analysis. However, with the advent of new molecular techniques, the microbial makeup of oral biofilms can be better identified. Some of these techniques include DNA-DNA hybridization, 16S rRNA gene sequencing, denaturing gradient gel electrophoresis, terminal restriction fragment length polymorphism, denaturing high-performance liquid chromatography and pyrosequencing. This review provides an overview of biofilm formation and examines the major molecular techniques currently used in oral biofilm analysis. Future applications of the molecular analysis of oral biofilms in the diagnosis and treatment of caries and periodontal disease are also discussed.

  1. Spaceflight promotes biofilm formation by Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Wooseong Kim

    Full Text Available Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.

  2. Biofilm ved kronisk rhinosinuitis og cystisk fibrose

    DEFF Research Database (Denmark)

    Fisker, Jacob; Buchwald, Christian von; Johansen, Helle Krogh

    2011-01-01

    Microbial biofilms are known to cause persistent foreign-body infections and have recently been acknowledged as involved in more than 65% of all human infections. Microbial biofilms have been detected in chronic rhinosinusitis, and chronic rhinosinusitis is mandatory in patients with cystic...

  3. Screening of Compounds against Gardnerella vaginalis Biofilms.

    Directory of Open Access Journals (Sweden)

    Cornelia Gottschick

    Full Text Available Bacterial vaginosis (BV is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of compounds for their ability to prevent biofilm formation and to resolve an existing G. vaginalis biofilm. The antibiotics metronidazole and tobramycin were highly effective in preventing biofilm formation, but had no effect on an established biofilm. The application of the amphoteric tenside sodium cocoamphoacetate (SCAA led to disintegration of existing biofilms, reducing biomass by 51% and viability by 61% and it was able to increase the effect of metronidazole by 40% (biomass and 61% (viability. Our data show that attacking the biofilm and the bacterial cells by the combination of an amphoteric tenside with the antibiotic metronidazole might be a useful strategy against BV.

  4. Ciliates as engineers of phototrophic biofilms.

    NARCIS (Netherlands)

    Weerman, E.J.; Geest, H.G.; Meulen, M.D.; Manders, E.M.M.; Van de Koppel, J.; Herman, P.M.J.; Admiraal, W.

    2011-01-01

    1.Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the ‘engineering’ effects

  5. Ciliates as engineers of phototrophic biofilms.

    NARCIS (Netherlands)

    Weerman, E.J.; van der Geest, H.G.; van der Meulen, M.D; Manders, E.M.M.; van de Koppel, J.; Herman, P.M.J.; Admiraal, W.

    2011-01-01

    1. Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the ‘engineering’ effect

  6. Introduction to Biofilms Thematic Minireview Series.

    Science.gov (United States)

    Allewell, Norma M

    2016-06-10

    The biofilms that many bacteria and fungi produce enable them to form communities, adhere tightly to surfaces, evade host immunity, and resist antibiotics. Pathogenic microorganisms that form biofilms are very difficult to eradicate and thus are a frequent source of life-threatening, hospital-acquired infections. This series of five minireviews from the Journal of Biological Chemistry provides a broad overview of our current understanding of biofilms and the challenges that remain. The structure, biosynthesis, and biological function of the biofilms produced by pathogenic fungi are the subject of the first article, by Sheppard and Howell. Gunn, Bakaletz, and Wozniak focus on the biochemistry and structure of bacterial biofilms, how these structures enable bacteria to evade host immunity, and current and developing strategies for overcoming this resistance. The third and fourth articles present two of the best understood cell signaling pathways involved in biofilm formation. Valentini and Filloux focus on cyclic di-GMP, while Kavanaugh and Horswill discuss the quorum-sensing (agr) system and the relationship between quorum sensing and biofilm formation. Mechanisms of antibiotic resistance, particularly the role of efflux pumps and the development of persister cells, are the topics of the final article by Van Acker and Coenye. The advances described in this series guarantee that ongoing interdisciplinary and international efforts will lead to new insights into the basic biology of biofilm formation, as well as new strategies for therapeutic interventions.

  7. Pseudomonas biofilms: possibilities of their control.

    Science.gov (United States)

    Masák, Jan; Čejková, Alena; Schreiberová, Olga; Rezanka, Tomáš

    2014-07-01

    Genus Pseudomonas includes a large number of species that can be encountered in biotechnological processes as well as in the role of serious human or plant pathogens. Pseudomonads easily form biofilms on various types of surfaces. The biofilm phenotype is characterized by an increased resistance to environmental influences including resistance to antibiotics and other disinfectants, causing a number of problems in health care, food industry, and other areas. Considerable attention is therefore paid to the possibilities of eradication/destruction of pseudomonads biofilms both in terms of understanding the mechanisms of biofilm formation and at the level of finding suitable antibiofilm tools applicable in practice. The first part of this review is devoted to an overview of the regulatory mechanisms that are directly or indirectly involved in the formation of biofilm. The most effective approaches to suppressing the formation of biofilm that do not cause the development of resistance are based on the application of substances that interfere with the regulatory molecules or block the appropriate regulatory mechanisms involved in biofilm development by the cells. Pseudomonads biofilm formation is, similar to other microorganisms, a sophisticated process with many regulatory elements. The suppression of this process therefore also requires multiple antibiofilm tools.

  8. Transferrin Impacts Bacillus thuringiensis Biofilm Levels

    Directory of Open Access Journals (Sweden)

    Bianca Garner

    2016-01-01

    Full Text Available The present study examined the impact of transferrin on Bacillus thuringiensis biofilms. Three commercial strains, an environmental strain (33679, the type strain (10792, and an isolate from a diseased insect (700872, were cultured in iron restricted minimal medium. All strains produced biofilm when grown in vinyl plates at 30°C. B. thuringiensis 33679 had a biofilm biomass more than twice the concentration exhibited by the other strains. The addition of transferrin resulted in slightly increased growth yields for 2 of the 3 strains tested, including 33679. In contrast, the addition of 50 μg/mL of transferrin resulted in an 80% decrease in biofilm levels for strain 33679. When the growth temperature was increased to 37°C, the addition of 50 μg/mL of transferrin increased culture turbidity for only strain 33679. Biofilm levels were again decreased in strain 33679 at 37°C. Growth of B. thuringiensis cultures in polystyrene resulted in a decrease in overall growth yields at 30°C, with biofilm levels significantly decreased for 33679 in the presence of transferrin. These findings demonstrate that transferrin impacts biofilm formation in select strains of B. thuringiensis. Identification of these differences in biofilm regulation may be beneficial in elucidating potential virulence mechanisms among the differing strains.

  9. Optimization and Evaluation of a Chitosan/Hydroxypropyl Methylcellulose Hydrogel Containing Toluidine Blue O for Antimicrobial Photodynamic Inactivation

    Directory of Open Access Journals (Sweden)

    Chueh-Pin Chen

    2015-09-01

    Full Text Available Photodynamic inactivation (PDI combined with chitosan has been shown as a promising antimicrobial approach. The purpose of this study was to develop a chitosan hydrogel containing hydroxypropyl methylcellulose (HPMC, chitosan and toluidine blue O (TBO to improve the bactericidal efficacy for topical application in clinics. The PDI efficacy of hydrogel was examined in vitro against the biofilms of Staphylococcus aureus (S. aureus and Pseudomonas aeruginosa (P. aeruginosa. Confocal scanning laser microscopy (CSLM was performed to investigate the penetration level of TBO into viable S. aureus biofilms. Incorporation of HMPC could increase the physicochemical properties of chitosan hydrogel including the hardness, viscosity as well as bioadhesion; however, higher HMPC concentration also resulted in reduced antimicrobial effect. CSLM analysis further demonstrated that higher HPMC concentration constrained TBO diffusion into the biofilm. The incubation of biofilm and hydrogel was further performed at an angle of 90 degrees. After light irradiation, compared to the mixture of TBO and chitosan, the hydrogel treated sample showed increased PDI efficacy indicated that incorporation of HPMC did improve antimicrobial effect. Finally, the bactericidal efficacy could be significantly augmented by prolonged retention of hydrogel in the biofilm as well as in the animal model of rat skin burn wounds after light irradiation.

  10. Optimization and Evaluation of a Chitosan/Hydroxypropyl Methylcellulose Hydrogel Containing Toluidine Blue O for Antimicrobial Photodynamic Inactivation.

    Science.gov (United States)

    Chen, Chueh-Pin; Hsieh, Chien-Ming; Tsai, Tsuimin; Yang, Jen-Chang; Chen, Chin-Tin

    2015-09-01

    Photodynamic inactivation (PDI) combined with chitosan has been shown as a promising antimicrobial approach. The purpose of this study was to develop a chitosan hydrogel containing hydroxypropyl methylcellulose (HPMC), chitosan and toluidine blue O (TBO) to improve the bactericidal efficacy for topical application in clinics. The PDI efficacy of hydrogel was examined in vitro against the biofilms of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). Confocal scanning laser microscopy (CSLM) was performed to investigate the penetration level of TBO into viable S. aureus biofilms. Incorporation of HMPC could increase the physicochemical properties of chitosan hydrogel including the hardness, viscosity as well as bioadhesion; however, higher HMPC concentration also resulted in reduced antimicrobial effect. CSLM analysis further demonstrated that higher HPMC concentration constrained TBO diffusion into the biofilm. The incubation of biofilm and hydrogel was further performed at an angle of 90 degrees. After light irradiation, compared to the mixture of TBO and chitosan, the hydrogel treated sample showed increased PDI efficacy indicated that incorporation of HPMC did improve antimicrobial effect. Finally, the bactericidal efficacy could be significantly augmented by prolonged retention of hydrogel in the biofilm as well as in the animal model of rat skin burn wounds after light irradiation.

  11. Mesoscale Elucidation of Biofilm Shear Behavior

    CERN Document Server

    Barai, Pallab; Mukherjee, Partha P

    2015-01-01

    Formation of bacterial colonies as biofilm on the surface/interface of various objects has the potential to impact not only human health and disease but also energy and environmental considerations. Biofilms can be regarded as soft materials, and comprehension of their shear response to external forces is a key element to the fundamental understanding. A mesoscale model has been presented in this article based on digitization of a biofilm microstructure. Its response under externally applied shear load is analyzed. Strain stiffening type behavior is readily observed under high strain loads due to the unfolding of chains within soft polymeric substrate. Sustained shear loading of the biofilm network results in strain localization along the diagonal direction. Rupture of the soft polymeric matrix can potentially reduce the intercellular interaction between the bacterial cells. Evolution of stiffness within the biofilm network under shear reveals two regions: a) initial increase in stiffness due to strain stiffe...

  12. Oral biofilms: emerging concepts in microbial ecology.

    Science.gov (United States)

    Filoche, S; Wong, L; Sissons, C H

    2010-01-01

    Oral biofilms develop under a range of different conditions and different environments. This review will discuss emerging concepts in microbial ecology and how they relate to oral biofilm development and the treatment of oral diseases. Clues to how oral biofilms develop may lie in other complex systems, such as interactions between host and gut microbiota, and even in factors that affect biofilm development on leaf surfaces. Most of the conditions under which oral biofilms develop are tightly linked to the overall health and biology of the host. Advances in molecular techniques have led to a greater appreciation of the diversity of human microbiota, the extent of interactions with the human host, and how that relates to inter-individual variation. As a consequence, plaque development may no longer be thought of as a generic process, but rather as a highly individualized process, which has ramifications for the treatment of the diseases it causes.

  13. Role of multicellular aggregates in biofilm formation

    DEFF Research Database (Denmark)

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin

    2016-01-01

    In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However......, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm...... initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends...

  14. The Physics of Biofilms -- An Introduction

    CERN Document Server

    Mazza, Marco G

    2016-01-01

    Biofilms are complex, self-organized consortia of microorganisms that produce a functional, protective matrix of biomolecules. Physically, the structure of a biofilm can be described as an entangled polymer network which grows and changes under the effect of gradients of nutrients, cell differentiation, quorum sensing, bacterial motion, and interaction with the environment. Its development is complex, and constantly adapting to environmental stimuli. Here, we review the fundamental physical processes the govern the inception, growth and development of a biofilm. Two important mechanisms guide the initial phase in a biofilm life cycle: (\\emph{i}) the cell motility near or at a solid interface, and (\\emph{ii}) the cellular adhesion. Both processes are crucial for initiating the colony and for ensuring its stability. A mature biofilm behaves as a viscoelastic fluid with a complex, history-dependent dynamics. We discuss progress and challenges in the determination of its physical properties. Experimental and theo...

  15. The ecology and biogeochemistry of stream biofilms.

    Science.gov (United States)

    Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

    2016-04-01

    Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

  16. Pseudomonas aeruginosa biofilms in cystic fibrosis

    DEFF Research Database (Denmark)

    Høiby, Niels; Ciofu, Oana; Bjarnsholt, Thomas

    2010-01-01

    The persistence of chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) patients is due to biofilm-growing mucoid (alginate-producing) strains. A biofilm is a structured consortium of bacteria, embedded in a self-produced polymer matrix consisting of polysaccharide, protein...... and DNA. In CF lungs, the polysaccharide alginate is the major part of the P. aeruginosa biofilm matrix. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and resist phagocytosis, as well as other components of the innate and the adaptive immune system....... As a consequence, a pronounced antibody response develops, leading to immune complex-mediated chronic inflammation, dominated by polymorphonuclear leukocytes. The chronic inflammation is the major cause of the lung tissue damage in CF. Biofilm growth in CF lungs is associated with an increased frequency...

  17. Stratified growth in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Werner, E.; Roe, F.; Bugnicourt, A.;

    2004-01-01

    In this study, stratified patterns of protein synthesis and growth were demonstrated in Pseudomonas aeruginosa biofilms. Spatial patterns of protein synthetic activity inside biofilms were characterized by the use of two green fluorescent protein (GFP) reporter gene constructs. One construct...... carried an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible gfpmut2 gene encoding a stable GFP. The second construct carried a GFP derivative, gfp-AGA, encoding an unstable GFP under the control of the growth-rate-dependent rrnBp(1) promoter. Both GFP reporters indicated that active protein...... of oxygen limitation in the biofilm. Oxygen microelectrode measurements showed that oxygen only penetrated approximately 50 mum into the biofilm. P. aeruginosa was incapable of anaerobic growth in the medium used for this investigation. These results show that while mature P. aeruginosa biofilms contain...

  18. A Subinhibitory Concentration of Clarithromycin Inhibits Mycobacterium avium Biofilm Formation

    OpenAIRE

    2004-01-01

    Mycobacterium avium causes disseminated infection in immunosuppressed individuals and lung infection in patients with chronic lung diseases. M. avium forms biofilm in the environment and possibly in human airways. Antibiotics with activity against the bacterium could inhibit biofilm formation. Clarithromycin inhibits biofilm formation but has no activity against established biofilm.

  19. Discovering Biofilms: Inquiry-Based Activities for the Classroom

    Science.gov (United States)

    Redelman, Carly V.; Marrs, Kathleen; Anderson, Gregory G.

    2012-01-01

    In nature, bacteria exist in and adapt to different environments by forming microbial communities called "biofilms." We propose simple, inquiry-based laboratory exercises utilizing a biofilm formation assay, which allows controlled biofilm growth. Students will be able to qualitatively assess biofilm growth via staining. Recently, we developed a…

  20. In vitro phenotypic differentiation towards commensal and pathogenic oral biofilms

    NARCIS (Netherlands)

    Janus, M.M.; Keijser, B.J.F.; Bikker, F.J.; Exterkate, R.A.M.; Crielaard, W.; Krom, B.P.

    2015-01-01

    Commensal oral biofilms, defined by the absence of pathology-related phenotypes, are ubiquitously present. In contrast to pathological biofilms commensal biofilms are rarely studied. Here, the effect of the initial inoculum and subsequent growth conditions on in vitro oral biofilms was studied. Biof

  1. Biofilms On Orbit and On Earth: Current Methods, Future Needs

    Science.gov (United States)

    Vega, Leticia

    2013-01-01

    Biofilms have played a significant role on the effectiveness of life support hardware on the Space Shuttle and International Space Station (ISS). This presentation will discuss how biofilms impact flight hardware, how on orbit biofilms are analyzed from an engineering and research perspective, and future needs to analyze and utilize biofilms for long duration, deep space missions.

  2. Maltodextrin enhances biofilm elimination by electrochemical scaffold.

    Science.gov (United States)

    Sultana, Sujala T; Call, Douglas R; Beyenal, Haluk

    2016-10-26

    Electrochemical scaffolds (e-scaffolds) continuously generate low concentrations of H2O2 suitable for damaging wound biofilms without damaging host tissue. Nevertheless, retarded diffusion combined with H2O2 degradation can limit the efficacy of this potentially important clinical tool. H2O2 diffusion into biofilms and bacterial cells can be increased by damaging the biofilm structure or by activating membrane transportation channels by exposure to hyperosmotic agents. We hypothesized that e-scaffolds would be more effective against Acinetobacter baumannii and Staphylococcus aureus biofilms in the presence of a hyperosmotic agent. E-scaffolds polarized at -600 mVAg/AgCl were overlaid onto preformed biofilms in media containing various maltodextrin concentrations. E-scaffold alone decreased A. baumannii and S. aureus biofilm cell densities by (3.92 ± 0.15) log and (2.31 ± 0.12) log, respectively. Compared to untreated biofilms, the efficacy of the e-scaffold increased to a maximum (8.27 ± 0.05) log reduction in A. baumannii and (4.71 ± 0.12) log reduction in S. aureus biofilm cell densities upon 10 mM and 30 mM maltodextrin addition, respectively. Overall ~55% decrease in relative biofilm surface coverage was achieved for both species. We conclude that combined treatment with electrochemically generated H2O2 from an e-scaffold and maltodextrin is more effective in decreasing viable biofilm cell density.

  3. Maltodextrin enhances biofilm elimination by electrochemical scaffold

    Science.gov (United States)

    Sultana, Sujala T.; Call, Douglas R.; Beyenal, Haluk

    2016-01-01

    Electrochemical scaffolds (e-scaffolds) continuously generate low concentrations of H2O2 suitable for damaging wound biofilms without damaging host tissue. Nevertheless, retarded diffusion combined with H2O2 degradation can limit the efficacy of this potentially important clinical tool. H2O2 diffusion into biofilms and bacterial cells can be increased by damaging the biofilm structure or by activating membrane transportation channels by exposure to hyperosmotic agents. We hypothesized that e-scaffolds would be more effective against Acinetobacter baumannii and Staphylococcus aureus biofilms in the presence of a hyperosmotic agent. E-scaffolds polarized at −600 mVAg/AgCl were overlaid onto preformed biofilms in media containing various maltodextrin concentrations. E-scaffold alone decreased A. baumannii and S. aureus biofilm cell densities by (3.92 ± 0.15) log and (2.31 ± 0.12) log, respectively. Compared to untreated biofilms, the efficacy of the e-scaffold increased to a maximum (8.27 ± 0.05) log reduction in A. baumannii and (4.71 ± 0.12) log reduction in S. aureus biofilm cell densities upon 10 mM and 30 mM maltodextrin addition, respectively. Overall ~55% decrease in relative biofilm surface coverage was achieved for both species. We conclude that combined treatment with electrochemically generated H2O2 from an e-scaffold and maltodextrin is more effective in decreasing viable biofilm cell density. PMID:27782161

  4. Combined Reactor and Microelectrode Measurements in Laboratory Grown Biofilms

    DEFF Research Database (Denmark)

    Larsen, Tove; Harremoës, Poul

    1994-01-01

    A combined biofilm reactor-/microelectrode experimental set-up has been constructed, allowing for simultaneous reactor mass balances and measurements of concentration profiles within the biofilm. The system consists of an annular biofilm reactor equipped with an oxygen microelectrode. Experiments...... were carried out with aerobic glucose and starch degrading biofilms. The well described aerobic glucose degradation biofilm system was used to test the combined reactor set-up. Results predicted from known biofilm kinetics were obtained. In the starch degrading biofilm, basic assumptions were tested...

  5. Antibiotic resistance in Pseudomonas aeruginosa biofilms: towards the development of novel anti-biofilm therapies.

    Science.gov (United States)

    Taylor, Patrick K; Yeung, Amy T Y; Hancock, Robert E W

    2014-12-10

    The growth of bacteria as structured aggregates termed biofilms leads to their protection from harsh environmental conditions such as physical and chemical stresses, shearing forces, and limited nutrient availability. Because of this highly adapted ability to survive adverse environmental conditions, bacterial biofilms are recalcitrant to antibiotic therapies and immune clearance. This is particularly problematic in hospital settings where biofilms are a frequent cause of chronic and device-related infections and constitute a significant burden on the health-care system. The major therapeutic strategy against infections is the use of antibiotics, which, due to adaptive resistance, are often insufficient to clear biofilm infections. Thus, novel biofilm-specific therapies are required. Specific features of biofilm development, such as surface adherence, extracellular matrix formation, quorum sensing, and highly regulated biofilm maturation and dispersal are currently being studied as targets to be exploited in the development of novel biofilm-specific treatments. Using Pseudomonas aeruginosa for illustrative purposes, this review highlights the antibiotic resistance mechanisms of biofilms, and discusses current research into novel biofilm-specific therapies.

  6. Plaque biofilms: the effect of chemical environment on natural human plaque biofilm architecture.

    Science.gov (United States)

    Robinson, C; Strafford, S; Rees, G; Brookes, S J; Kirkham, J; Shore, R C; Watson, P S; Wood, S

    2006-11-01

    The architecture of microbial biofilms especially the outer regions have an important influence on the interaction between biofilm and local environment particularly on the flux of materials into and out of biofilm compartments and as a consequence, biofilm metabolic behaviour. In the case of dental plaque biofilms, architecture will determine access of nutrients including acidogenic substrates and therapeutic materials to the microbial biomass and to the underlying tooth surface. Manipulation of this architecture may offer a means of altering mass transfer into the whole biofilm and biomass and raises the possibility of improving access of therapeutics. Plaque biofilms formed in vivo on human enamel were subjected to a number of different chemical conditions while under observation by confocal laser scanning microscopy in reflection mode. In this way the outer 50-100 microm or so of the biofilms was examined. Density and distribution of biomass were recorded as degree of reflectance. The amount and density of biofilm biomass increased from the plaque saliva interface towards the interior. Plaque biofilms were robust and little affected by mechanical manipulation, high ionic strength or low pH (2.5). Detergent (SLS), however, often appeared to either remove biomass and/or dramatically reduce its density.

  7. A mucosal model to study microbial biofilm development and anti-biofilm therapeutics

    Science.gov (United States)

    Anderson, Michele J.; Parks, Patrick J.; Peterson, Marnie L.

    2013-01-01

    Biofilms are a sessile colony of bacteria which adhere to and persist on surfaces. The ability of bacteria to form biofilms is considered a virulence factor, and in fact is central to the pathogenesis of some organisms. Biofilms are inherently resistant to chemotherapy and host immune responses. Clinically, biofilms are considered a primary cause of a majority of infections, such as otitis media, pneumonia in cystic fibrosis patients and endocarditis. However, the vast majority of the data on biofilm formation comes from traditional microtiter-based or flow displacement assays with no consideration given to host factors. These assays, which have been a valuable tool in high-throughput screening for biofilm-related factors, do not mimic a host-pathogen interaction and may contribute to an inappropriate estimation of the role of some factors in clinical biofilm formation. We describe the development of a novel ex vivo model of biofilm formation on a mucosal surface by an important mucosal pathogen, methicillin resistant S. aureus (MRSA). This model is being used for the identification of microbial virulence factors important in mucosal biofilm formation and novel anti-biofilm therapies. PMID:23246911

  8. Inactivation of Efflux Pumps Abolishes Bacterial Biofilm Formation

    DEFF Research Database (Denmark)

    Kvist, Malin; Hancock, Viktoria; Klemm, Per

    2008-01-01

    Bacterial biofilms cause numerous problems in health care and industry; notably, biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Bacteria rely on efflux pumps...... to get rid of toxic substances. We discovered that efflux pumps are highly active in bacterial biofilms, thus making efflux pumps attractive targets for antibiofilm measures. A number of efflux pump inhibitors (EPIs) are known. EPIs were shown to reduce biofilm formation, and in combination they could...... abolish biofilm formation completely. Also, EPIs were able to block the antibiotic tolerance of biofilms. The results of this feasibility study might pave the way for new treatments for biofilm-related infections and may be exploited for prevention of biofilms in general....

  9. Intrigues of biofilm: A perspective in veterinary medicine.

    Science.gov (United States)

    Abdullahi, Umar Faruk; Igwenagu, Ephraim; Mu'azu, Anas; Aliyu, Sani; Umar, Maryam Ibrahim

    2016-01-01

    Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which regulate the pathophysiology of biofilm. Ability of biofilm formation in a variety of inanimate surfaces such as animal food contact surfaces is responsible for a host of biofilm diseases affecting animals and humans. In this review, we highlighted some of the challenges of biofilm in livestock and food industries. Also highlighted are; mechanisms of biofilm development, best diagnostic approach and possible novel therapeutic measures needed to combat the menace of biofilm in veterinary medicine.

  10. Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter.

    Directory of Open Access Journals (Sweden)

    Adrián Golic

    Full Text Available We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1 BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.

  11. "Clothed in triple blues": sorting out the Italian blues.

    Science.gov (United States)

    Bimler, David; Uusküla, Mari

    2014-04-01

    Cross-cultural comparisons of color perception and cognition often feature versions of the "similarity sorting" procedure. By interpreting the assignment of two color samples to different groups as an indication that the dissimilarity between them exceeds some threshold, sorting data can be regarded as low-resolution similarity judgments. Here we analyze sorting data from speakers of Italian, Russian, and English, applying multidimensional scaling to delineate the boundaries between perceptual categories while highlighting differences between the three populations. Stimuli were 55 color swatches, predominantly from the blue region. Results suggest that at least two Italian words for "blue" are basic, a similar situation to Russian, in contrast to English where a single "blue" term is basic.

  12. Biofilm-specific extracellular matrix proteins of nontypeable Haemophilus influenzae.

    Science.gov (United States)

    Wu, Siva; Baum, Marc M; Kerwin, James; Guerrero, Debbie; Webster, Simon; Schaudinn, Christoph; VanderVelde, David; Webster, Paul

    2014-12-01

    Nontypeable Haemophilus influenzae (NTHi), a human respiratory tract pathogen, can form colony biofilms in vitro. Bacterial cells and the amorphous extracellular matrix (ECM) constituting the biofilm can be separated using sonication. The ECM from 24- and 96-h NTHi biofilms contained polysaccharides and proteinaceous components as detected by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) spectroscopy. More conventional chemical assays on the biofilm ECM confirmed the presence of these components and also DNA. Proteomics revealed eighteen proteins present in biofilm ECM that were not detected in planktonic bacteria. One ECM protein was unique to 24-h biofilms, two were found only in 96-h biofilms, and fifteen were present in the ECM of both 24- and 96-h NTHi biofilms. All proteins identified were either associated with bacterial membranes or cytoplasmic proteins. Immunocytochemistry showed two of the identified proteins, a DNA-directed RNA polymerase and the outer membrane protein OMP P2, associated with bacteria and biofilm ECM. Identification of biofilm-specific proteins present in immature biofilms is an important step in understanding the in vitro process of NTHi biofilm formation. The presence of a cytoplasmic protein and a membrane protein in the biofilm ECM of immature NTHi biofilms suggests that bacterial cell lysis may be a feature of early biofilm formation.

  13. Biofilms in Infections of the Eye

    Directory of Open Access Journals (Sweden)

    Paulo J. M. Bispo

    2015-03-01

    Full Text Available The ability to form biofilms in a variety of environments is a common trait of bacteria, and may represent one of the earliest defenses against predation. Biofilms are multicellular communities usually held together by a polymeric matrix, ranging from capsular material to cell lysate. In a structure that imposes diffusion limits, environmental microgradients arise to which individual bacteria adapt their physiologies, resulting in the gamut of physiological diversity. Additionally, the proximity of cells within the biofilm creates the opportunity for coordinated behaviors through cell–cell communication using diffusible signals, the most well documented being quorum sensing. Biofilms form on abiotic or biotic surfaces, and because of that are associated with a large proportion of human infections. Biofilm formation imposes a limitation on the uses and design of ocular devices, such as intraocular lenses, posterior contact lenses, scleral buckles, conjunctival plugs, lacrimal intubation devices and orbital implants. In the absence of abiotic materials, biofilms have been observed on the capsule, and in the corneal stroma. As the evidence for the involvement of microbial biofilms in many ocular infections has become compelling, developing new strategies to prevent their formation or to eradicate them at the site of infection, has become a priority.

  14. Oral biofilm architecture on natural teeth.

    Science.gov (United States)

    Zijnge, Vincent; van Leeuwen, M Barbara M; Degener, John E; Abbas, Frank; Thurnheer, Thomas; Gmür, Rudolf; Harmsen, Hermie J M

    2010-02-24

    Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and accessibility. Despite descriptions of initial plaque formation on the tooth surface, studies on mature plaque and plaque structure below the gum are limited to landmark studies from the 1970s, without appreciating the breadth of microbial diversity in the plaque. We used fluorescent in situ hybridization to localize in vivo the most abundant species from different phyla and species associated with periodontitis on seven embedded teeth obtained from four different subjects. The data showed convincingly the dominance of Actinomyces sp., Tannerella forsythia, Fusobacterium nucleatum, Spirochaetes, and Synergistetes in subgingival plaque. The latter proved to be new with a possibly important role in host-pathogen interaction due to its localization in close proximity to immune cells. The present study identified for the first time in vivo that Lactobacillus sp. are the central cells of bacterial aggregates in subgingival plaque, and that Streptococcus sp. and the yeast Candida albicans form corncob structures in supragingival plaque. Finally, periodontal pathogens colonize already formed biofilms and form microcolonies therein. These in vivo observations on oral biofilms provide a clear vision on biofilm architecture and the spatial distribution of predominant species.

  15. Crenarchaeal biofilm formation under extreme conditions.

    Directory of Open Access Journals (Sweden)

    Andrea Koerdt

    Full Text Available BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells. CONCLUSION: The study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.

  16. Iron and Acinetobacter baumannii Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Valentina Gentile

    2014-08-01

    Full Text Available Acinetobacter baumannii is an emerging nosocomial pathogen, responsible for infection outbreaks worldwide. The pathogenicity of this bacterium is mainly due to its multidrug-resistance and ability to form biofilm on abiotic surfaces, which facilitate long-term persistence in the hospital setting. Given the crucial role of iron in A. baumannii nutrition and pathogenicity, iron metabolism has been considered as a possible target for chelation-based antibacterial chemotherapy. In this study, we investigated the effect of iron restriction on A. baumannii growth and biofilm formation using different iron chelators and culture conditions. We report substantial inter-strain variability and growth medium-dependence for biofilm formation by A. baumannii isolates from veterinary and clinical sources. Neither planktonic nor biofilm growth of A. baumannii was affected by exogenous chelators. Biofilm formation was either stimulated by iron or not responsive to iron in the majority of isolates tested, indicating that iron starvation is not sensed as an overall biofilm-inducing stimulus by A. baumannii. The impressive iron withholding capacity of this bacterium should be taken into account for future development of chelation-based antimicrobial and anti-biofilm therapies.

  17. Alternating Current Influences Anaerobic Electroactive Biofilm Activity.

    Science.gov (United States)

    Wang, Xin; Zhou, Lean; Lu, Lu; Lobo, Fernanda Leite; Li, Nan; Wang, Heming; Park, Jaedo; Ren, Zhiyong Jason

    2016-09-06

    Alternating current (AC) is known to inactivate microbial growth in suspension, but how AC influences anaerobic biofilm activities has not been systematically investigated. Using a Geobacter dominated anaerobic biofilm growing on the electrodes of microbial electrochemical reactors, we found that high frequency AC ranging from 1 MHz to 1 kHz (amplitude of 5 V, 30 min) showed only temporary inhibition to the biofilm activity. However, lower frequency (100 Hz, 1.2 or 5 V) treatment led to 47 ± 19% permanent decrease in limiting current on the same biofilm, which is attributed to the action of electrohydrodynamic force that caused biofilm damage and loss of intercellular electron transfer network. Confocal microscopy images show such inactivation mainly occurred at the interface between the biofilm and the electrode. Reducing the frequency further to 1 Hz led to water electrolysis, which generated gas bubbles that flushed all attached cells out of the electrode. These findings provide new references on understanding and regulating biofilm growth, which has broader implications in biofouling control, anaerobic waste treatment, energy and product recovery, and general understanding of microbial ecology and physiology.

  18. Oral biofilm architecture on natural teeth.

    Directory of Open Access Journals (Sweden)

    Vincent Zijnge

    Full Text Available Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and accessibility. Despite descriptions of initial plaque formation on the tooth surface, studies on mature plaque and plaque structure below the gum are limited to landmark studies from the 1970s, without appreciating the breadth of microbial diversity in the plaque. We used fluorescent in situ hybridization to localize in vivo the most abundant species from different phyla and species associated with periodontitis on seven embedded teeth obtained from four different subjects. The data showed convincingly the dominance of Actinomyces sp., Tannerella forsythia, Fusobacterium nucleatum, Spirochaetes, and Synergistetes in subgingival plaque. The latter proved to be new with a possibly important role in host-pathogen interaction due to its localization in close proximity to immune cells. The present study identified for the first time in vivo that Lactobacillus sp. are the central cells of bacterial aggregates in subgingival plaque, and that Streptococcus sp. and the yeast Candida albicans form corncob structures in supragingival plaque. Finally, periodontal pathogens colonize already formed biofilms and form microcolonies therein. These in vivo observations on oral biofilms provide a clear vision on biofilm architecture and the spatial distribution of predominant species.

  19. Aging biofilm from a full-scale moving bed biofilm reactor: characterization and enzymatic treatment study.

    Science.gov (United States)

    Huang, Hui; Ren, Hongqiang; Ding, Lili; Geng, Jinju; Xu, Ke; Zhang, Yan

    2014-02-01

    Effective removal of aging biofilm deserves to receive more attention. This study aimed to characterized aging biofilm from a full-scale moving bed biofilm reactor treating pharmaceutical wastewater and evaluate the hydrolysis effects of biofilm by different enzymatic treatments. Results from FTIR and biochemical composition analyses showed that it was a predominately organic-based biofilm with the ratio of total protein (PN) to polysaccharide (PS) of 20.17. A reticular structure of extracellular polymeric matrix (EPM) with filamentous bacteria as the skeleton was observed on the basal layer through SEM-EDS test. Among the four commercial proteases and amylases from Genencor®, proteases were shown to have better performances than amylases either on the removal of MLSS and PN/MLSS or on DOC (i.e., dissolved organic carbon)/MLSS raising of biofilm pellets. Difference of dynamic fluorescence characteristics of dissolved organic matters after treated by the two proteases indicated distinguishing mechanisms of the treating process.

  20. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Directory of Open Access Journals (Sweden)

    Zhejun Wang

    Full Text Available Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM, peptide 1018 was able to significantly (p50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  1. Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Webb, J.S.; Rao, D.

    2006-01-01

    Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated...... specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms....

  2. Modulation of gut mucosal biofilms.

    Science.gov (United States)

    Kleessen, Brigitta; Blaut, Michael

    2005-04-01

    Non-digestible inulin-type fructans, such as oligofructose and high-molecular-weight inulin, have been shown to have the ability to alter the intestinal microbiota composition in such a way that members of the microbial community, generally considered as health-promoting, are stimulated. Bifidobacteria and lactobacilli are the most frequently targeted organisms. Less information exists on effects of inulin-type fructans on the composition, metabolism and health-related significance of bacteria at or near the mucosa surface or in the mucus layer forming mucosa-associated biofilms. Using rats inoculated with a human faecal flora as an experimental model we have found that inulin-type fructans in the diet modulated the gut microbiota by stimulation of mucosa-associated bifidobacteria as well as by partial reduction of pathogenic Salmonella enterica subsp. enterica serovar Typhimurium and thereby benefit health. In addition to changes in mucosal biofilms, inulin-type fructans also induced changes in the colonic mucosa stimulating proliferation in the crypts, increasing the release of mucins, and altering the profile of mucin components in the goblet cells and epithelial mucus layer. These results indicate that inulin-type fructans may stabilise the gut mucosal barrier. Dietary supplementation with these prebiotics could offer a new approach to supporting the barrier function of the mucosa.

  3. Implications of Biofilm Formation on Urological Devices

    Science.gov (United States)

    Cadieux, Peter A.; Wignall, Geoffrey R.; Carriveau, Rupp; Denstedt, John D.

    2008-09-01

    Despite millions of dollars and several decades of research targeted at their prevention and eradication, biofilm-associated infections remain the major cause of urological device failure. Numerous strategies have been aimed at improving device design, biomaterial composition, surface properties and drug delivery, but have been largely circumvented by microbes and their plethora of attachment, host evasion, antimicrobial resistance, and dissemination strategies. This is not entirely surprising since natural biofilm formation has been going on for millions of years and remains a major part of microorganism survival and evolution. Thus, the fact that biofilms develop on and in the biomaterials and tissues of humans is really an extension of this natural tendency and greatly explains why they are so difficult for us to combat. Firstly, biofilm structure and composition inherently provide a protective environment for microorganisms, shielding them from the shear stress of urine flow, immune cell attack and some antimicrobials. Secondly, many biofilm organisms enter a metabolically dormant state that renders them tolerant to those antibiotics and host factors able to penetrate the biofilm matrix. Lastly, the majority of organisms that cause biofilm-associated urinary tract infections originate from our own oral cavity, skin, gastrointestinal and urogenital tracts and therefore have already adapted to many of our host defenses. Ultimately, while biofilms continue to hold an advantage with respect to recurrent infections and biomaterial usage within the urinary tract, significant progress has been made in understanding these dynamic microbial communities and novel approaches offer promise for their prevention and eradication. These include novel device designs, antimicrobials, anti-adhesive coatings, biodegradable polymers and biofilm-disrupting compounds and therapies.

