Bacterial corrosion in low-temperature geothermal. Mechanisms of corrosion by sulphate-reducing bacteria

International Nuclear Information System (INIS)

Daumas, Sylvie

1987-01-01

Within the frame of researches aimed at determining the causes of damages noticed on geothermal equipment, this research thesis aims at assessing the respective importance of physical-chemical processes and bacterial intervention in corrosion phenomena. It proposes an ecological approach of the fluid sampled in the Creil geothermal power station. The aim is to define the adaptation and activity degree of isolated sulphate-reducing bacteria with respect to their environment conditions. The author studied the effect of the development of these bacteria on the corrosion of carbon steel used in geothermal. Thus, he proposes a contribution to the understanding of mechanisms related to iron attack by these bacteria. Electrochemical techniques have been adapted to biological processes and used to measure corrosion [fr

Sulphate-reducing bacteria associated with biocorrosion: a review

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Tania C. de Araujo-Jorge

1992-09-01

Full Text Available Biocorrosion means any process of corrosion in wich microorganisms are somehow involved. As far as the petroleum industry is concerned, the anaerobic type is the more important, with Sulphate-Reducing Bacteria (SRB accouting for half of the described processes. SRB are obligate anaerobs that use sulphur, sulphate or other oxidized sulphur compounds as oxidizing agents when decomposing organic material. A typical product of SRB metabolism, hydrogen sulphide -H2S-, is extremely toxic. In the present work we review the literature on mechanisms underlying biocorrosive process in wich SRB are involved and summarize some of the ultrastructural and eletrochemical work developed using SRB obtained from water injection flow in wells located on PETROBRAS offshore marine plataforms, sampled directly in the field over metallic probes, or cultured under laboratory conditions. Biofilms develop when SRB adhere to inert surfaces. A high diversity of morphological types is found inside these biofilms. Their extracellular matrix is highly hydrated and mainly anionic, as shown by its avid reaction with cationic compounds like ruthenium red. We have noted that variations in iron contet lead to interesting changes in the ultrastructure of the bacterial cell coat and also in the rate of corrosion induced in metallic test cupons. Since routine methods to prevent and treat SRB contamination and biodeterioration involve the use of biocides that are toxic and always have some environmental impact, an accurate diagnosis of biocorrosion is always required prior to a treatment decision. We developed a method that detects and semi-quantifies the presence of living or dead SRB by using free silver potentials as an indicator of corrosive action by SRB-associated sulphides. We found a correlation between sulphide levels (determined either by spectrophotometry, or using a silver electrode -E(Ag- that measured changes in free potentials induced by the presence of exogeneously

Removal heavy metals and sulphate from waste waters by sulphate-reducing bacteria

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Kušnierová Mária

2000-09-01

Full Text Available This article is devoted to the process of bacterial sulphate reduction, which is used to removal of heavy metals and sulphate ions from waste waters.The life of animals and plants depends on the existence of microscopic organisms – microorganisms (MO, which play an important role in cycle changes of biogenic elements on the earth. The sulphur cycle in the nature is considered as one of the oldest and most significant biological systems (Fig. 1. The sulphate-reducing bacteria (SRB miss the assimilatory part of the cycle and produce sulphides. The microbial population of this dissimilatory part is called “sulfuretum”. The SRB can be found in anaerobic mud and sediments of freshwater, thermal or non-thermal sulphur springs, mining waters from sulphide deposits, oil deposits, sea and ocean beds, and in the gastrointestinal tract of man and animals. The SRB represent a group of chemoorganotrophic, strictly anaerobic and gramnegative bacteria, which exhibit a great morphological and physiological diversity. Despite of their considerable morphological variety, they have one property in common, which is the ability to utilise preferentially sulphates (occasionally sulphites, thiosulphates, tetrathionates as electron acceptors, which are reduced to sulphides, during anaerobic respiration. The electron donors in these processes are simple organic compounds as lactate, malate, etc.,(heterotrophically reduction or gaseous hydrogen (autotrophically reduction. SRB can produce a considerable amount of hydrogen sulphide, which reacts easily in aqueous solution with the cations of heavy metals, forming metal sulphides that have low solubility. The bacterial sulphate reduction can be used for the treatment of acid mine drainage waters, which is considered to be the major problem associated with mining activities.In order to remove heavy metals from waste waters, e.g., from galvanizing plants, mine waters (Smolnik, Šobov locality and metallurgic plants (works

The clinical impact of bacterial biofilms

DEFF Research Database (Denmark)

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

2011-01-01

Bacteria survive in nature by forming biofilms on surfaces and probably most, if not all, bacteria (and fungi) are capable of forming biofilms. A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and extracellular DNA....... 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....... Likewise, chronic Pseudomonas aeruginosa lung infections in cystic fibrosis patients are caused by biofilm growing mucoid strains. Gradients of nutrients and oxygen exist from the top to the bottom of biofilms and the bacterial cells located in nutrient poor areas have decreased metabolic activity...

Removal of sulphates from waste waters by sulphate-reducing bacteria

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Luptáková Alena

2002-03-01

Full Text Available are present in almost all types of water, usually as a simple anion SO42-. The sulphates together with hydrogencarbonates and chlorides are principal anions in natural waters. In typical underground and surface waters, the concentration of sulphates is in the range from ten to hundreds milligrams per litre.Nowadays, the importance of the control of sulphate concentration in waste waters increases. According to the Slovak legislation the limit concentration of sulphates in surface and drinking waters is 250 mg.l-1 . In rivers the contents of sulphates increases mainly by the discharge of waste waters, which are coming mainly from chemical, textile, metallurgical, pharmaceutical, paper and mining industry. The concentration of sulphates in these waters is in the order of grams per litre.Many technologies for the sulphates removal from waste waters exist, including biologico-chemical processes. The principle of one of these methods is the reduction of sulphates by sulphate-reducing bacteria to hydrogen-sulphide.The objective of this work was to study the effect of initial sulphates concentration on the activity of anaerobic sulphate reducers as well as the kinetics of the anaerobic sulphate reduction. The batch reactor was used at temperature of 30°C and pH 7,5. Lactate was used as the carbon source.

Bacterial Biofilms in Jones Tubes.

Science.gov (United States)

Ahn, Eric S; Hauck, Matthew J; Kirk Harris, Jonathan; Robertson, Charles E; Dailey, Roger A

To investigate the presence and microbiology of bacterial biofilms on Jones tubes (JTs) by direct visualization with scanning electron microscopy and polymerase chain reaction (PCR) of representative JTs, and to correlate these findings with inflammation and/or infection related to the JT. In this study, prospective case series were performed. JTs were recovered from consecutive patients presenting to clinic for routine cleaning or recurrent irritation/infection. Four tubes were processed for scanning electron microscopy alone to visualize evidence of biofilms. Two tubes underwent PCR alone for bacterial quantification. One tube was divided in half and sent for scanning electron microscopy and PCR. Symptoms related to the JTs were recorded at the time of recovery. Seven tubes were obtained. Five underwent SEM, and 3 out of 5 showed evidence of biofilms (60%). Two of the 3 biofilms demonstrated cocci and the third revealed rods. Three tubes underwent PCR. The predominant bacteria identified were Pseudomonadales (39%), Pseudomonas (16%), and Staphylococcus (14%). Three of the 7 patients (43%) reported irritation and discharge at presentation. Two symptomatic patients, whose tubes were imaged only, revealed biofilms. The third symptomatic patient's tube underwent PCR only, showing predominantly Staphylococcus (56%) and Haemophilus (36%) species. Two of the 4 asymptomatic patients also showed biofilms. All symptomatic patients improved rapidly after tube exchange and steroid antibiotic drops. Bacterial biofilms were variably present on JTs, and did not always correlate with patients' symptoms. Nevertheless, routine JT cleaning is recommended to treat and possibly prevent inflammation caused by biofilms.

Inhibition of bio corrosion of steel coupon by sulphate reducing ...

African Journals Online (AJOL)

SRB) and Iron oxidizing bacteria (IOB) using Aloe vera (Aloe barbadensis) extract was tested. The water sample revealed a heterotrophic bacterial count of 1.7x103 cfu/ml for the sulphate reducing bacteria and 4.1x103 cfu/ml for the Iron oxidizing ...

[The bacterial biofilm and the possibilities of chemical plaque control. Literature review].

Science.gov (United States)

Gera, István

2008-06-01

Most microorganisms in the oral cavity attach to surfaces and form matrix-embedded biofilms. Biofilms are structured and spatially organized, composed of consortia of interacting microorganisms. The properties of the mass of biofilm are different from that of the simple sum of the component species. The older the plaque (biofilm) is the more structurally organized and become more resistant to environmental attacks. The bacterial community favors the growth of obligatory anaerobic microorganisms. The most effective means of the elimination of matured biofilm is the mechanical disruption of the interbacterial protective matrix and removal of bacterial colonies. The antiseptic agents are primarily effective in the prevention of biofilm formation and anticipation of the maturation of the bacterial plaque. Bacteria in matured biofilms are less susceptible to antimicrobial agents because several physical and biological factors protect the bacterial consortia. To kill bacteria in a matured, well organized biofilm, significantly higher concentration and longer exposition are required. Antiseptic mouthrinses in a conventional dose and time can only reach the superficial bacteria while the bacteria in the depth of the biofilm remains intact. Therefore, the efficacy of any antiseptic mouthwash depends not just on its microbicidal properties demonstrated in vitro, but also on its ability to penetrate the organized biofilm on the teeth. Recent studies have demonstrated that both bisbiguanid compounds and essential oils are capable of penetrating the biofilm, and reduce established plaque and gingivitis. The essential oils showed high penetrability and were more effective on organized biofilm than stannous fluorides or triclosan copolymer antiplaque agents.

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

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...

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....

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.

Chitosan-propolis nanoparticle formulation demonstrates anti-bacterial activity against Enterococcus faecalis biofilms.

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Teik Hwa Ong

Full Text Available Propolis obtained from bee hives is a natural substance with antimicrobial properties. It is limited by its insolubility in aqueous solutions; hence ethanol and ethyl acetate extracts of Malaysian propolis were prepared. Both the extracts displayed antimicrobial and anti-biofilm properties against Enterococcus faecalis, a common bacterium associated with hospital-acquired infections. High performance liquid chromatography (HPLC analysis of propolis revealed the presence of flavonoids like kaempferol and pinocembrin. This study investigated the role of propolis developed into nanoparticles with chitosan for its antimicrobial and anti-biofilm properties against E. faecalis. Bacteria that grow in a slimy layer of biofilm are resistant to penetration by antibacterial agents. The use of nanoparticles in medicine has received attention recently due to better bioavailability, enhanced penetrative capacity and improved efficacy. A chitosan-propolis nanoformulation was chosen based on ideal physicochemical properties such as particle size, zeta potential, polydispersity index, encapsulation efficiency and the rate of release of the active ingredients. This formulation inhibited E. faecalis biofilm formation and reduced the number of bacteria in the biofilm by ~90% at 200 μg/ml concentration. When tested on pre-formed biofilms, the formulation reduced bacterial number in the biofilm by ~40% and ~75% at 200 and 300 μg/ml, respectively. The formulation not only reduced bacterial numbers, but also physically disrupted the biofilm structure as observed by scanning electron microscopy. Treatment of biofilms with chitosan-propolis nanoparticles altered the expression of biofilm-associated genes in E. faecalis. The results of this study revealed that chitosan-propolis nanoformulation can be deemed as a potential anti-biofilm agent in resisting infections involving biofilm formation like chronic wounds and surgical site infections.

Studying bacterial multispecies biofilms

DEFF Research Database (Denmark)

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

2016-01-01

The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... 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...

Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

Science.gov (United States)

Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

2016-10-01

Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms underlying the emergence of these greatly different morphologies. Ginzburg-Landau kinetic method and Fourier spectral method are integrated to simulate the morphological evolution of bacterial biofilms. It is shown that the morphological instability of biofilms is triggered by the stresses induced by anisotropic and heterogeneous bacterial expansion, and involves the competition between membrane energy and bending energy. Local interfacial delamination further enriches the morphologies of biofilms. Phase diagrams are established to reveal how the anisotropy and spatial heterogeneity of growth modulate the surface patterns. The mechanics of three-dimensional microbial morphogenesis may also underpin self-organization in other development systems and provide a potential strategy for engineering microscopic structures from bacterial aggregates.

Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

International Nuclear Information System (INIS)

Godoy-Gallardo, Maria; Guillem-Marti, Jordi; Sevilla, Pablo; Manero, José M.; Gil, Francisco J.

2016-01-01

Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

Energy Technology Data Exchange (ETDEWEB)

Godoy-Gallardo, Maria, E-mail: maria.godoy.gallardo@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Guillem-Marti, Jordi, E-mail: jordi.guillem.marti@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Sevilla, Pablo, E-mail: psevilla@euss.es [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), C/ Passeig de Sant Bosco, 42, 08017 Barcelona (Spain); Manero, José M., E-mail: jose.maria.manero@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Gil, Francisco J., E-mail: francesc.xavier.gil@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); and others

2016-02-01

Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

Use of 16S rRNA-targeted oligonucleotide probes to investigate the distribution of sulphate-reducing bacteria in estuarine sediments.

Science.gov (United States)

Purdy, K J.; Nedwell, D B.; Embley, T M.; Takii, S

2001-07-01

The distribution of sulphate-reducing bacteria (SRBs) in three anaerobic sediments, one predominantly freshwater and low sulphate and two predominantly marine and high sulphate, on the River Tama, Tokyo, Japan, was investigated using 16S rRNA-targeted oligonucleotide probes. Hybridisation results and sulphate reduction measurements indicated that SRBs are a minor part of the bacterial population in the freshwater sediments. Only Desulfobulbus and Desulfobacterium were detected, representing 1.6% of the general bacterial probe signal. In contrast, the SRB community detected at the two marine-dominated sites was larger and more diverse, representing 10-11.4% of the bacterial signal and with Desulfobacter, Desulfovibrio, Desulfobulbus and Desulfobacterium detected. In contrast to previous reports our results suggest that Desulfovibrio may not always be the most abundant SRB in anaerobic sediments. Acetate-utilising Desulfobacter were the dominant SRB in the marine-dominated sediments, and Desulfobulbus and Desulfobacterium were active in low-sulphate sediments, where they may utilise electron acceptors other than sulphate.

[Bacterial biofilms and infection].

Science.gov (United States)

Lasa, I; Del Pozo, J L; Penadés, J R; Leiva, J

2005-01-01

In developed countries we tend to think of heart disease and the numerous forms of cancer as the main causes of mortality, but on a global scale infectious diseases come close, or may even be ahead: 14.9 million deaths in 2002 compared to cardiovascular diseases (16.9 million deaths) and cancer (7.1 million deaths) (WHO report 2004). The infectious agents responsible for human mortality have evolved as medical techniques and hygienic measures have changed. Modern-day acute infectious diseases caused by specialized bacterial pathogens such as diphtheria, tetanus, cholera, plague, which represented the main causes of death at the beginning of XX century, have been effectively controlled with antibiotics and vaccines. In their place, more than half of the infectious diseases that affect mildly immunocompromised patients involve bacterial species that are commensal with the human body; these can produce chronic infections, are resistant to antimicrobial agents and there is no effective vaccine against them. Examples of these infections are the otitis media, native valve endocarditis, chronic urinary infections, bacterial prostatitis, osteomyelitis and all the infections related to medical devices. Direct analysis of the surface of medical devices or of tissues that have been foci of chronic infections shows the presence of large numbers of bacteria surrounded by an exopolysaccharide matrix, which has been named the "biofilm". Inside the biofilm, bacteria grow protected from the action of the antibodies, phagocytic cells and antimicrobial treatments. In this article, we describe the role of bacterial biofilms in human persistent infections.

Pseudomonas aeruginosa Biofilm, a Programmed Bacterial Life for Fitness.

Science.gov (United States)

Lee, Keehoon; Yoon, Sang Sun

2017-06-28

A biofilm is a community of microbes that typically inhabit on surfaces and are encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environment and influence our lives tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients, including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicate the eradication of the biofilm infection, leading to the development of chronic infections. In this review, we discuss the history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms on their own or in association with other bacterial species ( i.e. , multispecies biofilms) are discussed in detail.

Modeling physiological resistance in bacterial biofilms.

Science.gov (United States)

Cogan, N G; Cortez, Ricardo; Fauci, Lisa

2005-07-01

A mathematical model of the action of antimicrobial agents on bacterial biofilms is presented. The model includes the fluid dynamics in and around the biofilm, advective and diffusive transport of two chemical constituents and the mechanism of physiological resistance. Although the mathematical model applies in three dimensions, we present two-dimensional simulations for arbitrary biofilm domains and various dosing strategies. The model allows the prediction of the spatial evolution of bacterial population and chemical constituents as well as different dosing strategies based on the fluid motion. We find that the interaction between the nutrient and the antimicrobial agent can reproduce survival curves which are comparable to other model predictions as well as experimental results. The model predicts that exposing the biofilm to low concentration doses of antimicrobial agent for longer time is more effective than short time dosing with high antimicrobial agent concentration. The effects of flow reversal and the roughness of the fluid/biofilm are also investigated. We find that reversing the flow increases the effectiveness of dosing. In addition, we show that overall survival decreases with increasing surface roughness.

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. © 2016 S. Karger AG, Basel.

Extracellular DNases of Ralstonia solanacearum modulate biofilms and facilitate bacterial wilt virulence.

Science.gov (United States)

Minh Tran, Tuan; MacIntyre, April; Khokhani, Devanshi; Hawes, Martha; Allen, Caitilyn

2016-11-01

Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Impact of disinfection on drinking water biofilm bacterial community.

Science.gov (United States)

Mi, Zilong; Dai, Yu; Xie, Shuguang; Chen, Chao; Zhang, Xiaojian

2015-11-01

Disinfectants are commonly applied to control the growth of microorganisms in drinking water distribution systems. However, the effect of disinfection on drinking water microbial community remains poorly understood. The present study investigated the impacts of different disinfectants (chlorine and chloramine) and dosages on biofilm bacterial community in bench-scale pipe section reactors. Illumina MiSeq sequencing illustrated that disinfection strategy could affect both bacterial diversity and community structure of drinking water biofilm. Proteobacteria tended to predominate in chloraminated drinking water biofilms, while Firmicutes in chlorinated and unchlorinated biofilms. The major proteobacterial groups were influenced by both disinfectant type and dosage. In addition, chloramination had a more profound impact on bacterial community than chlorination. Copyright © 2015. Published by Elsevier B.V.

Bacterial biofilms and antibiotic resistance

Directory of Open Access Journals (Sweden)

Liliana Caldas-Arias

2015-04-01

Full Text Available Biofilms give to bacteria micro-environmental benefits; confers protection against antimicrobials. Bacteria have antibiotic resistance by conventional and unusual mechanisms leading to delayed wound healing, to increase recurrent chronic infections and nosocomial contamination of medical devices. Objective: This narrative review aims to introduce the characteristics of Bacteria-biofilms, antimicrobial resistance mechanisms and potential alternatives for prevention and control of its formation. Methods: Search strategy was performed on records: PubMed / Medline, Lilacs, Redalyc; with suppliers such as EBSCO and thesaurus MeSH and DeCS. Conclusions: Knowledge and research performance of biofilm bacteria are relevant in the search of technology for detection and measuring sensitivity to antibiotics. The identification of Bacterial-biofilms needs no-traditional microbiological diagnosis.

Nanoindentation of Pseudomonas aeruginosa bacterial biofilm using atomic force microscopy

International Nuclear Information System (INIS)

Baniasadi, Mahmoud; Xu, Zhe; Du, Yingjie; Lu, Hongbing; Minary-Jolandan, Majid; Gandee, Leah; Zimmern, Philippe

2014-01-01

Bacterial biofilms are a source of many chronic infections. Biofilms and their inherent resistance to antibiotics are attributable to a range of health issues including affecting prosthetic implants, hospital-acquired infections, and wound infection. Mechanical properties of biofilm, in particular, at micro- and nano-scales, are governed by microstructures and porosity of the biofilm, which in turn may contribute to their inherent antibiotic resistance. We utilize atomic force microscopy (AFM)-based nanoindentation and finite element simulation to investigate the nanoscale mechanical properties of Pseudomonas aeruginosa bacterial biofilm. This biofilm was derived from human samples and represents a medically relevant model. (paper)

Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

International Nuclear Information System (INIS)

Kruszewski, Kristen M.; Nistico, Laura; Longwell, Mark J.; Hynes, Matthew J.; Maurer, Joshua A.; Hall-Stoodley, Luanne; Gawalt, Ellen S.

2013-01-01

Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH 3 ) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L

Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

Energy Technology Data Exchange (ETDEWEB)

Kruszewski, Kristen M., E-mail: kruszewskik@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States); Nistico, Laura, E-mail: lnistico@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Longwell, Mark J., E-mail: mlongwel@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Hynes, Matthew J., E-mail: mjhynes@go.wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Maurer, Joshua A., E-mail: maurer@wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Hall-Stoodley, Luanne, E-mail: L.Hall-Stoodley@soton.ac.uk [Southampton Wellcome Trust Clinical Research Facility/NIHR Respiratory BRU, University of Southampton Faculty of Medicine, Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD (United Kingdom); Gawalt, Ellen S., E-mail: gawalte@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, McGowan Institute for Regenerative Medicine, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States)

2013-05-01

Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH{sub 3}) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L.

Enzymatic removal and disinfection of bacterial biofilms

DEFF Research Database (Denmark)

Johansen, Charlotte; Falholt, Per; Gram, Lone

1997-01-01

-coated hydroxyapatite. The activity of enzymes against bacterial cells in biofilm was measured by fluorescence microscopy and an indirect conductance test in which evolution of carbon dioxide was measured. Glucose oxidase combined with lactoperoxidase was bactericidal against biofilm bacteria but did not remove...

Bacterial biofilms investigated by atomic force microscopy and electrochemistry

DEFF Research Database (Denmark)

Hu, Yifan

Bacterial biofilms are aggregates of microorganisms in which cells adhere to each other and adhere to a solid surface or an animal host cavity. Bacterial biofilms play important roles in human life, and cause serious harm for human society and huge economic losses. The complex composition of bact...

Bacterial Biofilms and Catheters: A Key to Understanding Bacterial Strategies in Catheter-Associated Urinary Tract Infection

Directory of Open Access Journals (Sweden)

J Curtis Nickel

1992-01-01

Full Text Available Despite major technological improvements in catheter drainage systems, the indwelling Foley catheter remains the most common cause of nosocomial infection in medical practice. By approaching this common complicated urinary tract infection from the perspective of the biofilm strategy bacteria appear to use to overcome obstacles to produce bacteriuria, one appreciates a new understanding of these infections. An adherent biofilm of bacteria in their secretory products ascends the luminal and external surface of the catheter and drainage system from a contaminated drainage spigot or urethral meatus into the bladder. If the intraluminal route of bacterial ascent is delayed by strict sterile closed drainage or addition of internal modifications to the system, the extraluminal or urethral route assumes greater importance in the development of bacteriuria, but takes significantly longer. Bacterial growth within these thick coherent biofilms confers a large measure of relative resistance to antibiotics even though the individual bacterium remains sensitive, thus accounting for the failure of antibiotic therapy. With disruption of the protective mucous layer of the bladder by mechanical irritation, the bacteria colonizing the catheter can adhere to the bladder’s mucosal surface and cause infection. An appreciation of the role of bacterial biofilms in these infections should suggest future directions for research that may ultimately reduce the risk of catheter-associated infection.

Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

Science.gov (United States)

Agogué, Hélène; Mallet, Clarisse; Orvain, Francis; De Crignis, Margot; Mornet, Françoise; Dupuy, Christine

2014-09-01

In intertidal mudflats, during low tide exposure, microphytobenthos (MPB) migrate vertically through the surface sediment and form, with the heterotrophic bacteria, a transient biofilm. Inside this biofilm, multiple interactions exist between MPB and bacteria. These micro-organisms secrete a wide range of extracellular polymeric substances (EPS), which are major components of the biofilm matrix. In this study, we used a tidal mesocosm experiment in order to decipher the interactions of the MPB-EPS-bacteria complex within the biofilm. We tried to determine if the EPS could control bacterial activities and/or production and/or richness according to the age of the biofilm and to the immersion/emersion period. The dynamics of biomasses of MPB and prokaryotes, the bacterial production, the hydrolysis of predominating organic constituents in the dissolved organic carbon (DOC) pool (i.e., carbohydrates and polypeptides), and the bacterial structure were studied in relation to the different EPS fractions (carbohydrates and proteins: colloidal and bound) dynamics during 8 days. Our experiment had emphasized the influence of the environmental conditions (light, immersion/emersion) on the interactions within the biofilm and also on the effects on biofilm aging. Bacterial production was always inhibited by the bound EPS-carbohydrate, especially during low tide. Our results suggest that the concentration and composition of EPS had a major role in the bacterial/MPB interactions: these interactions can be either positive or negative in order to regulate the productive phases of MPB and bacteria.

Alternative substrates of bacterial sulphate reduction suitable for the biological-chemical treatment of acid mine drainage

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Alena Luptakova

2012-12-01

Full Text Available The impacts of AMD pollution on biological systems are mostly severe and the problem may persist from many decadesto thousands of years. Consequently AMD prior to being released into the environment must be treated to meet government standardsfor the amount of metal and non-metal ions contained in the water. One of the best available technologies for the removal of metals fromAMD is precipitation as metal sulphides. SRB applications for AMD treatment involve a few principal stages. The first stageis the cultivation of SRB i.e. the bacterial sulphate reduction. At the laboratory conditions the sodium lactate is the energetic substratefor the growth of bacteria. Its price is not economic for the application in the practice and is needed investigate the alternativesubstitutes. The aim of this work was the cultivation of SRB using the selected energetic substrates such as: calcium lactate, ethanol,saccharose, glucose and whey. Experimental studies confirm that in the regard to the amount of reduced sulphates the calcium lactateand ethanol are the best alternative substrates for the bacterial sulphate-reduction.

Establishing a laboratory model of dental unit waterlines bacterial biofilms using a CDC biofilm reactor.

Science.gov (United States)

Yoon, Hye Young; Lee, Si Young

2017-11-01

In this study, a laboratory model to reproduce dental unit waterline (DUWL) biofilms was developed using a CDC biofilm reactor (CBR). Bacteria obtained from DUWLs were filtered and cultured in Reasoner's 2A (R2A) for 10 days, and were subsequently stored at -70°C. This stock was cultivated on R2A in batch mode. After culturing for five days, the bacteria were inoculated into the CBR. Biofilms were grown on polyurethane tubing for four days. Biofilm accumulation and thickness was 1.3 × 10 5  CFU cm -2 and 10-14 μm respectively, after four days. Bacteria in the biofilms included cocci and rods of short and medium lengths. In addition, 38 bacterial genera were detected in biofilms. In this study, the suitability and reproducibility of the CBR model for DUWL biofilm formation were demonstrated. The model provides a foundation for the development of bacterial control methods for DUWLs.

Probiotic E. coli Nissle 1917 biofilms on silicone substrates for bacterial interference against pathogen colonization.