  4. Laser Microbial Killing and Biofilm Disruption

    Science.gov (United States)

    Krespi, Yosef P.; Kizhner, Victor

    2009-06-01

    Objectives: To analyze the ability of NIR lasers to reduce bacterial load and demonstrate the capability of fiber-based Q-switched Nd:YAG laser disrupting biofilm. Study Design: NIR diode laser was tested in vitro and in vivo using pathogenic microorganisms (S. aureus, S. pneumoniae, P. aeruginosa). In addition biofilms were grown from clinical Pseudomonas isolates and placed in culture plates, screws, tympanostomy tubes and PET sutures. Methods: In the animal experiments acute rhinosinusitis model was created by packing the rabbit nose with bacteria soaked solution. The nasal pack was removed in two days and nose was exposed to laser irradiation. A 940 nm diode laser with fiber diffuser was used. Nasal cultures were obtained before and after the laser treatments. Animals were sacrificed fifteen days following laser treatment and bacteriologic/histologic results analyzed. Q-switched Nd:YAG laser generated shockwave pulses were delivered on biofilm using special probes over culture plates, screws, tubes, and PET sutures for the biofilm experiments. Results: Average of two log bacteria reduction was achieved with NIR laser compared to controls. Histologic studies demonstrated preservation of tissue integrity without significant damage to mucosa. Biofilms were imaged before, during and after treatment using a confocal microscope. During laser-generated shockwave application, biofilm was initially seen to oscillate and eventually break off. Large and small pieces of biofilm were totally and instantly removed from the surface to which they were attached in seconds. Conclusions: Significant bacterial reduction was achieved with NIR laser therapy in this experimental in vitro and animal study. In addition we disrupted Pseudomonas aeruginosa biofilms using Q-switched Nd:YAG laser and special probes generating plasma and shockwave. This new and innovative method of bacteria killing and biofilm disruption without injuring host tissue may have clinical application in the

  5. Prediction of optimal biofilm thickness for membrane-attached biofilms growing in an extractive membrane bioreactor.

    Science.gov (United States)

    Pavasant, P; Dos Santos, L M; Pistikopoulos, E N; Livingston, A G

    1996-11-05

    This article presents a mathematical model of membrane-attached biofilm (MAB) behavior in a single-tube extractive membrane bioreactor (STEMB). MABs can be used for treatment of wastewaters containing VOCs, treatment of saline wastewaters, and nitrification processes. Extractive membrane bioreactors (EMBs) are employed to prevent the direct contact between a toxic volatile pollutant and the aerated gas by allowing counterdiffusion of substrates; i.e., pollutant diffuses from the tube side into the biofilm, whereas oxygen diffuses from the shell side into the biofilm. This reduces the air stripping problems usually found in conventional bioreactors. In this study, the biodegradation of a toxic VOC (1,2-dichloroethane, DCE) present in a synthetic wastewater has been investigated. An unstructured model is used to describe cell growth and cell decay in the MAB. The model has been verified by comparing model predicted trends with experimental data collected over 5 to 20-day periods, and has subsequently been used to model steady states in biofilm behavior over longer time scales. The model is capable of predicting the correct trends in system variables such as biofilm thickness, DCE flux across the membrane, carbon dioxide evolution, and suspended biomass. Steady states (constant biofilm thickness and DCE flux) are predicted, and factors that affect these steady states, i.e., cell endogeneous decay rate, and biofilm attrition, are investigated. Biofilm attrition does not have a great influence on biofilm behavior at low values of detachment coefficient close to those typically reported in the literature. Steady-state biofilm thickness is found to be an important variable; a thin biofilm results in a high DCE flux across the membrane, but with the penalty of a high loss of DCE via air stripping. The optimal biofilm thickness at steady state can be determined by trading off the decrease in air stripping (desirable) and the decrease in DCE flux (undesirable) which occur

  6. Prevention of biofilm formation and removal of existing biofilms by extracellular DNases of Campylobacter jejuni.

    Science.gov (United States)

    Brown, Helen L; Reuter, Mark; Hanman, Kate; Betts, Roy P; van Vliet, Arnoud H M

    2015-01-01

    The fastidious nature of the foodborne bacterial pathogen Campylobacter jejuni contrasts with its ability to survive in the food chain. The formation of biofilms, or the integration into existing biofilms by C. jejuni, is thought to contribute to food chain survival. As extracellular DNA (eDNA) has previously been proposed to play a role in C. jejuni biofilms, we have investigated the role of extracellular DNases (eDNases) produced by C. jejuni in biofilm formation. A search of 2791 C. jejuni genomes highlighted that almost half of C. jejuni genomes contains at least one eDNase gene, but only a minority of isolates contains two or three of these eDNase genes, such as C. jejuni strain RM1221 which contains the cje0256, cje0566 and cje1441 eDNase genes. Strain RM1221 did not form biofilms, whereas the eDNase-negative strains NCTC 11168 and 81116 did. Incubation of pre-formed biofilms of NCTC 11168 with live C. jejuni RM1221 or with spent medium from a RM1221 culture resulted in removal of the biofilm. Inactivation of the cje1441 eDNase gene in strain RM1221 restored biofilm formation, and made the mutant unable to degrade biofilms of strain NCTC 11168. Finally, C. jejuni strain RM1221 was able to degrade genomic DNA from C. jejuni NCTC 11168, 81116 and RM1221, whereas strain NCTC 11168 and the RM1221 cje1441 mutant were unable to do so. This was mirrored by an absence of eDNA in overnight cultures of C. jejuni RM1221. This suggests that the activity of eDNases in C. jejuni affects biofilm formation and is not conducive to a biofilm lifestyle. These eDNases do however have a potential role in controlling biofilm formation by C. jejuni strains in food chain relevant environments.

  7. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    OpenAIRE

    Joe A Lemire; Demeter, Marc A.; Iain George; Howard Ceri; Turner, Raymond J.

    2015-01-01

    Moving bed biofilm reactors (MBBRs) are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR) carriers (biofilm support materials), allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that ...

  8. Why Do Proteins Glow Blue?

    CERN Document Server

    Sarkar, Sohini; Hazra, Partha; Mandal, Pankaj

    2014-01-01

    Recent literatures reported blue-green emission from amyloid fibril as exclusive signature of fibril formation. This unusual visible luminescence is regularly used to monitor fibril growth. Blue-green emission has also been observed in crystalline protein and in solution. However, the origin of this emission is not known exactly. Our spectroscopic study of serum proteins reveals that the blue-green emission is a property of protein monomer. Evidences suggest that semiconductor-like band structure of proteins with the optical band-gap in the visible region is possibly the origin of this phenomenon. We show here that the band structure of proteins is primarily the result of electron delocalization through the peptide chain, rather than through the hydrogen bond network in secondary structure.

  9. Biofilm formation in a hot water system

    DEFF Research Database (Denmark)

    Bagh, L.K.; Albrechtsen, Hans-Jørgen; Arvin, Erik

    2002-01-01

    The biofilm formation rate was measured in situ in a hot water system in an apartment building by specially designed sampling equipment, and the net growth of the suspended bacteria was measured by incubation of water samples with the indigeneous bacteria. The biofilm formation rate reached......, in the sludge, or in the water from the distribution system was negligible. This indicated that bacterial growth took place on the inner surfaces in the hot water system and biofilm formation and detachment of bacteria could account for most of the suspended bacteria actually measured in hot water. Therefore...

  10. Anaerobic granular sludge and biofilm reactors

    DEFF Research Database (Denmark)

    Skiadas, Ioannis V.; Gavala, Hariklia N.; Schmidt, Jens Ejbye

    2003-01-01

    by the immobilization of the biomass, which forms static biofilms, particle-supported biofilms, or granules depending on the reactor's operational conditions. The advantages of the high-rate anaerobic digestion over the conventional aerobic wastewater treatment methods has created a clear trend for the change......-rate anaerobic treatment systems based on anaerobic granular sludge and biofilm are described in this chapter. Emphasis is given to a) the Up-flow Anaerobic Sludge Blanket (UASB) systems, b) the main characteristics of the anaerobic granular sludge, and c) the factors that control the granulation process...

  11. Quorum sensing inhibitors disable bacterial biofilms

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    It is now evident that bacteria assume the biofilm mode of growth during chronic infections. The important hallmarks of biofilm infections are development of local inflammations, extreme tolerance to the action of conventional antimicrobial agents and an almost infinite capacity to evade the host...... defence systems in particular innate immunity. In the biofilm mode, bacteria use cell to cell communication termed quorum-sensing (QS) to coordinate expression of virulence, tolerance towards a number of antimicrobial agents and shielding against the host defence system. Chemical biology approaches may...

  12. A personal history of research on microbial biofilms and biofilm infections.

    Science.gov (United States)

    Høiby, Niels

    2014-04-01

    The observation of aggregated microorganisms surrounded by a self-produced matrix adhering to surfaces or located in tissues or secretions is as old as microbiology, with both Leeuwenhoek and Pasteur describing the phenomenon. In environmental and technical microbiology, biofilms were already shown 80-90 years ago to be important for biofouling on submerged surfaces, e.g. ships. The concept of biofilm infections and their importance in medicine is, however, biofilm was introduced into medicine in 1985 by Costerton. In the following decades, it became obvious that biofilm infections are widespread in medicine, and their importance is now generally accepted.

  13. Successional development of biofilms in moving bed biofilm reactor (MBBR) systems treating municipal wastewater.

    Science.gov (United States)

    Biswas, Kristi; Taylor, Michael W; Turner, Susan J

    2014-02-01

    Biofilm-based technologies, such as moving bed biofilm reactor (MBBR) systems, are widely used to treat wastewater. Biofilm development is important for MBBR systems as much of the microbial biomass is retained within reactors as biofilm on suspended carriers. Little is known about this process of biofilm development and the microorganisms upon which MBBRs rely. We documented successional changes in microbial communities as biofilms established in two full-scale MBBR systems treating municipal wastewater over two seasons. 16S rRNA gene-targeted pyrosequencing and clone libraries were used to describe microbial communities. These data indicate a successional process that commences with the establishment of an aerobic community dominated by Gammaproteobacteria (up to 52 % of sequences). Over time, this community shifts towards dominance by putatively anaerobic organisms including Deltaproteobacteria and Clostridiales. Significant differences were observed between the two wastewater treatment plants (WWTPs), mostly due to a large number of sequences (up to 55 %) representing Epsilonproteobacteria (mostly Arcobacter) at one site. Archaea in young biofilms included several lineages of Euryarchaeota and Crenarchaeota. In contrast, the mature biofilm consisted entirely of Methanosarcinaceae (Euryarchaeota). This study provides new insights into the community structure of developing biofilms at full-scale WWTPs and provides the basis for optimizing MBBR start-up and operational parameters.

  14. Fungal Biofilms: In Vivo Models for Discovery of Anti-Biofilm Drugs.

    Science.gov (United States)

    Nett, Jeniel E; Andes, David R

    2015-06-01

    During infection, fungi frequently transition to a biofilm lifestyle, proliferating as communities of surface-adherent aggregates of cells. Phenotypically, cells in a biofilm are distinct from free-floating cells. Their high tolerance of antifungals and ability to withstand host defenses are two characteristics that foster resilience. Biofilm infections are particularly difficult to eradicate, and most available antifungals have minimal activity. Therefore, the discovery of novel compounds and innovative strategies to treat fungal biofilms is of great interest. Although many fungi have been observed to form biofilms, the most well-studied is Candida albicans. Animal models have been developed to simulate common Candida device-associated infections, including those involving vascular catheters, dentures, urinary catheters, and subcutaneous implants. Models have also reproduced the most common mucosal biofilm infections: oropharyngeal and vaginal candidiasis. These models incorporate the anatomical site, immune components, and fluid dynamics of clinical niches and have been instrumental in the study of drug resistance and investigation of novel therapies. This chapter describes the significance of fungal biofilm infections, the animal models developed for biofilm study, and how these models have contributed to the development of new strategies for the eradication of fungal biofilm infections.

  15. Agminated blue nevus - Case report*

    Science.gov (United States)

    Lisboa, Alice Paixão; Silvestre, Keline Jácome; Pedreira, Renata Leite; Alves, Natália Ribeiro de Magalhães; Obadia, Daniel Lago; Azulay-Abulafia, Luna

    2016-01-01

    Blue nevi are benign melanocytic lesions located in the deeper reticular dermis, consequence of failure of melanocytic migration into the dermal-epidermal junction from the neural crest. Lesions are usually asymptomatic and solitary, but may present in a multiple or agminated (grouped) pattern. The agminated subtype is formed when bluish-pigmented lesions cluster together in a well-defined area. Lesions can be flat or raised. We report the case of a patient who presented multiple bluish macules (1-3 mm in diameter) grouped on the left upper back. Dermoscopy and anatomic pathological examination were consistent with blue nevus. PMID:27828645

  16. IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan

    2009-10-31

    This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms. This research is aimed at advancing understanding of biofilm formation and other complex processes involved in the degradation of the abundant cellulosic biomass, and the biology of the microbes involved. Information obtained from these studies is invaluable in the development of practical applications, such as the single-step bioconversion of cellulose-containing residues to fuels and other bioproducts. Our results have clearly shown that cellulose-decomposing microbes rapidly colonize cellulose and form complex structures typical of biofilms. Furthermore, our observations suggest that, as cells multiply on nutritive surfaces during biofilms formation, dramatic cell morphological changes occur. We speculated that morphological changes, which involve a transition from rod-shaped cells to more rounded forms, might be more apparent in a filamentous microbe. In order to test this hypothesis, we included in our research a study of biofilm formation by T. fusca, a thermophilic cellulolytic actinomycete commonly found in compost. The cellulase system of T. fusca has been extensively detailed through the work of David Wilson and colleagues at Cornell, and also, genome sequence of a T. fusca strain has been determine by the DOE Joint Genome Institute. Thus, T. fusca is an excellent subject for studies of biofilm development and its potential impacts on cellulose degradation. We also completed a study of the chitinase system of C. uda. This work provided essential background information for understanding how C. uda

  17. Characterization of starvation-induced dispersion in Pseudomonas putida biofilms

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Sternberg, Claus;

    2005-01-01

    that they must be able to regulate their ability to form biofilm and to dissolve biofilm. We present an investigation of a biofilm dissolution process occurring in flow-chamber-grown Pseudomonas putida biofilms. Local starvation-induced biofilm dissolution appears to be an integrated part of P. putida biofilm...... development that causes characteristic structural rearrangements. Rapid global dissolution of entire P. putida biofilms was shown to occur in response to carbon starvation. Genetic analysis suggested that the adjacent P. putida genes PP0164 and PP0165 play a role in P. putida biofilm formation and dissolution....... PP0164 encodes a putative periplasmic protein of previously unknown function, and PP0164 mutant bacteria are sticky, and unable to reduce their adhesiveness and dissolve their biofilm in response to carbon starvation. PP0165 encodes a putative transmembrane protein containing GGDEF and EAL domains...

  18. An improved protocol for harvesting Bacillus subtilis colony biofilms.

    Science.gov (United States)

    Fuchs, Felix Matthias; Driks, Adam; Setlow, Peter; Moeller, Ralf

    2017-03-01

    Bacterial biofilms cause severe problems in medicine and industry due to the high resistance to disinfectants and environmental stress of organisms within biofilms. Addressing challenges caused by biofilms requires full understanding of the underlying mechanisms for bacterial resistance and survival in biofilms. However, such work is hampered by a relative lack of systems for biofilm cultivation that are practical and reproducible. To address this problem, we developed a readily applicable method to culture Bacillus subtilis biofilms on a membrane filter. The method results in biofilms with highly reproducible characteristics, and which can be readily analyzed by a variety of methods with little further manipulation. This biofilm preparation method simplifies routine generation of B. subtilis biofilms for molecular and cellular analysis, and could be applicable to other microbial systems.

  19. Susceptibility of Porphyromonas gingivalis in biofilms to amoxicillin, doxycycline and metronidazole

    DEFF Research Database (Denmark)

    Larsen, T.

    2002-01-01

    Biofilm, Porphyromonas gingivalis, susceptibility testing, amoxicillin, doxycycline, metronidazole......Biofilm, Porphyromonas gingivalis, susceptibility testing, amoxicillin, doxycycline, metronidazole...

  20. Controlling the oral biofilm with antimicrobials.

    Science.gov (United States)

    Marsh, P D

    2010-06-01

    The aim of this article is to review the properties of compounds available for the control of dental plaque biofilms, and describe their mode of action. The mouth is colonised by a diverse but characteristic collection of micro-organisms, which confer benefit to host. Numerous antiplaque (e.g. surfactants, essential oils) and antimicrobial agents (e.g. bisbiguanides, metal ions, phenols, quaternary ammonium compounds, etc.) have been successfully formulated into toothpastes and mouthrinses to control plaque biofilms. At high concentrations, these agents can remove biofilm and/or kill disease-associated bacteria, while even at sub-lethal levels they can inhibit the expression of pathogenic traits. Successful antimicrobial agents are able to meet the apparently contradictory requirements of maintaining the oral biofilm at levels compatible with oral health but without disrupting the natural and beneficial properties of the resident oral microflora.

  1. Actinomyces naeslundii in intial dental biofilm formation

    DEFF Research Database (Denmark)

    Dige, Irene; Raarup, Merete Krog; Nyengaard, Jens Randel

    2009-01-01

    Combined use of Confocal Laser Scanning Microscopy (CLSM) and Fluorescent in situ Hybridization (FISH) offers new opportunities for analysing the spatial relationships and temporal changes of specific members of microbial populations in intact dental biofilms. AIMS: The purpose of this study...... was to analyse the patterns of colonization and population dynamics of A. naeslundii compared to Streptococcus spp. and other bacteria during the initial 48 h of biofilm formation. METHODS: Biofilms were collected on standardized glass slabs mounted in intra-oral appliances and worn by 10 individuals for 6, 12......, 24, and 48 h. The biofilms were subsequently labelled with probes against Streptococcus spp. (STR405), A. naeslundii (ACT476), or all bacteria (EUB338) and analysed by CLSM. Quantification of labelled bacteria was done by stereological tools: the unbiased counting frame and the 2D fractionator...

  2. Prospects for Anti-Biofilm Pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Philip S. Stewart

    2015-08-01

    Full Text Available This commentary highlights several avenues currently being pursued in research labs to the development of new anti-biofilm pharmaceuticals. There is a real need for alternative therapeutic modalities for treating the persistent infections that sometimes form on implanted medical devices or compromised niches within the body. Strategies being researched include discovering new antimicrobial agents that kill microorganisms in biofilms more effectively than do existing antibiotics, designing drugs that block microbial adhesion or interfere with intercellular communication, developing chemistries to disperse biofilms, and combining agents with different mechanisms of action. Though the need is great, the pathway to commercialization of new drugs is steep. One possible streamlined approach to navigating the regulatory approval process is to repurpose old drugs, a strategy that a few groups have shown can yield agents with anti-biofilm properties.

  3. Glycopeptide dendrimers as Pseudomonas aeruginosa biofilm inhibitors.

    Science.gov (United States)

    Reymond, Jean-Louis; Bergmann, Myriam; Darbre, Tamis

    2013-06-01

    Synthetic glycopeptide dendrimers composed of a branched oligopeptide tree structure appended with glycosidic groups at its multiple N-termini were investigated for binding to the Pseudomonas aeruginosa lectins LecB and LecA. These lectins are partly responsible for the formation of antibiotic resistant biofilms in the human pathogenic bacterium P. aeruginosa, which causes lethal airway infections in immune-compromised and cystic fibrosis patients. Glycopeptide dendrimers with high affinity to the lectins were identified by screening of combinatorial libraries. Several of these dendrimers, in particular the LecB specific glycopeptide dendrimers FD2 and D-FD2 and the LecA specific glycopeptide dendrimers GalAG2 and GalBG2, also efficiently block P. aeruginosa biofilm formation and induce biofilm dispersal in vitro. Structure-activity relationship and structural studies are reviewed, in particular the observation that multivalency is essential to the anti-biofilm effect in these dendrimers.

  4. Bacterial adhesion and biofilms on surfaces

    Institute of Scientific and Technical Information of China (English)

    Trevor Roger Garrett; Manmohan Bhakoo; Zhibing Zhang

    2008-01-01

    Bacterial adhesion has become a significant problem in industry and in the domicile,and much research has been done for deeper understanding of the processes involved.A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle,has been described and modified many times.The biofilm growth cycle encompasses bacterial adhesion at all levels,starting with the initial physical attraction of bacteria to a substrate,and ending with the eventual liberation of cell dusters from the biofilm matrix.When describing bacterial adhesion one is simply describing one or more stages of biofilm development,neglecting the fact that the population may not reach maturity.This article provides an overview of bacterial adhesion.cites examples of how bac-terial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive prop-erties of bacteria.

  5. Bursting the bubble on bacterial biofilms

    DEFF Research Database (Denmark)

    Crusz, Shanika A; Popat, Roman; Rybtke, Morten Theil;

    2012-01-01

    The flow cell biofilm system is an important and widely used tool for the in vitro cultivation and evaluation of bacterial biofilms under hydrodynamic conditions of flow. This paper provides an introduction to the background and use of such systems, accompanied by a detailed guide to the assembly...... of the apparatus including the description of new modifications which enhance its performance. As such, this is an essential guide for the novice biofilm researcher as well as providing valuable trouble-shooting techniques for even the most experienced laboratories. The adoption of a common and reliable...... methodology amongst researchers would enable findings to be shared and replicated amongst the biofilm research community, with the overall aim of advancing understanding and management of these complex and widespread bacterial communities....

  6. Multiple Roles of Biosurfactants in Biofilms.

    Science.gov (United States)

    Satputea, Surekha K; Banpurkar, Arun G; Banat, Ibrahim M; Sangshetti, Jaiprakash N; Patil, Rajendra H; Gade, Wasudev N

    2016-01-01

    Microbial growth and biofilms formation are a continuous source of contamination on most surfaces with biological, inanimate, natural or man-made. The use of chemical surfactants in daily practice to control growth, presence or adhesion of microorganisms and ultimately the formation of biofilms and biofouling is therefore becoming essential. Synthetic surfactants are, however, not preferred or ideal and biologically derived surface active biosurfactants (BSs) molecules produced mainly by microorganisms are therefore becoming attractive and sought by many industries. The search for innovative and interesting BS molecules that have effective antimicrobial activities and to use as innovative alternatives to chemical surfactants with added antimicrobial value among many other advantages has been ongoing for some time. This review discusses the various roles of BS molecules in association with biofilm formation. Recent updates on several mechanisms involved in biofilm development and control are presented vide this article.

  7. EFFICENCY OF PHOTOACTIVATED DISINFECTION ON EXPERIMENTAL BIOFILM - SCANING ELECTRON MICROSCOPY RESULTS

    Directory of Open Access Journals (Sweden)

    Ivan Filipov

    2013-10-01

    Full Text Available Photoactivated disinfection is a new antimicrobial method for root canal disinfection, based on photodynamic therapy.Purpose: The goal of this study is to investigate the antimicrobial effect of photoactivated disinfection on experimental biofilm from Enterococcus faecalis and Candida albicans, through scanning electron microscopy.Material and Methods: Freshly extracted, one root teeth were prepared with a sequence of rotary nickel-titanium files (ProTaper ; Dentsply ; Mailefer , irrigated, the external root canal surfaces isolated with nail polish and autoclaved. After the incubation with the experimental biofilm, the root canals were filled with photosensitizer - Toluidine Blue – 0,01% and irradiated with Foto San(CMS Dental, 630 nm, 2000mW/cm2 for 30 seconds.SEM was performed on the coronal, middle and apical third of the root canal, for evaluation of the results.Results and discussion: In the range of 600 to 8000, SEM showed significant reduction of microorganisms from the canal system. A large increase in microorganisms was observed, showing a disturbance in the cell membrane, as effect from the activation of chromophore with the laser and the penetration of the photosensitizer in dental tubules. In the apical third single microorganisms were observed. This may due to decreased penetration of the photosensitizer, incomplete pervasion of MB in the biofilm or insufficient oxygenation.Conclusion: FAD has the potential to be a good alternative and addition to the conventional root canal disinfection methods.SEM is a precise method for endodontic treatment result evaluation.

  8. Blue Ocean vs. Five Forces

    NARCIS (Netherlands)

    A.E. Burke (Andrew); A.J. van Stel (André); A.R. Thurik (Roy)

    2010-01-01

    textabstractThe article reports on the authors' research in the Netherlands which focused on a profit model in Dutch retail stores and a so-called blue-ocean approach which requires a new market that attracts consumers and increases profits. Topics include the competitive strategy approach to increa

  9. Blue rubber bleb naevus syndrome

    DEFF Research Database (Denmark)

    Lybecker, Martin Bell; Stawowy, Marek; Clausen, Niels

    2016-01-01

    Blue rubber bleb naevus syndrome (BRBNS) is a rare vascular disorder with malformed veins, or blebs, appearing in the skin or internal organs. Gastrointestinal tract involvement is the most common feature and often subject to bleeding, potentially resulting in chronic occult blood loss and iron...

  10. The blue revolution in asia

    DEFF Research Database (Denmark)

    Jespersen, Karen Sau; Ponte, Stefano; Kelling, Ingrid

    2014-01-01

    In this article, we examine the upgrading trajectories of selected aquaculture value chains in four Asian countries and the links between upgrading and three factors of value chain governance: coordination mechanisms; types of drivers; and domestic regulation. We find instances of improving produ...... of upgrading the "blue revolution" in Asia...

  11. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Science.gov (United States)

    Wang, Zhejun; de la Fuente-Núñez, Cesar; Shen, Ya; Haapasalo, Markus; Hancock, Robert E W

    2015-01-01

    Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM), peptide 1018 was able to significantly (pbiofilm formation over 3 days. The activity of the peptide on preformed biofilms was found to be concentration-dependent since more than 60% of the total plaque biofilm cell population was killed by 10 μg/ml of peptide 1018 in 3 days, while at 5 μg/ml 50% of cells were dead and at 1 μg/ml the peptide triggered cell death in around 30% of the total bacterial population, as revealed by confocal microscopy. The presence of saliva did not affect peptide activity, since no statistically significant difference was found in the ability of peptide 1018 to kill oral biofilms using either saliva coated and non-saliva coated hydroxyapatite surfaces. Scanning electron microscopy experiments indicated that peptide 1018 induced cell lysis in plaque biofilms. Furthermore, combined treatment using peptide 1018 and chlorhexidine (CHX) increased the anti-biofilm activity of each compound compared to when these were used alone, resulting in >50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  12. Physicochemical characteristics and microbial community evolution of biofilms during the start-up period in a moving bed biofilm reactor.

    Science.gov (United States)

    Zhu, Yan; Zhang, Yan; Ren, Hong-Qiang; Geng, Jin-Ju; Xu, Ke; Huang, Hui; Ding, Li-Li

    2015-03-01

    This study aimed to investigate biofilm properties evolution coupled with different ages during the start-up period in a moving bed biofilm reactor system. Physicochemical characteristics including adhesion force, extracellular polymeric substances (EPS), morphology as well as volatile solid and microbial community were studied. Results showed that the formation and development of biofilms exhibited four stages, including (I) initial attachment and young biofilm formation, (II) biofilms accumulation, (III) biofilm sloughing and updating, and (IV) biofilm maturation. During the whole start-up period, adhesion force was positively and significantly correlated with the contents of EPS, especially the content of polysaccharide. In addition, increased adhesion force and EPS were beneficial for biofilm retention. Gram-negative bacteria mainly including Sphaerotilus, Zoogloea and Haliscomenobacter were predominant in the initial stage. Actinobacteria was beneficial to resist sloughing. Furthermore, filamentous bacteria were dominant in maturation biofilm.

  13. Linking nitrifying biofilm characteristics and nitrification performance in moving-bed biofilm reactors for polluted raw water pretreatment.

    Science.gov (United States)

    Zhang, Shuangfu; Wang, Yayi; He, Weitao; Xing, Meiyan; Wu, Min; Yang, Jian; Gao, Naiyun; Sheng, Guangyao; Yin, Daqiang; Liu, Shanhu

    2013-10-01

    Biofilm physiology was characterized by four biofilm constituents, i.e., polysaccharides, proteins (PN), humic-like substances and phospholipids (PL), for the first time to explore the relationships between biofilm characteristics and nitrification performance in moving-bed biofilm reactors (MBBRs) designed for pretreatment of polluted raw surface water for potable supply. The biofilm compositions depended highly on the balance of microbial decay and nitrification processes. The increased ammonia loading greatly regulated the community structure, promoting the dominance of nitrifiers and their proportions in the nitrifying biofilm. Nitrification rate and activity correlated linearly with the fractions of volatile solids (VS), PN and PL, which were related to nitrification processes in the biofilm. The specific biofilm activity demonstrated an exponential-asymptotic relationship with ratios of PN/VS and PL/VS. Thus, analyzing biofilm characteristics can be valid for estimating nitrification performance in MBBRs, and may offer engineers with basis to optimize MBBR design and operation.

  14. Enzymes Enhance Biofilm Removal Efficiency of Cleaners

    OpenAIRE

    2016-01-01

    Efficient removal of biofilms from medical devices is a big challenge in health care to avoid hospital-acquired infections, especially from delicate devices like flexible endoscopes, which cannot be reprocessed using harsh chemicals or high temperatures. Therefore, milder solutions such as enzymatic cleaners have to be used, which need to be carefully developed to ensure efficacious performance. In vitro biofilm in a 96-well-plate system was used to select and optimize the formulation of nove...

  15. Regulation of Acinetobacter baumannii biofilm formation.

    Science.gov (United States)

    Gaddy, Jennifer A; Actis, Luis A

    2009-04-01

    Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen. This microorganism survives in hospital environments despite unfavorable conditions such as desiccation, nutrient starvation and antimicrobial treatments. It is hypothesized that its ability to persist in these environments, as well as its virulence, is a result of its capacity to form biofilms. A. baumannii forms biofilms on abiotic surfaces such as polystyrene and glass as well as biotic surfaces such as epithelial cells and fungal filaments. Pili assembly and production of the Bap surface-adhesion protein play a role in biofilm initiation and maturation after initial attachment to abiotic surfaces. Furthermore, the adhesion and biofilm phenotypes of some clinical isolates seem to be related to the presence of broad-spectrum antibiotic resistance. The regulation of the formation and development of these biofilms is as diverse as the surfaces on which this bacterium persists and as the cellular components that participate in this programmed multistep process. The regulatory processes associated with biofilm formation include sensing of bacterial cell density, the presence of different nutrients and the concentration of free cations available to bacterial cells. Some of these extracellular signals may be sensed by two-component regulatory systems such as BfmRS. This transcriptional regulatory system activates the expression of the usher-chaperone assembly system responsible for the production of pili, needed for cell attachment and biofilm formation on polystyrene surfaces. However, such a system is not required for biofilm formation on abiotic surfaces when cells are cultured in chemically defined media. Interestingly, the BfmRS system also controls cell morphology under particular culture conditions.

  16. Role of biofilm roughness and hydrodynamic conditions in Legionella pneumophila adhesion to and detachment from simulated drinking water biofilms.

    Science.gov (United States)

    Shen, Yun; Monroy, Guillermo L; Derlon, Nicolas; Janjaroen, Dao; Huang, Conghui; Morgenroth, Eberhard; Boppart, Stephen A; Ashbolt, Nicholas J; Liu, Wen-Tso; Nguyen, Thanh H

    2015-04-07

    Biofilms in drinking water distribution systems (DWDS) could exacerbate the persistence and associated risks of pathogenic Legionella pneumophila (L. pneumophila), thus raising human health concerns. However, mechanisms controlling adhesion and subsequent detachment of L. pneumophila associated with biofilms remain unclear. We determined the connection between L. pneumophila adhesion and subsequent detachment with biofilm physical structure characterization using optical coherence tomography (OCT) imaging technique. Analysis of the OCT images of multispecies biofilms grown under low nutrient condition up to 34 weeks revealed the lack of biofilm deformation even when these biofilms were exposed to flow velocity of 0.7 m/s, typical flow for DWDS. L. pneumophila adhesion on these biofilm under low flow velocity (0.007 m/s) positively correlated with biofilm roughness due to enlarged biofilm surface area and local flow conditions created by roughness asperities. The preadhered L. pneumophila on selected rough and smooth biofilms were found to detach when these biofilms were subjected to higher flow velocity. At the flow velocity of 0.1 and 0.3 m/s, the ratio of detached cell from the smooth biofilm surface was from 1.3 to 1.4 times higher than that from the rough biofilm surface, presumably because of the low shear stress zones near roughness asperities. This study determined that physical structure and local hydrodynamics control L. pneumophila adhesion to and detachment from simulated drinking water biofilm, thus it is the first step toward reducing the risk of L. pneumophila exposure and subsequent infections.

  17. Microbial pathogenesis and biofilm development

    DEFF Research Database (Denmark)

    Reisner, A.; Høiby, N.; Tolker-Nielsen, Tim

    2004-01-01

    Microbial infections constitute a major cause of premature death in large parts of the world, and for several years we have seen an alarming tendency towards increasing problems of controlling such infections by antibiotic treatments. It is hoped that an improved understanding of the infectious...... a highly significant role in connection with chronic infections [1]. Bacterial growth on surfaces depends on several factors [2]. In nature, surfaces are probably often conditioned with a thin film of organic molecules, which may serve as attractants for bacterial chemotactic systems and which subsequently...... permit bacterial growth to occur. In laboratory model systems the growth of the surface-associated bacteria is supported by the nutrient supply in the moving or standing liquid. A benchmark of biofilm formation by several organisms in vitro is the development of three-dimensional structures that have...

  18. Fremmedlegemeinfektioner--nyt om biofilm og quorum sensing

    DEFF Research Database (Denmark)

    Høiby, Niels; Johansen, Helle Krogh; Ciofu, Oana

    2007-01-01

    Biofilms are structured consortia of bacteria embedded in self-produced polymer matrix. Biofilms are resistant to antibiotics, disinfectives and phagocytosis. The persistence of foreign body infections is due to biofilms. Chronic P. aeruginosa lung infection in cystic fibrosis patients is a biofilm....... Bacteria in biofilms communicate by means of quorum sensing which activates genes for virulence factors. Biofilms can be prevented by antibiotic prophylaxis or early therapy or by quorum sensing inhibitors which make them susceptible to antibiotics and phagocytosis. Udgivelsesdato: 2007-Nov-26...

  19. The Host’s Reply to Candida Biofilm

    Directory of Open Access Journals (Sweden)

    Jeniel E. Nett

    2016-03-01

    Full Text Available Candida spp. are among the most common nosocomial fungal pathogens and are notorious for their propensity toward biofilm formation. When growing on a medical device or mucosal surface, these organisms reside as communities embedded in a protective matrix, resisting host defenses. The host responds to Candida biofilm by depositing a variety of proteins that become incorporated into the biofilm matrix. Compared to free-floating Candida, leukocytes are less effective against Candida within a biofilm. This review highlights recent advances describing the host’s response to Candida biofilms using ex vivo and in vivo models of mucosal and device-associated biofilm infections.

  20. Biofilm formation of Francisella noatunensis subsp. orientalis

    Science.gov (United States)

    Soto, Esteban; Halliday-Wimmonds, Iona; Francis , Stewart; Kearney, Michael T; Hansen, John D.

    2015-01-01

    Francisella noatunensis subsp. orientalis (Fno) is an emergent fish pathogen in both marine and fresh water environments. The bacterium is suspected to persist in the environment even without the presence of a suitable fish host. In the present study, the influence of different abiotic factors such as salinity and temperature were used to study the biofilm formation of different isolates of Fno including intracellular growth loci C (iglC)and pathogenicity determinant protein A (pdpA) knockout strains. Finally, we compared the susceptibility of planktonic and biofilm to three disinfectants used in the aquaculture and ornamental fish industry, namely Virkon®, bleach and hydrogen peroxide. The data indicates that Fno is capable of producing biofilms within 24 h where both salinity as well as temperature plays a role in the growth and biofilm formation of Fno. Mutations in theiglC or pdpA, both known virulence factors, do not appear to affect the capacity of Fno to produce biofilms, and the minimum inhibitory concentration, and minimum biocidal concentration for the three disinfectants were lower than the minimum biofilm eradication concentration values. This information needs to be taken into account if trying to eradicate the pathogen from aquaculture facilities or aquariums.