Science.gov (United States)

Chen, Quan; Zhu, Zhiling; Wang, Jun; Lopez, Analette I; Li, Siheng; Kumar, Amit; Yu, Fei; Chen, Haoqing; Cai, Chengzhi; Zhang, Lijuan

2017-03-01

Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, a non-pathogenic bacterial biofilm is used as a live, protective barrier to fence off pathogen colonization. In this work, biofilms formed by probiotic Escherichia coli strain Nissle 1917 (EcN) are investigated for their potential for long-term bacterial interference against infections associated with silicone-based urinary catheters and indwelling catheters used in the digestive system, such as feeding tubes and voice prostheses. We have shown that EcN can form stable biofilms on silicone substrates, particularly those modified with a biphenyl mannoside derivative. These biofilms greatly reduced the colonization by pathogenic Enterococcus faecalis in Lysogeny broth (LB) for 11days. Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, we use non-pathogenic bacteria to form a biofilm that serves as a live, protective barrier against pathogen colonization. Herein, we report the first use of preformed probiotic E. coli Nissle 1917 biofilms on the mannoside-presenting silicone substrates to prevent pathogen colonization. The biofilms serve as a live, protective barrier to fence off the pathogens, whereas current antimicrobial/antifouling coatings are subjected to gradual coverage by the biomass from the rapidly growing pathogens in a high-nutrient environment. It should be noted that E. coli Nissle 1917 is commercially available and has been used in many clinical trials. We also demonstrated that this probiotic strain performed significantly better than the non-commercial, genetically modified E. coli strain that we previously reported. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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.

Modulation of Candida albicans virulence by bacterial biofilms on titanium surfaces.

Science.gov (United States)

Cavalcanti, Yuri Wanderley; Wilson, Melanie; Lewis, Michael; Del-Bel-Cury, Altair Antoninha; da Silva, Wander José; Williams, David W

2016-01-01

Whilst Candida albicans occurs in peri-implant biofilms, its role in peri-implantitis remains unclear. This study therefore examined the virulence of C. albicans in mixed-species biofilms on titanium surfaces. Biofilms of C. albicans (Ca), C. albicans with streptococci (Streptococcus sanguinis, S. mutans) (Ca-Ss-Sm) and those incorporating Porphyromonas gingivalis (Ca-Pg and Ca-Ss-Sm-Pg) were developed. Expression of C. albicans genes associated with adhesion (ALS1, ALS3, HWP1) and hydrolytic enzymes (SAP2, SAP4, SAP6, PLD1) was measured and hyphal production by C. albicans quantified. Compared with Ca biofilms, significant (pbiofilms containing streptococci (Ca-Ss-Sm). In Ca-Pg biofilms, down-regulation of HWP1 and SAP4 expression, with reduced hyphal production occurred. Ca-Ss-Sm-Pg biofilms had increased hyphal proportions and up-regulation of ALS3, SAP2 and SAP6. In conclusion, C. albicans expressed virulence factors in biofilms that could contribute to peri-implantitis, but this was dependent on associated bacterial species.

Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate.

Science.gov (United States)

Wang, Xiaoling; Wang, Guoqing; Hao, Mudong

2015-01-01

Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick's first law, and Monod's kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates.

Development of molecularly imprinted polymers to block quorum sensing and inhibit bacterial biofilm formation.

Science.gov (United States)

Ma, Luyao; Feng, Shaolong; de la Fuente-Nunez, Cesar; Hancock, Robert E W; Lu, Xiaonan

2018-05-16

Bacterial biofilms are responsible for most clinical infections and show increased antimicrobial resistance. In this study, molecularly imprinted polymers (MIPs) were developed to specifically capture prototypical quorum sensing autoinducers [i.e., N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12AHL)], interrupt quorum sensing, and subsequently inhibit biofilm formation of Pseudomonas aeruginosa, an important human nosocomial pathogen. The synthesis of MIPs was optimized by considering the amount and type of the functional monomers itaconic acid (IA) and 2-hydroxyethyl methacrylate (HEMA). IA-based MIPs showed high adsorption affinity towards 3-oxo-C12AHL with an imprinting factor of 1.68. Compared to IA-based MIPs, the adsorption capacity of HEMA-based MIPs was improved 5-fold. HEMA-based MIPs significantly reduced biofilm formation (by ~65%), while biofilm suppression by IA-based MIPs was neutralized due to increased bacterial attachment. The developed MIPs represent promising alternative biofilm intervention agents that can be applied to surfaces relevant to clinical settings and food processing equipment.

Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers.

Science.gov (United States)

Kruszewski, Kristen M; Nistico, Laura; Longwell, Mark J; Hynes, Matthew J; Maurer, Joshua A; Hall-Stoodley, Luanne; Gawalt, Ellen S

2013-05-01

Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (-CH3) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an "active" antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Accelerated low water corrosion of carbon steel in the presence of a biofilm harbouring sulphate-reducing and sulphur-oxidising bacteria recovered from a marine sediment

Energy Technology Data Exchange (ETDEWEB)

Beech, Iwona B. [Applied Microbiology and Electrochemistry Group, University of Portsmouth, St. Michael' s Building, White Swan Road, Portsmouth PO1 2DT (United Kingdom)], E-mail: iwona.beech@port.ac.uk; Campbell, Sheelagh A. [Applied Microbiology and Electrochemistry Group, University of Portsmouth, St. Michael' s Building, White Swan Road, Portsmouth PO1 2DT (United Kingdom)

2008-12-01

Investigations were undertaken to elucidate causes of accelerated low water corrosion (ALWC) of steel piling in a harbour in Southern England. Visual inspection revealed features characteristic of ALWC such as the presence of poorly adherent, thick corrosion products of varying morphology, often seen as large blisters randomly located on sections of the structure at the low water mark. Upon the removal of blisters, a bright surface covered with shallow pits was exposed. Representative samples of the corrosion products were collected from the structure and water and sediment specimens were retrieved from selected areas in the harbour for microbiological, chemical and microscopy testing. In the laboratory, field samples were enriched to detect and enumerate communities of sulphur-oxidising bacteria (SOB) and sulphate-reducing bacteria (SRB). Biofilms, comprising SRB and SOB populations isolated from a sediment sample were grown under static conditions on surfaces of electrodes manufactured from steel piling material. Linear polarisation resistance (LPR) measurements revealed that the corrosion rate of steel with biofilms (0.518 mm y{sup -1}) was higher than that recorded in sterile seawater alone (0.054 mm y{sup -1}) and in sterile seawater to which nutrient was added (0.218 mm y{sup -1}). Scanning electron microscopy (SEM) imaging demonstrated enhanced pitting under biofilms. The results of our investigation revealed for the first time that the attack on steel piling in the presence of sediment SRB and SOB populations was characteristic of ALWC.

Accelerated low water corrosion of carbon steel in the presence of a biofilm harbouring sulphate-reducing and sulphur-oxidising bacteria recovered from a marine sediment

International Nuclear Information System (INIS)

Beech, Iwona B.; Campbell, Sheelagh A.

2008-01-01

Investigations were undertaken to elucidate causes of accelerated low water corrosion (ALWC) of steel piling in a harbour in Southern England. Visual inspection revealed features characteristic of ALWC such as the presence of poorly adherent, thick corrosion products of varying morphology, often seen as large blisters randomly located on sections of the structure at the low water mark. Upon the removal of blisters, a bright surface covered with shallow pits was exposed. Representative samples of the corrosion products were collected from the structure and water and sediment specimens were retrieved from selected areas in the harbour for microbiological, chemical and microscopy testing. In the laboratory, field samples were enriched to detect and enumerate communities of sulphur-oxidising bacteria (SOB) and sulphate-reducing bacteria (SRB). Biofilms, comprising SRB and SOB populations isolated from a sediment sample were grown under static conditions on surfaces of electrodes manufactured from steel piling material. Linear polarisation resistance (LPR) measurements revealed that the corrosion rate of steel with biofilms (0.518 mm y -1 ) was higher than that recorded in sterile seawater alone (0.054 mm y -1 ) and in sterile seawater to which nutrient was added (0.218 mm y -1 ). Scanning electron microscopy (SEM) imaging demonstrated enhanced pitting under biofilms. The results of our investigation revealed for the first time that the attack on steel piling in the presence of sediment SRB and SOB populations was characteristic of ALWC

Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate

Directory of Open Access Journals (Sweden)

Xiaoling Wang

2015-01-01

Full Text Available Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick’s first law, and Monod’s kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates.

Bacterial Biofilm Infection Detected in Breast Implant-Associated Anaplastic Large-Cell Lymphoma.

Science.gov (United States)

Hu, Honghua; Johani, Khalid; Almatroudi, Ahmad; Vickery, Karen; Van Natta, Bruce; Kadin, Marshall E; Brody, Garry; Clemens, Mark; Cheah, Chan Yoon; Lade, Stephen; Joshi, Preeti Avinash; Prince, H Miles; Deva, Anand K

2016-06-01

A recent association between breast implants and the development of anaplastic large-cell lymphoma (ALCL) has been observed. The purpose of this study was to identify whether bacterial biofilm is present in breast implant-associated ALCL and, if so, to compare the bacterial microbiome to nontumor capsule samples from breast implants with contracture. Twenty-six breast implant-associated ALCL samples were analyzed for the presence of biofilm by real-time quantitative polymerase chain reaction, next-generation sequencing, fluorescent in situ hybridization, and scanning electron microscopy, and compared to 62 nontumor capsule specimens. Both the breast implant-associated ALCL and nontumor capsule samples yielded high mean numbers of bacteria (breast implant-associated ALCL, 4.7 × 10 cells/mg of tissue; capsule, 4.9 × 10 cells/mg of tissue). Analysis of the microbiome in breast implant-associated ALCL specimens showed significant differences with species identified in nontumor capsule specimens. There was a significantly greater proportion of Ralstonia spp. present in ALCL specimens compared with nontumor capsule specimens (p capsule specimens compared with breast implant-associated ALCL specimens (p < 0.001). Bacterial biofilm was visualized both on scanning electron microscopy and fluorescent in situ hybridization. This novel finding of bacterial biofilm and a distinct microbiome in breast implant-associated ALCL samples points to a possible infectious contributing cause. Breast implants are widely used in both reconstructive and aesthetic surgery, and strategies to reduce their contamination should be more widely studied and practiced. Risk, V.

Efficacy of a marine bacterial nuclease against biofilm forming microorganisms isolated from chronic rhinosinusitis.

Directory of Open Access Journals (Sweden)

Robert C Shields

Full Text Available BACKGROUND: The persistent colonization of paranasal sinus mucosa by microbial biofilms is a major factor in the pathogenesis of chronic rhinosinusitis (CRS. Control of microorganisms within biofilms is hampered by the presence of viscous extracellular polymers of host or microbial origin, including nucleic acids. The aim of this study was to investigate the role of extracellular DNA in biofilm formation by bacteria associated with CRS. METHODS/PRINCIPAL FINDINGS: Obstructive mucin was collected from patients during functional endoscopic sinus surgery. Examination of the mucous by transmission electron microscopy revealed an acellular matrix punctuated occasionally with host cells in varying states of degradation. Bacteria were observed in biofilms on mucosal biopsies, and between two and six different species were isolated from each of 20 different patient samples. In total, 16 different bacterial genera were isolated, of which the most commonly identified organisms were coagulase-negative staphylococci, Staphylococcus aureus and α-haemolytic streptococci. Twenty-four fresh clinical isolates were selected for investigation of biofilm formation in vitro using a microplate model system. Biofilms formed by 14 strains, including all 9 extracellular nuclease-producing bacteria, were significantly disrupted by treatment with a novel bacterial deoxyribonuclease, NucB, isolated from a marine strain of Bacillus licheniformis. Extracellular biofilm matrix was observed in untreated samples but not in those treated with NucB and extracellular DNA was purified from in vitro biofilms. CONCLUSION/SIGNIFICANCE: Our data demonstrate that bacteria associated with CRS form robust biofilms which can be reduced by treatment with matrix-degrading enzymes such as NucB. The dispersal of bacterial biofilms with NucB may offer an additional therapeutic target for CRS sufferers.

Residual structure of Streptococcus mutans biofilm following complete disinfection favors secondary bacterial adhesion and biofilm re-development.

Directory of Open Access Journals (Sweden)

Tatsuya Ohsumi

Full Text Available Chemical disinfection of oral biofilms often leaves biofilm structures intact. This study aimed to examine whether the residual structure promotes secondary bacterial adhesion. Streptococcus mutans biofilms generated on resin-composite disks in a rotating disc reactor were disinfected completely with 70% isopropyl alcohol, and were again cultured in the same reactor after resupplying with the same bacterial solution. Specimens were subjected to fluorescence confocal laser scanning microscopy, viable cell counts and PCR-Invader assay in order to observe and quantify secondarily adhered cells. Fluorescence microscopic analysis, particularly after longitudinal cryosectioning, demonstrated stratified patterns of viable cells on the disinfected biofilm structure. Viable cell counts of test specimens were significantly higher than those of controls, and increased according to the amount of residual structure and culture period. Linear regression analysis exhibited a high correlation between viable and total cell counts. It was concluded that disinfected biofilm structures favored secondary bacterial adhesion.

Bacterial Biofilm Control by Perturbation of Bacterial Signaling Processes

Directory of Open Access Journals (Sweden)

Tim Holm Jakobsen

2017-09-01

Full Text Available The development of effective strategies to combat biofilm infections by means of either mechanical or chemical approaches could dramatically change today’s treatment procedures for the benefit of thousands of patients. Remarkably, considering the increased focus on biofilms in general, there has still not been invented and/or developed any simple, efficient and reliable methods with which to “chemically” eradicate biofilm infections. This underlines the resilience of infective agents present as biofilms and it further emphasizes the insufficiency of today’s approaches used to combat chronic infections. A potential method for biofilm dismantling is chemical interception of regulatory processes that are specifically involved in the biofilm mode of life. In particular, bacterial cell to cell signaling called “Quorum Sensing” together with intracellular signaling by bis-(3′-5′-cyclic-dimeric guanosine monophosphate (cyclic-di-GMP have gained a lot of attention over the last two decades. More recently, regulatory processes governed by two component regulatory systems and small non-coding RNAs have been increasingly investigated. Here, we review novel findings and potentials of using small molecules to target and modulate these regulatory processes in the bacterium Pseudomonas aeruginosa to decrease its pathogenic potential.

On the determining role of network structure titania in silicone against bacterial colonization: Mechanism and disruption of biofilm

International Nuclear Information System (INIS)

Depan, D.; Misra, R.D.K.

2014-01-01

Silicone-based biomedical devices are prone to microbial adhesion, which is the primary cause of concern in the functioning of the artificial device. Silicone exhibiting long-term and effective antibacterial ability is highly desirable to prevent implant related infections. In this regard, nanophase titania was incorporated in silicone as an integral part of the silicone network structure through cross-link mechanism, with the objective to reduce bacterial adhesion to a minimum. The bacterial adhesion was studied using crystal violet assay, while the mechanism of inhibition of biofilm formation was studied via electron microscopy. The incorporation of nanophase titania in silicone dramatically reduced the viability of Staphylococcus aureus (S. aureus) and the capability to adhere on the surface of hybrid silicone by ∼ 93% in relation to stand alone silicone. The conclusion of dramatic reduction in the viability of S. aureus is corroborated by different experimental approaches including biofilm inhibition assay, zone of inhibition, and through a novel experiment that involved incubation of biofilm with titania nanoparticles. It is proposed that the mechanism of disruption of bacterial film in the presence of titania involves puncturing of the bacterial cell membrane. - Highlights: • Network structure titania in silicone imparts antimicrobial activity. • Ability to microbial adhesion is significantly reduced. • Antimicrobial mechanism involves rupture of biofilm

The formation of biofilms on superduplex UNS S32750 steel subjected to different surface treatments

Energy Technology Data Exchange (ETDEWEB)

Pagnin, Sergio [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Barreiro Junior, Walter Cravo; Bott, Ivani de S. [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil)

2009-07-01

Biocorrosion is a phenomenon involving metallic surface deterioration accelerated, or induced, by microorganisms. Such microbiological mechanisms occur when microorganisms are deposited on the surfaces exposed to the carrier fluids. Various factors influence the deposition mechanisms, such as the physical characteristics and chemical composition of the metallic surfaces, both of which can cause significant alterations in the processes that lead to the formation of biofilms. The current study evaluates the formation of biofilms, of a sulphate-reducing strain of bacteria (SRB), on superduplex UNS S32750 stainless steels exposed to synthetic seawater containing this bacterial strain. The experiments were carried out in a dynamic system using a controlled-flow test loop, and the steel surfaces were prepared using different techniques, such as polishing and shot peening, in order to present different physical surface conditions and, consequently, different deposition rates. The levels of organic acids, and of the sulphates consumed and produced, were measured. The morphologies of the biofilms produced were also analysed, by scanning electron microscopy, and surface roughness was measured by atom force microscopy. The level of biocorrosion was determined by counting the pits formed. The results obtained revealed that, despite high bacterial adhesion levels for the various treated surfaces examined, no relevant pitting had occurred, indicating that a corrosive process had not taken place for the testing conditions considered. (author)

Biofilm-mediated Antibiotic-resistant Oral Bacterial Infections: Mechanism and Combat Strategies.

Science.gov (United States)

Kanwar, Indulata; Sah, Abhishek K; Suresh, Preeti K

2017-01-01

Oral diseases like dental caries and periodontal disease are directly associated with the capability of bacteria to form biofilm. Periodontal diseases have been associated to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Biofilm is a complex bacterial community that is highly resistant to antibiotics and human immunity. Biofilm communities are the causative agents of biological developments such as dental caries, periodontitis, peri-implantitis and causing periodontal tissue breakdown. The review recapitulates the latest advancements in treatment of clinical biofilm infections and scientific investigations, while these novel anti-biofilm strategies are still in nascent phases of development, efforts dedicated to these technologies could ultimately lead to anti-biofilm therapies that are superior to the current antibiotic treatment. This paper provides a review of the literature focusing on the studies on biofilm in the oral cavity, formation of dental plaque biofilm, drug resistance of bacterial biofilm and the antibiofilm approaches as biofilm preventive agents in dentistry, and their mechanism of biofilm inhibition. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Bacterial adhesion and biofilm formation on surfaces of variable roughness and hydrophobicity

DEFF Research Database (Denmark)

Tang, Lone; Pillai, Saju; Iversen, Anders

L.Biofilm formation on surfaces in food production and processing can deteriorate the quality of food products and be a hazard to consumers. The food industry currently uses a number of approaches to either remove biofilm or prevent its formation. Due to the inherent resilience of bacteria...... in biofilm, a particularly attractive approach is the modification of surfaces with the aim to impede the first step in biofilm formation, namely bacterial adhesion. Surface properties such as hydrophobicity, roughness and predisposition for fouling by protein are recognised as important in bacterial...... adhesion. Sol-gel technology and the recent availability of organic modified silicas have lead to development of hybrid organic/inorganic glass ceramic coatings with specialised surface properties. In this study we investigate bacterial adhesion and the subsequent biofilm formation on stainless steel (SS...

Biofilm bacterial communities in urban drinking water distribution systems transporting waters with different purification strategies.

Science.gov (United States)

Wu, Huiting; Zhang, Jingxu; Mi, Zilong; Xie, Shuguang; Chen, Chao; Zhang, Xiaojian

2015-02-01

Biofilm formation in drinking water distribution systems (DWDS) has many adverse consequences. Knowledge of microbial community structure of DWDS biofilm can aid in the design of an effective control strategy. However, biofilm bacterial community in real DWDS and the impact of drinking water purification strategy remain unclear. The present study investigated the composition and diversity of biofilm bacterial community in real DWDSs transporting waters with different purification strategies (conventional treatment and integrated treatment). High-throughput Illumina MiSeq sequencing analysis illustrated a large shift in the diversity and structure of biofilm bacterial community in real DWDS. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Nitrospirae, and Cyanobacteria were the major components of biofilm bacterial community. Proteobacteria (mainly Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria) predominated in each DWDS biofilm, but the compositions of the dominant proteobacterial classes and genera and their proportions varied among biofilm samples. Drinking water purification strategy could shape DWDS biofilm bacterial community. Moreover, Pearson's correlation analysis indicated that Actinobacteria was positively correlated with the levels of total alkalinity and dissolved organic carbon in tap water, while Firmicutes had a significant positive correlation with nitrite nitrogen.

A computer investigation of chemically mediated detachment in bacterial biofilms.

Science.gov (United States)

Hunt, Stephen M; Hamilton, Martin A; Sears, John T; Harkin, Gary; Reno, Jason

2003-05-01

A three-dimensional computer model was used to evaluate the effect of chemically mediated detachment on biofilm development in a negligible-shear environment. The model, BacLAB, combines conventional diffusion-reaction equations for chemicals with a cellular automata algorithm to simulate bacterial growth, movement and detachment. BacLAB simulates the life cycle of a bacterial biofilm from its initial colonization of a surface to the development of a mature biofilm with cell areal densities comparable to those in the laboratory. A base model founded on well established transport equations that are easily adaptable to investigate conjectures at the biological level has been created. In this study, the conjecture of a detachment mechanism involving a bacterially produced chemical detachment factor in which high local concentrations of this detachment factor cause the bacteria to detach from the biofilm was examined. The results show that the often observed 'mushroom'-shaped structure can occur if detachment events create voids so that the remaining attached cells look like mushrooms.

Shaping the growth behaviour of biofilms initiated from bacterial aggregates

DEFF Research Database (Denmark)

Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov

2016-01-01

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 so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell ag...

Detection of Pathogenic Biofilms with Bacterial Amyloid Targeting Fluorescent Probe, CDy11

DEFF Research Database (Denmark)

Kim, Jun Young; Sahu, Srikanta; Yau, Yin Hoe

2016-01-01

Bacterial biofilms are responsible for a wide range of persistent infections. In the clinic, diagnosis of biofilm-associated infections relies heavily on culturing methods, which fail to detect nonculturable bacteria. Identification of novel fluorescent probes for biofilm imaging will greatly...... facilitate diagnosis of pathogenic bacterial infection. Herein, we report a novel fluorescent probe, CDy11 (compound of designation yellow 11), which targets amyloid in the Pseudomonas aeruginosa biofilm matrix through a diversity oriented fluorescent library approach (DOFLA). CDy11 was further demonstrated...

Assessing the utility of ultraviolet irradiation to reduce bacterial biofilms in fish hatchery well water supplies

Science.gov (United States)

The accumulation of bacterial biofilms and consequent clogging of screens, pipes, and heat exchanger equipment is problematic for water supply systems contaminated with iron bacteria and other slime forming bacteria. Despite the ubiquitous threat posed by iron bacteria contamination in groundwater s...

Monitoring structural transformation of hydroxy-sulphate green rust in the presence of sulphate reducing bacteria

International Nuclear Information System (INIS)

Abdelmoula, M.; Zegeye, A.; Jorand, F.; Carteret, C.

2006-01-01

The activities of bacterial consortia enable organisms to maximize their metabolic capabilities. This article assesses the synergetic relationship between iron reducing bacteria (IRB), Shewanella putrefaciens and sulphate reducing bacteria (SRB) Desulfovibrio alaskensis. Thus, the aim of this study was first to form a biogenic hydroxy-sulpahte green rust GR2(SO 4 -2 ) through the bioreduction of lepidocrocite by S. putrefaciens and secondly to investigate if sulfate anions intercalated in the biogenic GR2(SO 4 -2 ) could serve as final electron acceptor for a sulfate reducing bacterium, D. alaskensis. The results indicate that the IRB lead to the formation of GR2(SO 4 -2 ) and this mineral serve as an electron acceptor for SRB. GR2(SO 4 -2 ) precipitation and its transformation was demonstrated by using X-ray diffraction (DRX), Moessbauer spectroscopy (TMS) and transmission electron spectroscopy (TEM). These observations point out the possible acceleration of steel corrosion in marine environment in presence of IRB/SRB consortia.

Phage “delay” towards enhancing bacterial escape from biofilms: a more comprehensive way of viewing resistance to bacteriophages

Directory of Open Access Journals (Sweden)

Stephen T. Abedon

2017-03-01

Full Text Available In exploring bacterial resistance to bacteriophages, emphasis typically is placed on those mechanisms which completely prevent phage replication. Such resistance can be detected as extensive reductions in phage ability to form plaques, that is, reduced efficiency of plating. Mechanisms include restriction-modification systems, CRISPR/Cas systems, and abortive infection systems. Alternatively, phages may be reduced in their “vigor” when infecting certain bacterial hosts, that is, with phages displaying smaller burst sizes or extended latent periods rather than being outright inactivated. It is well known, as well, that most phages poorly infect bacteria that are less metabolically active. Extracellular polymers such as biofilm matrix material also may at least slow phage penetration to bacterial surfaces. Here I suggest that such “less-robust” mechanisms of resistance to bacteriophages could serve bacteria by slowing phage propagation within bacterial biofilms, that is, delaying phage impact on multiple bacteria rather than necessarily outright preventing such impact. Related bacteria, ones that are relatively near to infected bacteria, e.g., roughly 10+ µm away, consequently may be able to escape from biofilms with greater likelihood via standard dissemination-initiating mechanisms including erosion from biofilm surfaces or seeding dispersal/central hollowing. That is, given localized areas of phage infection, so long as phage spread can be reduced in rate from initial points of contact with susceptible bacteria, then bacterial survival may be enhanced due to bacteria metaphorically “running away” to more phage-free locations. Delay mechanisms—to the extent that they are less specific in terms of what phages are targeted—collectively could represent broader bacterial strategies of phage resistance versus outright phage killing, the latter especially as require specific, evolved molecular recognition of phage presence. The

Evaluation of modified stainless steel surfaces targeted to reduce biofilm formation by common milk sporeformers.

Science.gov (United States)

Jindal, Shivali; Anand, Sanjeev; Huang, Kang; Goddard, Julie; Metzger, Lloyd; Amamcharla, Jayendra

2016-12-01

The development of bacterial biofilms on stainless steel (SS) surfaces poses a great threat to the quality of milk and other dairy products as the biofilm-embedded bacteria can survive thermal processing. Established biofilms offer cleaning challenges because they are resistant to most of the regular cleaning protocols. Sporeforming thermoduric organisms entrapped within biofilm matrix can also form heat-resistant spores, and may result in a long-term persistent contamination. The main objective of this study was to evaluate the efficacy of different nonfouling coatings [AMC 18 (Advanced Materials Components Express, Lemont, PA), Dursan (SilcoTek Corporation, Bellefonte, PA), Ni-P-polytetrafluoroethylene (PTFE, Avtec Finishing Systems, New Hope, MN), and Lectrofluor 641 (General Magnaplate Corporation, Linden, NJ)] on SS plate heat exchanger surfaces, to resist the formation of bacterial biofilms. It was hypothesized that modified SS surfaces would promote a lesser amount of deposit buildup and bacterial adhesion as compared with the native SS surface. Vegetative cells of aerobic sporeformers, Geobacillus stearothermophilus (ATCC 15952), Bacillus licheniformis (ATCC 6634), and Bacillus sporothermodurans (DSM 10599), were used to study biofilm development on the modified and native SS surfaces. The adherence of these organisms, though influenced by surface energy and hydrophobicity, exhibited no apparent relation with surface roughness. The Ni-P-PTFE coating exhibited the least bacterial attachment and milk solid deposition, and hence, was the most resistant to biofilm formation. Scanning electron microscopy, which was used to visualize the extent of biofilm formation on modified and native SS surfaces, also revealed lower bacterial attachment on the Ni-P-PTFE as compared with the native SS surface. This study thus provides evidence of reduced biofilm formation on the modified SS surfaces. Copyright © 2016 American Dairy Science Association. Published by Elsevier

Antibiotic-Loaded Synthetic Calcium Sulfate Beads for Prevention of Bacterial Colonization and Biofilm Formation in Periprosthetic Infections

Science.gov (United States)

Howlin, R. P.; Brayford, M. J.; Webb, J. S.; Cooper, J. J.; Aiken, S. S.

2014-01-01

Periprosthetic infection (PI) causes significant morbidity and mortality after fixation and joint arthroplasty and has been extensively linked to the formation of bacterial biofilms. Poly(methyl methacrylate) (PMMA), as a cement or as beads, is commonly used for antibiotic release to the site of infection but displays variable elution kinetics and also represents a potential nidus for infection, therefore requiring surgical removal once antibiotics have eluted. Absorbable cements have shown improved elution of a wider range of antibiotics and, crucially, complete biodegradation, but limited data exist as to their antimicrobial and antibiofilm efficacy. Synthetic calcium sulfate beads loaded with tobramycin, vancomycin, or vancomycin-tobramycin dual treatment (in a 1:0.24 [wt/wt] ratio) were assessed for their abilities to eradicate planktonic methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis relative to that of PMMA beads. The ability of the calcium sulfate beads to prevent biofilm formation over multiple days and to eradicate preformed biofilms was studied using a combination of viable cell counts, confocal microscopy, and scanning electron microscopy of the bead surface. Biofilm bacteria displayed a greater tolerance to the antibiotics than their planktonic counterparts. Antibiotic-loaded beads were able to kill planktonic cultures of 106 CFU/ml, prevent bacterial colonization, and significantly reduce biofilm formation over multiple days. However, established biofilms were harder to eradicate. These data further demonstrate the difficulty in clearing established biofilms; therefore, early preventive measures are key to reducing the risk of PI. Synthetic calcium sulfate loaded with antibiotics has the potential to reduce or eliminate biofilm formation on adjacent periprosthetic tissue and prosthesis material and, thus, to reduce the rates of periprosthetic infection. PMID:25313221

The Calgary Biofilm Device: New Technology for Rapid Determination of Antibiotic Susceptibilities of Bacterial Biofilms

OpenAIRE

Ceri, H.; Olson, M. E.; Stremick, C.; Read, R. R.; Morck, D.; Buret, A.

1999-01-01

Determination of the MIC, based on the activities of antibiotics against planktonic bacteria, is the standard assay for antibiotic susceptibility testing. Adherent bacterial populations (biofilms) present with an innate lack of antibiotic susceptibility not seen in the same bacteria grown as planktonic populations. The Calgary Biofilm Device (CBD) is described as a new technology for the rapid and reproducible assay of biofilm susceptibilities to antibiotics. The CBD produces 96 equivalent bi...

Spore-forming, Desulfosporosinus-like sulphate-reducing bacteria from a shallow aquifer contaminated with gasoline.

Science.gov (United States)

Robertson, W J; Franzmann, P D; Mee, B J

2000-02-01

Previous studies on the geochemistry of a shallow unconfined aquifer contaminated with hydrocarbons suggested that the degradation of some hydrocarbons was linked to bacterial sulphate reduction. There was attenuation of naphthalene, 1,3,5-trimethylbenzene (TMB), toluene, p-xylene and ethylbenzene in the groundwater with concomitant loss of sulphate. Here, the recovery of eight strains of sulphate-reducing bacteria (SRB) from the contaminated site is reported. All were straight or curved rod-shaped cells which formed endospores. Amplification and sequencing of the 16S rDNA indicated that the strains were all sulphate reducers of the Gram-positive line of descent, and were most closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 8344 (97-98.9% sequence similarity). The strains clustered in three phylogenetic groups based on 16S rRNA sequences. Whole cell fatty acid compositions were similar to those of D. orientis DSM 8344, and were consistent with previous studies of fatty acids in soil and groundwater from the site. Microcosms containing groundwater from this aquifer indicated a role for sulphate reduction in the degradation of [ring-UL-14C]toluene, but not for the degradation of [UL-14C]benzene which could also be degraded by the microcosms. Adding one of the strains that was isolated from the groundwater (strain T2) to sulphate-enriched microcosms increased the rate of toluene degradation four- to 10-fold but had no effect on the rate of benzene degradation. The addition of molybdate, an inhibitor of sulphate reduction, to the groundwater samples decreased the rate of toluene mineralization. There was no evidence to support the mineralization of [UL-14C]benzene, [ring-UL-14C]toluene or unlabelled m-xylene, p-xylene, ethylbenzene, TMB or naphthalene by any of the strains in pure culture. Growth of all the strains was completely inhibited by 100 micromol l-1 TMB.

Bacterial sulphate reduction and the development of alkalinity. II. Laboratory experiments with soils

Energy Technology Data Exchange (ETDEWEB)

Abd-El-Malek, Y; Rizk, S G

1963-01-01

In waterlogged soils sulphate reduction was characterized by increases in counts of sulphate reducers, and increase in titratable alkalinity, insoluble carbonate, and soluble sulphides, and a decrease in soluble Ca/sup 2 +/ + Mg/sup 2 +/. Presence of organic matter greatly enhanced sulphate reduction. A linear relationship between the amount of sulphate reduced and increases in titratable alkalinity and insoluble carbonate were apparent. The potential effects of sulphate reduction on soil fertility through the development of alkalinity are discussed.

Surface modification of platelet concentrate bags to reduce biofilm formation and transfusion sepsis.

Science.gov (United States)

Wilson-Nieuwenhuis, Joels S T; Dempsey-Hibbert, Nina; Liauw, Christopher M; Whitehead, Kathryn A

2017-12-01

Bacterial contamination of blood products poses a major risk in transfusion medicine, including transfusions involving platelet products. Although testing systems are in place for routine screening of platelet units, the formation of bacterial biofilms in such units may decrease the likelihood that bacteria will be detected. This work determined the surface properties of p-PVC platelet concentrate bags and investigated how these characteristics influenced biofilm formation. Serratia marcescens and Staphylococcus epidermidis, two species commonly implicated in platelet contamination, were used to study biofilm growth. The platelet concentrate bags were physically flattened to determine if reducing the surface roughness altered biofilm formation. The results demonstrated that the flattening process of the platelet bags affected the chemistry of the surface and reduced the surface hydrophobicity. Flattening of the surfaces resulted in a reduction in biofilm formation for both species after 5 days, with S. marcescens demonstrating a greater reduction. However, there was no significant difference between the smooth and flat surfaces following 7 days' incubation for S. marcescens and no significant differences between any of the surfaces following 7 days' incubation for S. epidermidis. The results suggest that flattening the p-PVC surfaces may limit potential biofilm formation for the current duration of platelet storage time of 5 days. It is hoped that this work will enhance the understanding of how surface properties influence the development of microbial biofilms in platelet concentrate bags in order to devise a solution to discourage biofilm formation. Copyright © 2017 Elsevier B.V. All rights reserved.

Interactions between multiple filaments and bacterial biofilms on the surface of an apple

Science.gov (United States)

He, CHENG; Maoyuan, XU; Shuhui, PAN; Xinpei, LU; Dawei, LIU

2018-04-01

In this paper, the interactions between two dielectric barrier discharge (DBD) filaments and three bacterial biofilms are simulated. The modeling of a DBD streamer is studied by means of 2D finite element calculation. The model is described by the proper governing equations of air DBD at atmospheric pressure and room temperature. The electric field in the computing domain and the self-consistent transportation of reactive species between a cathode and biofilms on the surface of an apple are realized by solving a Poisson equation and continuity equations. The electron temperature is solved by the electron energy conservation equation. The conductivity and permittivity of bacterial biofilms are considered, and the shapes of the bacterial biofilms are irregular in the uncertainty and randomness of colony growth. The distribution of the electrons suggests that two plasma channels divide into three plasma channels when the streamer are 1 mm from the biofilms. The toe-shapes of the biofilms and the simultaneous effect of two streamer heads result in a high electric field around the biofilms, therefore the stronger ionization facilitates the major part of two streamers combined into one streamer and three streamers arise. The distribution of the reactive oxygen species and the reactive nitrogen species captured by time fluences are non-uniform due to the toe-shaped bacterial biofilms. However, the plasma can intrude into the cavities in the adjacent biofilms due to the μm-scale mean free path. The two streamers case has a larger treatment area and realizes the simultaneous treatment of three biofilms compared with one streamer case.

Disinfection byproduct formation from chlorination of pure bacterial cells and pipeline biofilms.

Science.gov (United States)

Wang, Jun-Jian; Liu, Xin; Ng, Tsz Wai; Xiao, Jie-Wen; Chow, Alex T; Wong, Po Keung

2013-05-15

Disinfection byproduct (DBP) formation is commonly attributed to the reaction between natural organic matters and disinfectants, yet few have considered the contribution from disinfecting bacterial materials - the essential process of water disinfection. Here, we explored the DBP formation from chlorination and chloramination of Escherichia coli and found that most selected DBPs were detectable, including trihalomethanes, haloacetonitriles, chloral hydrate, chloropicrin, and 1,1,1-trichloro-2-propanone. A positive correlation (P = 0.08-0.09) between DBP formation and the log reduction of E. coli implied that breaking down of bacterial cells released precursors for DBP formation. As Pseudomonas aeruginosa is a dominant bacterial species in pipeline biofilms, the DBP formation potentials (DBPFPs) from its planktonic cells and biofilms were characterized. Planktonic cells formed 7-11 times greater trihalomethanes per carbon of those from biofilms but significantly lower (P biofilms on polyvinyl chloride compared to that on galvanized zinc. This study revealed both the in situ disinfection of bacterial planktonic cells in source water and ex situ reaction between biofilms and residual chlorine in pipeline networks as hitherto unknown DBP sources in drinking water. Copyright © 2013 Elsevier Ltd. All rights reserved.

High prevalence of biofilm synergy among bacterial soil isolates in cocultures indicates bacterial interspecific cooperation

DEFF Research Database (Denmark)

Ren, Dawei; Madsen, Jonas Stenløkke; Sørensen, Søren Johannes

2015-01-01

of single-species biofilms, indicating that all the individual strains benefit from inclusion in the multispecies community. Our results show a high prevalence of synergy in biofilm formation in multispecies consortia isolated from a natural bacterial habitat and suggest that interspecific cooperation...

N-Acetyl-l-Cysteine Affects Growth, Extracellular Polysaccharide Production, and Bacterial Biofilm Formation on Solid Surfaces

OpenAIRE

Olofsson, Ann-Cathrin; Hermansson, Malte; Elwing, Hans

2003-01-01

N-Acetyl-l-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Usi...

The reducibility of sulphuric acid and sulphate in aqueous solution

International Nuclear Information System (INIS)

Grauer, R.

1991-07-01

In connection with the Swedish project for final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister. A simple reaction between copper and sulphate is thermodynamically impossible, but copper can react to give copper sulphide if an additional electron donor such as iron(II) is available. The problem was extended to the more general question of the reducibility of sulphur(VI) in dilute aqueous solution. Chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 o C. In experiments on the reduction of sulphates under hydrothermal conditions a reaction only takes place at temperatures above 275-300 o C. The oxidising action of sulphuric acid on metals becomes perceptible only at acid concentrations over 45-50%. In experiments on the cathodic reduction of 74% sulphuric acid the formation of hydrogen sulphide and elementary sulphur starts, depending on the current density, at 50-130 o C, and polarographic measurements suggest that the reducible species is not the hydrogen sulphate ion but molecular sulphuric acid. The resistance of copper to oxygen-free sulphuric acid up to a concentration of 60% is well-known. Numerous processes in industrial electrochemistry take place in sulphuric acid or sulphate electrolytes. The reversible metal/metal-sulphate electrodes of lead and cadmium are unstable relative to the corresponding metal sulphides. Nevertheless the reversible lead sulphate electrode does not fail from sulphide formation. All these facts confirm that sulphur(VI) in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be almost certainly be ruled out. (author) 5 figs., 85 refs

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

International Nuclear Information System (INIS)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-01-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Energy Technology Data Exchange (ETDEWEB)

Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

2016-06-15

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Science.gov (United States)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-06-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Influence of fluoride on the bacterial composition of a dual-species biofilm composed of Streptococcus mutans and Streptococcus oralis.

Science.gov (United States)

Jung, Ji-Eun; Cai, Jian-Na; Cho, Sung-Dae; Song, Kwang-Yeob; Jeon, Jae-Gyu

2016-10-01

Despite the widespread use of fluoride for the prevention of dental caries, few studies have demonstrated the effects of fluoride on the bacterial composition of dental biofilms. This study investigated whether fluoride affects the proportion of Streptococcus mutans and S. oralis in mono- and dual-species biofilm models, via microbiological, biochemical, and confocal fluorescence microscope studies. Fluoride did not affect the bacterial count and bio-volume of S. mutans and S. oralis in mono-species biofilms, except for the 24-h-old S. mutans biofilms. However, fluoride reduced the proportion and bio-volume of S. mutans but did not decrease those of S. oralis during both S. oralis and S. mutans dual-species biofilm formation, which may be related to the decrease in extracellular polysaccharide formation by fluoride. These results suggest that fluoride may prevent the shift in the microbial proportion to cariogenic bacteria in dental biofilms, subsequently inhibiting the cariogenic bacteria dominant biofilm formation.

Candidate Targets for New Anti-Virulence Drugs: Selected Cases of Bacterial Adhesion and Biofilm Formation

DEFF Research Database (Denmark)

Klemm, Per; Hancock, Viktoria; Kvist, Malin

2007-01-01

is particularly problematic in medical contexts because biofilm-associated bacteria are particularly hard to eradicate. Several promising candidate drugs that target bacterial adhesion and biofilm formation are being developed. Some of these might be valuable weapons for fighting infectious diseases in the future...... formation are highly attractive targets for new drugs. Specific adhesion provides bacteria with target selection and prevents removal by hydrodynamic flow forces. Bacterial adhesion is of paramount importance for bacterial pathogenesis. Adhesion is also the first step in biofilm formation. Biofilm formation...

Susceptibility of metallic magnesium implants to bacterial biofilm infections.

Science.gov (United States)

Rahim, Muhammad Imran; Rohde, Manfred; Rais, Bushra; Seitz, Jan-Marten; Mueller, Peter P

2016-06-01

Magnesium alloys have promising mechanical and biological properties as biodegradable medical implant materials for temporary applications during bone healing or as vascular stents. Whereas conventional implants are prone to colonization by treatment resistant microbial biofilms in which bacteria are embedded in a protective matrix, magnesium alloys have been reported to act antibacterial in vitro. To permit a basic assessment of antibacterial properties of implant materials in vivo an economic but robust animal model was established. Subcutaneous magnesium implants were inoculated with bacteria in a mouse model. Contrary to the expectations, bacterial activity was enhanced and prolonged in the presence of magnesium implants. Systemic antibiotic treatments were remarkably ineffective, which is a typical property of bacterial biofilms. Biofilm formation was further supported by electron microscopic analyses that revealed highly dense bacterial populations and evidence for the presence of extracellular matrix material. Bacterial agglomerates could be detected not only on the implant surface but also at a limited distance in the peri-implant tissue. Therefore, precautions may be necessary to minimize risks of metallic magnesium-containing implants in prospective clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1489-1499, 2016. © 2016 Wiley Periodicals, Inc.

Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms.

Science.gov (United States)

Sugano, Marika; Morisaki, Hirobumi; Negishi, Yoichi; Endo-Takahashi, Yoko; Kuwata, Hirotaka; Miyazaki, Takashi; Yamamoto, Matsuo

2016-01-01

Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail. The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms. Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy. The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms. In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.

Proteolysis produced within biofilms of bacterial isolates from raw milk tankers.

Science.gov (United States)

Teh, Koon Hoong; Flint, Steve; Palmer, Jon; Andrewes, Paul; Bremer, Phil; Lindsay, Denise

2012-06-15

In this study, six bacterial isolates that produced thermo-resistant enzymes isolated from the internal surfaces of raw milk tankers were evaluated for their ability to produce proteolysis within either single culture biofilms or co-culture biofilms. Biofilms were formed in an in vitro model system that simulated the upper internal surface of a raw milk tanker during a typical summer's day of milk collection in New Zealand. The bacterial isolates were further evaluated for their ability to form biofilms at 25, 30 and 37°C. Mutual and competitive effects were observed in some of the co-culture biofilms, with all isolates being able to form biofilms in either single culture or co-culture at the three temperatures. The proteolysis was also evaluated in both biofilms and corresponding planktonic cultures. The proteolysis per cell decreased as the temperature of incubation (20-37°C) increased. Furthermore, mutualistic interactions in terms of proteolysis were observed when cultures were grown as co-culture biofilms. This is the first study to show that proteolytic enzymes can be produced in biofilms on the internal surfaces of raw milk tankers. This has important implications for the cleaning and the temperature control of raw milk transport tankers. Copyright © 2012 Elsevier B.V. All rights reserved.

An electrochemical impedance model for integrated bacterial biofilms

International Nuclear Information System (INIS)

Ben-Yoav, Hadar; Freeman, Amihay; Sternheim, Marek; Shacham-Diamand, Yosi

2011-01-01

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.

Surface nanocrystallization of stainless steel for reduced biofilm adherence

International Nuclear Information System (INIS)

Yu Bin; Li, D Y; Davis, Elisabeth M; Irvin, Randall T; Hodges, Robert S

2008-01-01

Stainless steel is one of the most common metallic biomedical materials. For medical applications, its resistance to the adherence of biofilms is of importance to the elimination or minimization of bacterial infections. In this study, we demonstrate the effectiveness of a process combining surface nanocrystallization and thermal oxidation (or a recovery heat treatment in air) for reducing the biofilm's adherence to stainless steel. During this treatment, a target surface was sandblasted and the resultant dislocation cells in the surface layer were turned into nanosized grains by a subsequent recovery treatment in air. This process generated a more protective oxide film that blocked the electron exchange or reduced the surface activity more effectively. As a result, the biofilm's adherence to the treated surface was markedly minimized. A synthetic peptide was utilized as a substitute of biofilms to evaluate the adhesion between a treated steel surface and biofilms using an atomic force microscope (AFM) through measuring the adhesive force between the target surface and a peptide-coated AFM tip. It was shown that the adhesive force decreased with a decrease in the grain size of the steel. The corresponding surface electron work function (EWF) of the steel was also measured, which showed a trend of variation in EWF with the grain size, consistent with corresponding changes in the adhesive force

Fate of deposited cells in an aerobic binary bacterial biofilm

International Nuclear Information System (INIS)

Banks, M.K.

1989-01-01

A biofilm is a matrix of microbial cells and their extracellular products that is associated with a solid surface. Previous studies on biofilm development have employed only dissolved compounds as growth limiting substrates, without the influence of microbial species invading from the bulk liquid. The goal of this research project was to quantify the kinetics of processes governing suspended biomass turnover in biofilm systems, and the accompanying effects of suspended cell deposition on biofilm population dynamics. Experiments were conducted with two species of bacteria, Pseudomonas putida ATCC 11172 grown on glucose, and Hyphomicrobium ZV620 grown on methanol. Cryptic growth and particulate hydrolysis studies were evaluated, using combinations of these two bacteria, by measuring the uptake of radiolabelled cell lysis products, under batch conditions. Biofilms studies were performed to investigate bacterial deposition, continual biofilm removal by shear induced erosion, and biofilm ecology. Biofilms were developed in a flow cell reactor, under laminar flow conditions. Bacterial species were differentiated by radioactively labelling each species with their carbon substrate. A mathematical model was developed to predict the biofilm ecology of mixed cultures. The equations developed predict biofilm accumulation, as well as substrate and oxygen consumption. Results indicate that cryptic growth will occur for bacteria growing on their own species soluble lysis products and in some cases, bacteria growing on the soluble lysis products of other species. Particulate hydrolysis only occurred for Pseudomonas putida growing on Pseudomonas putida lysis products, but the lack of particulate hydrolysis occurring in the other studies may have been due to the short experimental period

Inactivation of bacterial biofilms using visible-light-activated unmodified ZnO nanorods

Science.gov (United States)

Aponiene, Kristina; Serevičius, Tomas; Luksiene, Zivile; Juršėnas, Saulius

2017-09-01

Various zinc oxide (ZnO) nanostructures are widely used for photocatalytic antibacterial applications. Since ZnO possesses a wide bandgap, it is believed that only UV light may efficiently assist bacterial inactivation, and diverse crystal lattice modifications should be applied in order to narrow the bandgap for efficient visible-light absorption. In this work we show that even unmodified ZnO nanorods grown by an aqueous chemical growth technique are found to possess intrinsic defects that can be activated by visible light (λ = 405 nm) and successfully applied for total inactivation of various highly resistant bacterial biofilms rather than more sensitive planktonic bacteria. Time-resolved fluorescence analysis has revealed that visible-light excitation creates long-lived charge carriers (τ > 1 μs), which might be crucial for destructive biochemical reactions achieving significant bacterial biofilm inactivation. ZnO nanorods covered with bacterial biofilms of Enterococcus faecalis MSCL 302 after illumination by visible light (λ = 405 nm) were inactivated by 2 log, and Listeria monocytogenes ATCL3C 7644 and Escherichia coli O157:H7 biofilms by 4 log. Heterogenic waste-water microbial biofilms, consisting of a mixed population of mesophilic bacteria after illumination with visible light were also completely destroyed.

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

Science.gov (United States)

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

Bacterial biofilm formation in different surfaces of food industries

Directory of Open Access Journals (Sweden)

Karine Angélica Dalla Costa

2017-06-01

Full Text Available The term biofilm describes the sessile microbial life form, characterized by microorganism adhesion to any surface and with the production of extracellular polymeric substances. In food industries, the formation of biofilms results in serious problems, since it can be a contamination source of the food product, compromising the final product quality and consumer health. The aim of this study was to verify the adhesion of biofilms (sessile cells of pathogenic and/or deteriorating bacteria against surfaces of the food industry. The bacterial species tested were Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 19117 and Salmonella Typhimurium ATCC 14028. It was used stainless steel and polypropylene coupons as contact surfaces. The results demonstrated that P. aeruginosa and S. Typhimurium showed higher biofilm formation capacity. Statistically, there was no difference in count of P. aeruginosa and S. Typhimurium (p > 0.05 cells. The same occurred between L. monocytogenes and S. aureus. However, the counts of P. aeruginosa and S. Typhimurium cells were statistically higher than S. aureus and L. monocytogenes (p < 0.05. By means of scanning electron microscopy it was also found increased adhesion of P. aeruginosa. The results revealed that P. aeruginosa was the bacterial species with higher biofilm formation capacity among the others.

Bacterial signaling ecology and potential applications during aquatic biofilm construction.

Science.gov (United States)

Vega, Leticia M; Alvarez, Pedro J; McLean, Robert J C

2014-07-01

In their natural environment, bacteria and other microorganisms typically grow as surface-adherent biofilm communities. Cell signal processes, including quorum signaling, are now recognized as being intimately involved in the development and function of biofilms. In contrast to their planktonic (unattached) counterparts, bacteria within biofilms are notoriously resistant to many traditional antimicrobial agents and so represent a major challenge in industry and medicine. Although biofilms impact many human activities, they actually represent an ancient mode of bacterial growth as shown in the fossil record. Consequently, many aquatic organisms have evolved strategies involving signal manipulation to control or co-exist with biofilms. Here, we review the chemical ecology of biofilms and propose mechanisms whereby signal manipulation can be used to promote or control biofilms.

New weapons to fight old enemies: novel strategies for the (biocontrol of bacterial biofilms in the food industry

Directory of Open Access Journals (Sweden)

Laura Maria Coughlan

2016-10-01

Full Text Available Biofilms are microbial communities characterized by their adhesion to solid surfaces and the production of a matrix of exopolymeric substances (EPS, consisting of polysaccharides, proteins, DNA and lipids, which surround the microorganisms lending structural integrity and a unique biochemical profile to the biofilm. Biofilm formation enhances the ability of the producer/s to persist in a given environment. Pathogenic and spoilage bacterial species capable of forming biofilms are a significant problem for the healthcare and food industries, as their biofilm-forming ability protects them from common cleaning processes and allows them to remain in the environment post-sanitation. In the food industry, persistent bacteria colonize the inside of mixing tanks, vats and tubing, compromising food safety and quality. Strategies to overcome bacterial persistence through inhibition of biofilm formation or removal of mature biofilms are therefore necessary. Current biofilm control strategies employed in the food industry (cleaning and disinfection, material selection and surface preconditioning, plasma treatment, ultrasonication, etc., although effective to a certain point, fall short of biofilm control. Efforts have been explored, mainly with a view to their application in pharmaceutical and healthcare settings, which focus on targeting molecular determinants regulating biofilm formation. Their application to the food industry would greatly aid efforts to eradicate undesirable bacteria from food processing environments and, ultimately, from food products. These approaches, in contrast to bactericidal approaches, exert less selective pressure which in turn would reduce the likelihood of resistance development. A particularly interesting strategy targets quorum sensing systems, which regulate gene expression in response to fluctuations in cell-population density governing essential cellular processes including biofilm formation. This review article discusses

Changes in bacterial composition of biofilm in a metropolitan drinking water distribution system.

Science.gov (United States)

Revetta, R P; Gomez-Alvarez, V; Gerke, T L; Santo Domingo, J W; Ashbolt, N J

2016-07-01

This study examined the development of bacterial biofilms within a metropolitan distribution system. The distribution system is fed with different source water (i.e. groundwater, GW and surface water, SW) and undergoes different treatment processes in separate facilities. The biofilm community was characterized using 16S rRNA gene clone libraries and functional potential analysis, generated from total DNA extracted from coupons in biofilm annular reactors fed with onsite drinking water for up to 18 months. Differences in the bacterial community structure were observed between GW and SW. Representatives that explained the dissimilarity were associated with the classes Betaproteobacteria, Alphaproteobacteria, Actinobacteria, Gammaproteobacteria and Firmicutes. After 9 months the biofilm bacterial community from both GW and SW were dominated by Mycobacterium species. The distribution of the dominant operational taxonomic unit (OTU) (Mycobacterium) positively correlated with the drinking water distribution system (DWDS) temperature. In this study, the biofilm community structure observed between GW and SW were dissimilar, while communities from different locations receiving SW did not show significant differences. The results suggest that source water and/or the water quality shaped by their respective treatment processes may play an important role in shaping the bacterial communities in the distribution system. In addition, several bacterial groups were present in all samples, suggesting that they are an integral part of the core microbiota of this DWDS. These results provide an ecological insight into biofilm bacterial structure in chlorine-treated drinking water influenced by different water sources and their respective treatment processes. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Functional recovery of biofilm bacterial communities after copper exposure

International Nuclear Information System (INIS)

Boivin, Marie-Elene Y.; Massieux, Boris; Breure, Anton M.; Greve, Gerdit D.; Rutgers, Michiel; Admiraal, Wim

2006-01-01

Potential of bacterial communities in biofilms to recover after copper exposure was investigated. Biofilms grown outdoor in shallow water on glass dishes were exposed in the laboratory to 0.6, 2.1, 6.8 μmol/l copper amended surface water and a reference and subsequently to un-amended surface water. Transitions of bacterial communities were characterised with denaturing gradient gel electrophoresis (DGGE) and community-level physiological profiles (CLPP). Exposure to 6.8 μmol/l copper provoked distinct changes in DGGE profiles of bacterial consortia, which did not reverse upon copper depuration. Exposure to 2.1 and 6.8 μmol/l copper was found to induce marked changes in CLPP of bacterial communities that proved to be reversible during copper depuration. Furthermore, copper exposure induced the development of copper-tolerance, which was partially lost during depuration. It is concluded that bacterial communities exposed to copper contaminated water for a period of 26 days are capable to restore their metabolic attributes after introduction of unpolluted water in aquaria for 28 days. - Genetically different bacterial communities can have similar functions and tolerance to copper

Histo-FISH protocol to detect bacterial compositions and biofilms formation in vivo.