  1. Characterization of biofilm formed on intrauterine devices

    Directory of Open Access Journals (Sweden)

    Pruthi V

    2003-01-01

    Full Text Available PURPOSE: Intrauterine device (IUD is one of the most convenient contraceptive procedures used by women of Asian and African countries. Previous surveys have revealed that 75% of the IUDs recovered from patients suffering from reproductive tract infections (RTIs were covered with a consortium of microbes. This study was designed to characterize these microbes and recommend remedial measures. METHODS: Quantitative measurement of biofilm formation was assessed by a microtitre plate assay on 86 samples of microorganisms dislodged from IUDs of patients with RTIs. Susceptibility of biofilm to various antimicrobial agents was also quantified. Scanning electron microscopy (SEM was used to scrutinize the microorganisms adherent to IUDs. RESULTS: The organisms associated with IUDs were predominantly composed of Staphylococcus aureus (16%, Staphylococcus epidermidis (18%, Pseudomonas aeruginosa (5%, Escherichia coli (27%, Neisseria gonorrhoeae (2%, Candida albicans (20% and Candida dubliniesis (12%. SEM studies indicated that these organisms were organized into biofilms. Studies on the in vitro adherence pattern by crystal violet staining on 96 well microtitre plates revealed that the biofilms were stably established after 60 hours. These biofilms are resistant to an array of antibiotics tested. CONCLUSION: Biofilm formation may be one of the major causes for persistent infection and antibiotic resistance in IUD users.

  2. Escherichia coli biofilms: Accepting the therapeutic challenges

    Directory of Open Access Journals (Sweden)

    Trupti Bajpai

    2016-01-01

    Full Text Available Background: Urinary tract infections (UTI′s are a major public health concern globally. Recurrent UTI′s that are predominantly caused by uropathogenic Escherichia coli′s forms biofilm that is an intracellular, structured bacterial community, enclosed in a self-produced matrix, adherent to an inert, or living surface. Biofilm physiology is characterized by increased tolerance to stress, antibiotics, and immunological defenses, which is at the origin of their resilience in most medical and industrial settings. Materials and Methods: The present prospective study was carried out from December 2013 to May 2014 in the Department of Microbiology of a Teaching Tertiary Care hospital located in central India. A total of 100 consecutive, nonrepetitive E. coli isolates were subjected to biofilm formation study by Christensen′s tube adherence method. All the isolates were also subjected to antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method in accordance with the Clinical Laboratory Standard Institute 2013 guidelines. Results and Discussion: Out of the 100 E. coli isolates studied, 62 (62% were positive for biofilm formation. High percentage of resistance was detected in isolates among the male inpatient group. Overall drug resistance was found to be very high among both biofilm as well as nonbiofilm forming isolates indicating excessive drug resistance among both community and hospital organisms. Conclusion: A greater understanding of the nature of biofilm organisms in chronic UTI′s would help in the development of novel and more effective treatments for these problematic diseases.

  3. Formation of biofilms under phage predation: considerations concerning a biofilm increase.

    Science.gov (United States)

    Hosseinidoust, Zeinab; Tufenkji, Nathalie; van de Ven, Theo G M

    2013-01-01

    Bacteriophages are emerging as strong candidates for combating bacterial biofilms. However, reports indicating that host populations can, in some cases, respond to phage predation by an increase in biofilm formation are of concern. This study investigates whether phage predation can enhance the formation of biofilm and if so, if this phenomenon is governed by the emergence of phage-resistance or by non-evolutionary mechanisms (eg spatial refuge). Single-species biofilms of three bacterial pathogens (Pseudomonas aeruginosa, Salmonella enterica serotype Typhimurium, and Staphylococcus aureus) were pretreated and post-treated with species-specific phages. Some of the phage treatments resulted in an increase in the levels of biofilm of their host. It is proposed that the phenotypic change brought about by acquiring phage resistance is the main reason for the increase in the level of biofilm of P. aeruginosa. For biofilms of S. aureus and S. enterica Typhimurium, although resistance was detected, increased formation of biofilm appeared to be a result of non-evolutionary mechanisms.

  4. BiofilmQuant: a computer-assisted tool for dental biofilm quantification.

    Science.gov (United States)

    Mansoor, Awais; Patsekin, Valery; Scherl, Dale; Robinson, J Paul; Rajwa, Bartlomiej

    2014-01-01

    Dental biofilm is the deposition of microbial material over a tooth substratum. Several methods have recently been reported in the literature for biofilm quantification; however, at best they provide a barely automated solution requiring significant input needed from the human expert. On the contrary, state-of-the-art automatic biofilm methods fail to make their way into clinical practice because of the lack of effective mechanism to incorporate human input to handle praxis or misclassified regions. Manual delineation, the current gold standard, is time consuming and subject to expert bias. In this paper, we introduce a new semi-automated software tool, BiofilmQuant, for dental biofilm quantification in quantitative light-induced fluorescence (QLF) images. The software uses a robust statistical modeling approach to automatically segment the QLF image into three classes (background, biofilm, and tooth substratum) based on the training data. This initial segmentation has shown a high degree of consistency and precision on more than 200 test QLF dental scans. Further, the proposed software provides the clinicians full control to fix any misclassified areas using a single click. In addition, BiofilmQuant also provides a complete solution for the longitudinal quantitative analysis of biofilm of the full set of teeth, providing greater ease of usability.

  5. Candida/Candida biofilms. First description of dual-species Candida albicans/C. rugosa biofilm.

    Science.gov (United States)

    Martins, Carlos Henrique Gomes; Pires, Regina Helena; Cunha, Aline Oliveira; Pereira, Cristiane Aparecida Martins; Singulani, Junya de Lacorte; Abrão, Fariza; Moraes, Thais de; Mendes-Giannini, Maria José Soares

    2016-04-01

    Denture liners have physical properties that favour plaque accumulation and colonization by Candida species, irritating oral tissues and causing denture stomatitis. To isolate and determine the incidence of oral Candida species in dental prostheses, oral swabs were collected from the dental prostheses of 66 patients. All the strains were screened for their ability to form biofilms; both monospecies and dual-species combinations were tested. Candida albicans (63 %) was the most frequently isolated microorganism; Candida tropicalis (14 %), Candida glabrata (13 %), Candida rugosa (5 %), Candida parapsilosis (3 %), and Candida krusei (2 %) were also detected. The XTT assay showed that C. albicans SC5314 possessed a biofilm-forming ability significantly higher (p albicans Candida strains, after 6 h 37 °C. The total C. albicans CFU from a dual-species biofilm was less than the total CFU of a monospecies C. albicans biofilm. In contrast to the profuse hyphae verified in monospecies C. albicans biofilms, micrographies showed that the C. albicans/non-albicans Candida biofilms consisted of sparse yeast forms and profuse budding yeast cells that generated a network. These results suggested that C. albicans and the tested Candida species could co-exist in biofilms displaying apparent antagonism. The study provide the first description of C. albicans/C. rugosa mixed biofilm.

  6. QCD-inspired spectra from Blue`s functions

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, M.A. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik]|[Uniwersytet Jagiellonski, Cracow (Poland). Dept. of Theoretical Physics; Papp, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Lorand Eoetvoes Univ., Budapest (Hungary). Inst. for Theoretical Physics; Zahed, I. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics

    1996-03-01

    We use the law of addition in random matrix theory to analyze the spectral distributions of a variety of chiral random matrix models as inspired from QCD whether by symmetries or models. In terms of the Blue`s functions recently discussed by Zee, we show that most of the spectral distributions in the macroscopic limit and the quenched approximation, follow algebraically from the discontinuity of a pertinent solution to a cubic (Cardano) or a quartic (Ferrari) equation. We use the end-point equation of the energy spectra in chiral random matrix models to argue for novel phase structures, in which the Dirac density of states plays the role of an order parameter. (orig.)

  7. [Progress in study of oral biofilm dispersal-inducing agents].

    Science.gov (United States)

    Yan, Zhu; Jingmei, Yang; Dingyu, Duan; Yi, Xu

    2014-12-01

    Communities of bacteria wrapped in self-generated extracellular polymeric matrix and attached to a solid surface are known as biofilm. Biofilm formation and development can be divided into three stages: adhesion of cells to a surface, reproduction of the cells, and dispersion of cells. The procedure, which surface-attached biofilm disperses bacterial cells into the environment to colonize new sites, is defined as biofilm dispersal. Biofilm dispersal is an essential stage of biofilm life cycle. It plays an important role in the transmission of bacteria. For many pathogenic bacteria, biofilm dispersal can transform bacteria in biofilm into planktonic state and promote the spread of infection. The formation of biofilm may increase the resistance of bacteria to antimicrobial agent and host defence response compared with planktonic cells. In the oral cavity, oral microorganism can attach to the surface of oral tissue and prosthesis to form biofilm. Dental caries and periodontal disease are oral chronic infections diseases of the oral tissue. The occurrence of them has a close relationship with biofilm. The mechanism of dispersal is a hot topic in recent years. Some agents which promote dispersal might be a therapeutic potential against biofilm infections. The clinical implication of dispersal agents and potential application are promising. This article reviews the dispersal-inducing agents of oral biofilms.

  8. Antimicrobial susceptibility testing in biofilm-growing bacteria.

    Science.gov (United States)

    Macià, M D; Rojo-Molinero, E; Oliver, A

    2014-10-01

    Biofilms are organized bacterial communities embedded in an extracellular polymeric matrix attached to living or abiotic surfaces. The development of biofilms is currently recognized as one of the most relevant drivers of persistent infections. Among them, chronic respiratory infection by Pseudomonas aeruginosa in cystic fibrosis patients is probably the most intensively studied. The lack of correlation between conventional susceptibility test results and therapeutic success in chronic infections is probably a consequence of the use of planktonically growing instead of biofilm-growing bacteria. Therefore, several in vitro models to evaluate antimicrobial activity on biofilms have been implemented over the last decade. Microtitre plate-based assays, the Calgary device, substratum suspending reactors and the flow cell system are some of the most used in vitro biofilm models for susceptibility studies. Likewise, new pharmacodynamic parameters, including minimal biofilm inhibitory concentration, minimal biofilm-eradication concentration, biofilm bactericidal concentration, and biofilm-prevention concentration, have been defined in recent years to quantify antibiotic activity in biofilms. Using these parameters, several studies have shown very significant quantitative and qualitative differences for the effects of most antibiotics when acting on planktonic or biofilm bacteria. Nevertheless, standardization of the procedures, parameters and breakpoints, by official agencies, is needed before they are implemented in clinical microbiology laboratories for routine susceptibility testing. Research efforts should also be directed to obtaining a deeper understanding of biofilm resistance mechanisms, the evaluation of optimal pharmacokinetic/pharmacodynamic models for biofilm growth, and correlation with clinical outcome.

  9. Porphyromonas gingivalis and Treponema denticola synergistic polymicrobial biofilm development.

    Directory of Open Access Journals (Sweden)

    Ying Zhu

    Full Text Available Chronic periodontitis has a polymicrobial biofilm aetiology and interactions between key bacterial species are strongly implicated as contributing to disease progression. Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia have all been implicated as playing roles in disease progression. P. gingivalis cell-surface-located protease/adhesins, the gingipains, have been suggested to be involved in its interactions with several other bacterial species. The aims of this study were to determine polymicrobial biofilm formation by P. gingivalis, T. denticola and T. forsythia, as well as the role of P. gingivalis gingipains in biofilm formation by using a gingipain null triple mutant. To determine homotypic and polymicrobial biofilm formation a flow cell system was employed and the biofilms imaged and quantified by fluorescent in situ hybridization using DNA species-specific probes and confocal scanning laser microscopy imaging. Of the three species, only P. gingivalis and T. denticola formed mature, homotypic biofilms, and a strong synergy was observed between P. gingivalis and T. denticola in polymicrobial biofilm formation. This synergy was demonstrated by significant increases in biovolume, average biofilm thickness and maximum biofilm thickness of both species. In addition there was a morphological change of T. denticola in polymicrobial biofilms when compared with homotypic biofilms, suggesting reduced motility in homotypic biofilms. P. gingivalis gingipains were shown to play an essential role in synergistic polymicrobial biofilm formation with T. denticola.

  10. Decreased scattering coefficient of blue sclerae

    NARCIS (Netherlands)

    Lanting, P J; Borsboom, P C; te Meerman, G J; ten Kate, L P

    1985-01-01

    The optical scattering properties of blue and normal sclerae were studied with a fiber optic scattering monitor. The scattering was clearly reduced in two osteogenesis imperfecta patients with blue sclerae, and low normal in one osteogenesis imperfecta patient without blue sclerae.

  11. Production of tyrosol by Candida albicans biofilms and its role in quorum sensing and biofilm development.

    Science.gov (United States)

    Alem, Mohammed A S; Oteef, Mohammed D Y; Flowers, T Hugh; Douglas, L Julia

    2006-10-01

    Tyrosol and farnesol are quorum-sensing molecules produced by Candida albicans which accelerate and block, respectively, the morphological transition from yeasts to hyphae. In this study, we have investigated the secretion of tyrosol by C. albicans and explored its likely role in biofilm development. Both planktonic (suspended) cells and biofilms of four C. albicans strains, including three mutants with defined defects in the Efg 1 and Cph 1 morphogenetic signaling pathways, synthesized extracellular tyrosol during growth at 37 degrees C. There was a correlation between tyrosol production and biomass for both cell types. However, biofilm cells secreted at least 50% more tyrosol than did planktonic cells when tyrosol production was related to cell dry weight. The addition of exogenous farnesol to a wild-type strain inhibited biofilm formation by up to 33% after 48 h. Exogenous tyrosol appeared to have no effect, but scanning electron microscopy revealed that tyrosol stimulated hypha production during the early stages (1 to 6 h) of biofilm development. Experiments involving the simultaneous addition of tyrosol and farnesol at different concentrations suggested that the action of farnesol was dominant, and 48-h biofilms formed in the presence of both compounds consisted almost entirely of yeast cells. When biofilm supernatants were tested for their abilities to inhibit or enhance germ tube formation by planktonic cells, the results indicated that tyrosol activity exceeds that of farnesol after 14 h, but not after 24 h, and that farnesol activity increases significantly during the later stages (48 to 72 h) of biofilm development. Overall, our results support the conclusion that tyrosol acts as a quorum-sensing molecule for biofilms as well as for planktonic cells and that its action is most significant during the early and intermediate stages of biofilm formation.

  12. Biofilms of Candida albicans serotypes A and B differ in their sensitivity to photodynamic therapy.

    Science.gov (United States)

    Rossoni, Rodnei Dennis; Barbosa, Júnia Oliveira; de Oliveira, Felipe Eduardo; de Oliveira, Luciane Dias; Jorge, Antonio Olavo Cardoso; Junqueira, Juliana Campos

    2014-09-01

    Candida albicans is classified into different serotypes according to cell wall mannan composition and cell surface hydrophobicity. Since the effectiveness of photodynamic therapy (PDT) depends on the cell wall structure of microorganisms, the objective of this study was to compare the sensitivity of in vitro biofilms of C. albicans serotypes A and B to antimicrobial PDT. Reference strains of C. albicans serotype A (ATCC 36801) and serotype B (ATCC 36802) were used for the assays. A gallium-aluminum-arsenide laser (660 nm) was used as the light source and methylene blue (300 μM) as the photosensitizer. After biofilm formation on the bottom of a 96-well microplate for 48 h, each Candida strain was submitted to assays: PDT consisting of laser and photosensitizer application (L + P+), laser application alone (L + P-), photosensitizer application alone (L-P+), and application of saline as control (L-P-). After treatment, biofilm cells were scraped off and transferred to tubes containing PBS. The content of the tubes was homogenized, diluted, and seeded onto Sabouraud agar plates to determine the number of colony-forming units (CFU/mL). The results were compared by analysis of variance and Tukey test (p < 0.05). The two strains studied were sensitive to PDT (L + P+), with a log reduction of 0.49 for serotype A and of 2.34 for serotype B. Laser application alone only reduced serotype B cells (0.53 log), and the use of the photosensitizer alone had no effect on the strains tested. It can be concluded that in vitro biofilms of C. albicans serotype B were more sensitive to PDT.

  13. Quantitative molecular detection of 19 major pathogens in the interdental biofilm of periodontally healthy young adults

    Directory of Open Access Journals (Sweden)

    Florence eCarrouel

    2016-06-01

    Full Text Available In oral health, the interdental spaces are a real ecological niche for which the body has few or no alternative defenses and where the traditional daily methods for control by disrupting biofilm are not adequate. The interdental spaces are the source of many hypotheses regarding their potential associations with and/or causes of cardiovascular disease, diabetes, chronic kidney disease, degenerative disease, and depression. This PCR study is the first to describe the interdental microbiota in healthy adults aged 18-35 yrs old with reference to the Socransky complexes. The complexes tended to reflect microbial succession events in developing dental biofilms. Early colonizers included members of the yellow, green and purple complexes. The orange complex bacteria generally appear after the early colonizers and include many putative periodontal pathogens, such as F. nucleatum. The red complex (P. gingivalis, T. forsythia and T. denticola was considered the climax community and is on the list of putative periodontal pathogens. The 19 major periodontal pathogens tested were expressed at various levels. F. nucleatum was the most abundant species, and the least abundant were A. viscosus, P. gingivalis and A. actino. a. The genome counts for E. corrodens, C. concisus, C. rectus, T. denticola and T. forsythensis increased significantly with subject age. The study highlights the observation that bacteria from the yellow complex (Streptococcus spp., S. mitis, the green complex (E. corrodens, C. gracilis, C. ochracea, C. sputigena, A. actino a, the purple complex (V. parvula, A. ondotolitycus and the blue complex (A. viscosus are correlated. Concerning the orange complex, F. nucleatum is the most abundant species in interdental biofilm. The red complex, which is recognized as the most important pathogen in adult periodontal disease, represents 8.08% of the 19 bacteria analyzed. P. gingivalis was detected in 19% of healthy subjects and represents 0.02% of the

  14. Chemically Specific Cellular Imaging of Biofilm Formation

    Energy Technology Data Exchange (ETDEWEB)

    Herberg, J L; Schaldach, C; Horn, J; Gjersing, E; Maxwell, R

    2006-02-09

    This document and the accompanying manuscripts summarize the technical accomplishments for our one-year LDRD-ER effort. Biofilm forming microbes have existed on this planet for billions of years and make up 60% of the biological mass on earth. Such microbes exhibit unique biochemical pathways during biofilm formation and play important roles in human health and the environment. Microbial biofilms have been directly implicated in, for example, product contamination, energy losses, and medical infection that cost the loss of human lives and billions of dollars. In no small part due to the lack of detailed understanding, biofilms unfortunately are resistant to control, inhibition, and destruction, either through treatment with antimicrobials or immunological defense mechanisms of the body. Current biofilm research has concentrated on the study of biofilms in the bulk. This is primarily due to the lack of analytical and physical tools to study biofilms non-destructively, in three dimensions, and on the micron or sub-micron scale. This has hindered the development of a clear understanding of either the early stage mechanisms of biofilm growth or the interactions of biofilms with their environment. Enzymatic studies have deduced a biochemical reaction that results in the oxidation of reduced sulfur species with the concomitant reduction of nitrate, a common groundwater pollutant, to dinitrogen gas by the bacterium, Thiobacillus denitrificans (TD). Because of its unique involvement in biologically relevant environmental pathways, TD is scheduled for genome sequencing in the near future by the DOE's Joint Genome Institute and is of interest to DOE's Genomes to Life Program. As our ecosystem is exposed to more and more nitrate contamination large scale livestock and agricultural practices, a further understanding of biofilm formation by organisms that could alleviate these problems is necessary in order to protect out biosphere. However, in order to study this

  15. DNase I and proteinase K impair Listeria monocytogenes biofilm formation and induce dispersal of pre-existing biofilms.

    Science.gov (United States)

    Nguyen, Uyen T; Burrows, Lori L

    2014-09-18

    Current sanitation methods in the food industry are not always sufficient for prevention or dispersal of Listeria monocytogenes biofilms. Here, we determined if prevention of adherence or dispersal of existing biofilms could occur if biofilm matrix components were disrupted enzymatically. Addition of DNase during biofilm formation reduced attachment (biofilms with 100μg/ml of DNase for 24h induced incomplete biofilm dispersal, with biofilm remaining compared to control. In contrast, addition of proteinase K completely inhibited biofilm formation, and 72h biofilms-including those grown under stimulatory conditions-were completely dispersed with 100μg/ml proteinase K. Generally-regarded-as-safe proteases bromelain and papain were less effective dispersants than proteinase K. In a time course assay, complete dispersal of L. monocytogenes biofilms from both polystyrene and type 304H food-grade stainless steel occurred within 5min at proteinase K concentrations above 25μg/ml. These data confirm that both DNA and proteins are required for L. monocytogenes biofilm development and maintenance, and that these components of the biofilm matrix can be targeted for effective prevention and removal of biofilms.

  16. Extracellular matrix structure governs invasion resistance in bacterial biofilms.

    Science.gov (United States)

    Nadell, Carey D; Drescher, Knut; Wingreen, Ned S; Bassler, Bonnie L

    2015-08-01

    Many bacteria are highly adapted for life in communities, or biofilms. A defining feature of biofilms is the production of extracellular matrix that binds cells together. The biofilm matrix provides numerous fitness benefits, including protection from environmental stresses and enhanced nutrient availability. Here we investigate defense against biofilm invasion using the model bacterium Vibrio cholerae. We demonstrate that immotile cells, including those identical to the biofilm resident strain, are completely excluded from entry into resident biofilms. Motile cells can colonize and grow on the biofilm exterior, but are readily removed by shear forces. Protection from invasion into the biofilm interior is mediated by the secreted protein RbmA, which binds mother-daughter cell pairs to each other and to polysaccharide components of the matrix. RbmA, and the invasion protection it confers, strongly localize to the cell lineages that produce it.

  17. Oh What a Tangled Biofilm Web Bacteria Weave

    Science.gov (United States)

    ... Home Page Oh What a Tangled Biofilm Web Bacteria Weave By Elia Ben-Ari Posted May 1, ... a suitable surface, some water and nutrients, and bacteria will likely put down stakes and form biofilms. ...

  18. Metagenomic Analysis of Showerhead Biofilms from a Hospital in Ohio

    Science.gov (United States)

    Background: The National Institute of Health estimated that 80% of human microbial infections are associated with biofilms. Although water supplies and hospital equipments are constantly treated with disinfectants, the presence of biofilms in these areas has been frequently obser...

  19. Structure, composition, and strength of nitrifying membrane-aerated biofilms

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Smets, Barth F.

    2014-01-01

    Membrane-aerated biofilm reactors (MABRs) are a novel technology based on the growth of biofilms on oxygen-permeable membranes. Hereby, MABRs combine all the advantages of biofilm growth with a more flexible and efficient control of the oxygen load. In the present work, flow cell operation...... to achieve full nitrification revealed a significantly different structure of nitrifying MABR biofilms with respect to its co-diffusion counterparts reported in the literature (up to now assumed to have similar properties). Different levels of shear stress and oxygen loadings during MABR operation also...... affected these biofilm parameters. Furthermore, reactor operation at higher oxygen loads resulted in an increase of the biofilm cohesiveness, which depended on the EPS mass in the biofilms and the type of stress applied (more cohesive against normal than shear stresses). The EPS in the strongest biofilms...

  20. Status of Blue Ridge Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    1990-09-01

    This is one in a series of reports prepared by the Tennessee Valley Authority (TVA) for those interested in the conditions of TVA reservoirs. This overview of Blue Ridge Reservoir summarizes reservoir and watershed characteristics, reservoir uses and use impairments, water quality and aquatic biological conditions, and activities of reservoir management agencies. This information was extracted from the most current reports and data available, as well as interview with water resource professionals in various federal, state, and local agencies. Blue Ridge Reservoir is a single-purpose hydropower generating project. When consistent with this primary objective, the reservoir is also operated to benefit secondary objectives including water quality, recreation, fish and aquatic habitat, development of shoreline, aesthetic quality, and other public and private uses that support overall regional economic growth and development. 8 refs., 1 fig.

  1. Thermoluminescence (TL) of Egyptian Blue

    Energy Technology Data Exchange (ETDEWEB)

    Schvoerer, M.; Delavergne, M.-C.; Chapoulie, R.

    1988-01-01

    Egyptian Blue is a synthesized crystalline pictorial pigment with formula CaCuSi/sub 4/O/sub 10/. It has been used in Egypt and Mesopotamia from the 3rd millenium B.C. A preliminary experiment on a recently synthesized sample showed that this pigment is thermoluminescent after ..beta.. irradiation (/sup 90/Sr). As the signal intensity grows linearly with the administered dose within the temperature range commonly used in TL dating, we have been looking for this phenomenon from archaeological pigments. It was encountered with two samples found in excavation. From its intensity and stability we concluded that Egyptian Blue can be dated using TL. This first and positive result encouraged us to extend the method to other types of mineral pigments synthesized by early man, and to suggest that it may be used for direct dating of ancient murals.

  2. The Physics of the Blues

    Science.gov (United States)

    Gibson, J. Murray

    2009-03-01

    In looking at the commonalities between music and science, one sees that the musician's palette is based on the principles of physics. The pitch of a musical note is determined by the frequency of the sound wave. The scales that musicians use to create and play music can be viewed as a set of rules. What makes music interesting is how musicians develop those rules and create ambiguity with them. I will discuss the evolution of western musical scales in this context. As a particular example, ``Blue'' notes are very harmonic notes that are missing from the equal temperament scale. The techniques of piano blues and jazz represent the melding of African and Western music into something totally new and exciting. Live keyboard demonstrations will be used. Beyond any redeeming entertainment value the talk will emphasize the serious connections between science and art in music. Nevertheless tips will be accepted.

  3. Bacteriophages and their enzymes in biofilm control.

    Science.gov (United States)

    Chan, Benjamin K; Abedon, Stephen T

    2015-01-01

    Although free-swimming planktonic bacteria historically have been the typical focus of microbiological studies, the natural state of many or most bacteria is one where they instead are associated with surfaces and/or each other. For many pathogenic as well as nuisance bacteria, including biofouling bacteria, it consequently is within the context of this biofilm state that antibacterial strategies must be implemented. For reasons that are not fully understood, however, biofilm-associated bacteria tend to be less susceptible to treatments with standard chemical antibacterial agents than are planktonic bacteria, and this appears to be especially an issue with the use of less-harsh agents such as antibiotics. Within a variety of contexts the development of less- or selectively toxic antibacterial agents capable of clearing biofilms therefore would be welcome. In this review we consider the use of three categories of such agents as anti-biofilm antibacterials. These are lytic viruses of bacteria, that is, bacteriophages, effecting phage-mediated biocontrol of bacteria (a.k.a., phage therapy); purified phage-encoded enzymes that digest bacterial cell-wall material (endolysins or simply lysins); and a second category of phage-encoded enzymes that digest the extracellular polymeric substance (EPS) that are particularly notable components of bacterial biofilms (EPS depolymerases). These agents have been shown to reduce the bacterial density of a diversity of biofilms and, in many cases, tend to be lacking in inherent toxicity against the tissues of animals. Here we consider these phage-based anti-biofilm strategies with emphasis on ecological aspects of their action and with particular consideration of EPS depolymerases.

  4. Biofilms in churches built in grottoes

    Energy Technology Data Exchange (ETDEWEB)

    Cennamo, Paola, E-mail: paola.cennamo@unisob.na.it [Facoltà di Lettere, Università degli Studi Suor Orsola Benincasa di Napoli, Via Santa Caterina da Siena 37, 80135 Naples (Italy); Montuori, Naomi [Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223, 80139 Naples (Italy); Trojsi, Giorgio; Fatigati, Giancarlo [Facoltà di Lettere, Università degli Studi Suor Orsola Benincasa di Napoli, Via Santa Caterina da Siena 37, 80135 Naples (Italy); Moretti, Aldo [Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223, 80139 Naples (Italy)

    2016-02-01

    We investigated microorganisms dwelling on rocks, walls and paintings in two votive chapels built in grottoes in the Region of Campania, Italy. One grotto was near the coast in an area with a Mediterranean climate, and the other grotto was inland on a mountain in an area with a cold continental climate. Color and distribution of biofilms in various areas of the grottoes were examined. Microbial components of biofilms were identified by light and electron microscopy and by molecular techniques (DNA analyses and Automatic rRNA Intergenic Spacer Analysis). Biofilms were also analyzed by X-ray diffraction to detect inorganic constituents deriving from rocks in the grottoes and walls of the churches and by X-ray fluorescence to detect the elements that made up the pigments of the mural paintings; optical cross sections were used to observe their relationships with substrata. Species of eubacteria, cyanobacteria and green algae were identified. Some of these species occurred in both grottoes, while others were exclusive to only one of the grottoes. The diversity of species, their common or exclusive occurrence in the grottoes, the relationships among microbial communities and the differences in color and distribution of biofilms were discussed on the basis of the different climatic factors affecting the two grottoes and the different inorganic components of substrata. - Highlights: • Biofilms concur to the degradation of cultural heritage. • Microorganisms cause esthetic and structural damage in votive churches. • Biofilm features vary on different substrata, as limestone, plaster and paintings. • Features of biofilms mainly depend on environmental conditions. • Molecular biology techniques are indispensable in the study of biodegradation.

  5. Intrigues of biofilm: A perspective in veterinary medicine

    OpenAIRE

    Umar Faruk Abdullahi; Ephraim Igwenagu; Anas Mu’azu; Sani Aliyu; Maryam Ibrahim Umar

    2016-01-01

    Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which...

  6. The Composition and Metabolic Phenotype of Neisseria gonorrhoeae Biofilms

    Directory of Open Access Journals (Sweden)

    Michael A Apicella

    2011-04-01

    Full Text Available N. gonorrhoeae has been shown to form biofilms during cervical infection. Thus, biofilm formation may play an important role in the infection of women. The ability of N. gonorrhoeae to form membrane blebs is crucial to biofilm formation. Blebs contain DNA and outer membrane structures, which have been shown to be major constituents of the biofilm matrix. The organism expresses a DNA thermonuclease that is involved in remodeling of the biofilm matrix. Comparison of the transcriptional profiles of gonococcal biofilms and planktonic runoff indicate that genes involved in anaerobic metabolism and oxidative stress tolerance are more highly expressed in biofilm. The expression of aniA, ccp, and norB, which encode nitrite reductase, cytochrome c peroxidase, and nitric oxide reductase respectively, is required for mature biofilm formation over glass and human cervical cells. In addition, anaerobic respiration occurs in the substratum of gonococcal biofilms and disruption of the norB gene required for anaerobic respiration, results in a severe biofilm attenuation phenotype. It has been demonstrated that accumulation of nitric oxide (NO contributes to the phenotype of a norB mutant and can retard biofilm formation. However, NO can also enhance biofilm formation, and this is largely dependent on the concentration and donation rate or steady state kinetics of NO. The majority of the genes involved in gonococcal oxidative stress tolerance are also required for normal biofilm formation, as mutations in the following genes result in attenuated biofilm formation over cervical cells and/or glass: oxyR, gor, prx, mntABC, trxB, and estD. Overall, biofilm formation appears to be an adaptation for coping with the environmental stresses present in the female genitourinary tract. Therefore, this review will discuss the studies, which describe the composition and metabolic phenotype of gonococcal biofilms.

  7. Difference in initial dental biofilm accumulation between night and day

    DEFF Research Database (Denmark)

    Dige, Irene; Schlafer, Sebastian; Nyvad, Bente

    2012-01-01

    Objective. The study of initial microbial colonization on dental surfaces is a field of intensive research because of the aetiological role of biofilms in oral diseases. Most previous studies of de novo accumulation and composition of dental biofilms in vivo do not differentiate between biofilms ...

  8. Chemoinformatics-assisted development of new anti-biofilm compounds

    DEFF Research Database (Denmark)

    Dürig, Anna; Kouskoumvekaki, Irene; Vejborg, Rebecca Munk

    2010-01-01

    Bacterial biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Here, we use a novel cross-disciplinary approach combining microbiology and chemoinformatics to iden...

  9. A cathelicidin-2-derived peptide effectively impairs Staphylococcus epidermidis biofilms

    NARCIS (Netherlands)

    Molhoek, E.M.; Dijk, A. van; Veldhuizen, E.J.A.; Haagsman, H.P.; Bikker, F.J.

    2011-01-01

    Staphylococcus epidermidis is a major cause of nosocomial infections owing to its ability to form biofilms on the surface of medical devices. Biofilms are surface-adhered bacterial communities. In mature biofilms these communities are encased in an extracellular matrix composed of bacterial polysacc

  10. Epithelial interleukin-8 responses to oral bacterial biofilms.

    Science.gov (United States)

    Peyyala, R; Kirakodu, S; Novak, K F; Ebersole, J L

    2011-10-01

    An in vitro model of bacterial biofilms on rigid gas-permeable contact lenses (RGPLs) was developed to challenge oral epithelial cells. This novel model provided seminal data on oral biofilm-host cell interactions, and with selected bacteria, the biofilms were more effective than their planktonic counterparts at stimulating host cell responses.

  11. Effects of different osmolarities on bacterial biofilm formation

    OpenAIRE

    2014-01-01

    Biofilm formation depends on several factors. The influence of different osmolarities on bacterial biofilm formation was studied. Two strains (Enterobacter sp. and Stenotrophomonas sp.) exhibited the most remarkable alterations. Biofilm formation is an important trait and its use has been associated to the protection of organisms against environmental stresses.

  12. The effect of chemotherapeutic agents on titanium-adherent biofilms

    NARCIS (Netherlands)

    Ntrouka, V.; Hoogenkamp, M.; Zaura, E.; van der Weijden, F.

    2011-01-01

    Objective: To assess the effectiveness of different chemotherapeutic agents on biofilm-contaminated titanium surfaces. Material and methods: This study used a recently described biofilm model. In experiment 1, Streptococcus mutans biofilms grown on titanium discs were treated with (1) EDTA, (2) citr

  13. Influence of Streptococcus mutans on Enterococcus faecalis Biofilm Formation

    NARCIS (Netherlands)

    Deng, Dong Mei; Hoogenkamp, Michel A.; Exterkate, Rob A. M.; Jiang, Lei Meng; van der Sluis, Lucas W. M.; ten Cate, Jacob M.; Crielaard, Wim

    2009-01-01

    Introduction: An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of

  14. Biofilm Formation on Dental Restorative and Implant Materials

    NARCIS (Netherlands)

    Busscher, H. J.; Rinastiti, M.; Siswomihardjo, W.; van der Mei, H. C.

    2010-01-01

    Biomaterials for the restoration of oral function are prone to biofilm formation, affecting oral health. Oral bacteria adhere to hydrophobic and hydrophilic surfaces, but due to fluctuating shear, little biofilm accumulates on hydrophobic surfaces in vivo. More biofilm accumulates on rough than on s

  15. Induction of beta-lactamase production in Pseudomonas aeruginosa biofilm

    DEFF Research Database (Denmark)

    Giwercman, B; Jensen, E T; Høiby, N;

    1991-01-01

    Imipenem induced high levels of beta-lactamase production in Pseudomonas aeruginosa biofilms. Piperacillin also induced beta-lactamase production in these biofilms but to a lesser degree. The combination of beta-lactamase production with other protective properties of the biofilm mode of growth...

  16. High frequency ultrasound imaging of a single-species biofilm

    NARCIS (Netherlands)

    Shemesh, H.; Goertz, D. E.; van der Sluis, L. W. M.; de Jong, N.; Wu, M. K.; Wesselink, P. R.

    2007-01-01

    Objective: This study evaluated the feasibility of a high frequency ultrasound scan to examine the 3D morphology of Streptococcus mutans biofilms grown in vitro. Methods: Six 2-day S. mutans biofilms and six 7-day biofilms were grown on tissue culture membranes and on bovine dentine discs. A sterile

  17. Staphylococcus epidermidis biofilm quantification: effect of different solvents and dyes.

    Science.gov (United States)

    Wu, X; Santos, R R; Fink-Gremmels, J

    2014-06-01

    Staphylococcus epidermidis biofilm formed in the presence of the solvents DMSO, ethanol or methanol was quantified using safranin or crystal violet staining protocols. We found that biofilm quantification was the most accurate when safranin protocol was applied. Moreover, both DMSO and ethanol stimulated biofilm formation.

  18. Effects of bacteriocins on methicillin-resistant Staphylococcus aureus biofilm.

    Science.gov (United States)

    Okuda, Ken-ichi; Zendo, Takeshi; Sugimoto, Shinya; Iwase, Tadayuki; Tajima, Akiko; Yamada, Satomi; Sonomoto, Kenji; Mizunoe, Yoshimitsu

    2013-11-01

    Control of biofilms formed by microbial pathogens is an important subject for medical researchers, since the development of biofilms on foreign-body surfaces often causes biofilm-associated infections in patients with indwelling medical devices. The present study examined the effects of different kinds of bacteriocins, which are ribosomally synthesized antimicrobial peptides produced by certain bacteria, on biofilms formed by a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). The activities and modes of action of three bacteriocins with different structures (nisin A, lacticin Q, and nukacin ISK-1) were evaluated. Vancomycin, a glycopeptide antibiotic used in the treatment of MRSA infections, showed bactericidal activity against planktonic cells but not against biofilm cells. Among the tested bacteriocins, nisin A showed the highest bactericidal activity against both planktonic cells and biofilm cells. Lacticin Q also showed bactericidal activity against both planktonic cells and biofilm cells, but its activity against biofilm cells was significantly lower than that of nisin A. Nukacin ISK-1 showed bacteriostatic activity against planktonic cells and did not show bactericidal activity against biofilm cells. Mode-of-action studies indicated that pore formation leading to ATP efflux is important for the bactericidal activity against biofilm cells. Our results suggest that bacteriocins that form stable pores on biofilm cells are highly potent for the treatment of MRSA biofilm infections.