Science.gov (United States)

Madar, M; Slizova, M; Czerwinski, J; Hrckova, G; Mudronova, D; Gancarcikova, S; Popper, M; Pistl, J; Soltys, J; Nemcova, R

2015-01-01

The study of biofilm function in vivo in various niches of the gastrointestinal tract (GIT) is rather limited. It is more frequently used in in vitro approaches, as an alternative to the studies focused on formation mechanisms and function of biofilms, which do not represent the actual in vivo complexity of microbial structures. Additionally, in vitro tests can sometimes lead to unreliable results. The goal of this study was to develop a simple approach to detect bacterial populations, particularly Lactobacillus and Bifidobacterium in biofilms, in vivo by the fluorescent in situ hybridisation (FISH) method. We standardised a new Histo-FISH method based on specific fluorochrome labelling probes which are able to detect Lactobacillus spp. and Bifidobacterium spp. within biofilms on the mucosal surface of the GIT embedded in paraffin in histological slices. This method is also suitable for visualisation of bacterial populations in the GIT internal content. Depending on the labelling probes, the Histo-FISH method has the potential to detect other probiotic strains or pathogenic bacteria. This original approach permits us to analyse bacterial colonisation processes as well as biofilm formation in stomach and caecum of BALB/c and germ-free mice.

Bisphosphonates enhance bacterial adhesion and biofilm formation on bone hydroxyapatite.

Science.gov (United States)

Kos, Marcin; Junka, Adam; Smutnicka, Danuta; Szymczyk, Patrycja; Gluza, Karolina; Bartoszewicz, Marzenna

2015-07-01

Because of the suspicion that bisphosphonates enhance bacterial colonization, this study evaluated adhesion and biofilm formation by Streptococcus mutans 25175, Staphylococcus aureus 6538, and Pseudomonas aeruginosa 14454 reference strains on hydroxyapatite coated with clodronate, pamidronate, or zoledronate. Bacterial strains were cultured on bisphosphonate-coated and noncoated hydroxyapatite discs. After incubation, nonadhered bacteria were removed by centrifugation. Biofilm formation was confirmed by scanning electron microscopy. Bacterial colonization was estimated using quantitative cultures compared by means with Kruskal-Wallis and post-hoc Student-Newman-Keuls tests. Modeling of the interactions between bisphosphonates and hydroxyapatite was performed using the Density Functional Theory method. Bacterial colonization of the hydroxyapatite discs was significantly higher for all tested strains in the presence of bisphosphonates vs. Adherence in the presence of pamidronate was higher than with other bisphosphonates. Density Functional Theory analysis showed that the protonated amine group of pamidronate, which are not present in clodronate or zoledronate, forms two additional hydrogen bonds with hydroxyapatite. Moreover, the reactive cationic amino group of pamidronate may attract bacteria by direct electrostatic interaction. Increased bacterial adhesion and biofilm formation can promote osteomyelitis, cause failure of dental implants or bisphosphonate-coated joint prostheses, and complicate bone surgery in patients on bisphosphonates. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Quantitation and identification of methanogens and sulphate reducers in Olkiluoto groundwater

International Nuclear Information System (INIS)

Bomberg, M.; Nyyssoenen, M.; Itaevaara, M.

2010-08-01

The GEOFUNC Project focuses on the microbiology connected to safety and risk assessment of the final disposal of high radioactive nuclear waste. Methanogenic archaea and sulphate reducing bacteria are significant groups of microorganisms in anaerobic environments, and are of crucial concern for the safe long term storage of nuclear waste in deep bedrock. The sulphate reducing bacteria are able to produce sulphide which may cause corrosion of the copper in the radioactive waste storage capsules. Methanogens, on the other hand, may produce quantities of methane from various organic carbon compounds, CO 2 and H 2 . Methane may both serve as carbon source for methanotrophic microbial groups, and may also cause mobilization of radionuclides, as a result of gas discharge through fractures in the bedrock. The transition zones between the sulphate rich and methane rich waters are locations for microbial processes where the methane may serve as carbon source for sulphate reducing bacteria, which in turn would produce corrosive sulphides. It has been estimated that only 1-10 % of all the microorganisms present in the environment can be isolated and cultivated. Uncultured microorganisms can be identified and their numbers in the environment quantified by identification of specific marker genes that are essential for their functions by use of molecular methods. Methanogens, for example, can be identified by their genes for methyl coenzyme M reductase (mcrA), which is an essential enzyme involved in the production of methane. The mcrA is specifically present only in methanogenic archaea. Sulphate reducers are identified by their dissimilatory sulphite reductase genes (dsrB), which are present in and essential for all microorganisms performing dissimilatory sulphate reducing. In the GEOFUNC project, a quantitative PCR method (qPCR) was developed for the detection of methanogens and sulphate reducers. This method is based on specific quantitative detection of marker genes

Curcumin Quantum Dots Mediated Degradation of Bacterial Biofilms

Directory of Open Access Journals (Sweden)

Ashish K. Singh

2017-08-01

Full Text Available Bacterial biofilm has been reported to be associated with more than 80% of bacterial infections. Curcumin, a hydrophobic polyphenol compound, has anti-quorum sensing activity apart from having antimicrobial action. However, its use is limited by its poor aqueous solubility and rapid degradation. In this study, we attempted to prepare quantum dots of the drug curcumin in order to achieve enhanced solubility and stability and investigated for its antimicrobial and antibiofilm activity. We utilized a newer two-step bottom up wet milling approach to prepare Curcumin Quantum Dots (CurQDs using acetone as a primary solvent. Minimum inhibitory concentration against select Gram-positive and Gram-negative bacteria was performed. The antibiofilm assay was performed at first using 96-well tissue culture plate and subsequently validated by Confocal Laser Scanning Microscopy. Further, biofilm matrix protein was isolated using formaldehyde sludge and TCA/Acetone precipitation method. Protein extracted was incubated with varying concentration of CurQDs for 4 h and was subjected to SDS–PAGE. Molecular docking study was performed to observe interaction between curcumin and phenol soluble modulins as well as curli proteins. The biophysical evidences obtained from TEM, SEM, UV-VIS, fluorescence, Raman spectroscopy, and zeta potential analysis confirmed the formation of curcumin quantum dots with increased stability and solubility. The MICs of curcumin quantum dots, as observed against both select gram positive and negative bacterial isolates, was observed to be significantly lower than native curcumin particles. On TCP assay, Curcumin observed to be having antibiofilm as well as biofilm degrading activity. Results of SDS–PAGE and molecular docking have shown interaction between biofilm matrix proteins and curcumin. The results indicate that aqueous solubility and stability of Curcumin can be achieved by preparing its quantum dots. The study also demonstrates

Toxicity and transformation of graphene oxide and reduced graphene oxide in bacteria biofilm.

Science.gov (United States)

Guo, Zhiling; Xie, Changjian; Zhang, Peng; Zhang, Junzhe; Wang, Guohua; He, Xiao; Ma, Yuhui; Zhao, Bin; Zhang, Zhiyong

2017-02-15

Impact of graphene based material (GNMs) on bacteria biofilm has not been well understood yet. In this study, we compared the impact of graphene oxide (GO) and reduced graphene oxide (rGO) on biofilm formation and development in Luria-Bertani (LB) medium using Escherichia coli and Staphylococcus aureus as models. GO significantly enhanced the cell growth, biofilm formation, and biofilm development even up to a concentration of 500mg/L. In contrast, rGO (≥50mg/L) strongly inhibited cell growth and biofilm formation. However, the inhibitory effects of rGO (50mg/L and 100mg/L) were attenuated in the mature phase (>24h) and eliminated at 48h. GO at 250mg/L decreased the reactive oxygen species (ROS) levels in biofilm and extracellular region at mature phase. ROS levels were significantly increased by rGO at early phase, while they returned to the same levels as control at mature phase. These results suggest that oxidative stress contributed to the inhibitory effect of rGO on bacterial biofilm. We further found that supplement of extracellular polymeric substances (EPS) in the growth medium attenuated the inhibitory effect of rGO on the growth of developed biofilm. XPS results showed that rGO were oxidized to GO which can enhance the bacterial growth. We deduced that the elimination of the toxicity of rGO at mature phase was contributed by EPS protection and the oxidation of rGO. This study provides new insights into the interaction of GNMs with bacteria biofilm. Copyright © 2016 Elsevier B.V. All rights reserved.

Divergent composition of algal-bacterial biofilms developing under various external factors

NARCIS (Netherlands)

Barranguet, C.; Veuger, B.; van Beusekom, S.A.M.; Marvan, P.; Sinke, J.J.; Admiraal, W.

2005-01-01

The influence of external factors other than nutrients on biofilm development and composition was studied with a combination of optical (Confocal Laser Scanning Microscopy, PAM fluorometry) and chemical methods (EPS extraction, HPLC, TOC determination). The development of algal-bacterial biofilms

Bovine milk osteopontin - Targeting bacterial adhesion for biofilm control

DEFF Research Database (Denmark)

Kristensen, Mathilde Frost; Meyer, Rikke Louise; Schlafer, Sebastian

2016-01-01

Self-performed mechanical tooth cleaning does usually not result in complete biofilm removal, due to the complex oral anatomy and the strong adhesion of the biofilm to the tooth. Therefore, different supportive measures are employed, most of which aim at the chemical eradication of bacteria...... in dental biofilms. As their bactericidal action impacts the entire oral microflora, agents that inhibit biofilm formation without killing bacteria, such as the bovine milk protein osteopontin, have gained increasing attention. Here, we investigate the adhesion of 8 bacterial species associated with dental...... subsp. paracasei, Streptococcus mitis and Streptococcus oralis with 74.0%, 62.4%, 90.0%, 89.6% and 81.5%, respectively, compared to protein-free saliva. All reductions were statistically significant (p

Resistance of bacterial biofilms formed on stainless steel surface to disinfecting agent.

Science.gov (United States)

Królasik, Joanna; Zakowska, Zofia; Krepska, Milena; Klimek, Leszek

2010-01-01

The natural ability of microorganisms for adhesion and biofilm formation on various surfaces is one of the factors causing the inefficiency of a disinfection agent, despite its proven activity in vitro. The aim of the study was to determine the effectiveness of disinfecting substances on bacterial biofilms formed on stainless steel surface. A universally applied disinfecting agent was used in the tests. Bacterial strains: Listeria innocua, Pseudomonas putida, Micrococcus luteus, Staphylococcus hominis strains, were isolated from food contact surfaces, after a cleaning and disinfection process. The disinfecting agent was a commercially available acid specimen based on hydrogen peroxide and peroxyacetic acid, the substance that was designed for food industry usage. Model tests were carried out on biofilm formed on stainless steel (type 304, no 4 finish). Biofilms were recorded by electron scanning microscope. The disinfecting agent in usable concentration, 0.5% and during 10 minutes was ineffective for biofilms. The reduction of cells in biofilms was only 1-2 logarithmic cycles. The use of the agent in higher concentration--1% for 30 minutes caused reduction of cell number by around 5 logarithmic cycles only in the case of one microorganism, M. luteus. For other types: L. innocua, P. putida, S. hominis, the requirements placed on disinfecting agents were not fulfilled. The results of experiments proved that bacterial biofilms are resistant to the disinfectant applied in its operational parameters. Disinfecting effectiveness was achieved after twofold increase of the agent's concentration.

The Application of Sulphate-Reducing Bacteria for the Heavy Metals Elimination from Acid Mine Drainage

Directory of Open Access Journals (Sweden)

Alena Luptáková

2004-12-01

Full Text Available One of the most important problems affecting mining companies around the world is the treatment of acid mine drainage (AMD. AMD is characterised by its high acidity, high concentration of metals (Cu, Zn, Cd,… and high concentration of dissolved sulphates. The techniques traditionally used for the treatment of AMD have been based on chemical methods of neutralization and precipitation. A possible alternative to the chemical treatment of AMD is bioremediation using anaerobic sulphate-reducing bacteria (SRB. The treatment of AMD by SRB is based on the ability of SRB to reduce sulphates to hydrogen sulphide, which binds readily with metals to form sparingly soluble precipitates. In this study we have attempted to investigate the feasibility of anaerobic biotreatment of the copper contaminated model solution and a real effluent AMD from the shaft Pech (the locality Smolnik using SRB. This method involves three stages: The H2S production by sulphate-reducing bacteria, the metals precipitation by the biologically produced H2S and the metal sulphides filtration. The studies confirm that copper was effectively recovered from the solution using bacterial produced H2S. An initial copper concentration 10 mg.l-1 was decreased to less than 0.05 mg.l-1 after 3 hours. The most adequate pH value for cooper precipitation was 2.5. Results of the copper precipitation from the areal effluent indicates that the optimal pH value for the copper precipitation is 3.5, but the created precipitates contain a mixture of copper and iron sulphides.

Spatially resolved characterization of biogenic manganese oxideproduction within a bacterial biofilm

Energy Technology Data Exchange (ETDEWEB)

Toner, Brandy; Fakra, Sirine; Villalobos, Mario; Warwick, Tony; Sposito, Garrison

2004-10-01

Pseudomonas putida strain MnB1, a biofilm forming bacteria, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of Mn{sub (aq)}{sup +2} by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm using scanning transmission x-ray microscopy (STXM) combined with near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the Mn-L{sub 2,3} absorption edges. Subsamples were collected from growth flasks containing 0.1 mM and 1 mM total Mn at 16, 24, 36 and 48 hours after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at 40 nm resolution. Manganese NEXAFS spectra were extracted from x-ray energy sequences of STXM images (stacks) and fit with linear combinations of well characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III) and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn{sub (aq)}{sup +2} was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission x-ray microscopy is a promising tool to advance the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

New Weapons to Fight Old Enemies: Novel Strategies for the (Bio)control of Bacterial Biofilms in the Food Industry.

Science.gov (United States)

Coughlan, Laura M; Cotter, Paul D; Hill, Colin; Alvarez-Ordóñez, Avelino

2016-01-01

Biofilms are microbial communities characterized by their adhesion to solid surfaces and the production of a matrix of exopolymeric substances, consisting of polysaccharides, proteins, DNA and lipids, which surround the microorganisms lending structural integrity and a unique biochemical profile to the biofilm. Biofilm formation enhances the ability of the producer/s to persist in a given environment. Pathogenic and spoilage bacterial species capable of forming biofilms are a significant problem for the healthcare and food industries, as their biofilm-forming ability protects them from common cleaning processes and allows them to remain in the environment post-sanitation. In the food industry, persistent bacteria colonize the inside of mixing tanks, vats and tubing, compromising food safety and quality. Strategies to overcome bacterial persistence through inhibition of biofilm formation or removal of mature biofilms are therefore necessary. Current biofilm control strategies employed in the food industry (cleaning and disinfection, material selection and surface preconditioning, plasma treatment, ultrasonication, etc.), although effective to a certain point, fall short of biofilm control. Efforts have been explored, mainly with a view to their application in pharmaceutical and healthcare settings, which focus on targeting molecular determinants regulating biofilm formation. Their application to the food industry would greatly aid efforts to eradicate undesirable bacteria from food processing environments and, ultimately, from food products. These approaches, in contrast to bactericidal approaches, exert less selective pressure which in turn would reduce the likelihood of resistance development. A particularly interesting strategy targets quorum sensing systems, which regulate gene expression in response to fluctuations in cell-population density governing essential cellular processes including biofilm formation. This review article discusses the problems associated

Surface conditioning with Escherichia coli cell wall components can reduce biofilm formation by decreasing initial adhesion

Directory of Open Access Journals (Sweden)

Luciana C. Gomes

2017-07-01

Full Text Available Bacterial adhesion and biofilm formation on food processing surfaces pose major risks to human health. Non-efficient cleaning of equipment surfaces and piping can act as a conditioning layer that affects the development of a new biofilm post-disinfection. We have previously shown that surface conditioning with cell extracts could reduce biofilm formation. In the present work, we hypothesized that E. coli cell wall components could be implicated in this phenomena and therefore mannose, myristic acid and palmitic acid were tested as conditioning agents. To evaluate the effect of surface conditioning and flow topology on biofilm formation, assays were performed in agitated 96-well microtiter plates and in a parallel plate flow chamber (PPFC, both operated at the same average wall shear stress (0.07 Pa as determined by computational fluid dynamics (CFD. It was observed that when the 96-well microtiter plate and the PPFC were used to form biofilms at the same shear stress, similar results were obtained. This shows that the referred hydrodynamic feature may be a good scale-up parameter from high-throughput platforms to larger scale flow cell systems as the PPFC used in this study. Mannose did not have any effect on E. coli biofilm formation, but myristic and palmitic acid inhibited biofilm development by decreasing cell adhesion (in about 50%. These results support the idea that in food processing equipment where biofilm formation is not critical below a certain threshold, bacterial lysis and adsorption of cell components to the surface may reduce biofilm buildup and extend the operational time.

High bacterial diversity in epilithic biofilms of oligotrophic mountain lakes.

Science.gov (United States)

Bartrons, Mireia; Catalan, Jordi; Casamayor, Emilio O

2012-11-01

Benthic microbial biofilms attached to rocks (epilithic) are major sites of carbon cycling and can dominate ecosystem primary production in oligotrophic lakes. We studied the bacterial community composition of littoral epilithic biofilms in five connected oligotrophic high mountain lakes located at different altitudes by genetic fingerprinting and clone libraries of the 16S rRNA gene. Different intra-lake samples were analyzed, and consistent changes in community structure (chlorophyll a and organic matter contents, and bacterial community composition) were observed along the altitudinal gradient, particularly related with the location of the lake above or below the treeline. Epilithic biofilm genetic fingerprints were both more diverse among lakes than within lakes and significantly different between montane (below the tree line) and alpine lakes (above the tree line). The genetic richness in the epilithic biofilm was much higher than in the plankton of the same lacustrine area studied in previous works, with significantly idiosyncratic phylogenetic composition (specifically distinct from lake plankton or mountain soils). Data suggest the coexistence of aerobic, anaerobic, phototrophic, and chemotrophic microorganisms in the biofilm, Bacteroidetes and Cyanobacteria being the most important bacterial taxa, followed by Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Chlorobi, Planctomycetes, and Verrucomicrobia. The degree of novelty was especially high for epilithic Bacteroidetes, and up to 50 % of the sequences formed monophyletic clusters distantly related to any previously reported sequence. More than 35 % of the total sequences matched at <95 % identity to any previously reported 16S rRNA gene, indicating that alpine epilithic biofilms are unexplored habitats that contain a substantial degree of novelty within a short geographical distance. Further research is needed to determine whether these communities are involved in more biogeochemical pathways than

MULTIPLE IMAGING TECHNIQUES DEMONSTRATE THE MANIPULATION OF SURFACES TO REDUCE BACTERIAL CONTAMINATION

Science.gov (United States)

Surface imaging techniques were combined to determine appropriate manipulation of technologically important surfaces for commercial applications. Stainless steel surfaces were engineered to reduce bacterial contamination, biofilm formation, and corrosion during product processing...

Bacterial sulphate reduction and the development of alkalinity. I. Experiments with synthetic media

Energy Technology Data Exchange (ETDEWEB)

Abd-El-Malek, Y; Rizk, S G

1963-01-01

In liquid cultures of desulphovibrio desulphuricans the effects of the following on sulphate reduction were determined: The type of cation (ca++ or na+) attached to the sulphate ion; the presence of calcium carbonate alone and with sodium chloride; the concentration of sodium sulphate, sodium lactate and sodium chloride; and the initial pH. The titratable alkalinity formed as a result of sulphate reduction was found to be quantitatively related to the sulphate reduced, and apparently unaffected by strain variation or energy source.

Assessment of biofilm formation in device-associated clinical bacterial isolates in a tertiary level hospital

Directory of Open Access Journals (Sweden)

Summaiya A Mulla

2011-01-01

Full Text Available Background: Biofilm formation is a developmental process with intercellular signals that regulate growth. Biofilms contaminate catheters, ventilators, and medical implants; they act as a source of disease for humans, animals, and plants. Aim: In this study we have done quantitative assessment of biofilm formation in device-associated clinical bacterial isolates in response to various concentrations of glucose in tryptic soya broth and with different incubation time. Materials and Methods: The study was carried out on 100 positive bacteriological cultures of medical devices, which were inserted in hospitalized patients. The bacterial isolates were processed as per microtitre plate method with tryptic soya broth alone and with varying concentrations of glucose and were observed in response to time. Results: Majority of catheter cultures were positive. Out of the total 100 bacterial isolates tested, 88 of them were biofilm formers. Incubation period of 16-20 h was found to be optimum for biofilm development. Conclusions: Availability of nutrition in the form of glucose enhances the biofilm formation by bacteria. Biofilm formation depends on adherence of bacteria to various surfaces. Time and availability of glucose are important factors for assessment of biofilm progress.

Bacterial biofilm in chronic lesions of Hidradenitis Suppurativa

DEFF Research Database (Denmark)

Ring, H C; Bay, L; Nilsson, M

2017-01-01

BACKGROUND: Chronic non-healing or recurrent inflammatory lesions, reminiscent of infection but recalcitrant to antibiotic therapy generally characterize biofilm driven-diseases. Chronic lesions of Hidradenitis Suppurativa (HS) exhibit several aspects, which are compatible with well-known biofilm...... infections. OBJECTIVE: To determine and quantify the potential presence of bacterial aggregates in chronic HS lesions. METHODS: In 42 consecutive HS patients suffering from chronic lesions, biopsies were obtained from lesional as well as from perilesional skin. Samples were investigated using Peptide Nucleic...... Acid (PNA) - Fluorescence in situ Hybridization (FISH) in combination with Confocal Laser Scanning Microscopy (CLSM). In addition, corresponding histopathological analysis in hematoxylin and eosin slides were performed. RESULTS: Biofilms were seen in 67% of the samples of chronic lesions and in 75...

Nanostructured coatings for controlling bacterial biofilms and antibiotic resistance

OpenAIRE

Ivanova, Kristina Dimitrova

2017-01-01

The accelerated emergence of drug resistant bacteria is one of the most serious problems in healthcare and the difficulties in finding new antibiotics make it even more challenging. To overcome the action of antibiotics bacteria develop effective resistance mechanisms including the formation of biofilms. Biofilms are bacterial communities of cells embedded in a self-produced polymeric matrix commonly found on medical devices such as indwelling catheters. When pathogens adopt this mode of grow...

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms

Science.gov (United States)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S.; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-01-01

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a ‘last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections. PMID:26892159

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms.

Science.gov (United States)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang; Adav, Sunil S; Salido, May Margarette; Liu, Yang; Givskov, Michael; Sze, Siu Kwan; Tolker-Nielsen, Tim; Yang, Liang

2016-02-19

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm subpopulations, with colistin-tolerant cells using type IV pili to migrate onto the top of the colistin-killed biofilm. The colistin-tolerant cells employ quorum sensing (QS) to initiate the formation of new colistin-tolerant subpopulations, highlighting multicellular behaviour in antibiotic tolerance development. The macrolide erythromycin, which has been previously shown to inhibit the motility and QS of P. aeruginosa, boosts biofilm eradication by colistin. Our work provides insights on the mechanisms underlying the formation of antibiotic-tolerant populations in bacterial biofilms and indicates research avenues for designing more efficient treatments against biofilm-associated infections.

Microbiologically influenced corrosion of carbon steel in the presence of sulphate reducing bacteria

International Nuclear Information System (INIS)

Tunaru, M.; Velciu, L.; Mihalache, M.; Laurentiu, P.

2016-01-01

Sulphate-reducing bacteria (SRB) are the most important organisms in microbiologically induced corrosion. In this context, the paper presents an assessment (by experimental tests) of the behaviour of carbon steel samples (SA106gr.B) in SRB media. Some of samples were immersed in microbial environment in order microbiological analysis of their surface and another part was used to perform accelerated electrochemical tests to determine electrochemical parameters for the system carbon steel / microbial medium (corrosion rate, the polarization resistance of the surface, susceptibility to pitting corrosion). The surfaces of the tested samples were analyzed using the optical and electronic microscope, and emphasized the role of bacteria in the development of biofilms under which appeared characteristics of corrosion attack. The correlation of all results confirmed that SRB accelerated the localized corrosion of the surfaces of SA 106gr.B carbon steel. (authors)

Interspecific bacterial interactions are reflected in multispecies biofilm spatial organization

Directory of Open Access Journals (Sweden)

Wenzheng Liu

2016-08-01

Full Text Available Interspecies interactions are essential for the persistence and development of any kind of complex community, and microbial biofilms are no exception. Multispecies biofilms are structured and spatially defined communities that have received much attention due to their omnipresence in natural environments. Species residing in these complex bacterial communities usually interact both intra- and interspecifically. Such interactions are considered to not only be fundamental in shaping overall biomass and the spatial distribution of cells residing in multispecies biofilms, but also to result in coordinated regulation of gene expression in the different species present. These communal interactions often lead to emergent properties in biofilms, such as enhanced tolerance against antibiotics, host immune responses and other stresses, which have been shown to provide benefits to all biofilm members not only the enabling sub-populations. However, the specific molecular mechanisms of cellular processes affecting spatial organization, and vice versa, are poorly understood and very complex to unravel. Therefore, detailed description of the spatial organization of individual bacterial cells in multispecies communities can be an alternative strategy to reveal the nature of interspecies interactions of constituent species. Closing the gap between visual observation and biological processes may become crucial for resolving biofilm related problems, which is of utmost importance to environmental, industrial, and clinical implications. This review briefly presents the state of the art of studying interspecies interactions and spatial organization of multispecies communities, aiming to support theoretical and practical arguments for further advancement of this field.

Mass transfer of therapeutics through natural human plaque biofilms: a model for therapeutic delivery to pathological bacterial biofilms.

Science.gov (United States)

Robinson, Colin

2011-09-01

Bacterial biofilms in the mouth are prime mediators of the destruction of the dental and oral tissues. This brief review summarises recent work using a device for generating intact plaque in the mouth on natural enamel surfaces such that quantitative studies of mass transfer through natural plaque biofilms could be carried out in relation to plaque architecture. This data is discussed against the background of existing information. The device revealed complex plaque architecture with high a surface area to mass ratio decreasing from the exterior of the biofilm towards the tissue surface. Fluoride, a potent inhibitor of caries was concentrated in the outer regions of the biofilm. This implies some restriction of diffusion and possibly binding to the high surface area of the outer biofilm. Whilst all components examined conformed to this distribution pattern, some relatively uncharged materials penetrated the bacterial biomass whilst other, more highly charged materials tended to be restricted to the channels or biomass surface. Plaque architecture was robust but could be altered using detergent indicating that biomass architecture and chemistry could be manipulated as a possible means of facilitating mass transport of therapeutics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of humic acid on the interactions between zinc oxide nanoparticles and bacterial biofilms.

Science.gov (United States)

Ouyang, Kai; Yu, Xiao-Ying; Zhu, Yunlin; Gao, Chunhui; Huang, Qiaoyun; Cai, Peng

2017-12-01

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. However, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular polymeric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn 2+ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn 2+ on HA. The combined results from this work suggest that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of humic acid on the interactions between zinc oxide nanoparticles and bacterial biofilms

Energy Technology Data Exchange (ETDEWEB)

Ouyang, Kai; Yu, Xiao-Ying; Zhu, Yunlin; Gao, Chunhui; Huang, Qiaoyun; Cai, Peng

2017-12-01

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. However, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular poly-meric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn²⁺ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn²⁺ on HA. The combined results from this work suggest that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems.