  19. Biofilm Formation Characteristics of Pseudomonas lundensis Isolated from Meat.

    Science.gov (United States)

    Liu, Yong-Ji; Xie, Jing; Zhao, Li-Jun; Qian, Yun-Fang; Zhao, Yong; Liu, Xiao

    2015-12-01

    Biofilms formations of spoilage and pathogenic bacteria on food or food contact surfaces have attracted increasing attention. These events may lead to a higher risk of food spoilage and foodborne disease transmission. While Pseudomonas lundensis is one of the most important bacteria that cause spoilage in chilled meat, its capability for biofilm formation has been seldom reported. Here, we investigated biofilm formation characteristics of P. lundensis mainly by using crystal violet staining, and confocal laser scanning microscopy (CLSM). The swarming and swimming motility, biofilm formation in different temperatures (30, 10, and 4 °C) and the protease activity of the target strain were also assessed. The results showed that P. lundensis showed a typical surface-associated motility and was quite capable of forming biofilms in different temperatures (30, 10, and 4 °C). The strain began to adhere to the contact surfaces and form biofilms early in the 4 to 6 h. The biofilms began to be formed in massive amounts after 12 h at 30 °C, and the extracellular polysaccharides increased as the biofilm structure developed. Compared with at 30 °C, more biofilms were formed at 4 and 10 °C even by a low bacterial density. The protease activity in the biofilm was significantly correlated with the biofilm formation. Moreover, the protease activity in biofilm was significantly higher than that of the corresponding planktonic cultures after cultured 12 h at 30 °C.

  20. Novel entries in a fungal biofilm matrix encyclopedia

    Science.gov (United States)

    Virulence of Candida albicans is linked with its ability to form biofilms. Once established, biofilm infections are nearly impossible to eradicate. Biofilm cells live immersed in a self-produced matrix, a blend of extracellular biopolymers, many of which are uncharacterized. In this study, we conduc...

  1. Influence of Streptococcus mutans on enterococcus faecalis biofilm formation

    NARCIS (Netherlands)

    Deng, D.M.; Hoogenkamp, M.A.; Exterkate, R.A.M.; Jiang, L.M.; van der Sluis, L.W.M.; ten Cate, J.M.; Crielaard, W.

    2009-01-01

    Introduction: An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of

  2. Composition and architecture of biofilms on used voice prostheses

    NARCIS (Netherlands)

    Buijssen, Kevin J. D. A.; van der Laan, Bernard F. A. M.; van der Mei, Henny C.; Atema-Smit, Jelly; van den Huijssen, Pauline; Busscher, Henk J.; Harmsen, Hermie J. M.

    2012-01-01

    Background Biofilms on medical devices are a frequent reason for failure of the device. Voice prostheses in laryngectomized patients deteriorate within 3 to 4 months due to adhering biofilms, impeding proper functioning. Recently, we showed that these biofilms are dominated by Candida and lactobacil

  3. Biofilm and siderophore effects on secondary waste water disinfection.

    Science.gov (United States)

    Saidi, N; Kouki, S; Mehri, I; Ben Rejeb, A; Belila, A; Hassen, A; Ouzari, H

    2011-10-01

    The efficiency of ultraviolet (UV) light disinfection of wastewater effluent using a large-scale pilot system was studied. The relationship between biofilm and siderophore production and UV doses received by Pseudomonas aeruginosa strain ATCC 15442 was determined. UV decreased pyoverdine production and enhanced biofilm production. Consequently external factors conditioned by both pyoverdine and biofilm may affect the UV effect on bacterial disinfection.

  4. Extracellular DNA formation during biofilm development by freshwater bacteria

    DEFF Research Database (Denmark)

    Tang, Lone; Schramm, Andreas; Revsbech, Niels Peter

    2011-01-01

    of eDNA is most important. In this study, we investigated the significance of eDNA during biofilm formation in four freshwater isolates. The aim was to relate the quantity and timing of eDNA production to the isolates’ ability to form biofilms. eDNA and biofilm biomass was quantified over time during...

  5. Oral cavity anaerobic pathogens in biofilm formation on voice prostheses

    NARCIS (Netherlands)

    Bertl, Kristina; Zijnge, Vincent; Zatorska, Beata; Leonhard, Matthias; Schneider-Stickler, Berit; Harmsen, Hermie J. M.

    2015-01-01

    BACKGROUND: A polymerase chain reaction (PCR)-based method has been used to identify oral anaerobic pathogens in biofilms on voice prostheses. The purpose of the present study was to determine the location of those pathogens inside the biofilms. METHODS: Biofilms of 15 voice prostheses were sampled

  6. Fluid dynamic effects on staphylococci bacteria biofilms

    Science.gov (United States)

    Sherman, Erica; Bayles, Kenneth; Endres, Jennifer; Wei, Timothy

    2016-11-01

    Staphylococcus aureus bacteria are able to form biofilms and distinctive tower structures that facilitate their ability to tolerate treatment and to spread within the human body. The formation of towers, which break off, get carried downstream and serve to initiate biofilms in other parts of the body are of particular interest here. It is known that flow conditions play a role in the development, dispersion and propagation of biofilms in general. The influence of flow on tower formation, however, is not at all understood. This work is focused on the effect of applied shear on tower development. The hypothesis being examined is that tower structures form within a specific range of shear stresses and that there is an as yet ill defined fluid dynamic phenomenon that occurs hours before a tower forms. In this study, a range of shear stresses is examined that brackets 0.6 dynes/cm2, the nominal shear stress where towers seem most likely to form. This talk will include µPTV measurements and cell density data indicating variations in flow and biofilm evolution as a function of the applied shear. Causal relations between flow and biofilm development will be discussed.

  7. Microbial Biofilms: Persisters, Tolerance and Dosing

    Science.gov (United States)

    Cogan, N. G.

    2005-03-01

    Almost all moist surfaces are colonized by microbial biofilms. Biofilms are implicated in cross-contamination of food products, biofouling, medical implants and various human infections such as dental cavities, ulcerative colitis and chronic respiratory infections. Much of current research is focused on the recalcitrance of biofilms to typical antibiotic and antimicrobial treatments. Although the polymer component of biofilms impedes the penetration of antimicrobials through reaction-diffusion limitation, this does not explain the observed tolerance, it merely delays the action of the agent. Heterogeneities in growth-rate also slow the eradication of the bacteria since most antimicrobials are far less effective for non-growing, or slowly growing bacteria. This also does not fully describe biofilm tolerance, since heterogeneities arr primairly a result of nutrient consumption. In this investigation, we describe the formation of `persister' cells which neither grow nor die in the presence of antibiotics. We propose that the cells are of a different phenotype than typical bacterial cells and the expression of the phenotype is regulated by the growth rate and the antibiotic concentration. We describe several experiments which describe the dynamics of persister cells and which motivate a dosing protocol that calls for periodic dosing of the population. We then introduce a mathematical model, which describes the effect of such a dosing regiment and indicates that the relative dose/withdrawal times are important in determining the effectiveness of such a treatment. A reduced model is introduced and the similar behavior is demonstrated analytically.

  8. En rejse ind i dental biofilm

    DEFF Research Database (Denmark)

    Schlafer, Sebastian

    Som klinkassistent og tandplejer arbejder man hver dag med bakteriel biofilm på tandoverfladerne – plak. Alle ved udmærket, at denne biofilm er ansvarlig for mundhulens hyppigste sygdomme, caries og parodontitis. Vi renser patienternes tænder for biofilm og opfordrer dem til at fjerne biofilmen...... mindst to gange om dagen, så grundigt de kan. Desuden bruges der en lang række antibakterielle tilsætningsstoffer i både tandpasta og mundskyllevæsker, hvis hovedformål er at dræbe bakterierne i dental biofilm. Men er biofilmen virkelig kun farlig? Nyere forskning har vist, at mennesket faktisk i høj...... grad er afhængig af de bakterier, der koloniserer kroppen. Hvorfor gælder dette tilsyneladende ikke for mundhulen? I løbet af præsentationen vil jeg tage tilhørerne med på en rejse ind i dental biofilm. Jeg vil belyse den komplekse bakterielle arkitektur, som kendetegner biofilmen, og vil analysere de...

  9. Enzymes Enhance Biofilm Removal Efficiency of Cleaners.

    Science.gov (United States)

    Stiefel, Philipp; Mauerhofer, Stefan; Schneider, Jana; Maniura-Weber, Katharina; Rosenberg, Urs; Ren, Qun

    2016-06-01

    Efficient removal of biofilms from medical devices is a big challenge in health care to avoid hospital-acquired infections, especially from delicate devices like flexible endoscopes, which cannot be reprocessed using harsh chemicals or high temperatures. Therefore, milder solutions such as enzymatic cleaners have to be used, which need to be carefully developed to ensure efficacious performance. In vitro biofilm in a 96-well-plate system was used to select and optimize the formulation of novel enzymatic cleaners. Removal of the biofilm was quantified by crystal violet staining, while the disinfecting properties were evaluated by a BacTiter-Glo assay. The biofilm removal efficacy of the selected cleaner was further tested by using European standard (EN) for endoscope cleaning EN ISO 15883, and removal of artificial blood soil was investigated by treating TOSI (Test Object Surgical Instrument) cleaning indicators. Using the process described here, a novel enzymatic endoscope cleaner was developed, which removed 95% of Staphylococcus aureus and 90% of Pseudomonas aeruginosa biofilms in the 96-well plate system. With a >99% reduction of CFU and a >90% reduction of extracellular polymeric substances, this cleaner enabled subsequent complete disinfection and fulfilled acceptance criteria of EN ISO 15883. Furthermore, it efficiently removed blood soil and significantly outperformed comparable commercial products. The cleaning performance was stable even after storage of the cleaner for 6 months. It was demonstrated that incorporation of appropriate enzymes into the cleaner enhanced performance significantly.

  10. Electrochemical sensors for biofilm and biocorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Tribollet, B. [UPR 15 du CNRS, Universite Paris 6, 4 Place Jussieu, 75252 Paris Cedex05 (France)

    2003-07-01

    The presence of biofilm modifies the electrochemical properties of the interface and the mass transport near the interface. Two biofilm effects are damageable: the reduction of heat and/or mass transfer and the biocorrosion or microbiologically influenced corrosion (MIC). Two kinds of electrochemical sensors were developed: the first kind for the biofilm detection and the second one to evaluate the MIC risk. The biofilm detection is obtained by considering either the potential modification of the interface or the mass transport modification. The mass transport modification is analysed by considering the limiting diffusion current measured on a gold electrode where the biofilm development occurs. The MIC risk is evaluated with a sensor composed of two concentric electrodes in the material under investigation (e.g. carbon steel): a small disk electrode in the centre and a large ring. In a first step, a pit is artificially initiated by applying a current through these electrodes. In a second step, the risk factors of MIC are investigated by analysing the free coupling current circulating between these two short-circuited electrodes. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  11. Chlorine dioxide disinfection of single and dual species biofilms, detached biofilm and planktonic cells.

    Science.gov (United States)

    Behnke, Sabrina; Camper, Anne K

    2012-01-01

    Disinfection efficacy testing is usually done with planktonic cells or more recently, biofilms. While disinfectants are much less effective against biofilms compared to planktonic cells, questions regarding the disinfection tolerance of detached biofilm clusters remain largely unanswered. Burkholderia cepacia and Pseudomonas aeruginosa were grown in chemostats and biofilm tubing reactors, with the tubing reactor serving as a source of detached biofilm clusters. Chlorine dioxide susceptibility was assessed for B. cepacia and P. aeruginosa in these three sample types as monocultures and binary cultures. Similar doses of chlorine dioxide inactivated samples of chemostat and tubing reactor effluent and no statistically significant difference between the log(10) reductions was found. This contrasts with chlorine, shown previously to be generally less effective against detached biofilm particles. Biofilms were more tolerant and required chlorine dioxide doses ten times higher than chemostat and tubing reactor effluent samples. A second species was advantageous in all sample types and resulted in lower log(10) reductions when compared to the single species cultures, suggesting a beneficial interaction of the species.

  12. Patterned biofilm formation reveals a mechanism for structural heterogeneity in bacterial biofilms.

    Science.gov (United States)

    Gu, Huan; Hou, Shuyu; Yongyat, Chanokpon; De Tore, Suzanne; Ren, Dacheng

    2013-09-03

    Bacterial biofilms are ubiquitous and are the major cause of chronic infections in humans and persistent biofouling in industry. Despite the significance of bacterial biofilms, the mechanism of biofilm formation and associated drug tolerance is still not fully understood. A major challenge in biofilm research is the intrinsic heterogeneity in the biofilm structure, which leads to temporal and spatial variation in cell density and gene expression. To understand and control such structural heterogeneity, surfaces with patterned functional alkanthiols were used in this study to obtain Escherichia coli cell clusters with systematically varied cluster size and distance between clusters. The results from quantitative imaging analysis revealed an interesting phenomenon in which multicellular connections can be formed between cell clusters depending on the size of interacting clusters and the distance between them. In addition, significant differences in patterned biofilm formation were observed between wild-type E. coli RP437 and some of its isogenic mutants, indicating that certain cellular and genetic factors are involved in interactions among cell clusters. In particular, autoinducer-2-mediated quorum sensing was found to be important. Collectively, these results provide missing information that links cell-to-cell signaling and interaction among cell clusters to the structural organization of bacterial biofilms.

  13. Characterization of Pleurotus ostreatus biofilms by using the calgary biofilm device.

    Science.gov (United States)

    Pesciaroli, Lorena; Petruccioli, Maurizio; Fedi, Stefano; Firrincieli, Andrea; Federici, Federico; D'Annibale, Alessandro

    2013-10-01

    The adequacy of the Calgary biofilm device, often referred to as the MBEC system, as a high-throughput approach to the production and subsequent characterization of Pleurotus ostreatus biofilms was assessed. The hydroxyapatite-coating of pegs was necessary to enable biofilm attachment, and the standardization of vegetative inocula ensured a uniform distribution of P. ostreatus biofilms, which is necessary for high-throughput evaluations of several antimicrobials and exposure conditions. Scanning electron microscopy showed surface-associated growth, the occurrence of a complex aggregated growth organized in multilayers or hyphal bundles, and the encasement of hyphae within an extracellular matrix (ECM), the extent of which increased with time. Chemical analyses showed that biofilms differed from free-floating cultures for their higher contents of total sugars (TS) and ECM, with the latter being mainly composed of TS and, to a lesser extent, protein. Confocal laser scanning microscopy analysis of 4-day-old biofilms showed the presence of interspersed interstitial voids and water channels in the mycelial network, the density and compactness of which increased after a 7-day incubation, with the novel occurrence of ECM aggregates with an α-glucan moiety. In 4- and 7-day-old biofilms, tolerance to cadmium was increased by factors of 3.2 and 11.1, respectively, compared to coeval free-floating counterparts.

  14. Quantification of biofilm in microtiter plates: overview of testing conditions and practical recommendations for assessment of biofilm production by staphylococci.

    Science.gov (United States)

    Stepanović, Srdjan; Vuković, Dragana; Hola, Veronika; Di Bonaventura, Giovanni; Djukić, Slobodanka; Cirković, Ivana; Ruzicka, Filip

    2007-08-01

    The details of all steps involved in the quantification of biofilm formation in microtiter plates are described. The presented protocol incorporates information on assessment of biofilm production by staphylococci, gained both by direct experience as well as by analysis of methods for assaying biofilm production. The obtained results should simplify quantification of biofilm formation in microtiter plates, and make it more reliable and comparable among different laboratories.

  15. Adsorption of Methylene Blue, Bromophenol Blue, and Coomassie Brilliant Blue by α-chitin nanoparticles

    Directory of Open Access Journals (Sweden)

    Solairaj Dhananasekaran

    2016-01-01

    Full Text Available Expelling of dyestuff into water resource system causes major thread to the environment. Adsorption is the cost effective and potential method to remove the dyes from the effluents. Therefore, an attempt was made to study the adsorption of dyestuff (Methylene Blue (MB, Bromophenol Blue (BPB and Coomassie Brilliant Blue (CBB by α-chitin nanoparticles (CNP prepared from Penaeus monodon (Fabricius, 1798 shell waste. On contrary to the most recognizable adsorption studies using chitin, this is the first study using unique nanoparticles of ⩽50 nm used for the dye adsorption process. The results showed that the adsorption process increased with increase in the concentration of CNP, contact time and temperature with the dyestuff, whereas the adsorption process decreased with increase in the initial dye concentration and strong acidic pH. The results from Fourier transform infrared (FTIR spectroscopy confirmed that the interaction between dyestuff and CNP involved physical adsorption. The adsorption process obeys Langmuir isotherm (R2 values were 0.992, 0.999 and 0.992 for MB, BPB and CBB, and RL value lies between 0 and 1 for all the three dyes and pseudo second order kinetics (R2 values were 0.996, 0.999 and 0.996 for MB, BPB and CBB more effectively. The isotherm and kinetic models confirmed that CNP can be used as a suitable adsorbent material for the removal of dyestuff from effluents.

  16. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    Directory of Open Access Journals (Sweden)

    Joe A. Lemire

    2015-10-01

    Full Text Available Moving bed biofilm reactors (MBBRs are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR carriers (biofilm support materials, allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that mixed-species biofilms can be harvested from an industrial wastewater inoculum [oil sands process water (OSPW] using the Calgary Biofilm Device (CBD. Moreover, the resultant biofilm communities had the capacity to degrade organic toxins (naphthenic acids—NAs that are found in OSPW. Therefore, we hypothesized that harnessing microbial communities from industrial wastewater, as biofilms, on MBBR carriers may be an effective method to bioremediate industrial wastewater.Here, we detail our methodology adapting the workflow employed for using the CBD, to generate inoculant carriers to seed an MBBR.In this study, OSPW-derived biofilm communities were successfully grown, and their efficacy evaluated, on commercially available MBBR carriers affixed within a modified CBD system. The resultant biofilms demonstrated the capacity to transfer biomass to recipient carriers within a scaled MBBR. Moreover, MBBR systems inoculated in this manner were fully active 2 days post-inoculation, and readily degraded a select population of NAs. Together, these findings suggest that harnessing microbial communities on carriers affixed within a modified CBD system may represent a facile and rapid method for obtaining functional inoculants for use in wastewater MBBR treatment systems.

  17. Anti-Biofilm and Immunomodulatory Activities of Peptides That Inhibit Biofilms Formed by Pathogens Isolated from Cystic Fibrosis Patients.

    Science.gov (United States)

    de la Fuente-Núñez, César; Mansour, Sarah C; Wang, Zhejun; Jiang, Lucy; Breidenstein, Elena B M; Elliott, Melissa; Reffuveille, Fany; Speert, David P; Reckseidler-Zenteno, Shauna L; Shen, Ya; Haapasalo, Markus; Hancock, Robert E W

    2014-01-01

    Cystic fibrosis (CF) patients often acquire chronic respiratory tract infections due to Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc) species. In the CF lung, these bacteria grow as multicellular aggregates termed biofilms. Biofilms demonstrate increased (adaptive) resistance to conventional antibiotics, and there are currently no available biofilm-specific therapies. Using plastic adherent, hydroxyapatite and flow cell biofilm models coupled with confocal and scanning electron microscopy, it was demonstrated that an anti-biofilm peptide 1018 prevented biofilm formation, eradicated mature biofilms and killed biofilms formed by a wide range of P. aeruginosa and B. cenocepacia clinical isolates. New peptide derivatives were designed that, compared to their parent peptide 1018, showed similar or decreased anti-biofilm activity against P. aeruginosa biofilms, but increased activity against biofilms formed by the Gram-positive bacterium methicillin resistant Staphylococcus aureus. In addition, some of these new peptide derivatives retained the immunomodulatory activity of 1018 since they induced the production of the chemokine monocyte chemotactic protein-1 (MCP-1) and suppressed lipopolysaccharide-mediated tumor necrosis factor-α (TNF-α) production by human peripheral blood mononuclear cells (PBMC) and were non-toxic towards these cells. Peptide 1018 and its derivatives provide promising leads for the treatment of chronic biofilm infections and hyperinflammatory lung disease in CF patients.

  18. pH, redox potential and local biofilm potential microenvironments within Geobacter sulfurreducens biofilms and their roles in electron transfer.

    Science.gov (United States)

    Babauta, Jerome T; Nguyen, Hung Duc; Harrington, Timothy D; Renslow, Ryan; Beyenal, Haluk

    2012-10-01

    The limitation of pH inside electrode-respiring biofilms is a well-known concept. However, little is known about how pH and redox potential are affected by increasing current inside biofilms respiring on electrodes. Quantifying the variations in pH and redox potential with increasing current is needed to determine how electron transfer is tied to proton transfer within the biofilm. In this research, we quantified pH and redox potential variations in electrode-respiring Geobacter sulfurreducens biofilms as a function of respiration rates, measured as current. We also characterized pH and redox potential at the counter electrode. We concluded that (1) pH continued to decrease in the biofilm through different growth phases, showing that the pH is not always a limiting factor in a biofilm and (2) decreasing pH and increasing redox potential at the biofilm electrode were associated only with the biofilm, demonstrating that G. sulfurreducens biofilms respire in a unique internal environment. Redox potential inside the biofilm was also compared to the local biofilm potential measured by a graphite microelectrode, where the tip of the microelectrode was allowed to acclimatize inside the biofilm.

  19. Anti-Biofilm and Immunomodulatory Activities of Peptides That Inhibit Biofilms Formed by Pathogens Isolated from Cystic Fibrosis Patients

    Directory of Open Access Journals (Sweden)

    César de la Fuente-Núñez

    2014-10-01

    Full Text Available Cystic fibrosis (CF patients often acquire chronic respiratory tract infections due to Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc species. In the CF lung, these bacteria grow as multicellular aggregates termed biofilms. Biofilms demonstrate increased (adaptive resistance to conventional antibiotics, and there are currently no available biofilm-specific therapies. Using plastic adherent, hydroxyapatite and flow cell biofilm models coupled with confocal and scanning electron microscopy, it was demonstrated that an anti-biofilm peptide 1018 prevented biofilm formation, eradicated mature biofilms and killed biofilms formed by a wide range of P. aeruginosa and B. cenocepacia clinical isolates. New peptide derivatives were designed that, compared to their parent peptide 1018, showed similar or decreased anti-biofilm activity against P. aeruginosa biofilms, but increased activity against biofilms formed by the Gram-positive bacterium methicillin resistant Staphylococcus aureus. In addition, some of these new peptide derivatives retained the immunomodulatory activity of 1018 since they induced the production of the chemokine monocyte chemotactic protein-1 (MCP-1 and suppressed lipopolysaccharide-mediated tumor necrosis factor-α (TNF-α production by human peripheral blood mononuclear cells (PBMC and were non-toxic towards these cells. Peptide 1018 and its derivatives provide promising leads for the treatment of chronic biofilm infections and hyperinflammatory lung disease in CF patients.

  20. A personal history of research on microbial biofilms and biofilm infections

    DEFF Research Database (Denmark)

    Høiby, Niels

    2014-01-01

    80-90 years ago to be important for biofouling on submerged surfaces, e.g. ships. The concept of biofilm infections and their importance in medicine is, however, dental pellicles and my own observations of heaps of Pseudomonas...... aeruginosa cells in sputum and lung tissue from chronically infected cystic fibrosis patients. The term biofilm was introduced into medicine in 1985 by Costerton. In the following decades, it became obvious that biofilm infections are widespread in medicine, and their importance is now generally accepted....

  1. Esp-independent biofilm formation by Enterococcus faecalis.

    Science.gov (United States)

    Kristich, Christopher J; Li, Yung-Hua; Cvitkovitch, Dennis G; Dunny, Gary M

    2004-01-01

    Enterococcus faecalis is a gram-positive opportunistic pathogen known to form biofilms in vitro. In addition, this organism is often isolated from biofilms on the surfaces of various indwelling medical devices. However, the molecular mechanisms regulating biofilm formation in these clinical isolates are largely unknown. Recent work has suggested that a specific cell surface protein (Esp) of E. faecalis is critical for biofilm formation by this organism. However, in the same study, esp-deficient strains of E. faecalis were found to be capable of biofilm formation. To test the hypothesis that Esp is dispensable for biofilm formation by E. faecalis, we used microtiter plate assays and a chemostat-based biofilm fermentor assay to examine biofilm formation by genetically well-defined, non-Esp-expressing strains. Our results demonstrate that in vitro biofilm formation occurs, not only in the absence of esp, but also in the absence of the entire pathogenicity island that harbors the esp coding sequence. Using scanning electron microscopy to evaluate biofilms of E. faecalis OG1RF grown in the fermentor system, biofilm development was observed to progress through multiple stages, including attachment of individual cells to the substratum, microcolony formation, and maturation into complex multilayered structures apparently containing water channels. Microtiter plate biofilm analyses indicated that biofilm formation or maintenance was modulated by environmental conditions. Furthermore, our results demonstrate that expression of a secreted metalloprotease, GelE, enhances biofilm formation by E. faecalis. In summary, E. faecalis forms complex biofilms by a process that is sensitive to environmental conditions and does not require the Esp surface protein.

  2. Characterization of temporal protein production in Pseudomonas aeruginosa biofilms.

    Science.gov (United States)

    Southey-Pillig, Christopher J; Davies, David G; Sauer, Karin

    2005-12-01

    Phenotypic and genetic evidence supporting the notion of biofilm formation as a developmental process is growing. In the present work, we provide additional support for this hypothesis by identifying the onset of accumulation of biofilm-stage specific proteins during Pseudomonas aeruginosa biofilm maturation and by tracking the abundance of these proteins in planktonic and three biofilm developmental stages. The onset of protein production was found to correlate with the progression of biofilms in developmental stages. Protein identification revealed that proteins with similar function grouped within similar protein abundance patterns. Metabolic and housekeeping proteins were found to group within a pattern separate from virulence, antibiotic resistance, and quorum-sensing-related proteins. The latter were produced in a progressive manner, indicating that attendant features that are characteristic of biofilms such as antibiotic resistance and virulence may be part of the biofilm developmental process. Mutations in genes for selected proteins from several protein production patterns were made, and the impact of these mutations on biofilm development was evaluated. The proteins cytochrome c oxidase, a probable chemotaxis transducer, a two-component response regulator, and MexH were produced only in mature and late-stage biofilms. Mutations in the genes encoding these proteins did not confer defects in growth, initial attachment, early biofilm formation, or twitching motility but were observed to arrest biofilm development at the stage of cell cluster formation we call the maturation-1 stage. The results indicated that expression of theses genes was required for the progression of biofilms into three-dimensional structures on abiotic surfaces and the completion of the biofilm developmental cycle. Reverse transcription-PCR analysis confirmed the detectable change in expression of the respective genes ccoO, PA4101, and PA4208. We propose a possible mechanism for the

  3. THE FORMATION OF BIOFILMS BY PSEUDOMONAS AERUGINOSA STRAINS, AND METHODS OF ITS CONTROL (REVIEW

    Directory of Open Access Journals (Sweden)

    Sarkis-Ivanova VV

    2017-03-01

    investigate this problem the main source of nosocomial diseases and persistence factor of their causative agents in hospital ecosystems from air and water to inner surfaces of catheters and body systems are represented by biofilms. Bacteria of P. aeruginosa type are human opportunistic pathogens which being a part of biofilm may cause different nosological forms of pyoinflammatory diseases with severe course and high fatality in immunocompromised patients. These microorganisms are able to contaminate external and internal surfaces of catheters, probes, respiratory tubes, lenses, and form biofilm on them. The given information determines reasonability of searching the methods of control of biofilm production in P. aeruginosa cultures which can be used to increase the effectiveness of antibiotic treatment in blue pus infection and/or decontamination of medical equipment, and another objects of hospital environment. One of the methods to control biofilms produced by P. aeruginosa on abiotic surfaces from different materials is impact of antiseptics and decontaminants. Modern decontaminants are represented by a wide spectrum of chemical compounds of different classes which have a common ability to destroy microorganisms even in low concentrations. At present the impact of bacteria on separate elements of biofilm formation is considered to be one of the most perspective targets for the action of new antimicrobial medicines. Numerous investigations of recent 40 years demonstrated that the process of biofilm formation is complex and multistage. Currently the principal directions of development of new antimicrobial preparations are the following: development of antiadhesive coatings and preparations able to interrupt the function of eternal structures of cells in charge of adhesion (fimbriae, adhesins; development of preparations that block synthesis or destabilize matrix of biofilm; development of preparations that cause cell adhesion deficiency in microcolony, and block cell

  4. Application of biofilm bioreactors in white biotechnology.

    Science.gov (United States)

    Muffler, K; Lakatos, M; Schlegel, C; Strieth, D; Kuhne, S; Ulber, R

    2014-01-01

    The production of valuable compounds in industrial biotechnology is commonly done by cultivation of suspended cells or use of (immobilized) enzymes rather than using microorganisms in an immobilized state. Within the field of wastewater as well as odor treatment the application of immobilized cells is a proven technique. The cells are entrapped in a matrix of extracellular polymeric compounds produced by themselves. The surface-associated agglomerate of encapsulated cells is termed biofilm. In comparison to common immobilization techniques, toxic effects of compounds used for cell entrapment may be neglected. Although the economic impact of biofilm processes used for the production of valuable compounds is negligible, many prospective approaches were examined in the laboratory and on a pilot scale. This review gives an overview of biofilm reactors applied to the production of valuable compounds. Moreover, the characteristics of the utilized materials are discussed with respect to support of surface-attached microbial growth.

  5. Complement activation by Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Jensen, E T; Kharazmi, A; Garred, P

    1993-01-01

    In chronic infections, such as the bronchopulmonary Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients, bacteria persist despite an intact host immune defense and frequent antibiotic treatment. An important reason for the persistence of the bacteria is their capacity for the biofilm...... immuno-electrophoresis, C5a generation tested by a PMN chemotactic assay, and terminal complement complex formation measured by ELISA. Two of the four assays showed that P. aeruginosa grown in biofilm activated complement less than planktonic bacteria, and all assays showed that activation by intact...... influx of neutrophils are known to cause inflammatory changes in the lungs. P. aeruginosa persisting in biofilms may contribute to the constant inflammation taking place in the lungs of CF patients....

  6. Band gap narrowing of titanium dioxide (TiO2) nanocrystals by electrochemically active biofilms and their visible light activity.

    Science.gov (United States)

    Kalathil, Shafeer; Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

    2013-07-21

    We report a simple biogenic-route to narrow the band gap of TiO2 nanocrystals for visible light application by offering a greener method. When an electrochemically active biofilm (EAB) was challenged with a solution of Degussa-TiO2 using sodium acetate as the electron donor, greyish blue-colored TiO2 nanocrystals were obtained. A band gap study showed that the band gap of the modified TiO2 nanocrystals was significantly reduced (E(g) = 2.85 eV) compared to the unmodified white Degussa TiO2 (E(g) = 3.10 eV).

  7. Fire Whirls, Vortex Breakdown(?), and Blue Whirls

    Science.gov (United States)

    Oran, Elaine; Xiao, Huahua; Gollner, Michael

    2016-11-01

    As we were investigating the efficiency of fire-whirl burning on water, we observed the usual transformation of a pool fire to a fire whirl, and then suddenly, we saw the fire undergo a third transition. A blue cup appeared around the base of the fire whirl, surrounding the yellow flame, the yellow flame receded into the cup and finally disappeared. What remained was a small, rapidly spinning blue flame that burned until the fuel on the water was consumed. The blue whirl was shaped like a spinning cup, closed at the bottom near the water surface, and spreading in radius moving upwards towards the rim. Above the blue cup lip, there was a purple cone-shaped mist. The fuel was usually n-heptane, but at one point it was crude oil, and still the blue whirl formed naturally. The height of the fire whirl on the laboratory pan was larger than a half meter, and this evolved into a blue whirl about 4-8 cm high. Occasionally the blue whirl would become "unstable" and revert to a transitional state of blue cup holding a yellow flame. When the blue whirl formed, turbulence seemed to disappear, and the flame became quiet. We will show videos of how this happened and discuss the evolution of the fire whirl to the blue whirl in vortex-breakdown concepts. This work was supported by and EAGER award from NSF and Minta Martin Endowment Funds in the Department of Aerospace Engineering at the University of Maryland.

  8. Investigate Nasal Colonize Staphylococcus Species Biofilm Produced

    Directory of Open Access Journals (Sweden)

    Cemil Demir

    2014-03-01

    Full Text Available Aim: 127 S.aureus and 65 CoNS strains were isolated from patients noses%u2019. To produce a biofilm ability was investigated using three different methods. Slime-positive and negative staphylococcies%u2019 resistance were evaluated against different antibiotics. Material and Method: Swap samples puted 7% blood agar. Staphylococcus aureus and coagulase-negative staphylococci (CoNS isolates biofilm produced ability were investigated using Congo Red Agar (CRA, microplates (MP and Standard Tube (ST methods. In addition to that, presence of antibiotic resistance of the staphylococcal isolates are determined agar disc diffusion method. Results: The rate of biofilm producing Staphylococcus spp strains was found to be 72.4%, 67.7%, and 62.9%, respectively with CRA, MP, and ST tests. There was no significant relationship among the tests (p>0.05. In addition, antibiotic resistance of Staphylococcus spp. against various antibiotics was also determined by the agar disk diffusion method. Resistance rates of biofilm positive (BP Staphylococcus spp for penicilin G, ampicilin, amocycilin/clavulanic acid, tetracyclin, eritromycin, gentamycin, and enrofloxacin 71.7%, 69.7%, 6.2%, 20.7%, 21.4%, 1.4%, and 0.7%, respectively. Resistance rates of biofilm negative (BN spp for 42.6%, 23.4%, 4.3%, 14.9%, 19.1%, 0.0%, 0.0% respectively. All Staphylococcus isolates were found to be susceptible to vancomycin and teicaplonin. Although BP strains antibiotic resistance rates were observed higher than BN strains. But resistance rates were not found statistically significant (p>0.05. Discussion: CRA is the reliablity and specifity method to determine Staphylococcus spp. biofilm produce ability.

  9. Filifactor alocis - involvement in periodontal biofilms

    Directory of Open Access Journals (Sweden)

    Göbel Ulf B

    2010-03-01

    Full Text Available Abstract Background Bacteria in periodontal pockets develop complex sessile communities that attach to the tooth surface. These highly dynamic microfloral environments challenge both clinicians and researchers alike. The exploration of structural organisation and bacterial interactions within these biofilms is critically important for a thorough understanding of periodontal disease. In recent years, Filifactor alocis, a fastidious, Gram-positive, obligately anaerobic rod was repeatedly identified in periodontal lesions using DNA-based methods. It has been suggested to be a marker for periodontal deterioration. The present study investigated the epidemiology of F. alocis in periodontal pockets and analysed the spatial arrangement and architectural role of the organism in in vivo grown subgingival biofilms. Results A species-specific oligonucleotide probe, FIAL, was designed and evaluated. A total of 490 subgingival plaque samples were submitted to PCR and subsequent dot blot hybridization to compare the prevalence of F. alocis in patients suffering from generalized aggressive periodontitis (GAP, chronic periodontitis (CP, and control subjects resistant to periodontitis. Moreover, a specially designed carrier system was used to collect in vivo grown subgingival biofilms from GAP patients. Subsequent topographic analysis was performed using fluorescence in situ hybridization. While the majority of patients suffering from GAP or CP harboured F. alocis, it was rarely detected in the control group. In the examined carrier-borne biofilms the organism predominantly colonized apical parts of the pocket in close proximity to the soft tissues and was involved in numerous structures that constitute characteristic architectural features of subgingival periodontal biofilms. Conclusions F. alocis is likely to make a relevant contribution to the pathogenetic structure of biofilms accounting for periodontal inflammation and can be considered an excellent marker

  10. Biofilm transplantation in the deep sea.

    Science.gov (United States)

    Wagner-Döbler, Irene

    2016-05-01

    A gold rush is currently going on in microbial ecology, which is powered by the possibility to determine the full complexity of microbial communities through next-generation sequencing. Accordingly, enormous efforts are underway to describe microbiomes worldwide, in humans, animals, plants, soil, air and the ocean. While much can be learned from these studies, only experiments will finally unravel mechanisms. One of the key questions is how a microbial community is assembled from a pool of bacteria in the environment, and how it responds to change - be it the increase in CO2 concentration in the ocean, or antibiotic treatment of the gut microbiome. The study by Zhang et al. () in this issue is one of the very few that approaches this problem experimentally in the natural environment. The authors selected a habitat which is both extremely interesting and difficult to access. They studied the Thuwal Seep in the Red Sea at 850 m depth and used a remotely operated vehicle (ROV) to place a steel frame carrying substrata for biofilm growth into the brine pool and into the adjacent normal bottom water (NBW). Biofilms were allowed to develop for 3 days, and then those that had been growing in the brine pool were transported to normal bottom water and stayed there for another 3 days, and vice versa. The 'switched' biofilms were then compared with their source communities by metagenome sequencing. Strikingly, both 'switched' biofilms were now dominated by the same two species. These species were able to cope with conditions in both source ecosystems, as shown by assembly of their genomes and detection of expression of key genes. The biofilms had adapted to environmental change, rather than to brine pools or NBW. The study shows both the resilience and adaptability of biofilm communities and has implications for microbial ecology in general and even for therapeutic approaches such as transplantation of faecal microbiomes.

  11. Confocal Raman microscopy for identification of bacterial species in biofilms

    Science.gov (United States)

    Beier, Brooke D.; Quivey, Robert G.; Berger, Andrew J.

    2011-03-01

    Implemented through a confocal microscope, Raman spectroscopy has been used to distinguish between biofilm samples of two common oral bacteria species, Streptococcus sanguinis and mutans, which are associated with healthy and cariogenic plaque, respectively. Biofilms of these species are studied as a model of dental plaque. A prediction model has been calibrated and validated using pure biofilms. This model has been used to identify the species of transferred and dehydrated samples (much like a plaque scraping) as well as hydrated biofilms in situ. Preliminary results of confocal Raman mapping of species in an intact two-species biofilm will be shown.

  12. Etiology of bacterial vaginosis and polymicrobial biofilm formation.

    Science.gov (United States)

    Jung, Hyun-Sul; Ehlers, Marthie M; Lombaard, Hennie; Redelinghuys, Mathys J; Kock, Marleen M

    2017-03-30

    Microorganisms in nature rarely exist in a planktonic form, but in the form of biofilms. Biofilms have been identified as the cause of many chronic and persistent infections and have been implicated in the etiology of bacterial vaginosis (BV). Bacterial vaginosis is the most common form of vaginal infection in women of reproductive age. Similar to other biofilm infections, BV biofilms protect the BV-related bacteria against antibiotics and cause recurrent BV. In this review, an overview of BV-related bacteria, conceptual models and the stages involved in the polymicrobial BV biofilm formation will be discussed.

  13. Adsorption properties and gaseous mercury transformation rate of natural biofilm.

    Science.gov (United States)

    Cheng, Jinping; Zhao, Wenchang; Liu, Yuanyuan; Wu, Cheng; Liu, Caie; Wang, Wenhua

    2008-11-01

    Biofilms were developed on glass microscope slides in a natural aquatic environment and their mercury adsorption properties were evaluated. Results demonstrated that the biofilms contained a large number of bacterial cells and associated extracellular polymers. Mercury forms detected in the biofilms were mainly bound to residual matter and organic acids. The adsorption processes could be described by a Langmuir isotherm. The optimum conditions for adsorption of mercury to natural biofilm were an ionic strength of 0.1 mol/L, pH 6 and an optimum adsorption time of 40 min. The transformation rate was 0.79 microg gaseous mercury per gram of biofilm.

  14. Biofilm disruption with rotating microrods enhances antimicrobial efficacy

    Science.gov (United States)

    Mair, Lamar O.; Nacev, Aleksandar; Hilaman, Ryan; Stepanov, Pavel Y.; Chowdhury, Sagar; Jafari, Sahar; Hausfeld, Jeffrey; Karlsson, Amy J.; Shirtliff, Mark E.; Shapiro, Benjamin; Weinberg, Irving N.

    2017-04-01

    Biofilms are a common and persistent cause of numerous illnesses. Compared to planktonic microbes, biofilm residing cells often demonstrate significant resistance to antimicrobial agents. Thus, methods for dislodging cells from the biofilm may increase the antimicrobial susceptibility of such cells, and serve as a mechanical means of increasing antimicrobial efficacy. Using Aspergillus fumigatus as a model microbe, we magnetically rotate microrods in and around biofilm. We show that such rods can improve the efficacy of antimicrobial Amphotericin B treatments in vitro. This work represents a first step in using kinetic magnetic particle therapy for disrupting fungal biofilms.

  15. Raman imaging of biofilms using gold sputtered fiber optic probes

    Science.gov (United States)

    Christopher, Christina Grace Charlet; Manoharan, Hariharan; Subrahmanyam, Aryasomayajula; Sai, V. V. Raghavendra

    2016-12-01

    In this work we report characterization of bacterial biofilm using gold sputtered optical fiber probe as substrates for confocal Raman spectroscopy measurements. The chemical composition and the heterogeneity of biofilms in the extracellular polymeric substances (EPS) was evaluated. The spatial distribution of bacterial biofilm on the substrates during their growth phase was studied using Raman imaging. Further, the influence of substrate's surface on bacterial adhesion was investigated by studying growth of biofilms on surfaces with hydrophilic and hydrophobic coatings. This study validates the use of gold sputtered optical fiber probes as SERS substrates in confocal microscopic configuration to identify and characterize clinically relevant biofilms.

  16. Various Shades of Blue's Functions

    CERN Document Server

    Janik, R A; Papp, G; Zahed, I; Janik, Romuald A.; Nowak, Maciej A.; Papp, Gabor; Zahed, Ismail

    1997-01-01

    We discuss random matrix models in terms of elementary operations on Blue's functions (functional inverse of Green's functions). We show that such operations embody the essence of a number of physical phenomena whether at/or away from the critical points. We illustrate these assertions by borrowing on a number of recent results in effective QCD in vacuum and matter. We provide simple physical arguments in favor of the universality of the continuum QCD spectral oscillations, whether at zero virtuality, in the bulk of the spectrum or at the chiral critical points. We also discuss effective quantum systems of disorder with strong or weak dissipation (Hatano-Nelson localization).

  17. Microbial Biofilm as a Smart Material

    DEFF Research Database (Denmark)

    Garde, Christian; Welch, Martin; Ferkinghoff-Borg, Jesper

    2015-01-01

    Microbial biofilm colonies will in many cases form a smart material capable of responding to external threats dependent on their size and internal state. The microbial community accordingly switches between passive, protective, or attack modes of action. In order to decide which strategy to employ......, it is essential for the biofilm community to be able to sense its own size. The sensor designed to perform this task is termed a quorum sensor, since it only permits collective behaviour once a sufficiently large assembly of microbes have been established. The generic quorum sensor construct involves two genes...

  18. Biofilm ved kronisk rhinosinuitis og cystisk fibrose

    DEFF Research Database (Denmark)

    Fisker, Jacob; Buchwald, Christian von; Johansen, Helle Krogh

    2011-01-01

    Microbial biofilms are known to cause persistent foreign-body infections and have recently been acknowledged as involved in more than 65% of all human infections. Microbial biofilms have been detected in chronic rhinosinusitis, and chronic rhinosinusitis is mandatory in patients with cystic fibro...... fibrosis. We believe that a reservoir for a sustained lung infection in these patients might be found in the nasal sinuses, and that the sinuses may act as a reservoir for reinfection after CF-patient lung transplants. Further studies are necessary....

  19. Ginger extract inhibits biofilm formation by Pseudomonas aeruginosa PA14.

    Science.gov (United States)

    Kim, Han-Shin; Park, Hee-Deung

    2013-01-01

    Bacterial biofilm formation can cause serious problems in clinical and industrial settings, which drives the development or screening of biofilm inhibitors. Some biofilm inhibitors have been screened from natural products or modified from natural compounds. Ginger has been used as a medicinal herb to treat infectious diseases for thousands of years, which leads to the hypothesis that it may contain chemicals inhibiting biofilm formation. To test this hypothesis, we evaluated ginger's ability to inhibit Pseudomonas aeruginosa PA14 biofilm formation. A static biofilm assay demonstrated that biofilm development was reduced by 39-56% when ginger extract was added to the culture. In addition, various phenotypes were altered after ginger addition of PA14. Ginger extract decreased production of extracellular polymeric substances. This finding was confirmed by chemical analysis and confocal laser scanning microscopy. Furthermore, ginger extract formed noticeably less rugose colonies on agar plates containing Congo red and facilitated swarming motility on soft agar plates. The inhibition of biofilm formation and the altered phenotypes appear to be linked to a reduced level of a second messenger, bis-(3'-5')-cyclic dimeric guanosine monophosphate. Importantly, ginger extract inhibited biofilm formation in both Gram-positive and Gram-negative bacteria. Also, surface biofilm cells formed with ginger extract detached more easily with surfactant than did those without ginger extract. Taken together, these findings provide a foundation for the possible discovery of a broad spectrum biofilm inhibitor.

  20. Removal of Dental Biofilms with an Ultrasonically Activated Water Stream.

    Science.gov (United States)

    Howlin, R P; Fabbri, S; Offin, D G; Symonds, N; Kiang, K S; Knee, R J; Yoganantham, D C; Webb, J S; Birkin, P R; Leighton, T G; Stoodley, P

    2015-09-01

    Acidogenic bacteria within dental plaque biofilms are the causative agents of caries. Consequently, maintenance of a healthy oral environment with efficient biofilm removal strategies is important to limit caries, as well as halt progression to gingivitis and periodontitis. Recently, a novel cleaning device has been described using an ultrasonically activated stream (UAS) to generate a cavitation cloud of bubbles in a freely flowing water stream that has demonstrated the capacity to be effective at biofilm removal. In this study, UAS was evaluated for its ability to remove biofilms of the cariogenic pathogen Streptococcus mutans UA159, as well as Actinomyces naeslundii ATCC 12104 and Streptococcus oralis ATCC 9811, grown on machine-etched glass slides to generate a reproducible complex surface and artificial teeth from a typodont training model. Biofilm removal was assessed both visually and microscopically using high-speed videography, confocal scanning laser microscopy (CSLM), and scanning electron microscopy (SEM). Analysis by CSLM demonstrated a statistically significant 99.9% removal of S. mutans biofilms exposed to the UAS for 10 s, relative to both untreated control biofilms and biofilms exposed to the water stream alone without ultrasonic activation (P biofilm removal. The UAS was also highly effective at S. mutans, A. naeslundii, and S. oralis biofilm removal from machine-etched glass and S. mutans from typodont surfaces with complex topography. Consequently, UAS technology represents a potentially effective method for biofilm removal and improved oral hygiene.

  1. Biofilm formation on dental restorative and implant materials.

    Science.gov (United States)

    Busscher, H J; Rinastiti, M; Siswomihardjo, W; van der Mei, H C

    2010-07-01

    Biomaterials for the restoration of oral function are prone to biofilm formation, affecting oral health. Oral bacteria adhere to hydrophobic and hydrophilic surfaces, but due to fluctuating shear, little biofilm accumulates on hydrophobic surfaces in vivo. More biofilm accumulates on rough than on smooth surfaces. Oral biofilms mostly consist of multiple bacterial strains, but Candida species are found on acrylic dentures. Biofilms on gold and amalgam in vivo are thick and fully covering, but barely viable. Biofilms on ceramics are thin and highly viable. Biofilms on composites and glass-ionomer cements cause surface deterioration, which enhances biofilm formation again. Residual monomer release from composites influences biofilm growth in vitro, but effects in vivo are less pronounced, probably due to the large volume of saliva into which compounds are released and its continuous refreshment. Similarly, conflicting results have been reported on effects of fluoride release from glass-ionomer cements. Finally, biomaterial-associated infection of implants and devices elsewhere in the body is compared with oral biofilm formation. Biomaterial modifications to discourage biofilm formation on implants and devices are critically discussed for possible applications in dentistry. It is concluded that, for dental applications, antimicrobial coatings killing bacteria upon contact are more promising than antimicrobial-releasing coatings.

  2. Kinetics of biofilm formation by drinking water isolated Penicillium expansum.

    Science.gov (United States)

    Simões, Lúcia Chaves; Simões, Manuel; Lima, Nelson

    2015-01-01

    Current knowledge on drinking water (DW) biofilms has been obtained mainly from studies on bacterial biofilms. Very few reports on filamentous fungi (ff) biofilms are available, although they can contribute to the reduction in DW quality. This study aimed to assess the dynamics of biofilm formation by Penicillium expansum using microtiter plates under static conditions, mimicking water flow behaviour in stagnant regions of drinking water distribution systems. Biofilms were analysed in terms of biomass (crystal violet staining), metabolic activity (resazurin, fluorescein diacetate and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide [MTT]) and morphology (epifluorescence [calcofluor white M2R, FUN-1, FDA and acridine orange] and bright-field microscopies). Biofilm development over time showed the typical sigmoidal curve with noticeable different phases in biofilm formation (induction, exponential, stationary, and sloughing off). The methods used to assess metabolic activity provided similar results. The microscope analysis allowed identification of the involvement of conidia in initial adhesion (4 h), germlings (8 h), initial monolayers (12 h), a monolayer of intertwined hyphae (24 h), mycelial development, hyphal layering and bundling, and development of the mature biofilms (≥48 h). P. expansum grows as a complex, multicellular biofilm in 48 h. The metabolic activity and biomass of the fungal biofilms were shown to increase over time and a correlation between metabolism, biofilm mass and hyphal development was found.

  3. Bacteriophages as Weapons Against Bacterial Biofilms in the Food Industry.

    Science.gov (United States)

    Gutiérrez, Diana; Rodríguez-Rubio, Lorena; Martínez, Beatriz; Rodríguez, Ana; García, Pilar

    2016-01-01

    Microbiological contamination in the food industry is often attributed to the presence of biofilms in processing plants. Bacterial biofilms are complex communities of bacteria attached to a surface and surrounded by an extracellular polymeric material. Their extreme resistance to cleaning and disinfecting processes is related to a unique organization, which implies a differential bacterial growth and gene expression inside the biofilm. The impact of biofilms on health, and the economic consequences, has promoted the development of different approaches to control or remove biofilm formation. Recently, successful results in phage therapy have boosted new research in bacteriophages and phage lytic proteins for biofilm eradication. In this regard, this review examines the environmental factors that determine biofilm development in food-processing equipment. In addition, future perspectives for the use of bacteriophage-derived tools as disinfectants are discussed.

  4. A limited legacy effect of copper in marine biofilms.

    Science.gov (United States)

    McElroy, David J; Doblin, Martina A; Murphy, Richard J; Hochuli, Dieter F; Coleman, Ross A

    2016-08-15

    The effects of confounding by temporal factors remains understudied in pollution ecology. For example, there is little understanding of how disturbance history affects the development of assemblages. To begin addressing this gap in knowledge, marine biofilms were subjected to temporally-variable regimes of copper exposure and depuration. It was expected that the physical and biological structure of the biofilms would vary in response to copper regime. Biofilms were examined by inductively coupled plasma optical emission spectrometry, chlorophyll-a fluorescence and field spectrometry and it was found that (1) concentrations of copper were higher in those biofilms exposed to copper, (2) concentrations of copper remain high in biofilms after the source of copper is removed, and (3) exposure to and depuration from copper might have comparable effects on the photosynthetic microbial assemblages in biofilms. The persistence of copper in biofilms after depuration reinforces the need for consideration of temporal factors in ecology.

  5. [On Biofilms of Streptomycetes. II. Use in Biotechnology].

    Science.gov (United States)

    Vinogradoya, A; Bulgakova, V G; Polin, A N; Kozhevin, P A

    2015-01-01

    Streptomycetes or mycelial microorganisms are able to form biofilms under the natural, industrial and clinical conditions. The controlled use of biofilms in various industrial processes is much more efficient vs. the cultivation of plankton suspended cells. Optimization of biotechnological processes with the use of streptomycete biofilms is advisable in production of lactic acid and detoxication of the liquor in pyrolysis of plant biomass. Streptomycete biofilms are used in water purification systems. It is recommended to use biofilms for detoxication of wastes and bioremediation of soils contaminated with hard metals. The use of biofilms of streptomycetes producing biologically active substances is of special interest. High yields of.antibiotics and actinomycin D in particular was observed with. cultivation of antibioc-producing streptomycetes as biofilms in bioreactors of unique design.

  6. An update on Pseudomonas aeruginosa biofilm formation, tolerance, and dispersal

    DEFF Research Database (Denmark)

    Harmsen, Morten; Yang, Liang; Pamp, Sünje Johanna

    2010-01-01

    . aeruginosa biofilms. The second messenger, c-di-GMP, is established as an important regulator of the synthesis of polysaccharide and protein components of the biofilm matrix. Extracellular DNA is shown to be an essential component of the biofilm matrix. It has become apparent that biofilm formation involves......We review the recent advances in the understanding of the Pseudomonas aeruginosa biofilm lifestyle from studies using in vitro laboratory setups such as flow chambers and microtiter trays. Recent work sheds light on the role of nutrients, motility, and quorum sensing in structure formation in P...... interactions between different subpopulations. The molecular mechanisms underlying the tolerance of biofilm bacteria to antimicrobial agents are beginning to be unraveled, and new knowledge has been obtained regarding the environmental cues and regulatory mechanisms involved in biofilm dispersal....

  7. Modelling of toluene biodegradation and biofilm growth in a fixed biofilm reactor

    DEFF Research Database (Denmark)

    Arcangeli, Jean-Pierre; Arvin, Erik

    1992-01-01

    The modelling of aerobic biodegradation of toluene and the associated biofilm growth in a fixed biofilm system is presented. The model includes four biomass fractions, three dissolved components, and seven processes. It is assumed that part of the active biomass is composed of filamentous bacteria...... which grow relatively fast and detach easily, leading to a biomass growth delayed with respect to substrate degradation. The non-filamentous bacteria inside the biofilm also degrade toluene but with a slower rate compared to the filamentous bacteria. Because the nonfilamentous bacteria do not detach......, they are primarily responsible for the biofilm growth. The active biomass decays into biodegradable and ``inert'' dead biomass which is hydrolyzed into soluble products at two different rates. These products are partly degradable by the biomass and constitute the endogenous respiration. The dynamic growth phase...

  8. Gene transfer occurs with enhanced efficiency in biofilms and induces enhanced stabilisation of the biofilm structure

    DEFF Research Database (Denmark)

    Molin, Søren; Tolker-Nielsen, Tim

    2003-01-01

    There has been much interest in bioremediation based on the introduction of bacteria able to catabolise recalcitrant compounds deposited in the environment. In particular, the delivery of catabolic information in the form of conjugative plasmids to bacterial populations in situ has great potentia...... cycle and released DNA stabilises the biofilm structure. Both of these gene-transfer mechanisms may be autocatalytically promoted in biofilms, presenting new possibilities for efficient bio-enhancement strategies........ As most bacteria in the environment live in surface-associated communities (biofilms), the gene transfer systems within these communities need to be better characterised for bio-enhancement strategies to be developed. Recent findings suggest that gene transfer does take place within biofilms, but studies...

  9. Effect of Biosynthesized Silver Nanoparticles on Staphylococcus aureus Biofilm Quenching and Prevention of Biofilm Formation

    Institute of Scientific and Technical Information of China (English)

    Pratik R. Chaudhari∗; Shalaka A. Masurkar; Vrishali B. Shidore; Suresh P. Kamble

    2012-01-01

    The development of green experimental processes for the synthesis of nanoparticles is a need in the field of nanotechnology. The synthesis of silver nanoparticles was achieved using Bacillus cereus supernatant and 1 mM silver nitrate. 100 mM glucose was found to quicken the rate of reaction of silver nanoparticles synthesis. UV-visible spectrophotometric analysis was carried out to assess the synthesis of silver nanoparticles. The synthesized silver nanoparticles were further characterized by using Nanoparticle Tracking Analyzer (NTA), Transmission Electron Microscope and Energy Dispersive X-ray spectra. These silver nanoparticles showed enhanced quorum quenching activity against Staphylococcus aureus biofilm and prevention of biofilm formation which can be seen under inverted microscope (40 X). The synergistic effect of silver nanoparticles along with antibiotics in biofilm quenching was found to be effective. In the near future, silver nanoparticles could be used in the treatment of infections caused by highly antibiotic resistant biofilm.

  10. Hydrophobicity of biofilm coatings influences the transport dynamics of polystyrene nanoparticles in biofilm-coated sand.

    Science.gov (United States)

    Mitzel, Michael R; Sand, Stefanie; Whalen, Joann K; Tufenkji, Nathalie

    2016-04-01

    Engineered nanoparticles (ENPs) are used in the manufacture of over 2000 industrial and consumer products to enhance their material properties and functions or to enable new nanoparticle-dependent functions. The widespread use of ENPs will result in their release to the subsurface and aquatic environments, where they will interact with indigenous biota. Laboratory column experiments were designed to understand the influence of two different Pseudomonas aeruginosa biofilms on the mobility of polystyrene latex nanoparticles in granular porous media representative of groundwater aquifers or riverbank filtration settings. The transport behavior of 20 nm carboxylate-modified (CLPs) and sulfate (SLPs) polystyrene latex ENPs suspended in NaCl or CaCl2 (1 and 10 mM ionic strength, pH 7) was studied in columns packed with quartz sand coated with biofilms formed by two P. aeruginosa strains that differed in cell surface hydrophobicity (P. aeruginosa 9027™, relatively hydrophilic and P. aeruginosa PAO1, relatively hydrophobic). Biofilm-coated quartz sand retained more of the electrostatically-stabilized latex ENPs than clean, uncoated sand, regardless of the serotype. As IS increased, clear differences in the shape of the ENP breakthrough curves were observed for each type of biofilm coating. ENP breakthrough in the P. aeruginosa PAO1 biofilm-coated sand was generally constant with time whereby breakthrough in the P. aeruginosa 9027 biofilm-coated sand showed dynamic behavior. This indicates a fundamental difference in the mechanisms of ENP deposition onto hydrophilic or hydrophobic biofilm coatings due to the hydration properties of these biofilms. The results of this study demonstrate the importance of considering the surface properties of aquifer grain coatings when evaluating ENP fate in natural subsurface environments.

  11. Microsensor and transcriptomic signatures of oxygen depletion in biofilms associated with chronic wounds: Biofilms and oxygen

    Energy Technology Data Exchange (ETDEWEB)

    James, Garth A. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Ge Zhao, Alice [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Usui, Marcia [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Underwood, Robert A. [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Nguyen, Hung [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; Beyenal, Haluk [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; deLancey Pulcini, Elinor [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Agostinho Hunt, Alessandra [Department of Microbiology and Molecular Genetics, 5180 Biomedical and Physical Sciences, Michigan State University, East Lansing Michigan; Bernstein, Hans C. [Pacific Northwest National Laboratory, Chemical and Biological Signature Science, Richland Washington; Fleckman, Philip [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Olerud, John [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Williamson, Kerry S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Franklin, Michael J. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Stewart, Philip S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana

    2016-02-16

    Polymicrobial biofilms have been implicated in delayed wound healing, although the mechanisms by which biofilms impair wound healing are poorly understood. Many species of bacteria produce exotoxins and exoenzymes that may inhibit healing. In addition, oxygen consumption by biofilms may impede wound healing. In this study, we used oxygen microsensors to measure oxygen transects through in vitro-cultured biofilms, biofilms formed in vivo in a diabetic (db/db) mouse model, and ex vivo human chronic wound specimens. The results show that oxygen levels within both euthanized and live mouse wounds had steep gradients that reached minima ranging from 19 to 61% oxygen partial pressure, compared to atmospheric oxygen levels. The oxygen gradients in the mouse wounds were similar to those observed for clinical isolates cultured in vitro and for human ex vivo scabs. No oxygen gradients were observed for heat-killed scabs, suggesting that active metabolism by the viable bacteria contributed to the reduced oxygen partial pressure of the wounds. To characterize the metabolic activities of the bacteria in the mouse wounds, we performed transcriptomics analyses of Pseudomonas aeruginosa biofilms associated with the db/db mice wounds using Affymetrix microarrays. The results demonstrated that the bacteria expressed genes for metabolic activities associated with cell growth. Interestingly, the transcriptome results indicated that the bacteria within the wounds also experienced oxygen-limitation stress. Among the bacterial genes that were expressed in vivo were genes associated with the Anr-mediated hypoxia-stress response. Other bacterial stress response genes highly expressed in vivo were genes associated with stationary-phase growth, osmotic stress, and RpoH-mediated heat shock stress. Overall, the results support the hypothesis that the metabolic activities of bacteria in biofilms act as oxygen sinks in chronic wounds and that the depletion of oxygen contributes to the

  12. Production of Tyrosol by Candida albicans Biofilms and Its Role in Quorum Sensing and Biofilm Development▿

    OpenAIRE

    Alem, M.A.S.; Oteef, M.D.Y.; Flowers, T; Douglas, L J

    2006-01-01

    Tyrosol and farnesol are quorum-sensing molecules produced by Candida albicans which accelerate and block, respectively, the morphological transition from yeasts to hyphae. In this study, we have investigated the secretion of tyrosol by C. albicans and explored its likely role in biofilm development. Both planktonic (suspended) cells and biofilms of four C. albicans strains, including three mutants with defined defects in the Efg 1 and Cph 1 morphogenetic signaling pathways, synthesized extra...

  13. Geothermal Technologies Program Blue Ribbon Panel Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-06-17

    The Geothermal Technologies Program assembled a geothermal Blue Ribbon Panel on March 22-23, 2011 in Albuquerque, New Mexico for a guided discussion on the future of geothermal energy in the United States and the role of the DOE Program. The Geothermal Blue Ribbon Panel Report captures the discussions and recommendations of the experts. An addendum is available here: http://www.eere.energy.gov/geothermal/pdfs/gtp_blue_ribbon_panel_report_addendum10-2011.pdf

  14. A novel assay of biofilm antifungal activity reveals that amphotericin B and caspofungin lyse Candida albicans cells in biofilms.

    Science.gov (United States)

    DiDone, Louis; Oga, Duana; Krysan, Damian J

    2011-08-01

    The ability of Candida albicans to form drug-resistant biofilms is an important factor in its contribution to human disease. Assays to identify and characterize molecules with activity against fungal biofilms are crucial for the development of drugs with improved anti-biofilm activity. Here we report the application of an adenylate kinase (AK)-based cytotoxicity assay of fungal cell lysis to the characterization of agents active against C. albicans biofilms. We have developed three protocols for the AK assay. The first measures AK activity in the supernatants of biofilms treated with antifungal drugs and can be performed in parallel with a standard 2,3-bis-(2-methoxy-4-nitro-5-sulphophenyl)-2H-tetrazolium-5-caboxanilide-based biofilm susceptibility assay; a second, more sensitive protocol measures the AK activity present within the biofilm matrix; and a third procedure allows the direct visualization of lytic activity toward biofilms formed on catheter material. Amphotericin B and caspofungin, the two most effective anti-biofilm drugs currently used to treat fungal infections, both directly lyse planktonic C. albicans cells in vitro, leading to the release of AK into the culture medium. These studies serve to validate the AK-based lysis assay as a useful addition to the methods for the characterization of antifungal agents active toward biofilms and provide insights into the mode of action of amphotericin B and caspofungin against C. albicans biofilms.

  15. The Vibrio cholerae Pst2 phosphate transport system is upregulated in biofilms and contributes to biofilm-induced hyperinfectivity.

    Science.gov (United States)

    Mudrak, Benjamin; Tamayo, Rita

    2012-05-01

    Vibrio cholerae is the causative agent of the deadly diarrheal disease cholera. As part of its life cycle, V. cholerae persists in marine environments, where it forms surface-attached communities commonly described as biofilms. Evidence indicates that these biofilms constitute the infectious form of the pathogen during outbreaks. Previous work has shown that biofilm-derived V. cholerae cells, even when fully dispersed from the biofilm matrix, are vastly more infectious than planktonic (free-living) cells. Here, we sought to identify factors that contribute to biofilm-induced hyperinfectivity in V. cholerae, and we present evidence for one aspect of the molecular basis of this phenotype. We identified proteins upregulated during growth in biofilms and determined their contributions to the hyperinfectivity phenotype. We found that PstS2, the periplasmic component of the Pst2 phosphate uptake system, was enriched in biofilms. Another gene in the pst2 locus was transcriptionally upregulated in biofilms. Using the infant mouse model, we found that mutation of two pst2 components resulted in impaired colonization. Importantly, deletion of the Pst2 inner membrane complex caused a greater colonization defect after growth in a biofilm compared to shaking culture. Based on these data, we propose that V. cholerae cells in biofilms upregulate the Pst2 system and therefore gain an advantage upon entry into the host. Further characterization of factors contributing to biofilm-induced hyperinfectivity in V. cholerae will improve our understanding of the transmission of the bacteria from natural aquatic habitats to the human host.

  16. Essential factors of an integrated moving bed biofilm reactor-membrane bioreactor: Adhesion characteristics and microbial community of the biofilm.

    Science.gov (United States)

    Tang, Bing; Yu, Chunfei; Bin, Liying; Zhao, Yiliang; Feng, Xianfeng; Huang, Shaosong; Fu, Fenglian; Ding, Jiewei; Chen, Cuiqun; Li, Ping; Chen, Qianyu

    2016-07-01

    This work aims at revealing the adhesion characteristics and microbial community of the biofilm in an integrated moving bed biofilm reactor-membrane bioreactor, and further evaluating their variations over time. With multiple methods, the adhesion characteristics and microbial community of the biofilm on the carriers were comprehensively illuminated, which showed their dynamic variation along with the operational time. Results indicated that: (1) the roughness of biofilm on the carriers increased very quickly to a maximum value at the start-up stage, then, decreased to become a flat curve, which indicated a layer of smooth biofilm formed on the surface; (2) the tightly-bound protein and polysaccharide was the most important factor influencing the stability of biofilm; (3) the development of biofilm could be divided into three stages, and Gammaproteobacteria were the most dominant microbial species in class level at the last stage, which occupied the largest ratio (51.48%) among all microbes.

  17. Calcium-Phosphate-Osteopontin Particles Reduce Biofilm Formation and pH Drops in in situ-Grown Dental Biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Ibsen, Casper Jon Steenberg; Birkedal, Henrik;

    2016-01-01

    This two-period crossover study investigated the effect of calcium-phosphate-osteopontin particles on biofilm formation and pH in 48-h biofilms grown in situ. Bovine milk osteopontin is a highly phosphorylated glycoprotein that has been shown to interfere with bacterial adhesion to salivary......-coated surfaces. Calcium-phosphate-osteopontin particles have been shown to reduce biofilm formation and pH drops in a 5-species laboratory model of dental biofilm without affecting bacterial viability. Here, smooth surface biofilms from 10 individuals were treated ex vivo 6 times/day for 30 min with either...... calcium-phosphate-osteopontin particles or sterile saline. After growth, the amount of biofilm formed was determined by confocal microscopy, and pH drops upon exposure to glucose were monitored using confocal-microscopy-based pH ratiometry. A total of 160 biofilms were analysed. No adverse effects...

  18. Melaleuca alternifolia nanoparticles against Candida species biofilms.

    Science.gov (United States)

    Souza, M E; Lopes, L Q S; Bonez, P C; Gündel, A; Martinez, D S T; Sagrillo, M R; Giongo, J L; Vaucher, R A; Raffin, R P; Boligon, A A; Santos, R C V

    2017-03-01

    Candida infection is an important cause of morbidity and mortality on immunosuppressed patients. This growing trend has been associated with resistance to the antimicrobial therapy and the ability of microorganism to form biofilms. TTO oil is used as antimicrobial which shows antibiofilm activity against Candida species. However, it presents problems due to its poor solubility and high volatility. The present study aimed to evaluate in vitro antibiofilm activity of TTO nanoparticles against many Candida species. It was performed the characterization of the oil and nanoparticles. The levels of exopolysaccharides, proteins, and the biomass of biofilms were measured. The chromatographic profile demonstrated that the TTO oil is in accordance with ISO 4730 with major constituents of 41.9% Terpinen-4-ol, 20.1% of γ-Terpinene, 9,8% of α-Terpinene, and 6,0% of 1,8-Cineole. The TTO nanoparticles showed pH of 6.3, mean diameter of 158.2 ± 2 nm, polydispersion index of 0.213 ± 0.017, and zeta potential of -8.69 ± 0.80 mV. The addition of TTO and its nanoparticles represented a significant reduction of biofilm formed by all Candida species, as well as a reduction of proteins and exopolysaccharides levels. It was possible to visualize the reduction of biofilm in presence of TTO nanoparticles by Calcofluor White method.

  19. Persistence of Antibiotic Resistance Plasmids in Biofilms

    Science.gov (United States)

    2014-10-01

    wounds, facilitates the persistence of MDR plasmids in Acinetobacter baumannii , a problematic wound pathogen. Moreover, we have shown that plasmids...which plasmid persistence can improve in Acinetobacter baumannii and other wound pathogens when grown in biofilm environments. This project has the... Acinetobacter * baumannii ,!Klebsiella*pneumoniae,!Enterobacter*sp.,! and! Escherichia* coli! (Eardley! et! al.,! 2011;! Gaynes! &! Edwards,! 2005;! Murray

  20. Biofilm Formation of Pasteurella Multocida on Bentonite Clay

    Directory of Open Access Journals (Sweden)

    Ramachandranpillai Rajagopal

    2013-06-01

    Full Text Available Background and objectives: Biofilms are structural communities of bacterial cells enshrined in a self produced polymeric matrix. The studies on biofilm formation of Pasteurella multocida have become imperative since it is a respiratory pathogen and its biofilm mode could possibly be one of its virulence factors for survival inside a host. The present study describes a biofilm assay for P. multocida on inert hydrophilic material called bentonite clay.Materials and methods: The potential of the organism to form in vitro biofilm was assessed by growing the organism under nutrient restriction along with the inert substrate bentonite clay, which will provide a surface for attachment. For quantification of biofilm, plate count by the spread plate method was employed. Capsule production of the attached bacteria was demonstrated by light microscopic examination following Maneval staining and capsular polysaccharide estimation was done using standard procedures.Results and Conclusion: The biofilm formation peaked on the third day of incubation (1.54 ×106 cfu/g of bentonite clay while the planktonic cells were found to be at a maximum on day one post inoculation (8.10 ×108 cfu/ml of the broth. Maneval staining of late logarithmic phase biofilm cultures revealed large aggregates of bacterial cells, bacteria appearing as chains or as a meshwork. The capsular polysaccharide estimation of biofilm cells revealed a 3.25 times increase over the planktonic bacteria. The biofilm cells cultured on solid media also produced some exclusive colony morphotypes

  1. Frequency of biofilm formation in toothbrushes and wash basin junks

    Directory of Open Access Journals (Sweden)

    Abdulazeez A Abubakar

    2013-01-01

    Full Text Available Background: Biofilms are known to be resistant to several antibiotics once they are allowed to form on any surface. Aim: To investigate the biofilm forming ability of some bacterial isolates in toothbrushes and wash basin junks. Materials and Methods: A total of 606 students of Federal University of Technology, Yola were provided with new toothbrushes, which were collected after 1 month of usage and screened for biofilm formation. Another 620 swabs were collected from the wash basins of Federal Medical Centre, Specialist Hospital, Federal University of Technology, and students′ hostels in Yola and from some residence in Jimeta, Yola Metropolis; they were all screened for biofilm formation. Results: A total of 38.3% biofilm formation rate was recorded. Three types of bacterial isolates were identified in the biofilms of toothbrushes and wash basin junks, namely Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa at the prevalence rate of 48.0%, 29.1%, and 22.6%, respectively. Overall, 83.3% of the toothbrush biofilm were identified from female students, while 16.7% were from their male counterparts. Statistically, the frequency of biofilm formation showed a significant difference by gender (X 2 = 10.242, P 0.05. Conclusion: This study identified three microorganisms namely S. aureus, E. coli, and P. aeruginosa that were involved in wash basin junk biofilm formation. The findings also showed that occurrence of biofilm in females′ toothbrushes were significantly higher than in males′ (X 2 = 10.242, P < 0.05.

  2. An expanded regulatory network temporally controls Candida albicans biofilm formation.

    Science.gov (United States)

    Fox, Emily P; Bui, Catherine K; Nett, Jeniel E; Hartooni, Nairi; Mui, Michael C; Andes, David R; Nobile, Clarissa J; Johnson, Alexander D

    2015-06-01

    Candida albicans biofilms are composed of highly adherent and densely arranged cells with properties distinct from those of free-floating (planktonic) cells. These biofilms are a significant medical problem because they commonly form on implanted medical devices, are drug resistant and are difficult to remove. C. albicans biofilms are not static structures; rather they are dynamic and develop over time. Here we characterize gene expression in biofilms during their development, and by comparing them to multiple planktonic reference states, we identify patterns of gene expression relevant to biofilm formation. In particular, we document time-dependent changes in genes involved in adhesion and metabolism, both of which are at the core of biofilm development. Additionally, we identify three new regulators of biofilm formation, Flo8, Gal4, and Rfx2, which play distinct roles during biofilm development over time. Flo8 is required for biofilm formation at all time points, and Gal4 and Rfx2 are needed for proper biofilm formation at intermediate time points.

  3. Anti-Biofilm Compounds Derived from Marine Sponges

    Directory of Open Access Journals (Sweden)

    Christian Melander

    2011-10-01

    Full Text Available Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues—including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds.

  4. Farnesol induces cell detachment from established S. epidermidis biofilms.

    Science.gov (United States)

    Cerca, Nuno; Gomes, Fernanda; Bento, Joana C; França, Angela; Rolo, Joana; Miragaia, Maria; Teixeira, Pilar; Oliveira, Rosário

    2013-05-01

    Antibiotic resistance is a serious problem in Staphylococcus epidermidis infections as many clinical isolates of this organism are resistant to up to eight different antibiotics. The increased resistance to conventional antibiotic therapy has lead to the search for new antimicrobial therapeutic agents. Farnesol, an essential oil found in many plants, has been shown to be active against S. epidermidis. Using a type control strain we recently described that although farnesol was not efficient at killing biofilm bacteria, a strong reduction on biofilm biomass was detected, and we hypothesize that farnesol could, somehow, induce biofilm detachment. In this report, to test our hypothesis we used 36 representative clinical strains of S. epidermidis from different geographic locations and characterized them in terms of genetic variability by multilocus sequence typing and staphylococcal chromosome cassette mec. Strains were tested for biofilm formation, and the presence of ica, bhp and aap genes was determined. Stronger biofilms had always the presence of ica operon but often co-harbored bhp and aap genes. Farnesol was then used in biofilm-forming strains, and biofilm detachment was detected in half of the strains tested. Furthermore, we also showed that farnesol inability to kill biofilm bacteria was not the result of the biofilm structure but was related to high cell density. Our results demonstrate, for the first time, that the biomass reduction previously found by us, and many other groups, is the result not of cell killing but instead is the result of biofilm detachment.