Photodynamic therapy with water-soluble phtalocyanines against bacterial biofilms in teeth root canals

Science.gov (United States)

Gergova, Raina; Georgieva, Tzvetelina; Angelov, Ivan; Mantareva, Vanya; Valkanov, Serjoga; Mitov, Ivan; Dimitrov, Slavcho

2012-06-01

The study presents the PDT with metal phthalocyanines on biofilms grown in root canals of ten representatives of the Gram-positive and the Gram-negative bacterial species and a fungus Candida albicans which cause aqute teeth infections in root canals.. The extracted human single-root teeth infected for 48 h with microorganisms in conditions to form biofilms of the above pathogens were PDT treated. The stage of biofilm formation and PDT effect of the samples of the teeth were determined by the scaning electron microscopy and with standard microbial tests. The PDT treating procedure included 10 min incubation with the respected phthalocyanine and irradiated with 660 nm Diode laser for 10 min. The most strongly antibacterial activity was achieved with zinc(II) phthalocyanine (ZnPc) against Enterococcus faecalis, Staphylococcus aureus and Moraxella catarrhalis. The other Gram-negative bacteria and Candida albicans were 10-100 times more resistant than the Gram-positive species. The Gram-negative Moraxella catarrhalis and Acinetobacter baumannii were more sensitive than the enterobacteria, but eradication of Pseudomonas aeruginosa in biofilm was insignificant. The influence of the stage of biofilm formation and the initial conditions (bacterial density, photosensitizer concentration and energy fluence of radiation) to the obtained level of inactivation of biofilms was investigated. The PDT with ZnPc photosensitizers show a powerful antimicrobial activity against the most frequent pathogens in endodontic infections and this method for inactivation of pathogens may be used with sucsses for treatment of the bacterial biofilms in the root canals.

Nonleachable Imidazolium-Incorporated Composite for Disruption of Bacterial Clustering, Exopolysaccharide-Matrix Assembly, and Enhanced Biofilm Removal.

Science.gov (United States)

Hwang, Geelsu; Koltisko, Bernard; Jin, Xiaoming; Koo, Hyun

2017-11-08

Surface-grown bacteria and production of an extracellular polymeric matrix modulate the assembly of highly cohesive and firmly attached biofilms, making them difficult to remove from solid surfaces. Inhibition of cell growth and inactivation of matrix-producing bacteria can impair biofilm formation and facilitate removal. Here, we developed a novel nonleachable antibacterial composite with potent antibiofilm activity by directly incorporating polymerizable imidazolium-containing resin (antibacterial resin with carbonate linkage; ABR-C) into a methacrylate-based scaffold (ABR-modified composite; ABR-MC) using an efficient yet simplified chemistry. Low-dose inclusion of imidazolium moiety (∼2 wt %) resulted in bioactivity with minimal cytotoxicity without compromising mechanical integrity of the restorative material. The antibiofilm properties of ABR-MC were assessed using an exopolysaccharide-matrix-producing (EPS-matrix-producing) oral pathogen (Streptococcus mutans) in an experimental biofilm model. Using high-resolution confocal fluorescence imaging and biophysical methods, we observed remarkable disruption of bacterial accumulation and defective 3D matrix structure on the surface of ABR-MC. Specifically, the antibacterial composite impaired the ability of S. mutans to form organized bacterial clusters on the surface, resulting in altered biofilm architecture with sparse cell accumulation and reduced amounts of EPS matrix (versus control composite). Biofilm topology analyses on the control composite revealed a highly organized and weblike EPS structure that tethers the bacterial clusters to each other and to the surface, forming a highly cohesive unit. In contrast, such a structured matrix was absent on the surface of ABR-MC with mostly sparse and amorphous EPS, indicating disruption in the biofilm physical stability. Consistent with lack of structural organization, the defective biofilm on the surface of ABR-MC was readily detached when subjected to low shear

Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm

Energy Technology Data Exchange (ETDEWEB)

Liu, Hong; Yu, Tong, E-mail: tong.yu@ualberta.ca; Liu, Yang, E-mail: yang.liu@ualberta.ca

2015-12-01

Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H{sub 2}S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H{sub 2}S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. - Graphical abstract: The development of sulfate reducing bacteria (SRB) within Oil Sands Process-affected Water (OSPW) biofilm and the biofilm treatment of OSPW were evaluated by Liu and coworkers. Combined microsensor and molecular biology techniques were utilized in this study. Their results demonstrated that multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H{sub 2}S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. - Highlights: • Biofilm in oil sands wastewater was developed on engineered biocarriers. • Bacterial community and in situ activity of SRB were studied in the

Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm

International Nuclear Information System (INIS)

Liu, Hong; Yu, Tong; Liu, Yang

2015-01-01

Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H 2 S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H 2 S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. - Graphical abstract: The development of sulfate reducing bacteria (SRB) within Oil Sands Process-affected Water (OSPW) biofilm and the biofilm treatment of OSPW were evaluated by Liu and coworkers. Combined microsensor and molecular biology techniques were utilized in this study. Their results demonstrated that multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H 2 S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. - Highlights: • Biofilm in oil sands wastewater was developed on engineered biocarriers. • Bacterial community and in situ activity of SRB were studied in the biofilm. �

Control of bacterial biofilm growth on surfaces by nanostructural mechanics and geometry

International Nuclear Information System (INIS)

Epstein, A K; Hochbaum, A I; Kim, Philseok; Aizenberg, J

2011-01-01

Surface-associated communities of bacteria, called biofilms, pervade natural and anthropogenic environments. Mature biofilms are resistant to a wide range of antimicrobial treatments and therefore pose persistent pathogenic threats. The use of surface chemistry to inhibit biofilm growth has been found to only transiently affect initial attachment. In this work, we investigate the tunable effects of physical surface properties, including high-aspect-ratio (HAR) surface nanostructure arrays recently reported to induce long-range spontaneous spatial patterning of bacteria on the surface. The functional parameters and length scale regimes that control such artificial patterning for the rod-shaped pathogenic species Pseudomonas aeruginosa are elucidated through a combinatorial approach. We further report a crossover regime of biofilm growth on a HAR nanostructured surface versus the nanostructure effective stiffness. When the 'softness' of the hair-like nanoarray is increased beyond a threshold value, biofilm growth is inhibited as compared to a flat control surface. This result is consistent with the mechanoselective adhesion of bacteria to surfaces. Therefore by combining nanoarray-induced bacterial patterning and modulating the effective stiffness of the nanoarray—thus mimicking an extremely compliant flat surface—bacterial mechanoselective adhesion can be exploited to control and inhibit biofilm growth.

Chitosanase purified from bacterial isolate Bacillus licheniformis of ruined vegetables displays broad spectrum biofilm inhibition.

Science.gov (United States)

Muslim, Sahira Nsayef; Al-Kadmy, Israa M S; Hussein, Nadheema Hammood; Mohammed Ali, Alaa Naseer; Taha, Buthainah Mohammed; Aziz, Sarah Naji; Kheraif, Abdulaziz Abdullah Al; Divakar, Darshan Devang; Ramakrishnaiah, Ravikumar

2016-11-01

A number of bacterial species produces chitosanases which has variety of applications because of its high biodegradability, non-toxicity and antimicrobial assets. In the present study chitosanase is purified from new bacterial species Bacillus licheniformis from spoiled vegetable. This novel strain of Bacillus licheniformis isolated from spoilt cucumber and pepper samples has the ability to produce the chitosanase enzyme when grown on chitosan substrate. Study also examined its antibiofilm properties against diverse bacterial species with biofilm forming ability. The purified chitosanase inhibited the biofilm formation ability for all Gram-negative and Gram-positive biofilm-forming bacteria [biofilm producers] tested in this study in congo red agar and microtiter plate's methods. Highly antibiofilm activity of chitosanase was recorded against Pseudomonas aeruginosa followed by Klebsiella pneumoniae with reduction of biofilm formation upto 22 and 29%, respectively compared with [100] % of control. Biofilm formation has multiple role including ability to enhance resistance and self-protection from external stress. This chitosanase has promising benefit as antibiofilm agent against biofilm forming pathogenic bacteria and has promising application as alternative antibiofilm agents to combat the growing number of multidrug resistant pathogen-associated infections, especially in situation where biofilms are involved. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visualizing Antimicrobials in Bacterial Biofilms: Three-Dimensional Biochemical Imaging Using TOF-SIMS.

Science.gov (United States)

Davies, Sarah K; Fearn, Sarah; Allsopp, Luke P; Harrison, Freya; Ware, Ecaterina; Diggle, Stephen P; Filloux, Alain; McPhail, David S; Bundy, Jacob G

2017-01-01

Bacterial biofilms are groups of bacteria that exist within a self-produced extracellular matrix, adhering to each other and usually to a surface. They grow on medical equipment and inserts such as catheters and are responsible for many persistent infections throughout the body, as they can have high resistance to many antimicrobials. Pseudomonas aeruginosa is an opportunistic pathogen that can cause both acute and chronic infections and is used as a model for research into biofilms. Direct biochemical methods of imaging of molecules in bacterial biofilms are of high value in gaining a better understanding of the fundamental biology of biofilms and biochemical gradients within them. Time of flight-secondary-ion mass spectrometry (TOF-SIMS) is one approach, which combines relatively high spatial resolution and sensitivity and can perform depth profiling analysis. It has been used to analyze bacterial biofilms but has not yet been used to study the distribution of antimicrobials (including antibiotics and the antimicrobial metal gallium) within biofilms. Here we compared two methods of imaging of the interior structure of P. aeruginosa in biological samples using TOF-SIMS, looking at both antimicrobials and endogenous biochemicals: cryosectioning of tissue samples and depth profiling to give pseudo-three-dimensional (pseudo-3D) images. The sample types included both simple biofilms grown on glass slides and bacteria growing in tissues in an ex vivo pig lung model. The two techniques for the 3D imaging of biofilms are potentially valuable complementary tools for analyzing bacterial infection. IMPORTANCE Modern analytical techniques are becoming increasingly important in the life sciences; imaging mass spectrometry offers the opportunity to gain unprecedented amounts of information on the distribution of chemicals in samples-both xenobiotics and endogenous compounds. In particular, simultaneous imaging of antibiotics (and other antimicrobial compounds) and bacterium

Combination of Cold Atmospheric Plasma and Vitamin C Effectively Disrupts Bacterial Biofilms

DEFF Research Database (Denmark)

Pandit, Santosh; Mokkapati, Venkata R. S. S.; Helgadóttir, Saga Huld

2017-01-01

limitation is the susceptibility of the surrounding healthy tissues to higher doses. We have recently demonstrated that vitamin C, a natural food supplement, can be used to destabilize bacterial biofilms and render them more susceptible to the CAP killing treatment. Here we discuss the possible impact...... that a pre-treatment with vitamin C could have on CAP applications in medicine. Specifically, we argue that vitamin C could enhance the effectiveness of CAP treatments against both the bacterial biofilms and some selected tumors....

Molecular Characterisation and Co-cultivation of Bacterial Biofilm Communities Associated with the Mat-Forming Diatom Didymosphenia geminata.

Science.gov (United States)

Brandes, Josephin; Kuhajek, Jeanne M; Goodwin, Eric; Wood, Susanna A

2016-10-01

Didymosphenia geminata (Lyngbye) M. Schmidt is a stalked freshwater diatom that is expanding its range globally. In some rivers, D. geminata forms thick and expansive polysaccharide-dominated mats. Like other stalked diatoms, D. geminata cells attach to the substratum with a pad of adhesive extracellular polymeric substance. Research on D. geminata and other diatoms suggests that bacterial biofilm composition may contribute to successful attachment. The aim of this study was to investigate the composition and role of bacterial biofilm communities in D. geminata attachment and survival. Bacterial biofilms were collected at four sites in the main stem of a river (containing D. geminata) and in four tributaries (free of D. geminata). Samples were characterised using automated rRNA intergenic spacer analysis and high-throughput sequencing (HTS). Mat-associated bacteria were isolated and their effect on the early establishment of D. geminata cells assessed using co-culturing experiments. ARISA and HTS data showed differences in bacterial communities between samples with and without D. geminata at two of the four sites. Samples with D. geminata had a higher relative abundance of Sphingobacteria (p geminata reduced survival (p geminata. Attachment was enhanced by Micrococcus sp. and Pseudomonas sp. (p geminata, and may partly explain observed distribution patterns.

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.

Antibiotic Discovery: Combatting Bacterial Resistance in Cells and in Biofilm Communities

Directory of Open Access Journals (Sweden)

Anahit Penesyan

2015-03-01

Full Text Available Bacterial resistance is a rapidly escalating threat to public health as our arsenal of effective antibiotics dwindles. Therefore, there is an urgent need for new antibiotics. Drug discovery has historically focused on bacteria growing in planktonic cultures. Many antibiotics were originally developed to target individual bacterial cells, being assessed in vitro against microorganisms in a planktonic mode of life. However, towards the end of the 20th century it became clear that many bacteria live as complex communities called biofilms in their natural habitat, and this includes habitats within a human host. The biofilm mode of life provides advantages to microorganisms, such as enhanced resistance towards environmental stresses, including antibiotic challenge. The community level resistance provided by biofilms is distinct from resistance mechanisms that operate at a cellular level, and cannot be overlooked in the development of novel strategies to combat infectious diseases. The review compares mechanisms of antibiotic resistance at cellular and community levels in the light of past and present antibiotic discovery efforts. Future perspectives on novel strategies for treatment of biofilm-related infectious diseases are explored.

Correlative Imaging of Structural and Elemental Composition of Bacterial Biofilms

International Nuclear Information System (INIS)

Yang, Y; Heine, R; Xu, F; Helfen, L; Baumbach, T; Suhonen, H; Rosenhahn, A; Gorniak, T; Kirchen, S; Schwartz, T

2013-01-01

Synchrotron-based phase contrast tomography (holotomography) and scanning hard X-ray fluorescence microscopy (SXFM) are combined to characterize the three-dimensional (3D) structural and corresponding elemental distribution of bacterial biofilms of Pseudomonas aeruginosa. Samples were fixed without contrast agents or microtomal sectioning. Within an intact microbial community single bacteria are clearly resolved, and their morphology can be directly visualized together with the elemental content. Such 3D set of complementary information at cellular level is essential for gaining a deeper understanding of biofilm evolution aiming to develop potential strategies on biofilm growth control and prevention

[Bacterial biofilms as a natural form of existence of bacteria in the environment and host organism].

Science.gov (United States)

Romanova, Iu M; Gintsburg, A L

2011-01-01

Advances in microscopic analysis and molecular genetics research methods promoted the acquisition of evidence that natural bacteria populations exist predominately as substrate attached biofilms. Bacteria in biofilms are able to exchange signals and display coordinated activity that is inherent to multicellular organisms. Formation of biofilm communities turned out to be one of the main survival strategies of bacteria in their ecological niche. Bacteria in attached condition in biofilm are protected from the environmental damaging factors and effects of antibacterial substances in the environment and host organism during infection. According to contemporary conception, biofilm is a continuous layer of bacterial cells that are attached to a surface and each other, and contained in a biopolymer matrix. Such bacterial communities may be composed of bacteria of one or several species, and composed of actively functioning cells as well as latent and uncultured forms. Particular attention has recently been paid to the role of biofilms in the environment and host organism. Microorganisms form biofilm on any biotic and abiotic surfaces which creates serious problems in medicine and various areas of economic activity. Currently, it is established that biofilms are one of the pathogenetic factors of chronic inflection process formation. The review presents data on ubiquity of bacteria existence as biofilms, contemporary methods of microbial community analysis, structural-functional features of bacterial biofilms. Particular attention is paid to the role of biofilm in chronic infection process formation, heightened resistance to antibiotics of bacteria in biofilms and possible mechanisms of resistance. Screening approaches for agents against biofilms in chronic infections are discussed.

Modeling bacterial attachment to surfaces as an early stage of biofilm development.

Science.gov (United States)

El Moustaid, Fadoua; Eladdadi, Amina; Uys, Lafras

2013-06-01

Biofilms are present in all natural, medical and industrial surroundings where bacteria live. Biofilm formation is a key factor in the growth and transport of both beneficial and harmful bacteria. While much is known about the later stages of biofilm formation, less is known about its initiation which is an important first step in the biofilm formation. In this paper, we develop a non-linear system of partial differential equations of Keller-Segel type model in one-dimensional space, which couples the dynamics of bacterial movement to that of the sensing molecules. In this case, bacteria perform a biased random walk towards the sensing molecules. We derive the boundary conditions of the adhesion of bacteria to a surface using zero-Dirichlet boundary conditions, while the equation describing sensing molecules at the interface needed particular conditions to be set. The numerical results show the profile of bacteria within the space and the time evolution of the density within the free-space and on the surface. Testing different parameter values indicate that significant amount of sensing molecules present on the surface leads to a faster bacterial movement toward the surface which is the first step of biofilm initiation. Our work gives rise to results that agree with the biological description of the early stages of biofilm formation.

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

from the surface of the marine alga Ulva australis, were screened for synergistic interactions within biofilms when present together in different combinations. Four isolates, Microbacterium phyllosphaerae, Shewanella japonica, Dokdonia donghaensis, and Acinetobacter lwoffii, were found to interact......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...... synergistically in biofilms formed in 96-well microtiter plates: biofilm biomass was observed to increase by >167% in biofilms formed by the four strains compared to biofilms composed of single strains. When exposed to the antibacterial agent hydrogen peroxide or tetracycline, the relative activity (exposed...

Inhalable Antimicrobials for Treatment of Bacterial Biofilm-Associated Sinusitis in Cystic Fibrosis Patients

DEFF Research Database (Denmark)

Klodzinska, Sylvia Natalie; Priemel, Petra Alexandra; Rades, Thomas

2016-01-01

Bacterial biofilm-associated chronic sinusitis in cystic fibrosis (CF) patients caused by Pseudomonas aeruginosa infections and the lack of available treatments for such infections constitute a critical aspect of CF disease management. Currently, inhalation therapies to combat P. aeruginosa infec...... and management of biofilm infections caused by P. aeruginosa and discusses critical issues related to novel antimicrobial drug formulation design approaches.......Bacterial biofilm-associated chronic sinusitis in cystic fibrosis (CF) patients caused by Pseudomonas aeruginosa infections and the lack of available treatments for such infections constitute a critical aspect of CF disease management. Currently, inhalation therapies to combat P. aeruginosa....... aeruginosa from the respiratory tract after a first infection has been shown to delay chronic pulmonary infection with the bacteria for up to two years. The challenges with providing a suitable treatment for bacterial sinusitis include: (i) identifying a suitable antimicrobial compound; (ii) selecting...

The effect of iatrogenic Staphylococcus epidermidis intercellar adhesion operon on the formation of bacterial biofilm on polyvinyl chloride surfaces.

Science.gov (United States)

Lianhua, Ye; Yunchao, Huang; Guangqiang, Zhao; Kun, Yang; Xing, Liu; Fengli, Guo

2014-12-01

The intercellular adhesion gene (ica) of Staphylococcus epidermidis is a key factor for bacterial aggregation. This study explored the effect of ica on the formation of bacterial biofilm on polyvinyl chloride (PVC) surfaces. Genes related to bacterial biofilm formation, including 16S rRNA, autolysin (atlE), fibrinogen binding protein gene (fbe), and ica were identified and sequenced from 112 clinical isolates of iatrogenic S. epidermidis by polymerase chain reaction (PCR) and gene sequencing. Based on the sequencing result, ica operon-positive (icaADB+/atlE+/fbe+) and ica operon-negative (icaADB-/atlE+/fbe+) strains were separated and co-cultivated with PVC material. After 6, 12, 18, 24, and 30 h of co-culture, the thickness of the bacterial biofilm and quantity of bacterial colony on the PVC surface were measured under the confocal laser scanning microscope and scanning electron microscope. The positive rate of S. epidermidis-specific 16SrRNA in 112 iatrogenic strains was 100% (112/112). The genotype of ica-positive (icaADB+/atlE+/fbe+) strains accounted for 57.1% (64/112), and genotype of ica-negative (icaADB-/atlE+/fbe+) strains accounted for 37.5% (42/112). During 30 h of co-culture, no obvious bacterial biofilm formed on the surface of PVC in the ica-positive group, however, mature bacterial biofilm structure formed after 24 h. For all time points, thickness of bacterial biofilm and quantity of bacterial colony on PVC surfaces in the ica operon-positive group were significantly higher than those in ica operon-negative group (poperon-negative and ica operon-positive strains. The ica operon plays an important role in bacterial biofilm formation and bacterial multiplication on PVC material.

Three common metal contaminants of urban runoff (Zn, Cu and Pb) accumulate in freshwater biofilm and modify embedded bacterial communities

International Nuclear Information System (INIS)

Ancion, Pierre-Yves; Lear, Gavin; Lewis, Gillian D.

2010-01-01

We investigated the absorption rates of zinc, copper and lead in freshwater biofilm and assessed whether biofilm bacterial populations are affected by exposure to environmentally relevant concentrations of these metals in flow chamber microcosms. Metals were rapidly accumulated by the biofilm and then retained for at least 14 days after transfer to uncontaminated water. Changes in bacterial populations were assessed by Automated Ribosomal Intergenic Spacer Analysis (ARISA) and 16S rRNA gene clone libraries. Significant differences in bacterial community structure occurred within only three days of exposure to metals and remained detectable at least 14 days after transfer to uncontaminated water. The rapid uptake of stormwater-associated metals and their retention in the biofilm highlight the potential role of biofilms in the transfer of metals to organisms at higher trophic levels. The sensitivity of stream biofilm bacterial populations to metal exposure supports their use as an indicator of stream ecological health. - The rapid accumulation of metals in biofilms and their impact on bacterial communities provide new insights into how these contaminants affect freshwater ecosystems.

Characterization of Desulfovibrio desulfuricans biofilm on high-alloyed stainless steel: XPS and electrochemical studies

Energy Technology Data Exchange (ETDEWEB)

Dec, Weronika [Institute of Industrial Organic Chemistry, Branch Pszczyna, Doświadczalna Street 27, 43-200 Pszczyna (Poland); Mosiałek, Michał; Socha, Robert P. [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Jaworska-Kik, Marzena [Department of Biopharmacy, Medical University of Silesia, Jedności Street 8, 41-200 Sosnowiec (Poland); Simka, Wojciech [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland); Michalska, Joanna, E-mail: joanna.k.michalska@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland)

2017-07-01

Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C-N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed. - Highlights: • High-alloyed steels are rapidly colonized by sulphate-reducing bacteria. • Higher Ni content stimulates more intensive biofilm growth. • Extracellular polymeric substances indelibly bind to the high-alloyed steels. • Sulphate-reducing bacteria caused irreversible sulphidation of passive films.

Characterization of Desulfovibrio desulfuricans biofilm on high-alloyed stainless steel: XPS and electrochemical studies

International Nuclear Information System (INIS)

Dec, Weronika; Mosiałek, Michał; Socha, Robert P.; Jaworska-Kik, Marzena; Simka, Wojciech; Michalska, Joanna

2017-01-01

Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C-N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed. - Highlights: • High-alloyed steels are rapidly colonized by sulphate-reducing bacteria. • Higher Ni content stimulates more intensive biofilm growth. • Extracellular polymeric substances indelibly bind to the high-alloyed steels. • Sulphate-reducing bacteria caused irreversible sulphidation of passive films.

Identification of different bacterial species in biofilms using confocal Raman microscopy

Science.gov (United States)

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

2010-11-01

Confocal Raman microspectroscopy is used to discriminate between different species of bacteria grown in biofilms. Tests are performed using two bacterial species, Streptococcus sanguinis and Streptococcus mutans, which are major components of oral plaque and of particular interest due to their association with healthy and cariogenic plaque, respectively. Dehydrated biofilms of these species are studied as a simplified model of dental plaque. A prediction model based on principal component analysis and logistic regression is calibrated using pure biofilms of each species and validated on pure biofilms grown months later, achieving 96% accuracy in prospective classification. When biofilms of the two species are partially mixed together, Raman-based identifications are achieved within ~2 μm of the boundaries between species with 97% accuracy. This combination of spatial resolution and predication accuracy should be suitable for forming images of species distributions within intact two-species biofilms.

Involvement of bacterial migration in the development of complex multicellular structures in Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Klausen, Mikkel; Aaes-Jorgensen, A.; Molin, Søren

2003-01-01

development, we have performed an investigation with time-lapse confocal laser scanning microscopy of biofilms formed by various combinations of colour-coded P. aeruginosa wild type and motility mutants. We show that mushroom-shaped multicellular structures in P. aeruginosa biofilms can form in a sequential...... process involving a non-motile bacterial subpopulation and a migrating bacterial subpopulation. The non-motile bacteria form the mushroom stalks by growth in certain foci of the biofilm. The migrating bacteria form the mushroom caps by climbing the stalks and aggregating on the tops in a process which...

Characterization of Bacterial Etiologic Agents of Biofilm Formation in Medical Devices in Critical Care Setup

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Sangita Revdiwala

2012-01-01

Full Text Available Background. Biofilms contaminate catheters, ventilators, and medical implants; they act as a source of disease for humans, animals, and plants. Aim. Critical care units of any healthcare institute follow various interventional strategies with use of medical devices for the management of critical cases. Bacteria contaminate medical devices and form biofilms. Material and Methods. The study was carried out on 100 positive bacteriological cultures of medical devices which were inserted in hospitalized patients. The bacterial isolates were processed as per microtitre plate. All the isolates were subjected to antibiotic susceptibility testing by VITEK 2 compact automated systems. Results. Out of the total 100 bacterial isolates tested, 88 of them were biofilm formers. A 16–20-hour incubation period was found to be optimum for biofilm development. 85% isolates were multidrug resistants and different mechanisms of bacterial drug resistance like ESBL, carbapenemase, and MRSA were found among isolates. Conclusion. Availability of nutrition in the form of glucose enhances the biofilm formation by bacteria. Time and availability of glucose are important factors for assessment of biofilm progress. It is an alarm for those who are associated with invasive procedures and indwelling medical devices especially in patients with low immunity.

Boeravinone B, A Novel Dual Inhibitor of NorA Bacterial Efflux Pump of Staphylococcus aureus and Human P-Glycoprotein, Reduces the Biofilm Formation and Intracellular Invasion of Bacteria.

Science.gov (United States)

Singh, Samsher; Kalia, Nitin P; Joshi, Prashant; Kumar, Ajay; Sharma, Parduman R; Kumar, Ashok; Bharate, Sandip B; Khan, Inshad A

2017-01-01

This study elucidated the role of boeravinone B, a NorA multidrug efflux pump inhibitor, in biofilm inhibition. The effects of boeravinone B plus ciprofloxacin, a NorA substrate, were evaluated in NorA-overexpressing, wild-type, and knocked-out Staphylococcus aureus (SA-1199B, SA-1199, and SA-K1758, respectively). The mechanism of action was confirmed using the ethidium bromide accumulation and efflux assay. The role of boeravinone B as a human P -glycoprotein ( P -gp) inhibitor was examined in the LS-180 (colon cancer) cell line. Moreover, its role in the inhibition of biofilm formation and intracellular invasion of S. aureus in macrophages was studied. Boeravinone B reduced the minimum inhibitory concentration (MIC) of ciprofloxacin against S. aureus and its methicillin-resistant strains; the effect was stronger in SA-1199B. Furthermore, time-kill kinetics revealed that boeravinone B plus ciprofloxacin, at subinhibitory concentration (0.25 × MIC), is as equipotent as that at the MIC level. This combination also had a reduced mutation prevention concentration. Boeravinone B reduced the efflux of ethidium bromide and increased the accumulation, thus strengthening the role as a NorA inhibitor. Biofilm formation was reduced by four-eightfold of the minimal biofilm inhibitory concentration of ciprofloxacin, effectively preventing bacterial entry into macrophages. Boeravinone B effectively inhibited P -gp with half maximal inhibitory concentration (IC 50 ) of 64.85 μM. The study concluded that boeravinone B not only inhibits the NorA-mediated efflux of fluoroquinolones but also considerably inhibits the biofilm formation of S. aureus. Its P -gp inhibition activity demonstrates its potential as a bioavailability and bioefficacy enhancer.