  5. Inhibition of Staphylococcus epidermidis biofilm by trimethylsilane plasma coating.

    Science.gov (United States)

    Ma, Yibao; Chen, Meng; Jones, John E; Ritts, Andrew C; Yu, Qingsong; Sun, Hongmin

    2012-11-01

    Biofilm formation on implantable medical devices is a major impediment to the treatment of nosocomial infections and promotes local progressive tissue destruction. Staphylococcus epidermidis infections are the leading cause of biofilm formation on indwelling devices. Bacteria in biofilms are highly resistant to antibiotic treatment, which in combination with the increasing prevalence of antibiotic resistance among human pathogens further complicates treatment of biofilm-related device infections. We have developed a novel plasma coating technology. Trimethylsilane (TMS) was used as a monomer to coat the surfaces of 316L stainless steel and grade 5 titanium alloy, which are widely used in implantable medical devices. The results of biofilm assays demonstrated that this TMS coating markedly decreased S. epidermidis biofilm formation by inhibiting the attachment of bacterial cells to the TMS-coated surfaces during the early phase of biofilm development. We also discovered that bacterial cells on the TMS-coated surfaces were more susceptible to antibiotic treatment than their counterparts in biofilms on uncoated surfaces. These findings suggested that TMS coating could result in a surface that is resistant to biofilm development and also in a bacterial community that is more sensitive to antibiotic therapy than typical biofilms.

  6. Rot is a key regulator of Staphylococcus aureus biofilm formation

    Science.gov (United States)

    Mootz, Joe M.; Benson, Meredith A.; Heim, Cortney E.; Crosby, Heidi A.; Kavanaugh, Jeffrey S.; Dunman, Paul M.; Kielian, Tammy; Torres, Victor J.; Horswill, Alexander R.

    2015-01-01

    AUTHOR SUMMARY Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants. We investigated the biofilm regulatory cascade and discovered that the repressor of toxins (Rot) is part of this pathway. A USA300 community-associated methicillin-resistant S. aureus (CA-MRSA) strain deficient in Rot was unable to form a biofilm using multiple different assays, and we found rot mutants in other strain lineages were also biofilm deficient. By performing a global analysis of transcripts and protein production controlled by Rot, we observed that all the secreted protease genes were upregulated in a rot mutant, and we hypothesized that this regulation could be responsible for the biofilm phenotype. To investigate this question, we determined that Rot bound to the protease promoters, and we observed that activity levels of these enzymes, in particular the cysteine proteases, were increased in a rot mutant. By inactivating these proteases, biofilm capacity was restored to the mutant, demonstrating they are responsible for the biofilm negative phenotype. Finally, we tested the rot mutant in a mouse catheter model of biofilm infection and observed a significant reduction in biofilm burden. Thus S. aureus uses the transcription factor Rot to repress secreted protease levels in order to build a biofilm. PMID:25612137

  7. In vitro phenotypic differentiation towards commensal and pathogenic oral biofilms.

    Science.gov (United States)

    Janus, Marleen M; Keijser, Bart J F; Bikker, Floris J; Exterkate, Rob A M; Crielaard, Wim; Krom, Bastiaan P

    2015-01-01

    Commensal oral biofilms, defined by the absence of pathology-related phenotypes, are ubiquitously present. In contrast to pathological biofilms commensal biofilms are rarely studied. Here, the effect of the initial inoculum and subsequent growth conditions on in vitro oral biofilms was studied. Biofilms were inoculated with saliva and grown anaerobically for up to 21 days in McBain medium with or without fetal calf serum (FCS) or sucrose. Pathology-related phenotypes were quantified and the community composition was determined. Biofilms inoculated with pooled saliva or individual inocula were similar. Denaturing gradient gel electrophoresis (DGGE) analysis allowed differentiation of biofilms grown with sucrose, but not with FCS. Lactate production by biofilms was significantly increased by sucrose and protease activity by FCS. McBain grown biofilms showed low activity for both phenotypes. Three clinically relevant in vitro biofilm models were developed and could be differentiated based on pathology-related phenotypes but not DGGE analysis. These models allow analysis of health-to-disease shifts and the effectiveness of prevention measures.

  8. Ecology of Blue Straggler Stars

    CERN Document Server

    Boffin, H M J; Beccari, G

    2014-01-01

    The existence of blue straggler stars (BSS), which appear younger, hotter, and more massive than their siblings, is at odds with a simple picture of stellar evolution, as such stars should have exhausted their nuclear fuel and evolved long ago to become cooling white dwarfs. As such, BSS could just be some quirks but in fact their understanding requires a deep knowledge of many different areas in astronomy, from stellar evolution through cluster dynamics, from chemical abundances to stellar populations. In November 2012, a workshop on this important topic took place at the ESO Chilean headquarters in Santiago. The many topics covered at this workshop were introduced by very comprehensive invited reviews, providing a unique and insightful view on the field. These reviews have now become chapters of the first ever book on BSS.

  9. Liquid biofuels from blue biomass

    DEFF Research Database (Denmark)

    Kádár, Zsófia; Jensen, Annette Eva; Bangsø Nielsen, Henrik

    2011-01-01

    medium, light as energy source and they capture CO2 for the synthesis of new organic material, thus can grow on non-agricultural land, without increasing food prices, or using fresh water. Due to all these advantages in addition to very high biomass yield with high carbohydrate content, macroalgaes can......Marine (blue) biomasses, such as macroalgaes, represent a huge unexploited amount of biomass. With their various chemical compositions, macroalgaes can be a potential substrate for food, feed, biomaterials, pharmaceuticals, health care products and also for bioenergy. Algae use seawater as a growth...... be the well suited candidates as feedstock for biofuel production in the future. The aim of our studies is to examine the possibility producing liquid biofuel (ethanol and butanol) from macroalgaes....

  10. In vitro characterization of biofilms formed by Kingella kingae.

    Science.gov (United States)

    Kaplan, J B; Sampathkumar, V; Bendaoud, M; Giannakakis, A K; Lally, E T; Balashova, N V

    2016-10-07

    The Gram-negative bacterium Kingella kingae is part of the normal oropharyngeal mucosal flora of children kingae can enter the submucosa and cause infections of the skeletal system in children, including septic arthritis and osteomyelitis. The organism is also associated with infective endocarditis in children and adults. Although biofilm formation has been coupled with pharyngeal colonization, osteoarticular infections, and infective endocarditis, no studies have investigated biofilm formation in K. kingae. In this study we measured biofilm formation by 79 K. kingae clinical isolates using a 96-well microtiter plate crystal violet binding assay. We found that 37 of 79 strains (47%) formed biofilms. All strains that formed biofilms produced corroding colonies on agar. Biofilm formation was inhibited by proteinase K and DNase I. DNase I also caused the detachment of pre-formed K. kingae biofilm colonies. A mutant strain carrying a deletion of the pilus gene cluster pilA1pilA2fimB did not produce corroding colonies on agar, autoaggregate in broth, or form biofilms. Biofilm forming strains have higher levels of pilA1 expression. The extracellular components of biofilms contained 490 μg cm(-2) of protein, 0.68 μg cm(-2) of DNA, and 0.4 μg cm(-2) of total carbohydrates. We concluded that biofilm formation is common among K. kingae clinical isolates, and that biofilm formation is dependent on the production of proteinaceous pili and extracellular DNA. Biofilm development may have relevance to the colonization, transmission, and pathogenesis of this bacterium. Extracellular DNA production by K. kingae may facilitate horizontal gene transfer within the oral microbial community.

  11. Oral microbial biofilm stimulation of epithelial cell responses.

    Science.gov (United States)

    Peyyala, Rebecca; Kirakodu, Sreenatha S; Novak, Karen F; Ebersole, Jeffrey L

    2012-04-01

    Oral bacterial biofilms trigger chronic inflammatory responses in the host that can result in the tissue destructive events of periodontitis. However, the characteristics of the capacity of specific host cell types to respond to these biofilms remain ill-defined. This report describes the use of a novel model of bacterial biofilms to stimulate oral epithelial cells and profile select cytokines and chemokines that contribute to the local inflammatory environment in the periodontium. Monoinfection biofilms were developed with Streptococcus sanguinis, Streptococcus oralis, Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis on rigid gas-permeable contact lenses. Biofilms, as well as planktonic cultures of these same bacterial species, were incubated under anaerobic conditions with a human oral epithelial cell line, OKF4, for up to 24h. Gro-1α, IL1α, IL-6, IL-8, TGFα, Fractalkine, MIP-1α, and IP-10 were shown to be produced in response to a range of the planktonic or biofilm forms of these species. P. gingivalis biofilms significantly inhibited the production of all of these cytokines and chemokines, except MIP-1α. Generally, the biofilms of all species inhibited Gro-1α, TGFα, and Fractalkine production, while F. nucleatum biofilms stimulated significant increases in IL-1α, IL-6, IL-8, and IP-10. A. naeslundii biofilms induced elevated levels of IL-6, IL-8 and IP-10. The oral streptococcal species in biofilms or planktonic forms were poor stimulants for any of these mediators from the epithelial cells. The results of these studies demonstrate that oral bacteria in biofilms elicit a substantially different profile of responses compared to planktonic bacteria of the same species. Moreover, certain oral species are highly stimulatory when in biofilms and interact with host cell receptors to trigger pathways of responses that appear quite divergent from individual bacteria.

  12. Spore formation and toxin production in Clostridium difficile biofilms.

    Science.gov (United States)

    Semenyuk, Ekaterina G; Laning, Michelle L; Foley, Jennifer; Johnston, Pehga F; Knight, Katherine L; Gerding, Dale N; Driks, Adam

    2014-01-01

    The ability to grow as a biofilm can facilitate survival of bacteria in the environment and promote infection. To better characterize biofilm formation in the pathogen Clostridium difficile, we established a colony biofilm culture method for this organism on a polycarbonate filter, and analyzed the matrix and the cells in biofilms from a variety of clinical isolates over several days of biofilm culture. We found that biofilms readily formed in all strains analyzed, and that spores were abundant within about 6 days. We also found that extracellular DNA (eDNA), polysaccharide and protein was readily detected in the matrix of all strains, including the major toxins A and/or B, in toxigenic strains. All the strains we analyzed formed spores. Apart from strains 630 and VPI10463, which sporulated in the biofilm at relatively low frequencies, the frequencies of biofilm sporulation varied between 46 and 65%, suggesting that variations in sporulation levels among strains is unlikely to be a major factor in variation in the severity of disease. Spores in biofilms also had reduced germination efficiency compared to spores obtained by a conventional sporulation protocol. Transmission electron microscopy revealed that in 3 day-old biofilms, the outermost structure of the spore is a lightly staining coat. However, after 6 days, material that resembles cell debris in the matrix surrounds the spore, and darkly staining granules are closely associated with the spores surface. In 14 day-old biofilms, relatively few spores are surrounded by the apparent cell debris, and the surface-associated granules are present at higher density at the coat surface. Finally, we showed that biofilm cells possess 100-fold greater resistance to the antibiotic metronidazole then do cells cultured in liquid media. Taken together, our data suggest that C. difficile cells and spores in biofilms have specialized properties that may facilitate infection.

  13. The action of Pseudomonas aeruginosa biofilms in intrinsic drug resistance

    Institute of Scientific and Technical Information of China (English)

    XIE Yi; JIA Wen-xiang; ZENG Wei; YANG Wei-qing; CHENG Xi; LI Xue-ru; WANG Lan-lan; KANG Mei; ZHANG Zai-rong

    2005-01-01

    Background There is a growing interest in studying the relationship between intrinsic resistance and biofilms resistance to drugs. However, the relationship still remains unclear in the macroscopic bacterial growth. Our study is to illuminate the change of bacterial drug resistance of gyrA mutant and active efflux pump during the development of Pseudomonas aeruginosa (P. aeruginosa) biofilms. Methods The strains of type Ⅱ topoisomerase gene mutant (gyrA mutant) and multidrug resistance (MDR) efflux pump were clinical isolates and detected by polymerase chain reaction (PCR). The process of bacterial biofilms development was observed by scanning electron microscope. Triparental mating experiments were performed to transfer report gene of green fluorescent protein (GFP) into P. aeruginosa biofilms strains and followed by analysis of bacterial survival rate between intrinsic resistance and biofilms resistance.Results The fluorescent strains with pGFPuv could develop mature biofilms on Teflon surface. Before a period of 72 hours, the survival rate of biofilms bacteria and intrinsic resistance strains in ciprofloxacin solution was significantly different (P0.05). The carbonyl cyanide m-chlorophenylhydrazone and azithromycin could significantly reduce the drug resistance of biofilm strains and efflux pump strains.Conclusions In the development of P. aeruginosa biofilms, the strains of gyrA mutation and MDR efflux could be conferred with new level of drug resistance. When co-cultured mutated strains with biofilm strains, biofilms may play a major role in bacterial resistance. But after 72 hours incubation (a mature biofilms had been developed), there was no clearly difference between the number of mutant strains and biofilm strains.

  14. Spore formation and toxin production in Clostridium difficile biofilms.

    Directory of Open Access Journals (Sweden)

    Ekaterina G Semenyuk

    Full Text Available The ability to grow as a biofilm can facilitate survival of bacteria in the environment and promote infection. To better characterize biofilm formation in the pathogen Clostridium difficile, we established a colony biofilm culture method for this organism on a polycarbonate filter, and analyzed the matrix and the cells in biofilms from a variety of clinical isolates over several days of biofilm culture. We found that biofilms readily formed in all strains analyzed, and that spores were abundant within about 6 days. We also found that extracellular DNA (eDNA, polysaccharide and protein was readily detected in the matrix of all strains, including the major toxins A and/or B, in toxigenic strains. All the strains we analyzed formed spores. Apart from strains 630 and VPI10463, which sporulated in the biofilm at relatively low frequencies, the frequencies of biofilm sporulation varied between 46 and 65%, suggesting that variations in sporulation levels among strains is unlikely to be a major factor in variation in the severity of disease. Spores in biofilms also had reduced germination efficiency compared to spores obtained by a conventional sporulation protocol. Transmission electron microscopy revealed that in 3 day-old biofilms, the outermost structure of the spore is a lightly staining coat. However, after 6 days, material that resembles cell debris in the matrix surrounds the spore, and darkly staining granules are closely associated with the spores surface. In 14 day-old biofilms, relatively few spores are surrounded by the apparent cell debris, and the surface-associated granules are present at higher density at the coat surface. Finally, we showed that biofilm cells possess 100-fold greater resistance to the antibiotic metronidazole then do cells cultured in liquid media. Taken together, our data suggest that C. difficile cells and spores in biofilms have specialized properties that may facilitate infection.

  15. Antibiotic susceptibility of Aggregatibacter actinomycetemcomitans JP2 in a biofilm

    Directory of Open Access Journals (Sweden)

    Orit Oettinger-Barak

    2013-05-01

    Full Text Available Background: Localized aggressive periodontitis (LAgP is an inflammatory disease associated with specific bacteria, particularly Aggregatibacter actinomycetemcomitans, which can result in early tooth loss. The bacteria grow as a biofilm known as subgingival plaque. Treatment includes mechanical debridement of the biofilm, often associated with empirical antibiotic treatment. Objective: The aims of this study were to test in vitro the sensitivity of A. actinomycetemcomitans JP2 during planktonic and biofilm growth to doxycycline and to the combination of metronidazole and amoxicillin, which are two antibiotic protocols commonly used in clinical practice. Design: Two in vitro biofilm models were used to test the effects of the antibiotics: a static 96-well plate assay was used to investigate the effect of these antibiotics on biofilm formation whilst a flow chamber model was used to examine the effect on established biofilms. Results: Of the antibiotics tested in this model system, doxycycline was most efficacious with a minimal inhibitory concentration (MIC against planktonic cells of 0.21 mg/L and minimal biofilm inhibitory concentration (MBIC of 2.10 mg/L. The most commonly prescribed antibiotic regimen, amoxicillin + metronidazole, was much less effective against both planktonic and biofilm cells with an MIC and MBIC of 12.0 mg/L and 20.2 mg/L, respectively. A single treatment of the clinically achievable concentration of 10 mg/L doxycycline to sparse A. actinomycetemcomitans biofilms in the flow chamber model resulted in significant decreases in biofilm thickness, biovolume, and cell viability. Dense A. actinomycetemcomitans biofilms were significantly more resistant to doxycycline treatment. Low concentrations of antibiotics enhanced biofilm formation. Conclusion: A. actinomycetemcomitans JP2 homotypic biofilms were more susceptible in vitro to doxycycline than amoxicillin + metronidazole.

  16. Dynamics of biofilm formation during anaerobic digestion of organic waste.

    Science.gov (United States)

    Langer, Susanne; Schropp, Daniel; Bengelsdorf, Frank R; Othman, Maazuza; Kazda, Marian

    2014-10-01

    Biofilm-based reactors are effectively used for wastewater treatment but are not common in biogas production. This study investigated biofilm dynamics on biofilm carriers incubated in batch biogas reactors at high and low organic loading rates for sludge from meat industry dissolved air flotation units. Biofilm formation and dynamics were studied using various microscopic techniques. Resulting micrographs were analysed for total cell numbers, thickness of biofilms, biofilm-covered surface area, and the area covered by extracellular polymeric substances (EPS). Cell numbers within biofilms (10(11) cells ml(-1)) were up to one order of magnitude higher compared to the numbers of cells in the fluid reactor content. Further, biofilm formation and structure mainly correlated with the numbers of microorganisms present in the fluid reactor content and the organic loading. At high organic loading (45 kg VS m(-3)), the thickness of the continuous biofilm layer ranged from 5 to 160 μm with an average of 51 μm and a median of 26 μm. Conversely, at lower organic loading (15 kg VS m(-3)), only microcolonies were detectable. Those microcolonies increased in their frequency of occurrence during ongoing fermentation. Independently from the organic loading rate, biofilms were embedded completely in EPS within seven days. The maturation and maintenance of biofilms changed during the batch fermentation due to decreasing substrate availability. Concomitant, detachment of microorganisms within biofilms was observed simultaneously with the decrease of biogas formation. This study demonstrates that biofilms of high cell densities can enhance digestion of organic waste and have positive effects on biogas production.

  17. Blue Skies, Coffee Creamer, and Rayleigh Scattering

    Science.gov (United States)

    Liebl, Michael

    2010-01-01

    The first physical explanation of Earths blue sky was fashioned in 1871 by Lord Rayleigh. Many discussions of Rayleigh scattering and approaches to studying it both in and out of the classroom are available. Rayleigh scattering accounts for the blue color of the sky and the orange/red color of the Sun near sunset and sunrise, and a number of…

  18. Biofilms on Hospital Shower Hoses: Characterization and Implications for Nosocomial Infections

    Science.gov (United States)

    Although the source of drinking water used in hospitals is commonly, biofilms on water pipelines are refuge to bacteria that survive different disinfection strategies. Drinking water (DW) biofilms are well known to harbor opportunistic pathogens, however, these biofilm communitie...

  19. Electroactive mixed culture biofilms in microbial bioelectrochemical systems: the role of temperature for biofilm formation and performance.

    Science.gov (United States)

    Patil, Sunil A; Harnisch, Falk; Kapadnis, Balasaheb; Schröder, Uwe

    2010-10-15

    In this paper we investigate the temperature dependence and temperature limits of waste water derived anodic microbial biofilms. We demonstrate that these biofilms are active in a temperature range between 5°C and 45°C. Elevated temperatures during initial biofilm growth not only accelerate the biofilm formation process, they also influence the bioelectrocatalytic performance of these biofilms when measured at identical operation temperatures. For example, the time required for biofilm formation decreases from above 40 days at 15°C to 3.5 days at 35°C. Biofilms grown at elevated temperatures are more electrochemically active at these temperatures than those grown at lower incubation temperature. Thus, at 30°C current densities of 520 μA cm(-2) and 881 μA cm(-2) are achieved by biofilms grown at 22°C and 35°C, respectively. Vice versa, and of great practical relevance for waste water treatment plants in areas of moderate climate, at low operation temperatures, biofilms grown at lower temperatures outperform those grown at higher temperatures. We further demonstrate that all biofilms possess similar lower (0°C) and upper (50°C) temperature limits--defining the operational limits of a respective microbial fuel cell or microbial biosensor--as well as similar electrochemical electron transfer characteristics.

  20. Experimental model of biofilm implant-related osteomyelitis to test combination biomaterials using biofilms as initial inocula.

    Science.gov (United States)

    Williams, Dustin L; Haymond, Bryan S; Woodbury, Kassie L; Beck, J Peter; Moore, David E; Epperson, R Tyler; Bloebaum, Roy D

    2012-07-01

    Currently, the majority of animal models that are used to study biofilm-related infections use planktonic bacterial cells as initial inocula to produce positive signals of infection in biomaterials studies. However, the use of planktonic cells has potentially led to inconsistent results in infection outcomes. In this study, well-established biofilms of methicillin-resistant Staphylococcus aureus were grown and used as initial inocula in an animal model of a Type IIIB open fracture. The goal of the work was to establish, for the first time, a repeatable model of biofilm implant-related osteomyelitis, wherein biofilms were used as initial inocula to test combination biomaterials. Results showed that 100% of animals that were treated with biofilms developed osteomyelitis, whereas 0% of animals not treated with biofilm developed infection. The development of this experimental model may lead to an important shift in biofilm and biomaterials research by showing that when biofilms are used as initial inocula, they may provide additional insights into how biofilm-related infections in the clinic develop and how they can be treated with combination biomaterials to eradicate and/or prevent biofilm formation.

  1. Calcium-Phosphate-Osteopontin Particles Reduce Biofilm Formation and pH Drops in in situ Grown Dental Biofilms.

    Science.gov (United States)

    Schlafer, Sebastian; Ibsen, Casper J S; Birkedal, Henrik; Nyvad, Bente

    2017-01-01

    This 2-period crossover study investigated the effect of calcium-phosphate-osteopontin particles on biofilm formation and pH in 48-h biofilms grown in situ. Bovine milk osteopontin is a highly phosphorylated glycoprotein that has been shown to interfere with bacterial adhesion to salivary-coated surfaces. Calcium-phosphate-osteopontin particles have been shown to reduce biofilm formation and pH drops in a 5-species laboratory model of dental biofilm without affecting bacterial viability. Here, smooth surface biofilms from 10 individuals were treated ex vivo 6 times/day for 30 min with either calcium-phosphate-osteopontin particles or sterile saline. After growth, the amount of biofilm formed was determined by confocal microscopy, and pH drops upon exposure to glucose were monitored using confocal-microscopy-based pH ratiometry. A total of 160 biofilms were analysed. No adverse effects of repeated ex vivo treatment with calcium-phosphate-osteopontin particles were observed. Particle treatment resulted in a 32% lower amount of biofilm formed (p Biofilm pH was significantly higher upon particle treatment, both shortly after the addition of glucose and after 30 min of incubation with glucose (p biofilms as well as the remineralizing potential of the particles.

  2. Characteristics of biofilm attaching to carriers in moving bed biofilm reactor used to treat vitamin C wastewater.

    Science.gov (United States)

    Hu, Xiao-bing; Xu, Ke; Wang, Zhao; Ding, Li-li; Ren, Hong-qiang

    2013-01-01

    In order to investigate characteristics of biofilm attaching firmly to carriers in the moving bed biofilm reactor (MBBR) used for vitamin C wastewater treatment, experiments were undertaken with instrumental analysis methods. Scanning electron microscopy (SEM) micrographs of MBBR biofilms revealed that there were rod-shaped microbes and cocci in the biofilm, and microbes were embedded within medium substances and the biofilm matrix adhered firmly to carriers, leading to the formation of a smooth compacted surface at the base of the biofilm. Transmission electron microscopy (TEM) analysis revealed that extracellular polymeric substances (EPS) layer surrounded cell, sequestered inorganics to form a mixed structure, which ensured firm attachment of the biofilm to the carrier. X-ray diffraction (XRD) experiments and thermogravimetry analysis revealed that (i) the biofilm contained many inorganic substances, about 70.5%, and the inorganic substances contained multiple classes of inorganic with a high boiling point; (ii) inorganic elements such as calcium and phosphorous were selectively absorbed and accumulated in the biofilm as insoluble compounds with amorphous phases, rendering the biofilm highly resistant to detachment. Fourier-transform infrared (FTIR) spectroscopy showed carbohydrates were the main EPS.

  3. Triboelectric Nanogenerators for Blue Energy Harvesting.

    Science.gov (United States)

    Khan, Usman; Kim, Sang-Woo

    2016-07-26

    Blue energy in the form of ocean waves offers an enormous energy resource. However, it has yet to be fully exploited in order to make it available for the use of mankind. Blue energy harvesting is a challenging task as the kinetic energy from ocean waves is irregular in amplitude and is at low frequencies. Though electromagnetic generators (EMGs) are well-known for harvesting mechanical kinetic energies, they have a crucial limitation for blue energy conversion. Indeed, the output voltage of EMGs can be impractically low at the low frequencies of ocean waves. In contrast, triboelectric nanogenerators (TENGs) are highly suitable for blue energy harvesting as they can effectively harvest mechanical energies from low frequencies (blue energy harvesting. In this Perspective, we describe some of the recent progress and also address concerns related to durable packaging of TENGs in consideration of harsh marine environments and power management for an efficient power transfer and distribution for commercial applications.

  4. Individual or Combined Effects of Meropenem, Imipenem, Sulbactam, Colistin, and Tigecycline on Biofilm-Embedded Acinetobacter baumannii and Biofilm Architecture.

    Science.gov (United States)

    Wang, Yung-Chih; Kuo, Shu-Chen; Yang, Ya-Sung; Lee, Yi-Tzu; Chiu, Chun-Hsiang; Chuang, Ming-Fen; Lin, Jung-Chung; Chang, Feng-Yee; Chen, Te-Li

    2016-08-01

    Acinetobacter baumannii biofilms are difficult to eradicate. We investigated the effects of meropenem (2 mg/liter), imipenem (2 mg/liter), sulbactam (4 mg/liter), colistin (2 mg/liter), and tigecycline (2 mg/liter), alone or in combination, on biofilm-embedded carbapenem-resistant and carbapenem-susceptible A. baumannii (CRAb and CSAb, respectively) cells, as well as on the architecture of the biofilms. A. baumannii ATCC 15151 (Ab15151) and its OXA-82-overproducing transformant, along with two clinical CSAb and two clinical CRAb isolates of differing clonalities, were used. The minimal bactericidal concentrations for biofilm-embedded cells of the six tested isolates were >50-fold those of their planktonic cells. When used individually, meropenem exhibited a higher killing effect than the other four antimicrobials on biofilm-embedded CSAb cells in the colony biofilm assay. For two clinical CRAb isolates, meropenem plus sulbactam or sulbactam plus tigecycline showed >100-fold the bactericidal effect exhibited by these agents used alone after 48 h of treatment. The effect of antimicrobials on the architecture of Ab15151 biofilm emitting green fluorescence was determined by confocal laser scanning microscopy using COMSTAT software. Significant decreases in the maximum biofilm thickness were observed after exposure to meropenem and imipenem. Meropenem plus sulbactam significantly decreased the biomass and mean thickness and increased the roughness coefficient of biofilms, but sulbactam plus tigecycline only decreased the maximum and mean biofilm thickness compared to any of these agents used alone. Meropenem was active against biofilm-embedded CSAb, whereas meropenem plus sulbactam exhibited synergism against biofilm-embedded CRAb and caused significantly more damage to the biofilm architecture than did any of the agents used alone.

  5. Drinking water biofilm cohesiveness changes under chlorination or hydrodynamic stress.

    Science.gov (United States)

    Mathieu, L; Bertrand, I; Abe, Y; Angel, E; Block, J C; Skali-Lami, S; Francius, G

    2014-05-15

    Attempts at removal of drinking water biofilms rely on various preventive and curative strategies such as nutrient reduction in drinking water, disinfection or water flushing, which have demonstrated limited efficiency. The main reason for these failures is the cohesiveness of the biofilm driven by the physico-chemical properties of its exopolymeric matrix (EPS). Effective cleaning procedures should break up the matrix and/or change the elastic properties of bacterial biofilms. The aim of this study was to evaluate the change in the cohesive strength of two-month-old drinking water biofilms under increasing hydrodynamic shear stress τw (from ∼0.2 to ∼10 Pa) and shock chlorination (applied concentration at T0: 10 mg Cl2/L; 60 min contact time). Biofilm erosion (cell loss per unit surface area) and cohesiveness (changes in the detachment shear stress and cluster volumes measured by atomic force microscopy (AFM)) were studied. When rapidly increasing the hydrodynamic constraint, biofilm removal was found to be dependent on a dual process of erosion and coalescence of the biofilm clusters. Indeed, 56% of the biofilm cells were removed with, concomitantly, a decrease in the number of the 50-300 μm(3) clusters and an increase in the number of the smaller (i.e., 600 μm(3)) ones. Moreover, AFM evidenced the strengthening of the biofilm structure along with the doubling of the number of contact points, NC, per cluster volume unit following the hydrodynamic disturbance. This suggests that the compactness of the biofilm exopolymers increases with hydrodynamic stress. Shock chlorination removed cells (-75%) from the biofilm while reducing the volume of biofilm clusters. Oxidation stress resulted in a decrease in the cohesive strength profile of the remaining drinking water biofilms linked to a reduction in the number of contact points within the biofilm network structure in particular for the largest biofilm cluster volumes (>200 μm(3)). Changes in the cohesive

  6. Dynamic remodeling of microbial biofilms by functionally distinct exopolysaccharides.

    Science.gov (United States)

    Chew, Su Chuen; Kundukad, Binu; Seviour, Thomas; van der Maarel, Johan R C; Yang, Liang; Rice, Scott A; Doyle, Patrick; Kjelleberg, Staffan

    2014-08-05

    Biofilms are densely populated communities of microbial cells protected and held together by a matrix of extracellular polymeric substances. The structure and rheological properties of the matrix at the microscale influence the retention and transport of molecules and cells in the biofilm, thereby dictating population and community behavior. Despite its importance, quantitative descriptions of the matrix microstructure and microrheology are limited. Here, particle-tracking microrheology in combination with genetic approaches was used to spatially and temporally study the rheological contributions of the major exopolysaccharides Pel and Psl in Pseudomonas aeruginosa biofilms. Psl increased the elasticity and effective cross-linking within the matrix, which strengthened its scaffold and appeared to facilitate the formation of microcolonies. Conversely, Pel reduced effective cross-linking within the matrix. Without Psl, the matrix becomes more viscous, which facilitates biofilm spreading. The wild-type biofilm decreased in effective cross-linking over time, which would be advantageous for the spreading and colonization of new surfaces. This suggests that there are regulatory mechanisms to control production of the exopolysaccharides that serve to remodel the matrix of developing biofilms. The exopolysaccharides were also found to have profound effects on the spatial organization and integration of P. aeruginosa in a mixed-species biofilm model of P. aeruginosa-Staphylococcus aureus. Pel was required for close association of the two species in mixed-species microcolonies. In contrast, Psl was important for P. aeruginosa to form single-species biofilms on top of S. aureus biofilms. Our results demonstrate that Pel and Psl have distinct physical properties and functional roles during biofilm formation. Importance: Most bacteria grow as biofilms in the environment or in association with eukaryotic hosts. Removal of biofilms that form on surfaces is a challenge in clinical

  7. Chemically Specific Cellular Imaging of Biofilm Formation

    Energy Technology Data Exchange (ETDEWEB)

    Herberg, J L; Schaldach, C; Horn, J; Gjersing, E; Maxwell, R

    2006-02-09

    This document and the accompanying manuscripts summarize the technical accomplishments for our one-year LDRD-ER effort. Biofilm forming microbes have existed on this planet for billions of years and make up 60% of the biological mass on earth. Such microbes exhibit unique biochemical pathways during biofilm formation and play important roles in human health and the environment. Microbial biofilms have been directly implicated in, for example, product contamination, energy losses, and medical infection that cost the loss of human lives and billions of dollars. In no small part due to the lack of detailed understanding, biofilms unfortunately are resistant to control, inhibition, and destruction, either through treatment with antimicrobials or immunological defense mechanisms of the body. Current biofilm research has concentrated on the study of biofilms in the bulk. This is primarily due to the lack of analytical and physical tools to study biofilms non-destructively, in three dimensions, and on the micron or sub-micron scale. This has hindered the development of a clear understanding of either the early stage mechanisms of biofilm growth or the interactions of biofilms with their environment. Enzymatic studies have deduced a biochemical reaction that results in the oxidation of reduced sulfur species with the concomitant reduction of nitrate, a common groundwater pollutant, to dinitrogen gas by the bacterium, Thiobacillus denitrificans (TD). Because of its unique involvement in biologically relevant environmental pathways, TD is scheduled for genome sequencing in the near future by the DOE's Joint Genome Institute and is of interest to DOE's Genomes to Life Program. As our ecosystem is exposed to more and more nitrate contamination large scale livestock and agricultural practices, a further understanding of biofilm formation by organisms that could alleviate these problems is necessary in order to protect out biosphere. However, in order to study this

  8. Physiological stratification in electricity-producing biofilms of Geobacter sulfurreducens.

    Science.gov (United States)

    Schrott, Germán David; Ordoñez, María Victoria; Robuschi, Luciana; Busalmen, Juan Pablo

    2014-02-01

    The elucidation of mechanisms and limitations in electrode respiration by electroactive biofilms is significant for the development of rapidly emerging clean energy production and wastewater treatment technologies. In Geobacter sulfurreducens biofilms, the controlling steps in current production are thought to be the metabolic activity of cells, but still remain to be determined. By quantifying the DNA, RNA, and protein content during the long-term growth of biofilms on polarized graphite electrodes, we show in this work that current production becomes independent of DNA accumulation immediately after a maximal current is achieved. Indeed, the mean respiratory rate of biofilms rapidly decreases after this point, which indicates the progressive accumulation of cells that do not contribute to current production or contribute to a negligible extent. These results support the occurrence of physiological stratification within biofilms as a consequence of respiratory limitations imposed by limited biofilm conductivity.

  9. [Mechanism and risk factors of oral biofilm formation].

    Science.gov (United States)

    Pasich, Ewa; Walczewska, Maria; Pasich, Adam; Marcinkiewicz, Janusz

    2013-08-02

    Recent microbiological investigations completely changed our understanding of the role of biofilm in the formation of the mucosal immune barrier and in pathogenesis of chronic inflammation of bacterial etiology. It is now clear that formation of bacterial biofilm on dental surfaces is characteristic for existence of oral microbial communities. It has also been proved that uncontrolled biofilms on dental tissues, as well as on different biomaterials (e.g. orthodontic appliances), are the main cause of dental diseases such as dental caries and periodontitis. The aim of this paper is to explain mechanisms and consequences of orthodontic biofilm formation. We will discuss current opinions on the influence of different biomaterials employed for orthodontic treatment in biofilm formation and new strategies employed in prevention and elimination of oral biofilm ("dental plaque").

  10. Does dental biofilm accumulation differ between night and day?

    DEFF Research Database (Denmark)

    Dige, Irene; Nyvad, Bente

    Objective: The initial microbial colonization of dental surfaces has been studied thoroughly by classical ultrastructural and microbiological studies and further analysed by fluorescent methods. Most of these studies, however, do not differentiate between biofilms formed during night and day....... The purpose of the study was to perform a quantitative and qualitative analysis of in situ dental biofilms collected during night and day, respectively. We hypothesised that there is a circadian rhythm in the accumulation of bacteria during initial biofilm formation. Methods: Biofilms were collected....... The qualitative analysis confirmed this difference within all individuals but with large inter-individual variation in the degree of microbial coverage and bacterial composition. Conclusions: The study provides firm evidence that initial biofilm formation decreases during night. Low biofilm accumulation during...

  11. Anti-biofilm Activity as a Health Issue.

    Science.gov (United States)

    Miquel, Sylvie; Lagrafeuille, Rosyne; Souweine, Bertrand; Forestier, Christiane

    2016-01-01

    The formation and persistence of surface-attached microbial communities, known as biofilms, are responsible for 75% of human microbial infections (National Institutes of Health). Biofilm lifestyle confers several advantages to the pathogens, notably during the colonization process of medical devices and/or patients' organs. In addition, sessile bacteria have a high tolerance to exogenous stress including anti-infectious agents. Biofilms are highly competitive communities and some microorganisms exhibit anti-biofilm capacities such as bacterial growth inhibition, exclusion or competition, which enable them to acquire advantages and become dominant. The deciphering and control of anti-biofilm properties represent future challenges in human infection control. The aim of this review is to compare and discuss the mechanisms of natural bacterial anti-biofilm strategies/mechanisms recently identified in pathogenic, commensal and probiotic bacteria and the main synthetic strategies used in clinical practice, particularly for catheter-related infections.

  12. Optimizing future treatment of enterococcal infections: attacking the biofilm?

    Science.gov (United States)

    Paganelli, Fernanda L; Willems, Rob J; Leavis, Helen L

    2012-01-01

    Enterococcus faecalis and Enterococcus faecium are among the leading causative agents of nosocomial infections and are infamous for their resistance to many antibiotics. They cause difficult-to-treat infections, often originating from biofilm-mediated infections associated with implanted medical devices or endocarditis. Biofilms protect bacteria against antibiotics and phagocytosis, and physical removal of devices or infected tissue is often needed but is frequently not possible. Currently there are no clinically available compounds that disassemble biofilms. In this review we discuss all known structural and regulatory genes involved in enterococcal biofilm formation, the compounds directed against biofilm formation that have been studied, and potentially useful targets for future drugs to treat enterococcal biofilm-associated infections.

  13. Dynamic approaches of mixed species biofilm formation using modern technologies.

    Science.gov (United States)

    Doiron, Kim; Linossier, Isabelle; Fay, Fabienne; Yong, Julius; Abd Wahid, Effendy; Hadjiev, Dimitre; Bourgougnon, Nathalie

    2012-07-01

    Bacteria and diatoms exist in sessile communities and develop as biofilm on all surfaces in aqueous environments. The interaction between these microorganisms in biofilm was investigated with a bacterial genus Pseudoalteromonas sp. (strain 3J6) and two benthic diatoms Amphora coffeaeformis and Cylindrotheca closterium. Each biofilm was grown for 22 days. Images from the confocal microscopy show a difference of adhesion between Pseudoalteromonas 3J6 and diatoms. Indeed, a stronger adhesion is found with C. closterium suggesting cohabitation between Pseudoalteromonas 3J6 and C. closterium compared at an adaptation for bacteria and A. coffeaeformis. The cellular attachment and the growth evolution in biofilm formation depend on each species of diatoms in the biofilm. Behaviour of microalgae in presence of bacteria demonstrates the complexity of the marine biofilm.

  14. Marine and estuarine natural microbial biofilms: ecological and biogeochemical dimensions

    Directory of Open Access Journals (Sweden)

    O. Roger Anderson

    2016-08-01

    Full Text Available Marine and estuarine microbial biofilms are ubiquitously distributed worldwide and are increasingly of interest in basic and applied sciences because of their unique structural and functional features that make them remarkably different from the biota in the plankton. This is a review of some current scientific knowledge of naturally occurring microbial marine and estuarine biofilms including prokaryotic and microeukaryotic biota, but excluding research specifically on engineering and applied aspects of biofilms such as biofouling. Because the microbial communities including bacteria and protists are integral to the fundamental ecological and biogeochemical processes that support biofilm communities, particular attention is given to the structural and ecological aspects of microbial biofilm formation, succession, and maturation, as well as the dynamics of the interactions of the microbiota in biofilms. The intent is to highlight current state of scientific knowledge and possible avenues of future productive research, especially focusing on the ecological and biogeochemical dimensions.

  15. Microscopic findings for the study of biofilms in food environments.

    Science.gov (United States)

    Olszewska, Magdalena A

    2013-01-01

    The capability of bacteria to colonize food processing surfaces and to form biofilm has become an emerging concern for food industry. The presence and persistence of biofilm on food processing surfaces may pose a risk of food spoilage or food poisoning. A better understanding of bacterial adhesion and resistance of biofilms is needed to ensure quality and safety of food products. This review focuses on microscopic approaches incorporated to explore biofilm mode of existence in food processing environments. An application of antimicrobial agents for the biofilm control, in particular for bacteria connected with food processing environments, is also highlighted. In addition, some aspects of biofilm resistance, especially the phenomenon of persister cells, are discussed.

  16. Anti-biofilm activity as a health issue

    Directory of Open Access Journals (Sweden)

    Sylvie eMiquel

    2016-04-01

    Full Text Available The formation and persistence of surface-attached microbial communities, known as biofilms, are responsible for 75% of human microbial infections (National Institutes of Health. Biofilm lifestyle confers several advantages to the pathogens, notably during the colonization process of medical devices and/or patients’ organs. In addition, sessile bacteria have a high tolerance to exogenous stress including anti-infectious agents. Biofilms are highly competitive communities and some microorganisms exhibit anti-biofilm capacities such as bacterial growth inhibition, exclusion or competition, which enable them to acquire advantages and become dominant. The deciphering and control of anti-biofilm properties represent future challenges in human infection control. The aim of this review is to compare and discuss the mechanisms of natural bacterial anti-biofilm strategies/mechanisms recently identified in pathogenic, commensal and probiotic bacteria and the main synthetic strategies used in clinical practice, particularly for catheter-related infections.

  17. Shaping the Growth Behaviour of Bacterial Aggregates in Biofilms

    CERN Document Server

    Melaugh, Gavin; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Steve P; Gordon, Vernita; Allen, Rosalind J

    2015-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase meaning it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the role of aggregate shape, we find that the degree of spreading of an aggregate on a surface can play a key role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding bacterial cells is low, while initially rounded aggregates perform better when competition is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the...

  18. Biofilm mediated decontamination of pollutants from the environment

    Directory of Open Access Journals (Sweden)

    Arindam Mitra

    2016-01-01

    Full Text Available In this review, we highlight beneficial use of microbial biofilms in remediation of environmental pollutants by bioremediation. Bioremediation is an environment friendly, cost effective, sustainable technology that utilizes microbes to decontaminate and degrade a wide variety of pollutants into less harmful products. Relative to free-floating planktonic cells, microbes existing in biofilm mode are advantageous for bioremediation because of greater tolerance to pollutants, environmental stress and ability to degrade varied harsh pollutants via diverse catabolic pathways. In biofilm mode, microbes are immobilized in a self-synthesized matrix which offers protection from stress, contaminants and predatory protozoa. Contaminants ranging from heavy metals, petroleum, explosives, pesticides have been remediated using microbial consortia of biofilms. In the industry, biofilm based bioremediation is used to decontaminate polluted soil and groundwater. Here we discuss conventional and newer strategies utilizing biofilms in environmental remediation.

  19. Biofilms: strategies for metal corrosion inhibition employing microorganisms.

    Science.gov (United States)

    Zuo, Rongjun

    2007-10-01

    Corrosion causes dramatic economic loss. Currently widely used corrosion control strategies have disadvantages of being expensive, subject to environmental restrictions, and sometimes inefficient. Studies show that microbial corrosion inhibition is actually a common phenomenon. The present review summarizes recent progress in this novel strategy: corrosion control using beneficial bacteria biofilms. The possible mechanisms may involve: (1) removal of corrosive agents (such as oxygen) by bacterial physiological activities (e.g., aerobic respiration), (2) growth inhibition of corrosion-causing bacteria by antimicrobials generated within biofilms [e.g., sulfate-reducing bacteria (SRB) corrosion inhibition by gramicidin S-producing Bacillus brevis biofilm], (3) generation of protective layer by biofilms (e.g., Bacillus licheniformis biofilm produces on aluminum surface a sticky protective layer of gamma-polyglutamate). Successful utilization of this novel strategy relies on advances in study at the interface of corrosion engineering and biofilm biology.

  20. Reconstruction of biofilm images: combining local and global structural parameters

    Energy Technology Data Exchange (ETDEWEB)

    Resat, Haluk; Renslow, Ryan S.; Beyenal, Haluk

    2014-10-20

    Digitized images can be used for quantitative comparison of biofilms grown under different conditions. Using biofilm image reconstruction, it was previously found that biofilms with a completely different look can have nearly identical structural parameters and that the most commonly utilized global structural parameters were not sufficient to uniquely define these biofilms. Here, additional local and global parameters are introduced to show that these parameters considerably increase the reliability of the image reconstruction process. Assessment using human evaluators indicated that the correct identification rate of the reconstructed images increased from 50% to 72% with the introduction of the new parameters into the reconstruction procedure. An expanded set of parameters especially improved the identification of biofilm structures with internal orientational features and of structures in which colony sizes and spatial locations varied. Hence, the newly introduced structural parameter sets helped to better classify the biofilms by incorporating finer local structural details into the reconstruction process.

  1. Bacteriophage-Derived Peptidase CHAPK Eliminates and Prevents Staphylococcal Biofilms

    Directory of Open Access Journals (Sweden)

    Mark Fenton

    2013-01-01

    Full Text Available New antibacterial agents are urgently needed for the elimination of biofilm-forming bacteria that are highly resistant to traditional antimicrobial agents. Proliferation of such bacteria can lead to significant economic losses in the agri-food sector. This study demonstrates the potential of the bacteriophage-derived peptidase, CHAPK, as a biocidal agent for the rapid disruption of biofilm-forming staphylococci, commonly associated with bovine mastitis. Purified CHAPK applied to biofilms of Staphylococcus aureus DPC5246 completely eliminated the staphylococcal biofilms within 4 h. In addition, CHAPK was able to prevent biofilm formation by this strain. The CHAPK lysin also reduced S. aureus in a skin decolonization model. Our data demonstrates the potential of CHAPK as a biocidal agent for prevention and treatment of biofilm-associated staphylococcal infections or as a decontaminating agent in the food and healthcare sectors.

  2. The role of bacterial biofilms in chronic infections

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas

    2013-01-01

    treatment depends on accurate and fast diagnosis. However, in cases where the bacteria succeed in forming a biofilm within the human host, the infection often turns out to be untreatable and will develop into a chronic state. The important hallmarks of chronic biofilm-based infections are extreme resistance...... to antibiotics and many other conventional antimicrobial agents, and an extreme capacity for evading the host defences. In this thesis, I will assemble the current knowledge on biofilms with an emphasis on chronic infections, guidelines for diagnosis and treatment of these infections, before relating this to my...... previous research into the area of biofilms. I will present evidence to support a view that the biofilm lifestyle dominates chronic bacterial infections, where bacterial aggregation is the default mode, and that subsequent biofilm development progresses by adaptation to nutritional and environmental...

  3. Microscopic monitoring of extracellular pH in dental biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Garcia, Javier; Greve, Matilde

    pH in dental biofilm is a key virulence factor for the development of caries lesions. The complex three-dimensional architecture of dental biofilms leads to steep gradients of nutrients and metabolites, including organic acids, across the biofilm. For decades, measuring pH in dental biofilm has...... been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit to monitor horizontal pH gradients in real-time. Quantitative fluorescent microscopic techniques, such as fluorescence lifetime imaging or pH...... ratiometry, can be employed to map the pH landscape in dental biofilm with more detail. However, when pH sensitive fluorescent probes are used to visualize pH in biofilms, it is crucial to differentiate between extracellular and intracellular pH. Intracellular microbial pH and pH in the extracellular matrix...

  4. Modelling of the growth of a methanotrophic biofilm

    DEFF Research Database (Denmark)

    Arcangeli, J.-P.; Arvin, E.

    1997-01-01

    . It indicated that the most influential factors were those related to the biofilm (i.e. density; solid volume fraction; thickness). This suggests that in order to improve the model, further research is needed in the field of biofilm structure and composition. (C) 1997 IAWQ. Published by Elsevier Science Ltd.......A model describing the growth of a methanotrophic biofilm is presented. This model involves simultaneous growth of methanotrophs, heterotrophs and nitrifiers. Heterotrophic biomass grows on soluble polymers which arise from the hydrolysis of dead biomass entrapped in the biofilm. Nitrifiers develop...... because of the presence of ammonia in the mineral medium. A comparison of this model with experimental data showed that the biofilm growth, methane removal, oxygen consumption, product formation and biofilm detachment could be fitted well. Parameter estimation yielded a maximum growth rate...

  5. An electrochemical impedance model for integrated bacterial biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Yoav, Hadar, E-mail: benyoav@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University (Israel); Freeman, Amihay [Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University (Israel); Sternheim, Marek [The Center for Nanoscience and Nanotechnology, Tel Aviv University (Israel); Shacham-Diamand, Yosi [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University (Israel)

    2011-09-30

    Bacterial cells attachment onto solid surfaces and the following growth into mature microbial biofilms may result in highly antibiotic resistant biofilms. Such biofilms may be incidentally formed on tissues or implanted devices, or intentionally formed by directed deposition of microbial sensors on whole-cell bio-chip surface. A new method for electrical characterization of the later on-chip microbial biofilm buildup is presented in this paper. Measurement of impedance vs. frequency in the range of 100 mHz to 400 kHz of Escherichia coli cells attachment to indium-tin-oxide-coated electrodes was carried out while using optical microscopy estimating the electrode area coverage. We show that impedance spectroscopy measurements can be interpreted by a simple electrical equivalent model characterizing both attachment and growth of the biofilm. The correlation of extracted equivalent electrical lumped components with the visual biofilm parameters and their dependence on the attachment and growth phases is confirmed.

  6. Characterization of Acinetobacter baumannii biofilm associated components

    Science.gov (United States)

    Brossard, Kari A.

    Acinetobacter baumannii is a Gram-negative aerobic coccobaccillus that is a major cause of nosocomial infections worldwide. Infected individuals may develop pneumonia, urinary tract, wound, and other infections that are associated with the use of indwelling medical devices such as catheters and mechanical ventilation. Treatment is difficult because many A. baumannii isolates have developed multi-drug resistance and the bacterium can persist on abiotic surfaces. Persistence and resistance may be due to formation of biofilms, which leads to long-term colonization, evasion of the host immune system and resistance to treatment with antibiotics and disinfectants. While biofilms are complex multifaceted structures, two bacterial components that have been shown to be important in formation and stability are exopolysaccharides (EPS) and the biofilm-associated protein (Bap). An EPS, poly-beta-1,6-N-acetylglucosamine, PNAG, has been described for E. coli and S. epidermidis. PNAG acts as an intercellular adhesin. Production of this adhesin is dependent on the pga/icaABCD locus. We have identified a homologous locus in A. baumannii 307-0294 that is involved in production of an exopolysaccharide, recognized by an anti-PNAG antibody. We hypothesized that the A. baumannii pgaABCD locus plays a role in biofilm formation, and protection against host innate defenses and disinfectants suggesting that PNAG is a possible virulence factor for the organism. The first aim of this thesis will define the pgaABCD locus. We have previously identified Bap, a protein with similarity to those described for S. aureus and we have demonstrated that this protein is involved in maintaining the stability of biofilms on glass. We hypothesized that A. baumannii Bap plays a role in persistence and pathogenesis and is regulated by quorum sensing. In our second aim we will examine the role of Bap in attachment and biofilm formation on medically relevant surfaces and also determine if Bap is involved in

  7. Effects of patterned topography on biofilm formation

    Science.gov (United States)

    Vasudevan, Ravikumar

    2011-12-01

    Bacterial biofilms are a population of bacteria attached to each other and irreversibly to a surface, enclosed in a matrix of self-secreted polymers, among others polysaccharides, proteins, DNA. Biofilms cause persisting infections associated with implanted medical devices and hospital acquired (nosocomial) infections. Catheter-associated urinary tract infections (CAUTIs) are the most common type of nosocomial infections accounting for up to 40% of all hospital acquired infections. Several different strategies, including use of antibacterial agents and genetic cues, quorum sensing, have been adopted for inhibiting biofilm formation relevant to CAUTI surfaces. Each of these methods pertains to certain types of bacteria, processes and has shortcomings. Based on eukaryotic cell topography interaction studies and Ulva linza spore studies, topographical surfaces were suggested as a benign control method for biofilm formation. However, topographies tested so far have not included a systematic variation of size across basic topography shapes. In this study patterned topography was systematically varied in size and shape according to two approaches 1) confinement and 2) wetting. For the confinement approach, using scanning electron microscopy and confocal microscopy, orienting effects of tested topography based on staphylococcus aureus (s. aureus) (SH1000) and enterobacter cloacae (e. cloacae) (ATCC 700258) bacterial models were identified on features of up to 10 times the size of the bacterium. Psuedomonas aeruginosa (p. aeruginosa) (PAO1) did not show any orientational effects, under the test conditions. Another important factor in medical biofilms is the identification and quantification of phenotypic state which has not been discussed in the literature concerning bacteria topography characterizations. This was done based on antibiotic susceptibility evaluation and also based on gene expression analysis. Although orientational effects occur, phenotypically no difference

  8. Influence of chemical speciation and biofilm composition on mercury accumulation by freshwater biofilms.

    Science.gov (United States)

    Dranguet, P; Le Faucheur, S; Cosio, C; Slaveykova, V I

    2017-01-25

    Mercury (Hg) is a pollutant of high concern for aquatic systems due to the biomagnification of its methylated form along the food chain. However, in contrast to other metals, gaining knowledge of its bioavailable forms for aquatic microorganisms remains challenging, making Hg risk assessment difficult. Ubiquitous and sessile freshwater biofilms are well known to accumulate and to transform Hg present in their ambient environment. The present study thus aims to evaluate whether non-extractable (proxy of intracellular) Hg accumulated by biofilms could be a good indicator of Hg bioavailability for microorganisms in freshwater. To that end, the link between Hg concentration and speciation, as well as biofilm composition (percentage of abiotic, biotic, chlorophyll and phycocyanin-fractions and abundance of dsrA, gcs, merA and hgcA bacterial genes) and biofilm Hg accumulation was examined. The studied biofilms were grown on artificial substrata in four reservoirs along the Olt River (Romania), which was contaminated by Hg coming from chlor-alkali plant effluents. The 0.45 μm-filterable Hg concentrations in ambient waters were measured and inorganic IHg speciation was modelled. Biofilms were analyzed for their non-extractable IHg and methylmercury (MeHg) contents as well as for their composition. The non-extractable IHg content was related, but not significantly, to the concentration of total IHg (r(2) = 0.88, p = 0.061) whereas a significant correlation was found with the predicted IHg concentration that is not bound to dissolved organic matter (r(2) = 0.95, p = 0.027), despite its extremely low concentrations (10(-25) M), showing a limitation of the thermodynamic Hg modelling to predict Hg bioavailability. The studied biofilms were different in biomass and composition and a principal component analysis showed that the non-extractable IHg content correlated with the abundance of the merA and hgcA genes, while MeHg accumulation was only linked with the abundance of the r

  9. Investigating biofilm structure developing on carriers from lab-scale moving bed biofilm reactors based on light microscopy and optical coherence tomography.

    Science.gov (United States)

    Li, Chunyan; Felz, Simon; Wagner, Michael; Lackner, Susanne; Horn, Harald

    2016-01-01

    This study focused on characterizing the structure of biofilms developed on carriers used in lab-scale moving bed biofilm reactors. Both light microscopy (2D) and optical coherence tomography (OCT) were employed to track the biofilm development on carriers of different geometry and under different aeration rates. Biofilm structure was further characterized with respect to average biofilm thickness, biofilm growth velocity, biomass volume, compartment filling degree, surface area, etc. The results showed that carriers with a smaller compartment size stimulated a quick establishment of biofilms. Low aeration rates favored fast development of biofilms. Comparison between the results derived from 2D and 3D images revealed comparable results with respect to average biofilm thickness and compartment filling degree before the carrier compartments were fully willed with biomass. However, 3D imaging with OCT was capable of visualizing and quantifying the heterogeneous structure of biofilms, which cannot be achieved using 2D imaging.

  10. Anaerobic bacteria grow within Candida albicans biofilms and induce biofilm formation in suspension cultures.

    Science.gov (United States)

    Fox, Emily P; Cowley, Elise S; Nobile, Clarissa J; Hartooni, Nairi; Newman, Dianne K; Johnson, Alexander D

    2014-10-20

    The human microbiome contains diverse microorganisms, which share and compete for the same environmental niches. A major microbial growth form in the human body is the biofilm state, where tightly packed bacterial, archaeal, and fungal cells must cooperate and/or compete for resources in order to survive. We examined mixed biofilms composed of the major fungal species of the gut microbiome, Candida albicans, and each of five prevalent bacterial gastrointestinal inhabitants: Bacteroides fragilis, Clostridium perfringens, Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. We observed that biofilms formed by C. albicans provide a hypoxic microenvironment that supports the growth of two anaerobic bacteria, even when cultured in ambient oxic conditions that are normally toxic to the bacteria. We also found that coculture with bacteria in biofilms induces massive gene expression changes in C. albicans, including upregulation of WOR1, which encodes a transcription regulator that controls a phenotypic switch in C. albicans, from the "white" cell type to the "opaque" cell type. Finally, we observed that in suspension cultures, C. perfringens induces aggregation of C. albicans into "mini-biofilms," which allow C. perfringens cells to survive in a normally toxic environment. This work indicates that bacteria and C. albicans interactions modulate the local chemistry of their environment in multiple ways to create niches favorable to their growth and survival.

  11. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup

    2013-01-01

    , which are thought to be a source of extracellular DNA at sites of infections, increases the tolerance of P. aeruginosa biofilms toward aminoglycosides. Although biofilm-associated aminoglycoside tolerance recently has been linked to extracellular DNA-mediated activation of the pmr genes, we demonstrate...... that the aminoglycoside tolerance mediated by the presence of extracellular DNA is not caused by activation of the pmr genes in our P. aeruginosa biofilms but rather by a protective shield effect of the extracellular DNA....

  12. Simulating Biofilm Deformation and Detachment with the Immersed Boundary Method

    Science.gov (United States)

    Sudarsan, Rangarajan; Ghosh, Sudeshna; Stockie, John M.; Eberl, Hermann J.

    2016-03-01

    We apply the immersed boundary (or IB) method to simulate deformation and detachment of a periodic array of wall-bounded biofilm colonies in response to a linear shear flow. The biofilm material is represented as a network of Hookean springs that are placed along the edges of a triangulation of the biofilm region. The interfacial shear stress, lift and drag forces acting on the biofilm colony are computed by using fluid stress jump method developed by Williams, Fauci and Gaver [Disc. Contin. Dyn. Sys. B 11(2):519-540, 2009], with a modified version of their exclusion filter. Our detachment criterion is based on the novel concept of an averaged equivalent continuum stress tensor defined at each IB point in the biofilm which is then used to determine a corresponding von Mises yield stress; wherever this yield stress exceeds a given critical threshold the connections to that node are severed, thereby signalling the onset of a detachment event. In order to capture the deformation and detachment behaviour of a biofilm colony at different stages of growth, we consider a family of four biofilm shapes with varying aspect ratio. Our numerical simulations focus on the behaviour of weak biofilms (with relatively low yield stress threshold) and investigate features of the fluid-structure interaction such as locations of maximum shear and increased drag. The most important conclusion of this work is that the commonly employed detachment strategy in biofilm models based only on interfacial shear stress can lead to incorrect or inaccurate results when applied to the study of shear induced detachment of weak biofilms. Our detachment strategy based on equivalent continuum stresses provides a unified and consistent IB framework that handles both sloughing and erosion modes of biofilm detachment, and is consistent with strategies employed in many other continuum based biofilm models.

  13. Functional Relationship between Sucrose and a Cariogenic Biofilm Formation.

    Directory of Open Access Journals (Sweden)

    Jian-Na Cai

    Full Text Available Sucrose is an important dietary factor in cariogenic biofilm formation and subsequent initiation of dental caries. This study investigated the functional relationships between sucrose concentration and Streptococcus mutans adherence and biofilm formation. Changes in morphological characteristics of the biofilms with increasing sucrose concentration were also evaluated. S. mutans biofilms were formed on saliva-coated hydroxyapatite discs in culture medium containing 0, 0.05, 0.1, 0.5, 1, 2, 5, 10, 20, or 40% (w/v sucrose. The adherence (in 4-hour biofilms and biofilm composition (in 46-hour biofilms of the biofilms were analyzed using microbiological, biochemical, laser scanning confocal fluorescence microscopic, and scanning electron microscopic methods. To determine the relationships, 2nd order polynomial curve fitting was performed. In this study, the influence of sucrose on bacterial adhesion, biofilm composition (dry weight, bacterial counts, and water-insoluble extracellular polysaccharide (EPS content, and acidogenicity followed a 2nd order polynomial curve with concentration dependence, and the maximum effective concentrations (MECs of sucrose ranged from 0.45 to 2.4%. The bacterial and EPS bio-volume and thickness in the biofilms also gradually increased and then decreased as sucrose concentration increased. Furthermore, the size and shape of the micro-colonies of the biofilms depended on the sucrose concentration. Around the MECs, the micro-colonies were bigger and more homogeneous than those at 0 and 40%, and were surrounded by enough EPSs to support their structure. These results suggest that the relationship between sucrose concentration and cariogenic biofilm formation in the oral cavity could be described by a functional relationship.

  14. Streptococcus pneumoniae biofilm formation and dispersion during colonization and disease.

    Science.gov (United States)

    Chao, Yashuan; Marks, Laura R; Pettigrew, Melinda M; Hakansson, Anders P

    2014-01-01

    Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over one million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo. In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of pneumococcal biofilm

  15. Development of a high-throughput Candida albicans biofilm chip.

    Directory of Open Access Journals (Sweden)

    Anand Srinivasan

    Full Text Available We have developed a high-density microarray platform consisting of nano-biofilms of Candida albicans. A robotic microarrayer was used to print yeast cells of C. albicans encapsulated in a collagen matrix at a volume as low as 50 nL onto surface-modified microscope slides. Upon incubation, the cells grow into fully formed "nano-biofilms". The morphological and architectural complexity of these biofilms were evaluated by scanning electron and confocal scanning laser microscopy. The extent of biofilm formation was determined using a microarray scanner from changes in fluorescence intensities due to FUN 1 metabolic processing. This staining technique was also adapted for antifungal susceptibility testing, which demonstrated that, similar to regular biofilms, cells within the on-chip biofilms displayed elevated levels of resistance against antifungal agents (fluconazole and amphotericin B. Thus, results from structural analyses and antifungal susceptibility testing indicated that despite miniaturization, these biofilms display the typical phenotypic properties associated with the biofilm mode of growth. In its final format, the C. albicans biofilm chip (CaBChip is composed of 768 equivalent and spatially distinct nano-biofilms on a single slide; multiple chips can be printed and processed simultaneously. Compared to current methods for the formation of microbial biofilms, namely the 96-well microtiter plate model, this fungal biofilm chip has advantages in terms of miniaturization and automation, which combine to cut reagent use and analysis time, minimize labor intensive steps, and dramatically reduce assay costs. Such a chip should accelerate the antifungal drug discovery process by enabling rapid, convenient and inexpensive screening of hundreds-to-thousands of compounds simultaneously.

  16. Development of a high-throughput Candida albicans biofilm chip.

    Science.gov (United States)

    Srinivasan, Anand; Uppuluri, Priya; Lopez-Ribot, Jose; Ramasubramanian, Anand K

    2011-04-22

    We have developed a high-density microarray platform consisting of nano-biofilms of Candida albicans. A robotic microarrayer was used to print yeast cells of C. albicans encapsulated in a collagen matrix at a volume as low as 50 nL onto surface-modified microscope slides. Upon incubation, the cells grow into fully formed "nano-biofilms". The morphological and architectural complexity of these biofilms were evaluated by scanning electron and confocal scanning laser microscopy. The extent of biofilm formation was determined using a microarray scanner from changes in fluorescence intensities due to FUN 1 metabolic processing. This staining technique was also adapted for antifungal susceptibility testing, which demonstrated that, similar to regular biofilms, cells within the on-chip biofilms displayed elevated levels of resistance against antifungal agents (fluconazole and amphotericin B). Thus, results from structural analyses and antifungal susceptibility testing indicated that despite miniaturization, these biofilms display the typical phenotypic properties associated with the biofilm mode of growth. In its final format, the C. albicans biofilm chip (CaBChip) is composed of 768 equivalent and spatially distinct nano-biofilms on a single slide; multiple chips can be printed and processed simultaneously. Compared to current methods for the formation of microbial biofilms, namely the 96-well microtiter plate model, this fungal biofilm chip has advantages in terms of miniaturization and automation, which combine to cut reagent use and analysis time, minimize labor intensive steps, and dramatically reduce assay costs. Such a chip should accelerate the antifungal drug discovery process by enabling rapid, convenient and inexpensive screening of hundreds-to-thousands of compounds simultaneously.

  17. Red fluorescent biofilm: the thick, the old, and the cariogenic

    Directory of Open Access Journals (Sweden)

    Catherine M.C. Volgenant

    2016-04-01

    Full Text Available Background: Some dental plaque fluoresces red. The factors involved in this fluorescence are yet unknown. Objective: The aim of this study was to assess systematically the effect of age, thickness, and cariogenicity on the extent of red fluorescence produced by in vitro microcosm biofilms. Design: The effects of biofilm age and thickness on red fluorescence were tested in a constant depth film fermentor (CDFF by growing biofilms of variable thicknesses that received a constant supply of defined mucin medium (DMM and eight pulses of sucrose/day. The influence of cariogenicity on red fluorescence was tested by growing biofilm on dentin disks receiving DMM, supplemented with three or eight pulses of sucrose/day. The biofilms were analyzed at different time points after inoculation, up to 24 days. Emission spectra were measured using a fluorescence spectrophotometer (λexc405 nm and the biofilms were photographed with a fluorescence camera. The composition of the biofilms was assessed using 454-pyrosequecing of the 16S rDNA gene. Results: From day 7 onward, the biofilms emitted increasing intensities of red fluorescence as evidenced by the combined red fluorescence peaks. The red fluorescence intensity correlated with biofilm thickness but not in a linear way. Biofilm fluorescence also correlated with the imposed cariogenicity, evidenced by the induced dentin mineral loss. Increasing the biofilm age or increasing the sucrose pulsing frequency led to a shift in the microbial composition. These shifts in composition were accompanied by an increase in red fluorescence. Conclusions: The current study shows that a thicker, older, or more cariogenic biofilm results in a higher intensity of red fluorescence.

  18. Red fluorescent biofilm: the thick, the old, and the cariogenic

    Science.gov (United States)

    Volgenant, Catherine M.C.; Hoogenkamp, Michel A.; Buijs, Mark J.; Zaura, Egija; ten Cate, Jacob (Bob) M.; van der Veen, Monique H.

    2016-01-01

    Background Some dental plaque fluoresces red. The factors involved in this fluorescence are yet unknown. Objective The aim of this study was to assess systematically the effect of age, thickness, and cariogenicity on the extent of red fluorescence produced by in vitro microcosm biofilms. Design The effects of biofilm age and thickness on red fluorescence were tested in a constant depth film fermentor (CDFF) by growing biofilms of variable thicknesses that received a constant supply of defined mucin medium (DMM) and eight pulses of sucrose/day. The influence of cariogenicity on red fluorescence was tested by growing biofilm on dentin disks receiving DMM, supplemented with three or eight pulses of sucrose/day. The biofilms were analyzed at different time points after inoculation, up to 24 days. Emission spectra were measured using a fluorescence spectrophotometer (λexc405 nm) and the biofilms were photographed with a fluorescence camera. The composition of the biofilms was assessed using 454-pyrosequecing of the 16S rDNA gene. Results From day 7 onward, the biofilms emitted increasing intensities of red fluorescence as evidenced by the combined red fluorescence peaks. The red fluorescence intensity correlated with biofilm thickness but not in a linear way. Biofilm fluorescence also correlated with the imposed cariogenicity, evidenced by the induced dentin mineral loss. Increasing the biofilm age or increasing the sucrose pulsing frequency led to a shift in the microbial composition. These shifts in composition were accompanied by an increase in red fluorescence. Conclusions The current study shows that a thicker, older, or more cariogenic biofilm results in a higher intensity of red fluorescence. PMID:27060056

  19. Characterization of Mannheimia haemolytica biofilm formation in vitro.

    Science.gov (United States)

    Boukahil, Ismail; Czuprynski, Charles J

    2015-01-30

    Mannheimia haemolytica is the primary bacterial agent in the bovine respiratory disease complex. It is thought that M. haemolytica colonizes the tonsillar crypts of cattle as a commensal and subsequently descends into the lungs to cause disease. Many bacterial species persist in the host as biofilms. There is limited information about the ability of M. haemolytica to form biofilms. The aim of this study was to develop an in vitro model for M. haemolytica biofilm formation. We found that M. haemolytica required at least 36 h to form robust biofilms on plastic in vitro when incubated in RPMI-1640 tissue culture medium at 37 °C, with maximal biofilm formation being evident at 48 h. Biofilm formation was inhibited by adding the monosaccharides d(+) galactose and d(+) mannose to the growth medium. Addition of antibodies to the M. haemolytica surface protein OmpA also reduced biofilm formation. Upon evaluating the macromolecules within the biofilm extracellular polymeric substance we found it contained 9.7 μg/cm(2) of protein, 0.81 μg/cm(2) of total carbohydrate, and 0.47 μg/cm(2) of extracellular DNA. Furthermore, proteinase K treatment significantly decreased biofilms (P<0.05) while α-amylase and micrococcal nuclease decreased biofilms to a lesser extent. M. haemolytica biofilm cells were more resistant than planktonic cells to the antibiotics florfenicol, gentamicin, and tulathromycin. These results provide evidence that M. haemolytica can form biofilms, which could contribute to its ability to persist as a commensal in the bovine upper respiratory tract.

  20. Biocorrosion: towards understanding interactions between biofilms and metals.

    Science.gov (United States)

    Beech, Iwona B; Sunner, Jan

    2004-06-01

    The term microbially influenced corrosion, or biocorrosion, refers to the accelerated deterioration of metals owing to the presence of biofilms on their surfaces. The detailed mechanisms of biocorrosion are still poorly understood. Recent investigations into biocorrosion have focused on the influence of biomineralization processes taking place on metallic surfaces and the impact of extracellular enzymes, active within the biofilm matrix, on electrochemical reactions at the biofilm-metal interface.

  1. Improved Denitrification of Municipal Sludge in Biofilm-electrode Reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Le-hua; JIA Jin-ping; WANG Ya-lin; YANG Ji

    2004-01-01

    The denitrification of municipal sludge was improved by combining biofilm process with the electrochemical effect in a single novel reactor. Experiments in this reactor[electric current 60 mA, hydraulic retention time (HRTs) 6.0 h] showed that the removal of CODCr, ammonia nitrogen and total nitrogen in the biofilm-electrode reactor were 2.5%, 1.2%, 14.9%, respectively, higher than those in a traditional biofilm reactor.

  2. Halogenated Phenazines that Potently Eradicate Biofilms, MRSA Persister Cells in Non-Biofilm Cultures, and Mycobacterium tuberculosis.

    Science.gov (United States)

    Garrison, Aaron T; Abouelhassan, Yasmeen; Kallifidas, Dimitris; Bai, Fang; Ukhanova, Maria; Mai, Volker; Jin, Shouguang; Luesch, Hendrik; Huigens, Robert W

    2015-12-01

    Conventional antibiotics are ineffective against non-replicating bacteria (for example, bacteria within biofilms). We report a series of halogenated phenazines (HP), inspired by marine antibiotic 1, that targets persistent bacteria. HP 14 demonstrated the most potent biofilm eradication activities to date against MRSA, MRSE, and VRE biofilms (MBEC = 0.2-12.5 μM), as well as the effective killing of MRSA persister cells in non-biofilm cultures. Frontline MRSA treatments, vancomycin and daptomycin, were unable to eradicate MRSA biofilms or non-biofilm persisters alongside 14. HP 13 displayed potent antibacterial activity against slow-growing M. tuberculosis (MIC = 3.13 μM), the leading cause of death by bacterial infection around the world. HP analogues effectively target persistent bacteria through a mechanism that is non-toxic to mammalian cells and could have a significant impact on treatments for chronic bacterial infections.

  3. Nitritation performance and biofilm development of co- and counter-diffusion biofilm reactors: Modeling and experimental comparison

    DEFF Research Database (Denmark)

    Wang, Rongchang; Terada, Akihiko; Lackner, Susanne

    2009-01-01

    A comparative study was conducted on the start-up performance and biofilm development in two different biofilm reactors with aim of obtaining partial nitritation. The reactors were both operated under oxygen limited conditions, but differed in geometry. While substrates (O-2, NH3) co......-diffused in one geometry, they counter-diffused in the other. Mathematical simulations of these two geometries were implemented in two 1-D multispecies biofilm models using the AQUASIM software. Sensitivity analysis results showed that the oxygen mass transfer coefficient (K-i) and maximum specific growth rate...... results showed that the counter-diffusion biofilms developed faster and attained a larger maximum biofilm thickness than the co-diffusion biofilms. Under oxygen limited condition (DO

  4. Enhanced uranium immobilization and reduction by Geobacter sulfurreducens biofilms.

    Science.gov (United States)

    Cologgi, Dena L; Speers, Allison M; Bullard, Blair A; Kelly, Shelly D; Reguera, Gemma

    2014-11-01

    Biofilms formed by dissimilatory metal reducers are of interest to develop permeable biobarriers for the immobilization of soluble contaminants such as uranium. Here we show that biofilms of the model uranium-reducing bacterium Geobacter sulfurreducens immobilized substantially more U(VI) than planktonic cells and did so for longer periods of time, reductively precipitating it to a mononuclear U(IV) phase involving carbon ligands. The biofilms also tolerated high and otherwise toxic concentrations (up to 5 mM) of uranium, consistent with a respiratory strategy that also protected the cells from uranium toxicity. The enhanced ability of the biofilms to immobilize uranium correlated only partially with the biofilm biomass and thickness and depended greatly on the area of the biofilm exposed to the soluble contaminant. In contrast, uranium reduction depended on the expression of Geobacter conductive pili and, to a lesser extent, on the presence of the c cytochrome OmcZ in the biofilm matrix. The results support a model in which the electroactive biofilm matrix immobilizes and reduces the uranium in the top stratum. This mechanism prevents the permeation and mineralization of uranium in the cell envelope, thereby preserving essential cellular functions and enhancing the catalytic capacity of Geobacter cells to reduce uranium. Hence, the biofilms provide cells with a physically and chemically protected environment for the sustained immobilization and reduction of uranium that is of interest for the development of improved strategies for the in situ bioremediation of environments impacted by uranium contamination.