Bacterial biofilms with emphasis on coagulase-negative staphylococci

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A Oliveira

2008-01-01

Full Text Available In addition to their capacity to attach to surfaces, various groups of microorganisms also produce an extracellular polymeric substance known as "slime". This slime forms a thin layer around cells known as biofilm. Thus, biofilm structure comprises bacterial cells and an extracellular polymeric substance. It also presents a defined architecture, providing the microorganisms with an excellent protective environment and favoring the exchange of genetic material between cells as well as intercellular communication. The ability to produce biofilm is observed in a large group of bacteria, including coagulase-negative staphylococci (CNS which are the predominant microorganisms of normal skin flora and have been implicated as the causative agents of hospital infections. Bacteremia caused by these agents is common in immunodepressed persons, in patients with cancer, in adult and neonatal intensive care units (ICU and in patients using catheters or other prosthetic devices. The pathogenicity of CNS infections is probably related to the production of slime, which adheres preferentially to plastic and smooth surfaces, forming a biofilm that protects against attacks from the immune system and against antibiotic treatment, a fact hindering the eradication of these infections. The main objective of the present review was to describe basic and genetic aspects of biofilm formation and methods for its detection, with emphasis on biofilm creation by CNS and its relationship with diseases caused by these microorganisms which are becoming increasingly more frequent in the hospital environment.

Bacterial biofilms and quorum sensing: fidelity in bioremediation technology.

Science.gov (United States)

Mangwani, Neelam; Kumari, Supriya; Das, Surajit

Increased contamination of the environment with toxic pollutants has paved the way for efficient strategies which can be implemented for environmental restoration. The major problem with conventional methods used for cleaning of pollutants is inefficiency and high economic costs. Bioremediation is a growing technology having advanced potential of cleaning pollutants. Biofilm formed by various micro-organisms potentially provide a suitable microenvironment for efficient bioremediation processes. High cell density and stress resistance properties of the biofilm environment provide opportunities for efficient metabolism of number of hydrophobic and toxic compounds. Bacterial biofilm formation is often regulated by quorum sensing (QS) which is a population density-based cell-cell communication process via signaling molecules. Numerous signaling molecules such as acyl homoserine lactones, peptides, autoinducer-2, diffusion signaling factors, and α-hydroxyketones have been studied in bacteria. Genetic alteration of QS machinery can be useful to modulate vital characters valuable for environmental applications such as biofilm formation, biosurfactant production, exopolysaccharide synthesis, horizontal gene transfer, catabolic gene expression, motility, and chemotaxis. These qualities are imperative for bacteria during degradation or detoxification of any pollutant. QS signals can be used for the fabrication of engineered biofilms with enhanced degradation kinetics. This review discusses the connection between QS and biofilm formation by bacteria in relation to bioremediation technology.

Connecting the dots between bacterial biofilms and ice cream

Science.gov (United States)

Stanley-Wall, Nicola R.; MacPhee, Cait E.

2015-12-01

Emerging research is revealing a diverse array of interfacially-active proteins that are involved in varied biological process from foaming horse sweat to bacterial raincoat formation. We describe an interdisciplinary approach to study the molecular and biophysical mechanisms controlling the activity of an unusual bacterial protein called BslA. This protein is needed for biofilm formation and forms a protective layer or raincoat over the bacterial community, but also has a multitude of potential applications in multiphase formulations. Here we document our journey from fundamental research to an examination of the applications for this surface-active protein in ice cream.

The reducibility of sulphuric acid and sulphate in aqueous solution (translated from German)

International Nuclear Information System (INIS)

Grauer, R.

1990-07-01

In connection with the Swedish project for the final storage of spent fuel elements it was necessary to assess whether dissolved sulphate can corrode the copper canister without the intervention of sulphate-reducing bacteria. A simple reaction between copper and sulphate is thermodynamically impossible. On the other hand, copper can react to give copper sulphide if an additional electron donor such as iron is available. Because little specific information is available about this subject the problem was extended to the much more general question of the reducibility of sulphur in dilute aqueous solution. It is a part of the general knowledge of chemistry, and there is also unanimity about it in the geochemical literature, that purely chemical reduction of sulphate does not take place in dilute solution at temperatures below 100 degrees C. This fact is, however, poorly documented and it was therefore necessary to substantiate it by drawing on numerous individual findings from different areas of pure and applied chemistry. The investigation confirms that sulphur in dilute solution is completely inert towards chemical reducing agents and also to cathodic reduction. Thus corrosion of copper by sulphate under final-storage conditions and in the absence of sulphate reducing bacteria can be ruled out with a probability verging on certainty. (85 refs.)

Role of bacterial biofilm in development of middle ear effusion.

Science.gov (United States)

Tawfik, Sedeek Abd El-Salam; Ibrahim, Ahmed Aly; Talaat, Iman Mamdoh; El-Alkamy, Soliman Samy Abd El-Raouf; Youssef, Ahmed

2016-11-01

Biofilms have been implicated in the development of several chronic upper respiratory tract infections. Role of bacterial biofilms has been well studied in the pathogenesis of chronic rhinosinusitis. However, its impact on development of middle ear effusion is still a matter of debate. To study the extent of surface adenoid biofilm and evaluate its role in the pathogenesis of chronic otitis media with effusion in children. The study was carried out on 40 children in Alexandria Main University Hospital between 1 and 16 years of age without sex predilection, who were divided into two groups. The first group (20 children) had otitis media with effusion associated with adenoid hypertrophy, whereas the second group (20 children) had adenoid hypertrophy without middle ear effusion. Adenoidectomy with ventilation tube insertion was done for group 1 cases, whereas, only Adenoidectomy was done for group 2 cases. The samples were processed for the detection of biofilms by scanning electron microscopy. The biofilm formation was graded according to extension. Biofilm formation was detected on all samples for group 1. Adenoids removed from patients with otitis media with effusion had higher-grade biofilm formation than the other group (P 0.0001). No correlation was found between adenoid size and biofilm formation. In pediatric population, adenoid surface biofilm formation may be involved in the pathogenesis otitis media with effusion.

Quantitative characterization of the influence of the nanoscale morphology of nanostructured surfaces on bacterial adhesion and biofilm formation.

Directory of Open Access Journals (Sweden)

Ajay Vikram Singh

Full Text Available Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological

Sulphate reduction and vertical distribution of sulphate-reducing bacteria quantified by rRNA slot-blot hybridization in a coastal marine sediment

DEFF Research Database (Denmark)

Sahm, K.; MacGregor, BJ; Jørgensen, BB

1999-01-01

In the past, enumeration of sulphate-reducing bacteria (SRB) by cultivation-based methods generally contradicted measurements of sulphate reduction, suggesting unrealistically high respiration rates per cell. Here, we report evidence that quantification of SRB rRNA by slot-blot hybridization......, directly above the sulphate reduction maximum. Cell numbers calculated by converting the relative contribution of SRB rRNA to the percentage of DAPI-stained cells indicated a population size for SRB of 2.4-6.1 x 10(8) cells cm(-3) wet sediment. Cellular sulphate reduction rates calculated on the basis...

Prosthesis infections after orthopedic joint replacement: the possible role of bacterial biofilms

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Zhijun Song

2013-06-01

Full Text Available Prosthesis-related infection is a serious complication for patients after orthopedic joint replacement, which is currently difficult to treat with antibiotic therapy. Consequently, in most cases, removal of the infected prosthesis is the only solution to cure the infection. It is, therefore, important to understand the comprehensive interaction between the microbiological situation and the host immune responses that lead to prosthesis infections. Evidence indicates that prosthesis infections are actually biofilm-correlated infections that are highly resistant to antibiotic treatment and the host immune responses. The authors reviewed the related literature in the context of their clinical experience, and discussed the possible etiology and mechanism leading to the infections, especially problems related to bacterial biofilm, and prophylaxis and treatment of infection, including both microbiological and surgical measures. Recent progress in research into bacterial biofilm and possible future treatment options of prosthesis-related infections are discussed.

Distinctive colonization of Bacillus sp. bacteria and the influence of the bacterial biofilm on electrochemical behaviors of aluminum coatings.

Science.gov (United States)

Abdoli, Leila; Suo, Xinkun; Li, Hua

2016-09-01

Formation of biofilm is usually essential for the development of biofouling and crucially impacts the corrosion of marine structures. Here we report the attachment behaviors of Bacillus sp. bacteria and subsequent formation of bacterial biofilm on stainless steel and thermal sprayed aluminum coatings in artificial seawater. The colonized bacteria accelerate the corrosion of the steel plates, and markedly enhance the anti-corrosion performances of the Al coatings in early growth stage of the bacterial biofilm. After 7days incubation, the biofilm formed on the steel is heterogeneous while exhibits homogeneous feature on the Al coating. Atomic force microscopy examination discloses inception of formation of local pitting on steel plates associated with significantly roughened surface. Electrochemical testing suggests that the impact of the bacterial biofilm on the corrosion behaviors of marine structures is not decided by the biofilm alone, it is instead attributed to synergistic influence by both the biofilm and physicochemical characteristics of the substratum materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Bacterial cell numbers and community structures of seawater biofilms depend on the attachment substratum

KAUST Repository

Yap, Scott A.

2018-02-02

Seawater is increasingly being used as a source for various industrial applications. For such applications, biofilm growth creates various problems including but not limited to pipe biocorrosion. In this study, it is hypothesized that the material type is preferred by certain bacterial populations in the seawater to attach and establish biofilms. By comparing differences in the total cell counts and microbial communities attached to high-density polyethylene (HDPE), polycarbonate, stainless steel (SS316) and titanium, the appropriate material can be used to minimize biofilm growth. All four materials have hydrophilic surfaces, but polycarbonate exhibits higher surface roughness. There were no significant differences in the cell numbers attached to polycarbonate, HDPE and titanium. Instead, there were significantly fewer cells attached to SS316. However, there was a higher relative abundance of genera associated with opportunistic pathogens on SS316. Copy numbers of genes representing Desulfobacteraceae and Desulfobulbaceae, both of which are sulfate-reducing bacteria (SRB), were approximately 10-fold higher in biofilms sampled from SS316. The enrichment of SRB in the biofilm associated with SS316 indicates that this material may be prone to biocorrosion. This study highlights the need for industries to consider the choice of material used in seawater applications to minimize microbial-associated problems.

Bacterial cell numbers and community structures of seawater biofilms depend on the attachment substratum

KAUST Repository

Yap, Scott A.; Scarascia, Giantommaso; Hong, Pei-Ying

2018-01-01

Seawater is increasingly being used as a source for various industrial applications. For such applications, biofilm growth creates various problems including but not limited to pipe biocorrosion. In this study, it is hypothesized that the material type is preferred by certain bacterial populations in the seawater to attach and establish biofilms. By comparing differences in the total cell counts and microbial communities attached to high-density polyethylene (HDPE), polycarbonate, stainless steel (SS316) and titanium, the appropriate material can be used to minimize biofilm growth. All four materials have hydrophilic surfaces, but polycarbonate exhibits higher surface roughness. There were no significant differences in the cell numbers attached to polycarbonate, HDPE and titanium. Instead, there were significantly fewer cells attached to SS316. However, there was a higher relative abundance of genera associated with opportunistic pathogens on SS316. Copy numbers of genes representing Desulfobacteraceae and Desulfobulbaceae, both of which are sulfate-reducing bacteria (SRB), were approximately 10-fold higher in biofilms sampled from SS316. The enrichment of SRB in the biofilm associated with SS316 indicates that this material may be prone to biocorrosion. This study highlights the need for industries to consider the choice of material used in seawater applications to minimize microbial-associated problems.

Selective labelling and eradication of antibiotic-tolerant bacterial populations in Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Chua, Song Lin; Yam, Joey Kuok Hoong; Hao, Piliang

2016-01-01

Drug resistance and tolerance greatly diminish the therapeutic potential of antibiotics against pathogens. Antibiotic tolerance by bacterial biofilms often leads to persistent infections, but its mechanisms are unclear. Here we use a proteomics approach, pulsed stable isotope labelling with amino...... acids (pulsed-SILAC), to quantify newly expressed proteins in colistin-tolerant subpopulations of Pseudomonas aeruginosa biofilms (colistin is a 'last-resort' antibiotic against multidrug-resistant Gram-negative pathogens). Migration is essential for the formation of colistin-tolerant biofilm...

Inhibition of biofilm formation by D-tyrosine: Effect of bacterial type and D-tyrosine concentration.

Science.gov (United States)

Yu, Cong; Li, Xuening; Zhang, Nan; Wen, Donghui; Liu, Charles; Li, Qilin

2016-04-01

D-Tyrosine inhibits formation and triggers disassembly of bacterial biofilm and has been proposed for biofouling control applications. This study probes the impact of D-tyrosine in different biofilm formation stages in both G+ and G- bacteria, and reveals a non-monotonic correlation between D-tyrosine concentration and biofilm inhibition effect. In the attachment stage, cell adhesion was studied in a flow chamber, where D-tyrosine caused significant reduction in cell attachment. Biofilms formed by Pseudomonas aeruginosa and Bacillus subtilis were characterized by confocal laser scanning microscopy as well as quantitative analysis of cellular biomass and extracellular polymeric substances. D-Tyrosine exhibited strong inhibitive effects on both biofilms with an effective concentration as low as 5 nM; the biofilms responded to D-tyrosine concentration change in a non-monotonic, bi-modal pattern. In addition, D-tyrosine showed notable and different impact on EPS production by G+ and G- bacteria. Extracellular protein was decreased in P. aeruginosa biofilms, but increased in those of B. subtilis. Exopolysaccharides production by P. aeruginosa was increased at low concentrations and reduced at high concentrations while no impact was found in B. subtilis. These results suggest that distinct mechanisms are at play at different D-tyrosine concentrations and they may be species specific. Dosage of D-tyrosine must be carefully controlled for biofouling control applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Calcium Extraction from Blast-Furnace-Slag-Based Mortars in Sulphate Bacterial Medium

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Adriana Estokova

2018-01-01

Full Text Available Wastewater structures, such as treatment plants or sewers can be easily affected by bio-corrosion influenced by microorganisms living in waste water. The activity of these microbes results in deterioration and can cause the reduction in structural performance of such structures. In order to improve the durability of mortar and concrete, different admixtures are being used and the best impact is observed in cement based materials combined with blast furnace slag. In this study, mortar samples with blast furnace slag were exposed to bacterial sulphate attack for 90 and 180 days. The leaching of calcium ions from the cement matrix and equivalent damaged depths of studied mortar samples were evaluated. The results showed more significant leaching of samples placed in bacterial environment, compared to the samples placed in non-bacterial environment. Similarly, the equivalent damaged depths of mortars were much higher for the bacteria-influenced samples. The slag-based cement mortars did not clearly show improved resistance in bacterial medium in terms of calcium leaching.

Bacterial biofilm under flow: First a physical struggle to stay, then a matter of breathing.

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Philippe Thomen

Full Text Available Bacterial communities attached to surfaces under fluid flow represent a widespread lifestyle of the microbial world. Through shear stress generation and molecular transport regulation, hydrodynamics conveys effects that are very different by nature but strongly coupled. To decipher the influence of these levers on bacterial biofilms immersed in moving fluids, we quantitatively and simultaneously investigated physicochemical and biological properties of the biofilm. We designed a millifluidic setup allowing to control hydrodynamic conditions and to monitor biofilm development in real time using microscope imaging. We also conducted a transcriptomic analysis to detect a potential physiological response to hydrodynamics. We discovered that a threshold value of shear stress determined biofilm settlement, with sub-piconewton forces sufficient to prevent biofilm initiation. As a consequence, distinct hydrodynamic conditions, which set spatial distribution of shear stress, promoted distinct colonization patterns with consequences on the growth mode. However, no direct impact of mechanical forces on biofilm growth rate was observed. Consistently, no mechanosensing gene emerged from our differential transcriptomic analysis comparing distinct hydrodynamic conditions. Instead, we found that hydrodynamic molecular transport crucially impacts biofilm growth by controlling oxygen availability. Our results shed light on biofilm response to hydrodynamics and open new avenues to achieve informed design of fluidic setups for investigating, engineering or fighting adherent communities.

Linearmycins Activate a Two-Component Signaling System Involved in Bacterial Competition and Biofilm Morphology

Science.gov (United States)

2017-01-01

ABSTRACT Bacteria use two-component signaling systems to adapt and respond to their competitors and changing environments. For instance, competitor bacteria may produce antibiotics and other bioactive metabolites and sequester nutrients. To survive, some species of bacteria escape competition through antibiotic production, biofilm formation, or motility. Specialized metabolite production and biofilm formation are relatively well understood for bacterial species in isolation. How bacteria control these functions when competitors are present is not well studied. To address fundamental questions relating to the competitive mechanisms of different species, we have developed a model system using two species of soil bacteria, Bacillus subtilis and Streptomyces sp. strain Mg1. Using this model, we previously found that linearmycins produced by Streptomyces sp. strain Mg1 cause lysis of B. subtilis cells and degradation of colony matrix. We identified strains of B. subtilis with mutations in the two-component signaling system yfiJK operon that confer dual phenotypes of specific linearmycin resistance and biofilm morphology. We determined that expression of the ATP-binding cassette (ABC) transporter yfiLMN operon, particularly yfiM and yfiN, is necessary for biofilm morphology. Using transposon mutagenesis, we identified genes that are required for YfiLMN-mediated biofilm morphology, including several chaperones. Using transcriptional fusions, we found that YfiJ signaling is activated by linearmycins and other polyene metabolites. Finally, using a truncated YfiJ, we show that YfiJ requires its transmembrane domain to activate downstream signaling. Taken together, these results suggest coordinated dual antibiotic resistance and biofilm morphology by a single multifunctional ABC transporter promotes competitive fitness of B. subtilis. IMPORTANCE DNA sequencing approaches have revealed hitherto unexplored diversity of bacterial species in a wide variety of environments that

Fluid-Structure Interaction in Continuum Models of Bacterial Biofilms

Science.gov (United States)

Hicks, Jared A.

Bacterial biofilms are aggregates of cells that adhere to nearly any solid-fluid interface. While many have harmful effects, such as industrial damage and nosocomial infections, certain biofilm species are now generating renewable energy as the fundamental components of Microbial Fuel Cells (MFCs). In an MFC, bacteria consume organic waste and, as they respire, produce free electrons. To do so efficiently, the bacteria must operate at peak metabolic activity, and so require an ample supply of nutrients. But existing MFC systems face several nutrient delivery problems, including clogging and downstream depletion. Ameliorating these problems will require a better understanding of the interplay between structural development and the surrounding fluid flow. In addition to delivering nutrients that affect biofilm growth, the fluid also exerts stresses that cause erosion, detachment, and deformation. These structural changes, in turn, affect the flow and alter the nutrient distribution. To account for this feedback effect, I have developed a continuum model that couples the growth and deformation processes. My model augments an existing growth model with evolution equations derived from Morphoelasticity Theory, by showing that the growth tensor can be directly related to the biofilm velocity potential. This result helps overcome one of the major practical limitations of Morphoelasticity--there is no physical framework for specifying the growth tensor. Through further analysis of the growth tensor, I define the related adjugate and anisotropic growth tensors, which can be more meaningful measures of growth for some models. Under the assumption of small strain, I show that there exists a small correction to the biofilm growth velocity (the accommodation velocity) that represents the effect of the elastic response on the evolution of the biofilm shape. I derive a solvability condition for the accommodation velocity, and show that it leads to a novel evolution equation for

Biofilm Formation Mechanisms of Pseudomonas aeruginosa Predicted via Genome-Scale Kinetic Models of Bacterial Metabolism

Science.gov (United States)

2016-03-15

RESEARCH ARTICLE Biofilm Formation Mechanisms of Pseudomonas aeruginosa Predicted via Genome-Scale Kinetic Models of Bacterial Metabolism Francisco G...jaques.reifman.civ@mail.mil Abstract A hallmark of Pseudomonas aeruginosa is its ability to establish biofilm -based infections that are difficult to...eradicate. Biofilms are less susceptible to host inflammatory and immune responses and have higher antibiotic tolerance than free-living planktonic

Assessing the impact of water treatment on bacterial biofilms in drinking water distribution systems using high-throughput DNA sequencing.

Science.gov (United States)

Shaw, Jennifer L A; Monis, Paul; Fabris, Rolando; Ho, Lionel; Braun, Kalan; Drikas, Mary; Cooper, Alan

2014-12-01

Biofilm control in drinking water distribution systems (DWDSs) is crucial, as biofilms are known to reduce flow efficiency, impair taste and quality of drinking water and have been implicated in the transmission of harmful pathogens. Microorganisms within biofilm communities are more resistant to disinfection compared to planktonic microorganisms, making them difficult to manage in DWDSs. This study evaluates the impact of four unique drinking water treatments on biofilm community structure using metagenomic DNA sequencing. Four experimental DWDSs were subjected to the following treatments: (1) conventional coagulation, (2) magnetic ion exchange contact (MIEX) plus conventional coagulation, (3) MIEX plus conventional coagulation plus granular activated carbon, and (4) membrane filtration (MF). Bacterial biofilms located inside the pipes of each system were sampled under sterile conditions both (a) immediately after treatment application ('inlet') and (b) at a 1 km distance from the treatment application ('outlet'). Bacterial 16S rRNA gene sequencing revealed that the outlet biofilms were more diverse than those sampled at the inlet for all treatments. The lowest number of unique operational taxonomic units (OTUs) and lowest diversity was observed in the MF inlet. However, the MF system revealed the greatest increase in diversity and OTU count from inlet to outlet. Further, the biofilm communities at the outlet of each system were more similar to one another than to their respective inlet, suggesting that biofilm communities converge towards a common established equilibrium as distance from treatment application increases. Based on the results, MF treatment is most effective at inhibiting biofilm growth, but a highly efficient post-treatment disinfection regime is also critical in order to prevent the high rates of post-treatment regrowth. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sulphate reduction and vertical distribution of sulphate-reducing bacteria quantified by rRNA slot-blot hybridization in a coastal marine sediment

DEFF Research Database (Denmark)

Sahm, K.; MacGregor, BJ; Jørgensen, BB

1999-01-01

In the past, enumeration of sulphate-reducing bacteria (SRB) by cultivation-based methods generally contradicted measurements of sulphate reduction, suggesting unrealistically high respiration rates per cell. Here, we report evidence that quantification of SRB rRNA by slot-blot hybridization...... between 18% and 25% to the prokaryotic rRNA pool. The dominant SRB were related to complete oxidizing genera (Desulphococcus, Desulphosarcina and Desulphobacterium), while Desulpho-bacter could not be detected. The vertical profile and quantity of rRNA from SRB was compared with sulphate reduction rates......, directly above the sulphate reduction maximum. Cell numbers calculated by converting the relative contribution of SRB rRNA to the percentage of DAPI-stained cells indicated a population size for SRB of 2.4-6.1 x 10(8) cells cm(-3) wet sediment. Cellular sulphate reduction rates calculated on the basis...

Molecular Analysis of Bacterial Communities in Biofilms of a Drinking Water Clearwell

Science.gov (United States)

Zhang, Minglu; Liu, Wenjun; Nie, Xuebiao; Li, Cuiping; Gu, Junnong; Zhang, Can

2012-01-01

Microbial community structures in biofilms of a clearwell in a drinking water supply system in Beijing, China were examined by clone library, terminal restriction fragment length polymorphism (T-RFLP) and 454 pyrosequencing of the amplified 16S rRNA gene. Six biofilm samples (designated R1–R6) collected from six locations (upper and lower sites of the inlet, middle and outlet) of the clearwell revealed similar bacterial patterns by T-RFLP analysis. With respect to the dominant groups, the phylotypes detected by clone library and T-RFLP generally matched each other. A total of 9,543 reads were obtained from samples located at the lower inlet and the lower outlet sites by pyrosequencing. The bacterial diversity of the two samples was compared at phylum and genus levels. Alphaproteobacteria dominated the communities in both samples and the genus of Sphingomonas constituted 75.1%–99.6% of this phylum. A high level of Sphingomonas sp. was first observed in the drinking water biofilms with 0.6–1.0 mg L−1 of chlorine residual. Disinfectant-resistant microorganisms deserve special attention in drinking water management. This study provides novel insights into the microbial populations in drinking water systems and highlights the important role of Sphingomonas species in biofilm formation. PMID:23059725

Propolis-Sahara honeys preparation exhibits antibacterial and anti-biofilm activity against bacterial biofims formed on urinary catheters

Directory of Open Access Journals (Sweden)

Saad Aissat

2016-11-01

Full Text Available Objective: To evaluate the antibacterial effect of Sahara honeys (SHs against bacterial biofilms formed on urinary catheters in combination with propolis-Sahara honeys (P-SHs. Methods: Three clinical isolates were subjected to biofilm detection methods. The antibacterial and anti-biofilm activity for SHs and P-SHs were determined using agar well diffusion and the percentage of biofilm inhibition (PBI methods. Results: The PBI for Gram-positive bacteria [Staphylococcus aureus (S. aureus] was in the range of 0%–20%, while PBI for Gram-negative bacteria [Pseudomonas aeruginosa and Escherichia coli (E. coli] were in range of 17%–57% and 16%–65%, respectively. The highest PBI (65% was produced by SH2 only on E. coli. In agar well diffusion assay, zones of inhibition ranged from 11–20 mm (S. aureus, 9–19 mm (Pseudomonas aeruginosa and 11–19 mm (E. coli. The highest inhibition (20 mm was produced by SH1 only on S. aureus. In addition, the treatment of SHs and P-SHs catheters with a polymicrobial biofilms reduced biofilm formation after 48 h exposure period. Conclussions: SHs and P-SHs applied as a natural agent can be used as a prophylactic agent to prevent the formation of in vitro biofilm.

Bacterial biofilm formation versus mammalian cell growth on titanium-based mono- and bi-functional coating

Directory of Open Access Journals (Sweden)

G Subbiahdoss

2010-05-01

Full Text Available Biomaterials-associated-infections (BAI are serious complications in modern medicine. Although non-adhesive coatings, like polymer-brush coatings, have been shown to prevent bacterial adhesion, they do not support cell growth. Bi-functional coatings are supposed to prevent biofilm formation while supporting tissue integration. Here, bacterial and cellular responses to poly(ethylene glycol (PEG brush-coatings on titanium oxide presenting the integrin-active peptide RGD (arginine-glycine-aspartic acid (bioactive “PEG-RGD” were compared to mono-functional PEG brush-coatings (biopassive “PEG” and bare titanium oxide (TiO2 surfaces under flow. Staphylococcus epidermidis ATCC 35983 was deposited on the surfaces under a shear rate of 11 s-1 for 2 h followed by seeding of U2OS osteoblasts. Subsequently, both S. epidermidis and U2OS cells were grown simultaneously on the surfaces for 48 h under low shear (0.14 s-1. After 2 h, staphylococcal adhesion was reduced to 3.6±1.8 × 103 and 6.0±3.9 × 103 cm-2 on PEG and PEG-RGD coatings respectively, compared to 1.3±0.4 × 105 cm-2 for the TiO2 surface. When allowed to grow for 48 h, biofilms formed on all surfaces. However, biofilms detached from the PEG and PEG-RGD coatings when exposed to an elevated shear (5.6 s-1 U2OS cells neither adhered nor spread on PEG brush-coatings, regardless of the presence of biofilm. In contrast, in the presence of biofilm, U2OS cells adhered and spread on PEG-RGD coatings with a significantly higher surface coverage than on bare TiO2. The detachment of biofilm and the high cell surface coverage revealed the potential significance of PEG-RGD coatings in the context of the “race for the surface” between bacteria and mammalian cells.

Inhibition of Nitzschia ovalis biofilm settlement by a bacterial bioactive compound through alteration of EPS and epiphytic bacteria

Directory of Open Access Journals (Sweden)

Claudia D. Infante

2018-05-01

Full Text Available Background: Marine ecosystems contain benthic microalgae and bacterial species that are capable of secreting extracellular polymeric substances (EPS, suggesting that settlement of these microorganisms can occur on submerged surfaces, a key part of the first stage of biofouling. Currently, anti-fouling treatments that help control this phenomenon involve the use of biocides or antifouling paints that contain heavy metals, which over a long period of exposure can spread to the environment. The bacterium Alteromonas sp. Ni1-LEM has an inhibitory effect on the adhesion of Nitzschia ovalis, an abundant diatom found on submerged surfaces. Results: We evaluated the effect of the bioactive compound secreted by this bacterium on the EPS of biofilms and associated epiphytic bacteria. Three methods of EPS extraction were evaluated to determine the most appropriate and efficient methodology based on the presence of soluble EPS and the total protein and carbohydrate concentrations. Microalgae were cultured with the bacterial compound to evaluate its effect on EPS secretion and variations in its protein and carbohydrate concentrations. An effect of the bacterial supernatant on EPS was observed by assessing biofilm formation and changes in the concentration of proteins and carbohydrates present in the biofilm. Conclusions: These results indicate that a possible mechanism for regulating biofouling could be through alteration of biofilm EPS and alteration of the epiphytic bacterial community associated with the microalga.How to cite: Infante, C.D., Castillo, F., Pérez, V., et al. Inhibition of Nitzschia ovalis biofilm settlement by a bacterial bioactive compound through alteration of EPS and epiphytic bacteria. Electron J Biotechnol 2018;33 https://doi.org/10.1016/j.ejbt.2018.03.002. Keywords: Anti-fouling, Benthic microalgae, Biofilm, Biofouling, Epiphytic bacterial community, EPS, Marine ecosystems, Metagenomic, Nitzschia ovalis, Settlement inhibition

Effects of eutrophication, seasonality and macrofouling on the diversity of bacterial biofilms in equatorial coral reefs.

Directory of Open Access Journals (Sweden)

Yvonne Sawall

Full Text Available Biofilms play an important role as a settlement cue for invertebrate larvae and significantly contribute to the nutrient turnover in aquatic ecosystems. Nevertheless, little is known about how biofilm community structure generally responds to environmental changes. This study aimed to identify patterns of bacterial dynamics in coral reef biofilms in response to associated macrofouling community structure, microhabitat (exposed vs. sheltered, seasonality, and eutrophication. Settlement tiles were deployed at four reefs along a cross-shelf eutrophication gradient and were exchanged every 4 months over 20 months. The fouling community composition on the tiles was recorded and the bacterial community structure was assessed with the community fingerprinting technique Automated Ribosomal Intergenic Spacer Analysis (ARISA. Bacterial operational taxonomic unit (OTU number was higher on exposed tiles, where the fouling community was homogenous and algae-dominated, than in sheltered habitats, which were occupied by a variety of filter feeders. Furthermore, OTU number was also highest in eutrophied near-shore reefs, while seasonal variations in community structure were most pronounced in the oligotrophic mid-shelf reef. In contrast, the macrofouling community structure did not change significantly with seasons. Changes in bacterial community patterns were mostly affected by microhabitat, seasonal and anthropogenically derived changes in nutrient availability, and to a lesser extent by changes in the macrofouling community structure. Path analysis revealed a complex interplay of various environmental and biological factors explaining the spatial and temporal variations in bacterial biofilm communities under natural conditions.

Bacterial exopolysaccharide and biofilm formation stimulate chickpea growth and soil aggregation under salt stress

Directory of Open Access Journals (Sweden)

Aisha Waheed Qurashi

2012-09-01

Full Text Available To compensate for stress imposed by salinity, biofilm formation and exopolysaccharide production are significant strategies of salt tolerant bacteria to assist metabolism. We hypothesized that two previously isolated salt-tolerant strains Halomonas variabilis (HT1 and Planococcus rifietoensis (RT4 have an ability to improve plant growth, These strains can form biofilm and accumulate exopolysacharides at increasing salt stress. These results showed that bacteria might be involved in developing microbial communities under salt stress and helpful in colonizing of bacterial strains to plant roots and soil particles. Eventually, it can add to the plant growth and soil structure. We investigated the comparative effect of exopolysacharide and biofilm formation in two bacterial strains Halomonas variabilis (HT1 and Planococcus rifietoensis (RT4 in response to varying salt stress. We found that biofilm formation and exopolysaccharide accumulation increased at higher salinity. To check the effect of bacterial inoculation on the plant (Cicer arietinum Var. CM-98 growth and soil aggregation, pot experiment was conducted by growing seedlings under salt stress. Inoculation of both strains increased plant growth at elevated salt stress. Weight of soil aggregates attached with roots and present in soil were added at higher salt concentrations compared to untreated controls. Soil aggregation was higher at plant roots under salinity. These results suggest the feasibility of using above strains in improving plant growth and soil fertility under salinity.

The biofilm matrix destabilizers, EDTA and DNaseI, enhance the susceptibility of nontypeable Hemophilus influenzae biofilms to treatment with ampicillin and ciprofloxacin.

Science.gov (United States)

Cavaliere, Rosalia; Ball, Jessica L; Turnbull, Lynne; Whitchurch, Cynthia B

2014-08-01

Nontypeable Hemophilus influenzae (NTHi) is a Gram-negative bacterial pathogen that causes chronic biofilm infections of the ears and airways. The biofilm matrix provides structural integrity to the biofilm and protects biofilm cells from antibiotic exposure by reducing penetration of antimicrobial compounds into the biofilm. Extracellular DNA (eDNA) has been found to be a major matrix component of biofilms formed by many species of Gram-positive and Gram-negative bacteria, including NTHi. Interestingly, the cation chelator ethylenediaminetetra-acetic acid (EDTA) has been shown to reduce the matrix strength of biofilms of several bacterial species as well as to have bactericidal activity against various pathogens. EDTA exerts its antimicrobial activity by chelating divalent cations necessary for growth and membrane stability and by destabilizing the matrix thus enhancing the detachment of bacterial cells from the biofilm. In this study, we have explored the role of divalent cations in NTHi biofilm development and stability. We have utilized in vitro static and continuous flow models of biofilm development by NTHi to demonstrate that magnesium cations enhance biofilm formation by NTHi. We found that the divalent cation chelator EDTA is effective at both preventing NTHi biofilm formation and at treating established NTHi biofilms. Furthermore, we found that the matrix destablilizers EDTA and DNaseI increase the susceptibility of NTHi biofilms to ampicillin and ciprofloxacin. Our observations indicate that DNaseI and EDTA enhance the efficacy of antibiotic treatment of NTHi biofilms. These observations may lead to new strategies that will improve the treatment options available to patients with chronic NTHi infections. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The efficacy of different anti-microbial metals at preventing the formation of, and eradicating bacterial biofilms of pathogenic indicator strains.

Science.gov (United States)

Gugala, Natalie; Lemire, Joe A; Turner, Raymond J

2017-06-01

The emergence of multidrug-resistant pathogens and the prevalence of biofilm-related infections have generated a demand for alternative anti-microbial therapies. Metals have not been explored in adequate detail for their capacity to combat infectious disease. Metal compounds can now be found in textiles, medical devices and disinfectants-yet, we know little about their efficacy against specific pathogens. To help fill this knowledge gap, we report on the anti-microbial and antibiofilm activity of seven metals: silver, copper, titanium, gallium, nickel, aluminum and zinc against three bacterial strains, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. To evaluate the capacity of metal ions to prevent the growth of, and eradicate biofilms and planktonic cells, bacterial cultures were inoculated in the Calgary Biofilm Device (minimal biofilm eradication concentration) in the presence of the metal salts. Copper, gallium and titanium were capable of preventing planktonic and biofilm growth, and eradicating established biofilms of all tested strains. Further, we observed that the efficacies of the other tested metal salts displayed variable efficacy against the tested strains. Further, contrary to the enhanced resistance anticipated from bacterial biofilms, particular metal salts were observed to be more effective against biofilm communities versus planktonic cells. In this study, we have demonstrated that the identity of the bacterial strain must be considered before treatment with a particular metal ion. Consequent to the use of metal ions as anti-microbial agents to fight multidrug-resistant and biofilm-related infections increases, we must aim for more selective deployment in a given infectious setting.

Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species.

Science.gov (United States)

Brinkman, Cassandra L; Schmidt-Malan, Suzannah M; Karau, Melissa J; Greenwood-Quaintance, Kerryl; Hassett, Daniel J; Mandrekar, Jayawant N; Patel, Robin

2016-01-01

Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the 'electricidal effect', in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS.

[Bacterial diversity in sequencing batch biofilm reactor (SBBR) for landfill leachate treatment using PCR-DGGE].

Science.gov (United States)

Xiao, Yong; Yang, Zhao-hui; Zeng, Guang-ming; Ma, Yan-he; Liu, You-sheng; Wang, Rong-juan; Xu, Zheng-yong

2007-05-01

For studying the bacterial diversity and the mechanism of denitrification in sequencing bath biofilm reactor (SBBR) treating landfill leachate to provide microbial evidence for technique improvements, total microbial DNA was extracted from samples which were collected from natural landfill leachate and biofilm of a SBBR that could efficiently remove NH4+ -N and COD of high concentration. 16S rDNA fragments were amplified from the total DNA successfully using a pair of universal bacterial 16S rDNA primer, GC341F and 907R, and then were used for denaturing gradient gel electrophoresis (DGGE) analysis. The bands in the gel were analyzed by statistical methods and excided from the gel for sequencing, and the sequences were used for homology analysis and then two phylogenetic trees were constructed using DNAStar software. Results indicated that the bacterial diversity of the biofilm in SBBR and the landfill leachate was abundant, and no obvious change of community structure happened during running in the biofilm, in which most bacteria came from the landfill leachate. There may be three different modes of denitrification in the reactor because several different nitrifying bacteria, denitrifying bacteria and anaerobic ammonia oxidation bacteria coexisted in it. The results provided some valuable references for studying microbiological mechanism of denitrification in SBBR.

Maggot excretions inhibit biofilm formation on biomaterials.

Science.gov (United States)

Cazander, Gwendolyn; van de Veerdonk, Mariëlle C; Vandenbroucke-Grauls, Christina M J E; Schreurs, Marco W J; Jukema, Gerrolt N

2010-10-01

Biofilm-associated infections in trauma surgery are difficult to treat with conventional therapies. Therefore, it is important to develop new treatment modalities. Maggots in captured bags, which are permeable for larval excretions/secretions, aid in healing severe, infected wounds, suspect for biofilm formation. Therefore we presumed maggot excretions/secretions would reduce biofilm formation. We studied biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis, and Enterobacter cloacae on polyethylene, titanium, and stainless steel. We compared the quantities of biofilm formation between the bacterial species on the various biomaterials and the quantity of biofilm formation after various incubation times. Maggot excretions/secretions were added to existing biofilms to examine their effect. Comb-like models of the biomaterials, made to fit in a 96-well microtiter plate, were incubated with bacterial suspension. The formed biofilms were stained in crystal violet, which was eluted in ethanol. The optical density (at 595 nm) of the eluate was determined to quantify biofilm formation. Maggot excretions/secretions were pipetted in different concentrations to (nonstained) 7-day-old biofilms, incubated 24 hours, and finally measured. The strongest biofilms were formed by S. aureus and S. epidermidis on polyethylene and the weakest on titanium. The highest quantity of biofilm formation was reached within 7 days for both bacteria. The presence of excretions/secretions reduced biofilm formation on all biomaterials. A maximum of 92% of biofilm reduction was measured. Our observations suggest maggot excretions/secretions decrease biofilm formation and could provide a new treatment for biofilm formation on infected biomaterials.

The effect of sulphate-reducing bacteria biofilm on passivity and development of pitting on 2205 duplex stainless steel

International Nuclear Information System (INIS)

Dec, Weronika; Mosiałek, Michał; Socha, Robert P.; Jaworska-Kik, Marzena; Simka, Wojciech; Michalska, Joanna

2016-01-01

Results on biofilm formation and microbiologically influenced corrosion induced by pure D. desulfuricans strain on 2205 duplex stainless steel (DSS) are presented. Biofilm development stimulated by DSM642 standard strain was evaluated with reference to their metabolic activity and to the surface characterization including the structure and configuration of the biofilm. Electrochemical techniques (open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves) and X-ray photoelectron spectroscopy (XPS) were carried out to determine the effect of bacteria on the passivity and corrosion resistance of 2205 DSS. The electrochemical results showed that the DSS corrosion resistance was affected in the presence of DSM642 biofilm. This statement was based on the significant decrease in the charge transfer resistance (R_1) obtained from EIS and the increase in the measured current densities obtained from potentiodynamic polarization curves. Although the breakdown potentials (E_b) were still high, SEM observations revealed micropits as well as signs of crevice attack on the steel surface. Significant sulphidation of the passive film affected the nature of cathodic behaviour of steel and helped to impede micropit growth. XPS analysis revealed the layered structure of the biofilm. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C−N bonds were detected along the biofilm thickness in the XPS analysis.

Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

DEFF Research Database (Denmark)

Knoblauch, C.; Jørgensen, BB

1999-01-01

Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields...... at in site conditions....

Comparison of methods for the determination of reduced inorganic sulphur in acid sulphate soils

International Nuclear Information System (INIS)

Santomartino, S.L.

1999-01-01

Full text: The management of acid sulphate soils requires analytical methods that provide accurate data on the quantity of reduced inorganic sulphur within a soil, as it is this fraction that produces acid upon oxidation. This study uses sulphidic Coode Island Silt samples to compare common analytical methods including POCAS (Peroxide Oxidation-Combined Acidity and Sulphate) which consists of TSA (Total Sulphidic Acidity), S pos (Peroxide Oxidisable Sulphur), TOS (Total Oxidisable Sulphur) and chromium-reducible sulphur. The determination of total sulphur by Leco sulphur is strongly correlated with, but slightly less than, that analysed by XRF. Comparison of soil sulphide content by chromium-reducible sulphur, TSA and TOS methods indicates that TOS values are substantially higher than both other methods. The problem with the TOS method lies in the sulphate extraction procedure. Hot distilled water and HCI are commonly used as extractants, however hot distilled water fails to remove organic sulphur, thereby overestimating the sulphide content of the soil. Leco carbon analyses verify that a substantial proportion of organic matter exists within the samples. The HCI extraction process, which uses Ion Chromatography to analyse for sulphate, produces highly inaccurate results due to the interference of the sulphate peak by the chloride peak during analysis. An alternative method involving HCI extraction and XRF analysis of the soil residue is currently being undertaken. The use of KCI to extract sulphate generally produces values similar to the hot distilled water method. The sulphidic content measured by TSA is strongly correlated with, but slightly higher than that determined by the chromium-reducible sulphur method. This is attributed to the use of hydrogen peroxide in the TSA method, which oxidises organic matter to organic acids in addition to oxidising sulphides. These preliminary findings indicate that the chromium-reducible sulphur method is the most suitable

Disinfection of bacterial biofilms in pilot-scale cooling tower systems.

Science.gov (United States)

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P; Packman, Aaron I

2011-04-01

The impact of continuous chlorination and periodic glutaraldehyde treatment on planktonic and biofilm microbial communities was evaluated in pilot-scale cooling towers operated continuously for 3 months. The system was operated at a flow rate of 10,080 l day(-1). Experiments were performed with a well-defined microbial consortium containing three heterotrophic bacteria: Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. The persistence of each species was monitored in the recirculating cooling water loop and in biofilms on steel and PVC coupons in the cooling tower basin. The observed bacterial colonization in cooling towers did not follow trends in growth rates observed under batch conditions and, instead, reflected differences in the ability of each organism to remain attached and form biofilms under the high-through flow conditions in cooling towers. Flavobacterium was the dominant organism in the community, while P. aeruginosa and K. pneumoniae did not attach well to either PVC or steel coupons in cooling towers and were not able to persist in biofilms. As a result, the much greater ability of Flavobacterium to adhere to surfaces protected it from disinfection, whereas P. aeruginosa and K. pneumoniae were subject to rapid disinfection in the planktonic state.

Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation.

Science.gov (United States)

Rich, Joseph O; Leathers, Timothy D; Bischoff, Kenneth M; Anderson, Amber M; Nunnally, Melinda S

2015-11-01

Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grind corn fuel ethanol facility. Among eight sites sampled in the facility, the combined liquefaction stream and yeast propagation tank were consistently contaminated, leading to contamination of early fermentation tanks. Among 768 contaminants isolated, 92% were identified as Lactobacillus sp., with the most abundant species being Lactobacillus plantarum, Lactobacillus casei, Lactobacillus mucosae, and Lactobacillus fermentum. Seven percent of total isolates showed the ability to form biofilms in pure cultures, and 22% showed the capacity to significantly inhibit ethanol production. However, these traits were not correlated. Ethanol inhibition appeared to be related to acetic acid production by contaminants, particularly by obligately heterofermentative species such as L. fermentum and L. mucosae. Published by Elsevier Ltd.

Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

International Nuclear Information System (INIS)

Zrelli, K; Galy, O; Henry, N; Latour-Lambert, P; Ghigo, J M; Beloin, C; Kirwan, L

2013-01-01

Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms. (paper)

Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

Science.gov (United States)

Zrelli, K.; Galy, O.; Latour-Lambert, P.; Kirwan, L.; Ghigo, J. M.; Beloin, C.; Henry, N.

2013-12-01

Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms.

Treatment of biofilms in bacterial vaginosis by an amphoteric tenside pessary-clinical study and microbiota analysis.

Science.gov (United States)

Gottschick, Cornelia; Deng, Zhi-Luo; Vital, Marius; Masur, Clarissa; Abels, Christoph; Pieper, Dietmar H; Rohde, Manfred; Mendling, Werner; Wagner-Döbler, Irene

2017-09-13

Bacterial vaginosis (BV) is the most common vaginal syndrome among women in their reproductive years. It is associated with an increased risk of acquiring sexually transmitted infections and complications like preterm labor. BV is characterized by a high recurrence rate for which biofilms frequently found on vaginal epithelial cells may be a reason. Here, we report a controlled randomized clinical trial that tested the safety and effectiveness of a newly developed pessary containing an amphoteric tenside (WO3191) to disrupt biofilms after metronidazole treatment of BV. Pessaries containing lactic acid were provided to the control group, and microbial community composition was determined via Illumina sequencing of the V1-V2 region of the 16S rRNA gene. The most common community state type (CST) in healthy women was characterized by Lactobacillus crispatus. In BV, diversity was high with communities dominated by either Lactobacillus iners, Prevotella bivia, Sneathia amnii, or Prevotella amnii. Women with BV and proven biofilms had an increased abundance of Sneathia sanguinegens and a decreased abundance of Gardnerella vaginalis. Following metronidazole treatment, clinical symptoms cleared, Nugent score shifted to Lactobacillus dominance, biofilms disappeared, and diversity (Shannon index) was reduced in most women. Most of the patients responding to therapy exhibited a L. iners CST. Treatment with WO 3191 reduced biofilms but did not prevent recurrence. Women with high diversity after antibiotic treatment were more likely to develop recurrence. Stabilizing the low diversity healthy flora by promoting growth of health-associated Lactobacillus sp. such as L. crispatus may be beneficial for long-term female health. ClinicalTrials.gov NCT02687789.

Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

Science.gov (United States)

Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

2016-10-01

Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

Biofilm is a Major Virulence Determinant in Bacterial Colonization of Chronic Skin Ulcers Independently from the Multidrug Resistant Phenotype

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Enea Gino Di Domenico

2017-05-01

Full Text Available Bacterial biofilm is a major factor in delayed wound healing and high levels of biofilm production have been repeatedly described in multidrug resistant organisms (MDROs. Nevertheless, a quantitative correlation between biofilm production and the profile of antimicrobial drug resistance in delayed wound healing remains to be determined. Microbial identification, antibiotic susceptibility and biofilm production were assessed in 135 clinical isolates from 87 patients. Gram-negative bacteria were the most represented microorganisms (60.8% with MDROs accounting for 31.8% of the total isolates. Assessment of biofilm production revealed that 80% of the strains were able to form biofilm. A comparable level of biofilm production was found with both MDRO and not-MDRO with no significant differences between groups. All the methicillin-resistant Staphylococcus aureus (MRSA and 80% of Pseudomonas aeruginosa MDR strains were found as moderate/high biofilm producers. Conversely, less than 17% of Klebsiella pneumoniae extended-spectrum beta-lactamase (ESBL, Escherichia coli-ESBL and Acinetobacter baumannii were moderate/high biofilm producers. Notably, those strains classified as non-biofilm producers, were always associated with biofilm producer bacteria in polymicrobial colonization. This study shows that biofilm producers were present in all chronic skin ulcers, suggesting that biofilm represents a key virulence determinant in promoting bacterial persistence and chronicity of ulcerative lesions independently from the MDRO phenotype.

Balancing the organic load and light supply in symbiotic microalgal–bacterial biofilm reactors treating synthetic municipal wastewater

NARCIS (Netherlands)

Boelee, N.C.; Temmink, B.G.; Janssen, M.; Buisman, C.J.N.; Wijffels, R.H.

2014-01-01

Symbiotic microalgal–bacterial biofilms can be very attractive for municipal wastewater treatment. Microalgae remove nitrogen and phosphorus and simultaneously produce the oxygen that is required for the aerobic, heterotrophic degradation of organic pollutants. For the application of these biofilms

Surface physicochemical properties at the micro and nano length scales: role on bacterial adhesion and Xylella fastidiosa biofilm development.

Science.gov (United States)

Lorite, Gabriela S; Janissen, Richard; Clerici, João H; Rodrigues, Carolina M; Tomaz, Juarez P; Mizaikoff, Boris; Kranz, Christine; de Souza, Alessandra A; Cotta, Mônica A

2013-01-01

The phytopathogen Xylella fastidiosa grows as a biofilm causing vascular occlusion and consequently nutrient and water stress in different plant hosts by adhesion on xylem vessel surfaces composed of cellulose, hemicellulose, pectin and proteins. Understanding the factors which influence bacterial adhesion and biofilm development is a key issue in identifying mechanisms for preventing biofilm formation in infected plants. In this study, we show that X. fastidiosa biofilm development and architecture correlate well with physicochemical surface properties after interaction with the culture medium. Different biotic and abiotic substrates such as silicon (Si) and derivatized cellulose films were studied. Both biofilms and substrates were characterized at the micro- and nanoscale, which corresponds to the actual bacterial cell and membrane/ protein length scales, respectively. Our experimental results clearly indicate that the presence of surfaces with different chemical composition affect X. fastidiosa behavior from the point of view of gene expression and adhesion functionality. Bacterial adhesion is facilitated on more hydrophilic surfaces with higher surface potentials; XadA1 adhesin reveals different strengths of interaction on these surfaces. Nonetheless, despite different architectural biofilm geometries and rates of development, the colonization process occurs on all investigated surfaces. Our results univocally support the hypothesis that different adhesion mechanisms are active along the biofilm life cycle representing an adaptation mechanism for variations on the specific xylem vessel composition, which the bacterium encounters within the infected plant.

Polyphasic analysis of an Azoarcus-Leptothrix-dominated bacterial biofilm developed on stainless steel surface in a gasoline-contaminated hypoxic groundwater.

Science.gov (United States)

Benedek, Tibor; Táncsics, András; Szabó, István; Farkas, Milán; Szoboszlay, Sándor; Fábián, Krisztina; Maróti, Gergely; Kriszt, Balázs

2016-05-01

Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of β-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems.

Bacterial community dynamics during the early stages of biofilm formation in a chlorinated experimental drinking water distribution system: implications for drinking water discolouration.

Science.gov (United States)

Douterelo, I; Sharpe, R; Boxall, J

2014-07-01

To characterize bacterial communities during the early stages of biofilm formation and their role in water discolouration in a fully representative, chlorinated, experimental drinking water distribution systems (DWDS). Biofilm development was monitored in an experimental DWDS over 28 days; subsequently the system was disturbed by raising hydraulic conditions to simulate pipe burst, cleaning or other system conditions. Biofilm cell cover was monitored by fluorescent microscopy and a fingerprinting technique used to assess changes in bacterial community. Selected samples were analysed by cloning and sequencing of the 16S rRNA gene. Fingerprinting analysis revealed significant changes in the bacterial community structure over time (P < 0·05). Cell coverage increased over time accompanied by an increase in bacterial richness and diversity. Shifts in the bacterial community structure were observed along with an increase in cell coverage, bacterial richness and diversity. Species related to Pseudomonas spp. and Janthinobacterium spp. dominated the process of initial attachment. Based on fingerprinting results, the hydraulic regimes did not affect the bacteriological composition of biofilms, but they did influence their mechanical stability. This study gives a better insight into the early stages of biofilm formation in DWDS and will contribute to the improvement of management strategies to control the formation of biofilms and the risk of discolouration. © 2014 The Authors. published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.

Bacterial community dynamics during the early stages of biofilm formation in a chlorinated experimental drinking water distribution system: implications for drinking water discolouration

Science.gov (United States)

Douterelo, I; Sharpe, R; Boxall, J

2014-01-01

Aims To characterize bacterial communities during the early stages of biofilm formation and their role in water discolouration in a fully representative, chlorinated, experimental drinking water distribution systems (DWDS). Methods and Results Biofilm development was monitored in an experimental DWDS over 28 days; subsequently the system was disturbed by raising hydraulic conditions to simulate pipe burst, cleaning or other system conditions. Biofilm cell cover was monitored by fluorescent microscopy and a fingerprinting technique used to assess changes in bacterial community. Selected samples were analysed by cloning and sequencing of the 16S rRNA gene. Fingerprinting analysis revealed significant changes in the bacterial community structure over time (P < 0·05). Cell coverage increased over time accompanied by an increase in bacterial richness and diversity. Conclusions Shifts in the bacterial community structure were observed along with an increase in cell coverage, bacterial richness and diversity. Species related to Pseudomonas spp. and Janthinobacterium spp. dominated the process of initial attachment. Based on fingerprinting results, the hydraulic regimes did not affect the bacteriological composition of biofilms, but they did influence their mechanical stability. Significance and Importance of the Study This study gives a better insight into the early stages of biofilm formation in DWDS and will contribute to the improvement of management strategies to control the formation of biofilms and the risk of discolouration. PMID:24712449

Heterogeneous corrosion of mild steel under SRB-biofilm characterised by electrochemical mapping technique

International Nuclear Information System (INIS)

Dong Zehua; Shi Wei; Ruan Hongmei; Zhang Guoan

2011-01-01

Highlights: → Highly conductive SRB-biofilm can shield the potential differences of mild steel. → Potential maps fail to indicate the localised corrosion of steel under SRB-biofilm. → Galvanic current maps can detect the location of localised corrosion under biofilm. → SRB-biofilm is super-capacitive due to the conductive sulphide micropores. - Abstract: Heterogeneous corrosion of mild steel under sulphate reducing bacteria (SRB)-biofilm was characterised by wire beam electrode (WBE) technique and electrochemical impedance spectrum. The potential/current distributions of the WBE under SRB-biofilm showed that the potential maps could not indicate the localised corrosion of steels beneath biofilm due to the fact that all wire electrodes were short-circuited by the highly conductive sulphide precipitates embedded in SRB-biofilm. Instead, the galvanic current maps may give a good indication. The characteristic of super-capacitance (0.21 F/cm 2 ) of SRB-biofilm was attributed to the huge specific surface area of conductive pore walls inside biofilm.