  5. An optical microfluidic platform for spatiotemporal biofilm treatment monitoring

    Science.gov (United States)

    Kim, Young Wook; Mosteller, Matthew P.; Subramanian, Sowmya; Meyer, Mariana T.; Bentley, William E.; Ghodssi, Reza

    2016-01-01

    Bacterial biofilms constitute in excess of 65% of clinical microbial infections, with the antibiotic treatment of biofilm infections posing a unique challenge due to their high antibiotic tolerance. Recent studies performed in our group have demonstrated that a bioelectric effect featuring low-intensity electric signals combined with antibiotics can significantly improve the efficacy of biofilm treatment. In this work, we demonstrate the bioelectric effect using sub-micron thick planar electrodes in a microfluidic device. This is critical in efforts to develop microsystems for clinical biofilm infection management, including both in vivo and in vitro applications. Adaptation of the method to the microscale, for example, can enable the development of localized biofilm infection treatment using microfabricated medical devices, while augmenting existing capabilities to perform biofilm management beyond the clinical realm. Furthermore, due to scale-down of the system, the voltage requirement for inducing the electric field is reduced further below the media electrolysis threshold. Enhanced biofilm treatment using the bioelectric effect in the developed microfluidic device elicited a 56% greater reduction in viable cell density and 26% further decrease in biomass growth compared to traditional antibiotic therapy. This biofilm treatment efficacy, demonstrated in a micro-scale device and utilizing biocompatible voltage ranges, encourages the use of this method for future clinical biofilm treatment applications.

  6. BIOFILM DETECTION AND CLINICAL SIGNIFICANCE OF STAPHYLOCOCCUS EPIDERMIDIS ISOLATES

    Directory of Open Access Journals (Sweden)

    Sudha Rani

    2015-04-01

    Full Text Available CONTEXT: Isolates of Staphylococcus epidermidis . AIMS : To detect biofilm among clinical isolates of Staphylococcus epidermidis . MATERIAL AND METHODS : 50 Staphylococcus epidermidis isolates were collected from clinical samples like blood, IV catheter tips, catheterized urine, wound swabs and exudates received from various clinical departments. Biofilm formation was studied in these isolates. The study was carried out over a period o f one year i. e from March 2011 - February 2012. The specimens received were processed by conventional methods. Tissue Culture plate method was used for detection of biofilm. RESULTS: IV catheter tip samples revealed 25%, implant device associated infection s revealed 20%, the Catheterized urine samples showed 16%, blood culture 8%, ventilator associated infections 10%, post - operative wound infections 11% & exudates 5% of Staphylococcus epidermidis isolates. Isolates with O. D. values more than 0. 2 were consi dered as high biofilm producers. 40% of S. epidermidis isolates were weak biofilm producers, 24% were moderate biofilm producers and 36% were high biofilm producers. Isolates from IV catheter tips showed high biofilm formation. CONCLUSIONS: In the modern h ealth care set up, various devices such as IV catheters, urine catheters, shunts, implanted prosthetic devices etc are being increasingly used thereby causing the device associated infections particularly of Staphylococcus epidermidis. Device associated in fections caused by Staphylococcus epidermidis are mainly due to biofilm formation which ultimately makes the treatment difficult.

  7. Protocols to study the physiology of oral biofilms.

    Science.gov (United States)

    Lemos, José A; Abranches, Jacqueline; Koo, Hyun; Marquis, Robert E; Burne, Robert A

    2010-01-01

    The oral cavity harbors several hundred different bacterial species that colonize both hard (teeth) and soft tissues, forming complex populations known as microbial biofilms. It is widely accepted that the phenotypic characteristics of bacteria grown in biofilms are substantially different from those grown in suspensions. Because biofilms are the natural habitat for the great majority of oral bacteria, including those contributing to oral diseases, a better understanding of the physiology of adherent populations is clearly needed to control oral microbes in health and disease. In this chapter, we use oral streptococci as examples for studying the physiology of oral biofilms.

  8. Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Vad, Brian Stougaard; Dueholm, Morten Simonsen

    2015-01-01

    The success of Pseudomonas species as opportunistic pathogens derives in great part from their ability to form stable biofilms that offer protection against chemical and mechanical attack. The extracellular matrix of biofilms contains numerous biomolecules, and it has recently been discovered...... that in Pseudomonas one of the components includes β-sheet rich amyloid fibrils (functional amyloid) produced by the fap operon. However, the role of the functional amyloid within the biofilm has not yet been investigated in detail. Here we investigate how the fap-based amyloid produced by Pseudomonas affects biofilm...

  9. MATHEMATICAL MODELING OF EXTRACELLULAR ELECTRON TRANSFER IN BIOFILMS

    Energy Technology Data Exchange (ETDEWEB)

    Renslow, Ryan S.; Babauta, Jerome T.; Kuprat, Andrew P.; Schenk, Jim; Ivory, Cornelius; Fredrickson, Jim K.; Beyenal, Haluk

    2015-09-12

    Electrochemically active biofilms have a unique form of respiration in which they utilize solid external materials as terminal electron acceptors for their metabolism. Currently, two primary mechanisms have been identified for long-range extracellular electron transfer (EET): a diffusion- and a conduction-based mechanism. Evidence in the literature suggests that some biofilms, particularly Shewanella oneidensis, produce the requisite components for both mechanisms. In this study, a generic model is presented that incorporates the diffusion- and the conduction-based mechanisms and allows electrochemically active biofilms to utilize both simultaneously. The model was applied to S. oneidensis and Geobacter sulfurreducens biofilms using experimentally generated data found in the literature. Our simulation results show that 1) biofilms having both mechanisms available, especially if they can interact, may have a metabolic advantage over biofilms that can use only a single mechanism; 2) the thickness of G. sulfurreducens biofilms is likely not limited by conductivity; 3) accurate intrabiofilm diffusion coefficient values are critical for current generation predictions; and 4) the local biofilm potential and redox potential are two distinct parameters and cannot be assumed to have identical values. Finally, we determined that simulated cyclic and squarewave voltammetry based on our model are currently not capable of determining the specific percentages of extracellular electron transfer mechanisms in a biofilm. The developed model will be a critical tool for designing experiments to explain EET mechanisms.

  10. Study on the Curcumin dynamics and distribution through living biofilms

    Science.gov (United States)

    Carvalho, Mariana T.; Dovigo, Lívia N.; Rastelli, Alessandra N. S.; Bagnato, Vanderlei S.

    2013-03-01

    Human oral cavity is colonized by a wide range of microorganisms, often organized in biofilms. These biofilms are responsible for the pathogenesis of caries and most periodontal diseases. A possible alternative to reduce biofilms is the photodynamic inactivation (PDI). The success of the PDI depends on different factors. The time required by the PS to remain in contact with the target cells prior to illumination is determinant for the technique's efficacy. This study aimed to assess the interaction between the PS and the biofilm prior to the PDI. We used confocal microscopy and FLIM to evaluate the interaction between the PS and the biofilm's microorganism during the pre-irradiation time (PIT). The study of this dynamics can lead to the understanding of why only some PSs are effective and why is necessary a long PIT for some microorganisms. Our results showed that are differences for each PIT. These differences can be the determinate for the efficacy of the PDI. We observed that the microorganism needs time to concentrate and/or transport the PS within the biofilm. We presented preliminary results for biofilms of Candida albicans and Streptococcus mutans in the presence of Curcumin and compared it with the literature. We observed that the effectiveness of the PDI might be directly correlated to the position of the PS with the biofilm. Further analyses will be conducted in order to confirm the potential of FLIM to assess the PS dynamics within the biofilms.

  11. Differential effects of planktonic and biofilm MRSA on human fibroblasts.

    Science.gov (United States)

    Kirker, Kelly R; James, Garth A; Fleckman, Philip; Olerud, John E; Stewart, Philip S

    2012-01-01

    Bacteria colonizing chronic wounds often exist as biofilms, yet their role in chronic wound pathogenesis remains unclear. Staphylococcus aureus biofilms induce apoptosis in dermal keratinocytes, and given that chronic wound biofilms also colonize dermal tissue, it is important to investigate the effects of bacterial biofilms on dermal fibroblasts. The effects of a predominant wound pathogen, methicillin-resistant S. aureus, on normal, human, dermal fibroblasts were examined in vitro. Cell-culture medium was conditioned with equivalent numbers of either planktonic or biofilm methicillin-resistant S. aureus and then fed to fibroblast cultures. Fibroblast response was evaluated using scratch, viability, and apoptosis assays. The results suggested that fibroblasts experience the same fate when exposed to the soluble products of either planktonic or biofilm methicillin-resistant S. aureus, namely limited migration followed by death. Enzyme-linked immunosorbent assays demonstrated that fibroblast production of cytokines, growth factors, and proteases were differentially affected by planktonic and biofilm-conditioned medium. Planktonic-conditioned medium induced more interleukin-6, interleukin-8, vascular endothelial growth factor, transforming growth factor-β1, heparin-bound epidermal growth factor, matrix metalloproteinase-1, and metalloproteinase-3 production in fibroblasts than the biofilm-conditioned medium. Biofilm-conditioned medium induced more tumor necrosis factor-α production in fibroblasts compared with planktonic-conditioned medium, and suppressed metalloproteinase-3 production compared with controls.

  12. Redox Conductivity of Current-Producing Mixed Species Biofilms

    Science.gov (United States)

    Fan, Yanzhen; Liu, Hong

    2016-01-01

    While most biological materials are insulating in nature, efficient extracellular electron transfer is a critical property of biofilms associated with microbial electrochemical systems and several microorganisms are capable of establishing conductive aggregates and biofilms. Though construction of these conductive microbial networks is an intriguing and important phenomenon in both natural and engineered systems, few studies have been published related to conductive biofilms/aggregates and their conduction mechanisms, especially in mixed-species environments. In the present study, current-producing mixed species biofilms exhibited high conductivity across non-conductive gaps. Biofilm growth observed on the inactive electrode contributed to overall power outputs, suggesting that an electrical connection was established throughout the biofilm assembly. Electrochemical gating analysis of the biofilms over a range of potentials (-600–200 mV, vs. Ag/AgCl) resulted in a peak-manner response with maximum conductance of 3437 ± 271 μS at a gate potential of -360 mV. Following removal of the electron donor (acetate), a 96.6% decrease in peak conductivity was observed. Differential responses observed in the absence of an electron donor and over varying potentials suggest a redox driven conductivity mechanism in mixed-species biofilms. These results demonstrated significant differences in biofilm development and conductivity compared to previous studies using pure cultures. PMID:27159497

  13. Tracking the autochthonous carbon transfer in stream biofilm food webs.

    Science.gov (United States)

    Risse-Buhl, Ute; Trefzger, Nicolai; Seifert, Anne-Gret; Schönborn, Wilfried; Gleixner, Gerd; Küsel, Kirsten

    2012-01-01

    Food webs in the rhithral zone rely mainly on allochthonous carbon from the riparian vegetation. However, autochthonous carbon might be more important in open canopy streams. In streams, most of the microbial activity occurs in biofilms, associated with the streambed. We followed the autochthonous carbon transfer toward bacteria and grazing protozoa within a stream biofilm food web. Biofilms that developed in a second-order stream (Thuringia, Germany) were incubated in flow channels under climate-controlled conditions. Six-week-old biofilms received either ¹³C- or ¹²C-labeled CO₂, and uptake into phospholipid fatty acids was followed. The dissolved inorganic carbon of the flow channel water became immediately labeled. In biofilms grown under 8-h light/16-h dark conditions, more than 50% of the labeled carbon was incorporated in biofilm algae, mainly filamentous cyanobacteria, pennate diatoms, and nonfilamentous green algae. A mean of 29% of the labeled carbon reached protozoan grazer. The testate amoeba Pseudodifflugia horrida was highly abundant in biofilms and seemed to be the most important grazer on biofilm bacteria and algae. Hence, stream biofilms dominated by cyanobacteria and algae seem to play an important role in the uptake of CO₂ and transfer of autochthonous carbon through the microbial food web.

  14. In vitro study of biofilm growth on biologic prosthetics.

    Science.gov (United States)

    Bellows, Charles; Smith, Alison

    2014-01-01

    Biologic prosthetics are increasingly used for the repair of abdominal wall hernia defects but can become infected as a result of peri- or early post-operative bacterial contamination. Data evaluating biofilm formation on biologic prosthetics is lacking. The aim of this study was to investigate the influence of different biologic prosthetics on the growth behavior of two different bacterial species and their ability to form biofilms. Methicillin resistant Staphylococcus aureus (MRSA) or Pseudomrnonas aeruginosa were incubated on disks of two biologic prosthetics-human acellular dermis (ADM), and porcine small intestinal submucosa (SIS). The bacteria were allowed to attach to the prosthetics and propagate into mature biofilms for 24 hours at 370C. Images of biofilms were obtained using confocal microscopy and scanning electron microscopy (SEM). The number of viable cells and the biofilm biomass were quantified by colony forming units (CFUs) and crystal violet staining respectively. Analysis of variance was performed to compare the mean values for the different prosthetics. Each biologic matrix had a distinct surface characteristic. SEM visualized mature biofilms characterized by highly organized multi-cellular structures on surface of both biologic prosthetics. Quantification of bacterial growth over time showed that ADM had the lowest CFUs and biofilm biomass at 24 hours post-inoculation compared to SIS for both bacterial strains. MRSA and P. aeruginosa can form mature biofilms on biologic prosthetics but the relative abundance of the biofilm varies on different prosthetic constructs. Biologic material composition and manufacturing methods may influence bacterial adherence.

  15. Biofilm detachment mechanisms in a liquid-fluidized bed.

    Science.gov (United States)

    Chang, H T; Rittmann, B E; Amar, D; Heim, R; Ehlinger, O; Lesty, Y

    1991-08-20

    Bed fluidization offers the possibility of gaining the advantages of fixed-film biological processes without the disadvantage of pore clogging. However, the biofilm detachment rate, due to hydrodynamics and particle-to-particle attrition, is very poorly understood for fluidized-bed biofilm processes. In this work, a two-phase fluidized-bed biofilm was operated under a constant surface loading (0.09 mg total organic carbon/cm(2) day) and with a range of bed height (H), fluid velocities (U), and support-particle concentrations (C(p)). Direct measurements were made for the specific biofilm loss rate coefficient (b(s))and the total biofilm accumulation (X(f)L(f)). A hydrodynamic model allowed independent determination of the biofilm density (X(f)), biofilm thickness (L(f)), liquid shear stress (tau), and Reynolds number (Re). Multiple regression analysis of the results showed that increased particle-to-particle attrition, proportional to C(p) and increased turbulence, described by Re, caused the biofilms to be denser and thinner. The specific detachment rate coefficient (b(s)) increased as C(p) and Re increased. Almost all of the 6, values were larger than predicted by a previous model derived for smooth biofilms on a nonfluidized surface. Therefore, the turbulence and attrition of bed fluidization appear to be dominant detachment mechanisms.

  16. Fluorescence lifetime imaging of oxygen in dental biofilm

    Science.gov (United States)

    Gerritsen, Hans C.; de Grauw, Cees J.

    2000-12-01

    Dental biofilm consists of micro-colonies of bacteria embedded in a matrix of polysaccharides and salivary proteins. pH and oxygen concentration are of great importance in dental biofilm. Both can be measured using fluorescence techniques. The imaging of dental biofilm is complicated by the thickness of the biofilms that can be up to several hundred micrometers thick. Here, we employed a combination of two-photon excitation microscopy with fluorescence lifetime imaging to quantify the oxygen concentration in dental biofilm. Collisional quenching of fluorescent probes by molecular oxygen leads to a reduction of the fluorescence lifetime of the probe. We employed this mechanism to measure the oxygen concentration distribution in dental biofilm by means of fluorescence lifetime imaging. Here, TRIS Ruthenium chloride hydrate was used as an oxygen probe. A calibration procedure on buffers was use to measure the lifetime response of this Ruthenium probe. The results are in agreement with the Stern-Volmer equation. A linear relation was found between the ratio of the unquenched and the quenched lifetime and the oxygen concentration. The biofilm fluorescence lifetime imaging results show a strong oxygen gradient at the buffer - biofilm interface and the average oxygen concentration in the biofilm amounted to 50 μM.

  17. Can greening of aquaculture sequester blue carbon?

    Science.gov (United States)

    Ahmed, Nesar; Bunting, Stuart W; Glaser, Marion; Flaherty, Mark S; Diana, James S

    2016-11-15

    Globally, blue carbon (i.e., carbon in coastal and marine ecosystems) emissions have been seriously augmented due to the devastating effects of anthropogenic pressures on coastal ecosystems including mangrove swamps, salt marshes, and seagrass meadows. The greening of aquaculture, however, including an ecosystem approach to Integrated Aquaculture-Agriculture (IAA) and Integrated Multi-Trophic Aquaculture (IMTA) could play a significant role in reversing this trend, enhancing coastal ecosystems, and sequestering blue carbon. Ponds within IAA farming systems sequester more carbon per unit area than conventional fish ponds, natural lakes, and inland seas. The translocation of shrimp culture from mangrove swamps to offshore IMTA could reduce mangrove loss, reverse blue carbon emissions, and in turn increase storage of blue carbon through restoration of mangroves. Moreover, offshore IMTA may create a barrier to trawl fishing which in turn could help restore seagrasses and further enhance blue carbon sequestration. Seaweed and shellfish culture within IMTA could also help to sequester more blue carbon. The greening of aquaculture could face several challenges that need to be addressed in order to realize substantial benefits from enhanced blue carbon sequestration and eventually contribute to global climate change mitigation.

  18. Lethal photosensitization of biofilm-grown bacteria

    Science.gov (United States)

    Wilson, Michael

    1997-12-01

    Antibacterial agents are increasingly being used for the prophylaxis and treatment of oral diseases. As these agents can be rendered ineffective by resistance development in the target organisms there is a need to develop alternative antimicrobial approaches. Light-activated antimicrobial agents release singlet oxygen and free radicals which can kill adjacent bacteria and a wide range of cariogenic and periodontopathogenic bacteria has been shown to be susceptible to such agents. In the oral cavity these organisms are present as biofilms (dental plaques) which are less susceptible to traditional antimicrobial agents than bacterial suspensions. The results of these studies have shown that biofilm-grown oral bacteria are also susceptible to lethal photosensitization although the light energy doses required are grater than those needed to kill the organisms when they are grown as aqueous suspensions.

  19. Emergent pattern formation in an interstitial biofilm

    CERN Document Server

    Zachreson, Cameron; Whitchurch, Cynthia; Toth, Milos

    2016-01-01

    Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment, and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient {\\gamma}), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological ...

  20. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Schembri, Mark; Kjærgaard, K.; Klemm, Per

    2003-01-01

    in expression have no current defined function. These genes, as well as those induced by stresses relevant to biofilm growth such as oxygen and nutrient limitation, may be important factors that trigger enhanced resistance mechanisms of sessile communities to antibiotics and hydrodynamic shear forces.......It is now apparent that microorganisms undergo significant changes during the transition from planktonic to biofilm growth. These changes result in phenotypic adaptations that allow the formation of highly organized and structured sessile communities, which possess enhanced resistance...... to antimicrobial treatments and host immune defence responses. Escherichia coli has been used as a model organism to study the mechanisms of growth within adhered communities. In this study, we use DNA microarray technology to examine the global gene expression profile of E. coli during sessile growth compared...

  1. Cell death in Pseudomonas aeruginosa biofilm development

    DEFF Research Database (Denmark)

    Webb, J.S.; Thompson, L.S.; James, S.

    2003-01-01

    . However, key developmental processes regulating these events are poorly understood. A normal component of multicellular development is cell death. Here we report that a repeatable pattern of cell death and lysis occurs in biofilms of P. aeruginosa during the normal course of development. Cell death....... We propose that prophage-mediated cell death is an important mechanism of differentiation inside microcolonies that facilitates dispersal of a subpopulation of surviving cells....

  2. Characterization of biofilm formed on intrauterine devices

    OpenAIRE

    2003-01-01

    PURPOSE: Intrauterine device (IUD) is one of the most convenient contraceptive procedures used by women of Asian and African countries. Previous surveys have revealed that 75% of the IUDs recovered from patients suffering from reproductive tract infections (RTIs) were covered with a consortium of microbes. This study was designed to characterize these microbes and recommend remedial measures. METHODS: Quantitative measurement of biofilm formation was assessed by a microtitre plate assa...

  3. Effect of Lactoferrin on Oral Biofilm Formation

    Science.gov (United States)

    2009-10-01

    and free-floating forms. In the oral cavity, microbial biofilms including dental plaque, are involved in the pathogenesis of caries, periodontitis ...plaque-associated oral infections, including dental caries and periodontitis . One of these candidates is lactoferrin [LF]. Lactoferrin, a...research data was subsequently submitted to Oral Microbiology and Immunology journal for publication. Both the PI and Dr. Kai Leung at the USADTRD

  4. Blue outliers among intermediate redshift quasars

    CERN Document Server

    Marziani, P; Stirpe, G M; Dultzin, D; Del Olmo, A; Martínez-Carballo, M A

    2015-01-01

    [Oiii]{\\lambda}{\\lambda}4959,5007 "blue outliers" -- that are suggestive of outflows in the narrow line region of quasars -- appear to be much more common at intermediate z (high luminosity) than at low z. About 40% of quasars in a Hamburg ESO intermediate-z sample of 52 sources qualify as blue outliers (i.e., quasars with [OIII] {\\lambda}{\\lambda}4959,5007 lines showing large systematic blueshifts with respect to rest frame). We discuss major findings on what has become an intriguing field in active galactic nuclei research and stress the relevance of blue outliers to feedback and host galaxy evolution.

  5. Emergent pattern formation in an interstitial biofilm

    Science.gov (United States)

    Zachreson, Cameron; Wolff, Christian; Whitchurch, Cynthia B.; Toth, Milos

    2017-01-01

    Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient γ ), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological parameters. Our findings are applicable to a broad range of biofilms and provide insights into the relationship between bacterial movement and their environment, and basic mechanisms behind self-organization of biophysical systems.

  6. Bacterial Extracellular Polysaccharides Involved in Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Elena P. Ivanova

    2009-07-01

    Full Text Available Extracellular polymeric substances (EPS produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of the biofilm matrix. The key functions of EPS comprise the mediation of the initial attachment of cells to different substrata and protection against environmental stress and dehydration. The aim of this review is to present a summary of the current status of the research into the role of EPS in bacterial attachment followed by biofilm formation. The latter has a profound impact on an array of biomedical, biotechnology and industrial fields including pharmaceutical and surgical applications, food engineering, bioremediation and biohydrometallurgy. The diverse structural variations of EPS produced by bacteria of different taxonomic lineages, together with examples of biotechnological applications, are discussed. Finally, a range of novel techniques that can be used in studies involving biofilm-specific polysaccharides is discussed.

  7. STUDY OF ASPARTAME ON BIOFILM PRODUCTION

    Directory of Open Access Journals (Sweden)

    Sourabh

    2015-02-01

    Full Text Available Aspartame is an odourless white crystalline powder 160 - 200 times sweeter than sucrose used in beverages. The present study has been planned to observe the biofilm production of Streptococcus mutans over a biosurface and to assess the influence of aspartame on biofilm production ov er that surface. The lyophilic standard Streptococcus mutans ATCC 25175 (Hi media lab was reactivated in Trypiticase Soy Broth incubated at37 0 C with 10% CO 2 for 18 hrs. 2.5 ml of this liquid culture was added in two 5ml of Brain Heart Infusion Broths with sucrose, congo red and sterile human tooth one with 0.3% aspartame and other without as partame and incubated at 37 0 C with 10% CO 2 for 18 hrs. Biofilm production was evidenced by blackeni n g of tooth along with black deposits .Blackening appeared less in the broth containing aspartame which was further proved by subculturing from both over Brain Heart Infusion (BHI agar with sucrose and Congo red.

  8. Biofilm and dental implant: The microbial link

    Science.gov (United States)

    Dhir, Sangeeta

    2013-01-01

    Mouth provides a congenial environment for the growth of the microorganisms as compared to any other part of the human body by exhibiting an ideal nonshedding surface. Dental plaque happens to be a diverse community of the microorganisms found on the tooth surface. Periodontal disease and the peri-implant disease are specific infections that are originating from these resident microbial species when the balance between the host and the microbial pathogenicity gets disrupted. This review discusses the biofilms in relation to the peri-implant region, factors affecting its presence, and the associated treatment to manage this complex microbial colony. Search Methodology: Electronic search of the medline was done with the search words: Implants and biofilms/dental biofilm formation/microbiology at implant abutment interface/surface free energy/roughness and implant, periimplantitis/local drug delivery and dental implant. Hand search across the journals – clinical oral implant research, implant dentistry, journal of dental research, international journal of oral implantology, journal of prosthetic dentistry, perioodntology 2000, journal of periodontology were performed. The articles included in the review comprised of in vivo studies, in vivo (animal and human) studies, abstracts, review articles. PMID:23633764

  9. Biofilm and dental implant: The microbial link

    Directory of Open Access Journals (Sweden)

    Sangeeta Dhir

    2013-01-01

    Full Text Available Mouth provides a congenial environment for the growth of the microorganisms as compared to any other part of the human body by exhibiting an ideal nonshedding surface. Dental plaque happens to be a diverse community of the microorganisms found on the tooth surface. Periodontal disease and the peri-implant disease are specific infections that are originating from these resident microbial species when the balance between the host and the microbial pathogenicity gets disrupted. This review discusses the biofilms in relation to the peri-implant region, factors affecting its presence, and the associated treatment to manage this complex microbial colony. Search Methodology: Electronic search of the medline was done with the search words: Implants and biofilms/dental biofilm formation/microbiology at implant abutment interface/surface free energy/roughness and implant, periimplantitis/local drug delivery and dental implant. Hand search across the journals - clinical oral implant research, implant dentistry, journal of dental research, international journal of oral implantology, journal of prosthetic dentistry, perioodntology 2000, journal of periodontology were performed. The articles included in the review comprised of in vivo studies, in vivo (animal and human studies, abstracts, review articles.

  10. Evaluation of intraspecies interactions in biofilm formation by Methylobacterium species isolated from pink-pigmented household biofilms.

    Science.gov (United States)

    Xu, Fang-Fang; Morohoshi, Tomohiro; Wang, Wen-Zhao; Yamaguchi, Yuka; Liang, Yan; Ikeda, Tsukasa

    2014-01-01

    Concern regarding household biofilms has grown due to their widespread existence and potential to threaten human health by serving as pathogen reservoirs. Previous studies identified Methylobacterium as one of the dominant genera found in household biofilms. In the present study, we examined the mechanisms underlying biofilm formation by using the bacterial consortium found in household pink slime. A clone library analysis revealed that Methylobacterium was the predominant genus in household pink slime. In addition, 16 out of 21 pink-pigmented bacterial isolates were assigned to the genus Methylobacterium. Although all of the Methylobacterium isolates formed low-level biofilms, the amount of the biofilms formed by Methylobacterium sp. P-1M and P-18S was significantly increased by co-culturing with other Methylobacterium strains that belonged to a specific phylogenetic group. The single-species biofilm was easily washed from the glass surface, whereas the dual-species biofilm strongly adhered after washing. A confocal laser scanning microscopy analysis showed that the dual-species biofilms were significantly thicker and tighter than the single-species biofilms.

  11. Three-dimensional stratification of bacterial biofilm populations in a moving bed biofilm reactor for nitritation-anammox.

    Science.gov (United States)

    Almstrand, Robert; Persson, Frank; Daims, Holger; Ekenberg, Maria; Christensson, Magnus; Wilén, Britt-Marie; Sörensson, Fred; Hermansson, Malte

    2014-01-29

    Moving bed biofilm reactors (MBBRs) are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox) processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB) and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH) to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  12. Three-Dimensional Stratification of Bacterial Biofilm Populations in a Moving Bed Biofilm Reactor for Nitritation-Anammox

    Directory of Open Access Journals (Sweden)

    Robert Almstrand

    2014-01-01

    Full Text Available Moving bed biofilm reactors (MBBRs are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  13. Staphylokinase Control of Staphylococcus aureus Biofilm Formation and Detachment Through Host Plasminogen Activation.

    Science.gov (United States)

    Kwiecinski, Jakub; Peetermans, Marijke; Liesenborghs, Laurens; Na, Manli; Björnsdottir, Halla; Zhu, Xuefeng; Jacobsson, Gunnar; Johansson, Bengt R; Geoghegan, Joan A; Foster, Timothy J; Josefsson, Elisabet; Bylund, Johan; Verhamme, Peter; Jin, Tao

    2016-01-01

    Staphylococcus aureus biofilms, a leading cause of persistent infections, are highly resistant to immune defenses and antimicrobial therapies. In the present study, we investigated the contribution of fibrin and staphylokinase (Sak) to biofilm formation. In both clinical S. aureus isolates and laboratory strains, high Sak-producing strains formed less biofilm than strains that lacked Sak, suggesting that Sak prevents biofilm formation. In addition, Sak induced detachment of mature biofilms. This effect depended on plasminogen activation by Sak. Host-derived fibrin, the main substrate cleaved by Sak-activated plasminogen, was a major component of biofilm matrix, and dissolution of this fibrin scaffold greatly increased susceptibility of biofilms to antibiotics and neutrophil phagocytosis. Sak also attenuated biofilm-associated catheter infections in mouse models. In conclusion, our results reveal a novel role for Sak-induced plasminogen activation that prevents S. aureus biofilm formation and induces detachment of existing biofilms through proteolytic cleavage of biofilm matrix components.

  14. Treatment of Oral Biofilms by a D-Enantiomeric Peptide

    Science.gov (United States)

    Zhang, Tian; Wang, Zhejun; Hancock, Robert E. W.; de la Fuente-Núñez, César; Haapasalo, Markus

    2016-01-01

    Almost all dental diseases are caused by biofilms that consist of multispecies communities. DJK-5, which is a short D-enantiomeric, protease-resistant peptide with broad-spectrum anti-biofilm activity, was tested for its effect on oral multispecies biofilms. Peptide DJK-5 at 10 μg/mL effectively prevented the growth of these microbes in culture media in a time-dependent manner. In addition to the prevention of growth, peptide DJK-5 completely killed both Streptococcus mutans and Enterococcus faecalis suspended from biofilms after 30 minutes of incubation in liquid culture media. DJK-5 also led to the effective killing of microbes in plaque biofilm. The proportion of bacterial cells killed by 10 μg/mL of DJK-5 was similar after 1 and 3 days, both exceeding 85%. DJK-5 was able to significantly prevent biofilm formation over 3 days (P = 0.000). After 72 hours of exposure, DJK-5 significantly reduced and almost completely prevented plaque biofilm production by more than 90% of biovolume compared to untreated controls (P = 0.000). The proportion of dead biofilm bacteria at the 10 μg/mL DJK-5 concentration was similar for 1- and 3-day-old biofilms, whereby >86% of the bacteria were killed. DJK-5 was also able to kill >79% and >85% of bacteria, respectively, after one-time and three brief treatments of 3-day-old biofilms. The combination of DJK-5 and chlorhexidine showed the best bacterial killing among all treatments, with ~83% and >88% of bacterial cells killed after 1 and 3 minutes, respectively. No significant difference was found in the percentage of biofilm killing amongst three donor plaque samples after DJK-5 treatment. In particular, DJK-5 showed strong performance in inhibiting biofilm development and eradicating pre-formed oral biofilms compared to L-enantiomeric peptide 1018. DJK-5 was very effective against oral biofilms when used alone or combined with chlorhexidine, and may be a promising agent for use in oral anti-biofilm strategies in the future. PMID

  15. Incorporation of Listeria monocytogenes strains in raw milk biofilms.

    Science.gov (United States)

    Weiler, Christiane; Ifland, Andrea; Naumann, Annette; Kleta, Sylvia; Noll, Matthias

    2013-02-01

    Biofilms develop successively on devices of milk production without sufficient cleaning and originate from the microbial community of raw milk. The established biofilm matrices enable incorporation of pathogens like Listeria monocytogenes, which can cause a continuous contamination of food processing plants. L. monocytogenes is frequently found in raw milk and non-pasteurized raw milk products and as part of a biofilm community in milk meters and bulk milk tanks. The aim of this study was to analyze whether different L. monocytogenes strains are interacting with the microbial community of raw milk in terms of biofilm formation in the same manner, and to identify at which stage of biofilm formation a selected L. monocytogenes strain settles best. Bacterial community structure and composition of biofilms were analyzed by a cloning and sequencing approach and terminal restriction fragment length polymorphism analysis (T-RFLP) based on the bacterial 16S rRNA gene. The chemical composition of biofilms was analyzed by Fourier transform infrared spectroscopy (FTIR), while settled L. monocytogenes cells were quantified by fluorescence in situ hybridization (FISH). Addition of individual L. monocytogenes strains to raw milk caused significant shifts in the biofilm biomass, in the chemical as well as in the bacterial community composition. Biofilm formation and attachment of L. monocytogenes cells were not serotype but strain specific. However, the added L. monocytogenes strains were not abundant since mainly members of the genera Citrobacter and Lactococcus dominated the bacterial biofilm community. Overall, added L. monocytogenes strains led to a highly competitive interaction with the raw milk community and triggered alterations in biofilm formation.

  16. Hsp90 governs dispersion and drug resistance of fungal biofilms.

    Directory of Open Access Journals (Sweden)

    Nicole Robbins

    2011-09-01

    Full Text Available Fungal biofilms are a major cause of human mortality and are recalcitrant to most treatments due to intrinsic drug resistance. These complex communities of multiple cell types form on indwelling medical devices and their eradication often requires surgical removal of infected devices. Here we implicate the molecular chaperone Hsp90 as a key regulator of biofilm dispersion and drug resistance. We previously established that in the leading human fungal pathogen, Candida albicans, Hsp90 enables the emergence and maintenance of drug resistance in planktonic conditions by stabilizing the protein phosphatase calcineurin and MAPK Mkc1. Hsp90 also regulates temperature-dependent C. albicans morphogenesis through repression of cAMP-PKA signalling. Here we demonstrate that genetic depletion of Hsp90 reduced C. albicans biofilm growth and maturation in vitro and impaired dispersal of biofilm cells. Further, compromising Hsp90 function in vitro abrogated resistance of C. albicans biofilms to the most widely deployed class of antifungal drugs, the azoles. Depletion of Hsp90 led to reduction of calcineurin and Mkc1 in planktonic but not biofilm conditions, suggesting that Hsp90 regulates drug resistance through different mechanisms in these distinct cellular states. Reduction of Hsp90 levels led to a marked decrease in matrix glucan levels, providing a compelling mechanism through which Hsp90 might regulate biofilm azole resistance. Impairment of Hsp90 function genetically or pharmacologically transformed fluconazole from ineffectual to highly effective in eradicating biofilms in a rat venous catheter infection model. Finally, inhibition of Hsp90 reduced resistance of biofilms of the most lethal mould, Aspergillus fumigatus, to the newest class of antifungals to reach the clinic, the echinocandins. Thus, we establish a novel mechanism regulating biofilm drug resistance and dispersion and that targeting Hsp90 provides a much-needed strategy for improving

  17. Blue Ribbon Panel Report - BRP - Cancer Moonshot

    Science.gov (United States)

    The Blue Ribbon Panel Report outlines 10 recommendations to accelerate progress against cancer. The panel was established to ensure that the Cancer Moonshot's approaches are grounded in the best science.

  18. Blue Ribbon Panel 2016 Video Playlist

    Science.gov (United States)

    Blue Ribbon Panel members discuss recommendations from the panel report that was presented to the National Cancer Advisory Board on September 7, 2016. The playlist includes an overview video and 10 videos on the specific recommendations.

  19. Elementary Theorems Regarding Blue Isocurvature Perturbations

    CERN Document Server

    Chung, Daniel J H

    2015-01-01

    Blue CDM-photon isocurvature perturbations are attractive in terms of observability and may be typical from the perspective of generic mass relations in supergravity. We present and apply three theorems useful for blue isocurvature perturbations arising from linear spectator scalar fields. In the process, we give a more precise formula for the blue spectrum associated with the work of 0904.3800, which can in a parametric corner give a factor of O(10) correction. We explain how a conserved current associated with Peccei-Quinn symmetry plays a crucial role and explicitly plot several example spectra including the breaks in the spectra. We also resolve a little puzzle arising from a naive multiplication of isocurvature expression that sheds light on the gravitational imprint of the adiabatic perturbations on the fields responsible for blue isocurvature fluctuations.

  20. Properties of blue-stained wood

    Directory of Open Access Journals (Sweden)

    Miha Humar

    2008-07-01

    Full Text Available Discoloration of wood is frequently caused by blue-stain fungi. Among them Aureobasidium pullulans and Sclerophoma pithyophila are reported as the most important staining organism. In previous researches, it was generally considered that blue-stain fungi do not influence mechanical properties. However, there were some opposite results published as well. In order to elucidate this issue, specimens made of Scots pine (Pinus sylvestris sapwood were exposed to two blue stain fungi A. pullulans and S. pithyophila for periods between two and eight weeks. FTIR, weight, colour and non-destructive modulus of elasticity measurements were performed before and after exposure. The results showed that blue stain fungi, besides considerable discoloration, do not cause any significant damage to wood. Surprisingly the non-destructive MoE analysis showed that modulus of elasticity even slightly increase after fungal exposure.