Bacterial community radial-spatial distribution in biofilms along pipe wall in chlorinated drinking water distribution system of East China.

Science.gov (United States)

Liu, Jingqing; Ren, Hongxing; Ye, Xianbei; Wang, Wei; Liu, Yan; Lou, Liping; Cheng, Dongqing; He, Xiaofang; Zhou, Xiaoyan; Qiu, Shangde; Fu, Liusong; Hu, Baolan

2017-01-01

Biofilms in the pipe wall may lead to water quality deterioration and biological instability in drinking water distribution systems (DWDSs). In this study, bacterial community radial-spatial distribution in biofilms along the pipe wall in a chlorinated DWDS of East China was investigated. Three pipes of large diameter (300, 600, and 600 mm) were sampled in this DWDS, including a ductile cast iron pipe (DCIP) with pipe age of 11 years and two gray cast iron pipes (GCIP) with pipe ages of 17 and 19 years, and biofilms in the upper, middle, and lower parts of each pipe wall were collected. Real-time quantitative polymerase chain reaction (qPCR) and culture-based method were used to quantify bacteria. 454 pyrosequencing was used for bacterial community analysis. The results showed that the biofilm density and total solid (TS) and volatile solid (VS) contents increased gradually from the top to the bottom along the pipe wall. Microorganisms were concentrated in the upper and lower parts of the pipe wall, together accounting for more than 80 % of the total biomass in the biofilms. The bacterial communities in biofilms were significantly different in different areas of the pipe wall and had no strong interaction. Compared with the upper and lower parts of the pipe wall, the bacterial community in the middle of the pipe wall was distributed evenly and had the highest diversity. The 16S rRNA genes of various possible pathogens, including Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Salmonella enterica, were detected in the biofilms, and the abundances of these possible pathogens were highest in the middle of the pipe wall among three areas. The detachment of the biofilms is the main reason for the deterioration of the water quality in DWDSs. The results of this study suggest that the biofilms in the middle of the pipe wall have highly potential risk for drinking water safety, which provides new ideas for the study of the microbial ecology in

Effect of radiation on activity of sulphate reducing bacteria

International Nuclear Information System (INIS)

Agaev, N.M.; Smorodin, A.E.; Gusejnov, M.M.

1985-01-01

The effect of γ-radiation on activity of sulphate reducing bacteria has been studied. Concentration of biogenic hydrogen, generated in the medium, is the main criterion, characterizing corrosion activity of the bacteria studied. The developed method of suppression of active development of sulfate reducing bacteria considerably reduces, and at lethal doses of γ-radiation eliminates altogether the bacteria activity and formation of the main corrosion agent-hydrogen sulphide-in the medium and that, in its turn, liquidates hydrogen sulphide corrosion

Bacteriophage Isolated from Sewage Eliminates and Prevents the Establishment of Escherichia Coli Biofilm

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Karla Veloso Gonçalves Ribeiro

2018-03-01

Full Text Available Purpose: Biofilm growth exerts a negative impact on industry and health, necessitating the development of strategies to control. The objective of this work was study the lytic activity of the phage isolated from the sewage network in the formation and degradation of Escherichia coli biofilms. Methods: E. coli cultures were incubated in 96-well polystyrene microplates under controlled conditions to evaluate the biofilm formation. The E. coli cultures and established biofilms were treated with the suspensions of the vB_EcoM-UFV017 (EcoM017 bacteriophage obtained from sewage for 24 hours. The E. coli bacterial density was measured using absorbance at 600 nm and the biofilms were measured by crystal violet staining. Polystyrene coupons were used as support for Scanning Electron Microscopy and Confocal Microscopy to evaluate biofilm formation. Results: The E. coli strains formed biofilms in polystyrene microplates after 48 hours’ incubation. The highest EcoM017 phage titer, in the prevention and degradation experiments, reduced the bacterial growth and the quantity of biofilm formed by E. coli in 90.0% and 87.5%, respectively. The minimum dose capable of reducing the biofilms of this bacterium was 101 PFU/mL after 24 hours. The preformed E. coli biofilm mass was reduced 79% post exposure to the phage in the degradation assay. Microscopic analysis confirmed the results obtained in the plates assays. Conclusion: The EcoM017 phage prevented biofilm formation and degraded the E. coli-established ones. The EcoM017 phage isolated from sewage can reduce bacterial attachment and lyse the E. coli associated biofilm cells, offering biotechnological potential applicability for this phage.

Wound biofilms: lessons learned from oral biofilms

OpenAIRE

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 relati...

Biogenic selenium and tellurium nanoparticles synthesized by environmental microbial isolates efficaciously inhibit bacterial planktonic cultures and biofilms

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Emanuele eZonaro

2015-06-01

Full Text Available The present study deals with Se0- and Te0-based nanoparticles bio-synthesized by two selenite- and tellurite-reducing bacterial strains, namely Stenotrophomonas maltophilia SeITE02 and Ochrobactrum sp. MPV1, isolated from polluted sites. We discovered that, by regulating culture conditions and exposure time to the selenite and tellurite oxyanions, differently sized zero-valent Se and Te nanoparticles were produced. The results revealed that these Se0 and Te0 nanoparticles possess antimicrobial and biofilm eradication activity against E. coli JM109, P. aeruginosa PAO1, and S. aureus ATCC 25923. In particular, Se0 nanoparticles exhibited antimicrobial activity at quite low concentrations, below that of selenite. Toxic effects of both Se0 and Te0 nanoparticles can be related to the production of reactive oxygen species upon exposure of the bacterial cultures. Evidence so far achieved suggests that the antimicrobial activity seems to be strictly linked to the dimensions of the nanoparticles: indeed, the highest activity was shown by nanoparticles of smaller sizes. In particular, it is worth noting how the bacteria tested in biofilm mode responded to the treatment by Se0 and Te0 nanoparticles with a susceptibility similar to that observed in planktonic cultures. This suggests a possible exploitation of both Se0 and Te0 nanoparticles as efficacious antimicrobial agents with a remarkable biofilm eradication capacity.

Combination of cupric ion with hydroxylamine and hydrogen peroxide for the control of bacterial biofilms on RO membranes.

Science.gov (United States)

Lee, Hye-Jin; Kim, Hyung-Eun; Lee, Changha

2017-03-01

Combinations of Cu(II) with hydroxylamine (HA) and hydrogen peroxide (H 2 O 2 ) (i.e., Cu(II)/HA, Cu(II)/H 2 O 2 , and Cu(II)/HA/H 2 O 2 systems) were investigated for the control of P. aeruginosa biofilms on reverse osmosis (RO) membranes. These Cu(II)-based disinfection systems effectively inactivated P. aeruginosa cells, exhibiting different behaviors depending on the state of bacterial cells (planktonic or biofilm) and the condition of biofilm growth and treatment (normal or pressurized condition). The Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems were the most effective reagents for the inactivation of planktonic cells. However, these systems were not effective in inactivating cells in biofilms on the RO membranes possibly due to the interactions of Cu(I) with extracellular polymeric substances (EPS), where biofilms were grown and treated in center for disease control (CDC) reactors. Different from the results using CDC reactors, in a pressurized cross-flow RO filtration unit, the Cu(II)/HA/H 2 O 2 treatment significantly inactivated biofilm cells formed on the RO membranes, successfully recovering the permeate flux reduced by the biofouling. The pretreatment of feed solutions by Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems (applied before the biofilm formation) effectively mitigated the permeate flux decline by preventing the biofilm growth on the RO membranes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nonabsorbable Antibiotics Reduce Bacterial and Endotoxin Translocation in Hepatectomised Rats

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S. K. Kakkos

1997-01-01

Full Text Available There is increasing evidence that septic complications, occurring after major hepatectomies, may be caused by gram negative bacteria, translocating from the gut. We investigated in rats, the effect of extended hepatectomy on the structure and morphology of the intestinal mucosa as well as on the translocation of intestinal bacteria and endotoxins. We also examined the effect of nonabsorbable antibiotics on reducing the intestinal flora and consequently the phenomenon of translocation by administering neomycin sulphate and cefazoline. Hepatectomy was found to increase translocation, while administration of nonabsorbable antibiotics decreased it significantly. In addition, hepatectomy increased the aerobic cecal bacterial population, which normalised in the group receiving antibiotics. Among the histological parameters evaluated, villus height demonstrated a significant reduction after hepatectomy, while the number of villi per cm and the number of mitoses per crypt, remained unchanged. Our results indicate that administration of nonabsorbable antibiotics presents a positive effect on bacterial and endotoxin translocation after extended hepatectomy, and this may be related to reduction of colonic bacterial load as an intraluminal effect of antibiotics.

Characteristics of hydrogen evolution and oxidation catalyzed by Desulfovibrio caledoniensis biofilm on pyrolytic graphite electrode

International Nuclear Information System (INIS)

Yu Lin; Duan Jizhou; Zhao Wei; Huang Yanliang; Hou Baorong

2011-01-01

Highlights: → The sulphate-reducing bacteria (SRB) have the ability to catalyze the hydrogen evolution and oxidation on pyrolytic graphite electrode. → The SRB biofilm decreases the overpotential and electron transfer resistance by the CV and EIS detection. → The SRB biofilm can transfer electrons to the 0.24 V polarized pyrolytic graphite electrode and the maximum current is 0.035 mA, which is attributed to SRB catalyzed hydrogen oxidation. → The SRB biofilm also can obtain electron from the -0.61 V polarized PGE to catalyze the hydrogen evolution. - Abstract: Hydrogenase, an important electroactive enzyme of sulphate-reducing bacteria (SRB), has been discovered having the capacity to connect its activity to solid electrodes by catalyzing hydrogen evolution and oxidation. However, little attention has been paid to similar electroactive characteristics of SRB. In this study, the electroactivities of pyrolytic graphite electrode (PGE) coated with SRB biofilm were investigated. Two corresponding redox peaks were observed by cyclic voltammetry detection, which were related to the hydrogen evolution and oxidation. Moreover, the overpotential for the reactions decreased by about 0.2 V in the presence of the SRB biofilm. When the PGE coated with the SRB biofilm was polarized at 0.24 V (vs. SHE), an oxidation current related to the hydrogen oxidation was found. The SRB biofilm was able to obtain electrons from the -0.61 V (vs. SHE) polarized PGE to form hydrogen, and the electron transfer resistance also decreased with the formation of SRB biofilm, as measured by the non-destructive electrochemical impendence spectroscopy detection. It was concluded that the hydrogen evolution and oxidation was an important way for the electron transfer between SRB biofilm and solid electrode in anaerobic environment.

Establishing bacterial communities by 'word of mouth': LuxS and autoinducer 2 in biofilm development.

Science.gov (United States)

Hardie, Kim Rachael; Heurlier, Karin

2008-08-01

Multicellular bacterial communities (biofilms) abound in nature, and their successful formation and survival is likely to require cell-cell communication--including quorum sensing--to co-ordinate appropriate gene expression. The only mode of quorum sensing that is shared by both Gram-positive and Gram-negative bacteria involves the production of the signalling molecule autoinducer 2 by LuxS. A survey of the current literature reveals that luxS contributes to biofilm development in some bacteria. However, inconsistencies prevent biofilm development being attributed to the production of AI2 in all cases.

Biotreatment of Cr(VI) contaminated waters by sulphate reducing bacteria fed with ethanol

International Nuclear Information System (INIS)

Pagnanelli, F.; Cruz Viggi, C.; Cibati, A.; Uccelletti, D.; Toro, L.; Palleschi, C.

2012-01-01

Highlights: ► Use of ethanol as electron donor for sulphate-reducing bacteria for the treatment of Cr(VI). ► Isolation of contribution in Cr removal (adsorption vs. bioprecipitation). ► Bioassessment of the process effectiveness by ecotoxicological in vivo tests using C. elegans. - Abstract: Biological treatment of Cr(VI) contaminated waters was performed in fixed bed reactors inoculated with SRB (sulphate-reducing bacteria) growing on ethanol. Treatment efficiency was evaluated by checking chemical abatement of Cr(VI) and by ecotoxicological tests using the nematode Caenorhabditis elegans. A preliminary comparison between ethanol and lactate was performed, denoting that using ethanol, the same values of final sulphate abatement were obtained. In addition ethanol showed to be a substrate more competitive than lactate in kinetic terms. Fixed bed column reactors were continuously fed with a solution containing sulphates (3 g L −1 ), ethanol (1.5 g L −1 ) and Cr(VI) (50 mg L −1 ). At steady state the column inoculated with SRB removed 65 ± 5% of sulphate and 95 ± 5% of chromium. Bioactive removal mechanisms predominated over biosorption. Diminution of Cr(VI) toxicity was assessed by using the nematode C. elegans as a test organism showing that the survival of nematodes was 20% in the presence of the untreated influent and raised up to 53% when the nematodes were exposed to the treated effluent.

Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis.

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Xiuchun Ge

Full Text Available Biofilms play important roles in microbial communities and are related to infectious diseases. Here, we report direct evidence that a bacterial nox gene encoding NADH oxidase is involved in biofilm formation. A dramatic reduction in biofilm formation was observed in a Streptococcus sanguinis nox mutant under anaerobic conditions without any decrease in growth. The membrane fluidity of the mutant bacterial cells was found to be decreased and the fatty acid composition altered, with increased palmitic acid and decreased stearic acid and vaccenic acid. Extracellular DNA of the mutant was reduced in abundance and bacterial competence was suppressed. Gene expression analysis in the mutant identified two genes with altered expression, gtfP and Idh, which were found to be related to biofilm formation through examination of their deletion mutants. NADH oxidase-related metabolic pathways were analyzed, further clarifying the function of this enzyme in biofilm formation.

Novel approaches to mitigating bacterial biofilm formation and intercellular communication

Science.gov (United States)

Kasper, Stephen H.

Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical signals, often controlling the expression of diverse virulence factors (e.g. toxins, proteases). Biofilm formation and QS are cooperative processes that are often leveraged as bacteria coordinate infection processes, and can therefore be novel targets for anti-infective treatments that differ from conventional antibiotic treatment. Our lab has previously identified a novel class of small molecules that inhibit biofilm formation and disrupt QS by the pathogenic bacterium Pseudomonas aeruginosa. These organosulfur-based compounds are either natural products or related derivatives of the tropical plant Petiveria alliacea. Because oral biofilm (e.g. dental plaque) is a major conduit of oral and systemic disease, and is also a site for horizontal transfer for genes encoding antibiotic resistance, there exists a need for novel strategies for inhibiting oral biofilm development. Therefore, a small library (˜50 compounds) of structural derivatives was developed and screened for their ability to inhibit biofilm formation by multiple orally associated bacteria. The screening effort uncovered several related compounds that inhibited oral biofilm development. To determine how natural product-based organosulfur compounds could be inducing QS inhibitory effects, an

Cold Plasma Inactivation of Bacterial Biofilms and Reduction of Quorum Sensing Regulated Virulence Factors.

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Dana Ziuzina

Full Text Available The main objectives of this work were to investigate the effect of atmospheric cold plasma (ACP against a range of microbial biofilms commonly implicated in foodborne and healthcare associated human infections and against P. aeruginosa quorum sensing (QS-regulated virulence factors, such as pyocyanin, elastase (Las B and biofilm formation capacity post-ACP treatment. The effect of processing factors, namely treatment time and mode of plasma exposure on antimicrobial activity of ACP were also examined. Antibiofilm activity was assessed for E. coli, L. monocytogenes and S. aureus in terms of reduction of culturability and retention of metabolic activity using colony count and XTT assays, respectively. All samples were treated 'inpack' using sealed polypropylene containers with a high voltage dielectric barrier discharge ACP generated at 80 kV for 0, 60, 120 and 300 s and a post treatment storage time of 24 h. According to colony counts, ACP treatment for 60 s reduced populations of E. coli to undetectable levels, whereas 300 s was necessary to significantly reduce populations of L. monocytogenes and S. aureus biofilms. The results obtained from XTT assay indicated possible induction of viable but non culturable state of bacteria. With respect to P. aeruginosa QS-related virulence factors, the production of pyocyanin was significantly inhibited after short treatment times, but reduction of elastase was notable only after 300 s and no reduction in actual biofilm formation was achieved post-ACP treatment. Importantly, reduction of virulence factors was associated with reduction of the cytotoxic effects of the bacterial supernatant on CHO-K1 cells, regardless of mode and duration of treatment. The results of this study point to ACP technology as an effective strategy for inactivation of established biofilms and may play an important role in attenuation of virulence of pathogenic bacteria. Further investigation is warranted to propose direct evidence

Bacterial community changes in copper and PEX drinking water pipeline biofilms under extra disinfection and magnetic water treatment.

Science.gov (United States)

Inkinen, J; Jayaprakash, B; Ahonen, M; Pitkänen, T; Mäkinen, R; Pursiainen, A; Santo Domingo, J W; Salonen, H; Elk, M; Keinänen-Toivola, M M

2018-02-01

To study the stability of biofilms and water quality in pilot scale drinking water copper and PEX pipes in changing conditions (extra disinfection, magnetic water treatment, MWT). Next-generation sequencing (NGS) of 16S ribosomal RNA genes (rDNA) to describe total bacterial community and ribosomal RNA (rRNA) to describe active bacterial members in addition to traditional microbiological methods were applied. Biofilms from control copper and PEX pipes shared same most abundant bacteria (Methylobacterium spp., Sphingomonas spp., Zymomonas spp.) and average species diversities (Shannon 3·8-4·2) in rDNA and rRNA libraries, whereas few of the taxa differed by their abundance such as lower total Mycobacterium spp. occurrence in copper (disinfection (total chlorine increase from c. 0·5 to 1 mg l -1 ) affected total and active population in biofilms seen as decrease in many bacterial species and diversity (Shannon 2·7, P disinfected copper and PEX samples formed separate clusters in unweighted non-metric multidimensional scaling plot (rRNA) similarly to MWT-treated biofilms of copper (but not PEX) pipes that instead showed higher species diversity (Shannon 4·8, P < 0·05 interaction). Minor chlorine dose addition increased selection pressure and many species were sensitive to chlorination. Pipe material seemed to affect mycobacteria occurrence, and bacterial communities with MWT in copper but not in PEX pipes. This study using rRNA showed that chlorination affects especially active fraction of bacterial communities. Copper and PEX differed by the occurrence of some bacterial members despite similar community profiles. © 2017 The Society for Applied Microbiology.

Detection of Sulphate-Reducing Bacteria and Others Cultivable Facultative Bacteria in Dental Tissues

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Lúcio de Souza Gonçalves

2014-01-01

Full Text Available Aim: To detect for the presence of sulphate-reducing bacteria (SRB and evaluate the possible association between SRB and cultivable facultative bacterial of oral sites with different periodontal conditions. Methods: The study was carried out on 9 samples from different oral sites in 8 patients (two samples were collected from the same patient. Material was collected using modified Postgate E culture medium, indicated for the growth and isolation of SRB. In addition, a reducing solution for anaerobic bacteria was used as a transport solution for facultative bacteria and identified by polymerase chain reaction amplification (PCR and sequencing of the 16S rRNA gene. Results: SRB was found in 3 patient samples: the first in a root fragment, the second in a root fragment and a healthy tooth with vertical bone loss and a mobility degree of 3; and the third in a healthy tooth extracted for orthodontic treatment. In the final patient, the cultivable facultative species Lactobacillus casei was identified. Other facultative bacterial species were identified in patient 5 (Kurthia Gibsonii and patient 7 (Pseudomonas aeruginosa. Conclusions: The detection of SRB in different dental tissues with distinct periodontal features demonstrated that new studies need to be developed in order to determine the true role of SRB in the oral microbiota. In addition, it was possible to verify the presence of Lactobacillus casei together with SRB in one sample.

Influence of type-I fimbriae and fluid shear stress on bacterial behavior and multicellular architecture of early Escherichia coli biofilms at single-cell resolution.

Science.gov (United States)

Wang, Liyun; Keatch, Robert; Zhao, Qi; Wright, John A; Bryant, Clare E; Redmann, Anna L; Terentjev, Eugene M

2018-01-12

Biofilm formation on abiotic surfaces in food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine cellular architecture of early biofilms and bacterial behavior of the constituent cells remains largely unknown. In this study we examine the specific role of type-I fimbriae in nascent stages of biofilm formation and the response of micro-colonies to environmental flow shear at single-cell resolution. The results show that type-I fimbriae are not required for reversible adhesion from plankton, but critical for irreversible adhesion of Escherichia coli ( E.coli ) MG1655 forming biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing a firm cell-surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E.coli on the surface. After application of shear stress, bacterial retention is dominated by the 3D architecture of colonies independent of the population and the multi-layered structure could protect the embedded cells from being insulted by fluid shear, while cell membrane permeability mainly depends on the biofilm population and the duration time of the shear stress. Importance Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level, thus little is known about how individual bacterial behavior within biofilms and multicellular architecture are influenced by bacterial appendages (e.g. pili/fimbriae) and environmental factors during early biofilm formation. We apply Confocal Laser Scanning Microscopy (CLSM) to visualize E.coli micro-colonies at single-cell resolution. Our findings suggest that type-I fimbriae are vital to the initiation of bacterial proliferation on surfaces and that the responses of biofilm architecture and cell membrane permeability of constituent bacteria to fluid shear stress are different, which are

Bio-corrosion of water pipeline by sulphate-reducing bacteria in a ...

African Journals Online (AJOL)

esiri

2013-11-13

Nov 13, 2013 ... Key words: Sulphate-reducing bacteria, corrosion, water pipeline, biocide. INTRODUCTION ... small amount of organic material required to produce biomass):. )1(. 3. 2 .... Oil, gas and shipping industries are seriously affected.

CHANGES IN BACTERIAL COMPOSITION OF BIOFILM IN A METROPOLITAN DRINKING WATER DISTRIBUTION SYSTEM

Science.gov (United States)

This study examined the development of bacterial biofilms within a metropolitan distribution system. The distribution system is fed with different source water (i.e., groundwater, GW and surface water, SW) and undergoes different treatment processes in separate facilities. The b...

Establishment and Early Succession of Bacterial Communities in Monochloramine-Treated Drinking Water Biofilms

Science.gov (United States)

Monochloramine is increasingly used as a drinking water disinfectant because it forms lower levels of regulated disinfection by-products. While its use has been shown to increase nitrifying bacteria, little is known about the bacterial succession within biofilms in monochloramin...

Reproducible Biofilm Cultivation of Chemostat-Grown Escherichia coli and Investigation of Bacterial Adhesion on Biomaterials Using a Non-Constant-Depth Film Fermenter

Science.gov (United States)

Lüdecke, Claudia; Jandt, Klaus D.; Siegismund, Daniel; Kujau, Marian J.; Zang, Emerson; Rettenmayr, Markus; Bossert, Jörg; Roth, Martin

2014-01-01

Biomaterials-associated infections are primarily initiated by the adhesion of microorganisms on the biomaterial surfaces and subsequent biofilm formation. Understanding the fundamental microbial adhesion mechanisms and biofilm development is crucial for developing strategies to prevent such infections. Suitable in vitro systems for biofilm cultivation and bacterial adhesion at controllable, constant and reproducible conditions are indispensable. This study aimed (i) to modify the previously described constant-depth film fermenter for the reproducible cultivation of biofilms at non-depth-restricted, constant and low shear conditions and (ii) to use this system to elucidate bacterial adhesion kinetics on different biomaterials, focusing on biomaterials surface nanoroughness and hydrophobicity. Chemostat-grown Escherichia coli were used for biofilm cultivation on titanium oxide and investigating bacterial adhesion over time on titanium oxide, poly(styrene), poly(tetrafluoroethylene) and glass. Using chemostat-grown microbial cells (single-species continuous culture) minimized variations between the biofilms cultivated during different experimental runs. Bacterial adhesion on biomaterials comprised an initial lag-phase I followed by a fast adhesion phase II and a phase of saturation III. With increasing biomaterials surface nanoroughness and increasing hydrophobicity, adhesion rates increased during phases I and II. The influence of materials surface hydrophobicity seemed to exceed that of nanoroughness during the lag-phase I, whereas it was vice versa during adhesion phase II. This study introduces the non-constant-depth film fermenter in combination with a chemostat culture to allow for a controlled approach to reproducibly cultivate biofilms and to investigate bacterial adhesion kinetics at constant and low shear conditions. The findings will support developing and adequate testing of biomaterials surface modifications eventually preventing biomaterial

The in vitro effect of fluoridated milk in a bacterial biofilm--enamel model.

Science.gov (United States)

Arnold, Wolfgang H; Forer, Stefan; Heesen, Joerg; Yudovich, Keren; Steinberg, Doron; Gaengler, Peter

2006-07-01

The purpose of this study was to investigate the effect of milk and fluoridated milk on bacterially induced caries-like lesions. Extracted impacted human molars were cut in half and covered with a varnish leaving a 4*4 mm window. The samples were coated with biofilm of S. sobrinus and were further divided into three experimental groups of S. sobrinus, S. sobrinus and milk and S. sobrinus and fluoridated milk. As negative controls served teeth incubated in saline. Of twenty tooth halves serial ground sections were cut through the lesions and investigated with polarization light microscopy (PLM) and scanning electron microscopy (SEM) and EDX element analysis. The PLM photographs were used for 3D reconstruction, volumetric assessment and determination of the extension of the lesion zones. Of eight tooth halves the biofilm on the enamel surface was studied with SEM and EDX element analysis. Volumetric assessment showed a statistically significant difference in the volume of the body of the lesion and the translucent zone between the milk group and fluoridated milk group. Quantitative element analysis demonstrated significant differences between sound enamel and the superficial layer in the fluoridated milk group. The biofilm on the enamel surface showed an increased Ca content in the milk group and fluoridated milk group. Milk as a common nutrient seems to play a complex role in in-vitro biofilm--enamel interactions stimulating bacterial demineralization on one hand, and, as effective fluoride carrier, inhibits caries-like demineralization.

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...

Monitoring bacterial biofilms with a microfluidic flow chip designed for imaging with white-light interferometry

Energy Technology Data Exchange (ETDEWEB)

Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane; Larimer, Curtis

2017-07-01

There is a need for imaging and sensing instrumentation that can monitor transitions in biofilm structure in order to better understand biofilm development and emergent properties such as anti-microbial resistance. Herein, we expanded on our previously reported technique for measuring and monitoring the thickness and topology of live biofilms using white-light interferometry (WLI). A flow cell designed for WLI enabled the use of this non-disruptive imaging method for the capture of high resolution three-dimensional profile images of biofilm growth over time. The fine axial resolution (3 nm) and wide field of view (>1 mm by 1 mm) enabled detection of biofilm formation as early as three hours after inoculation of the flow cell with a live bacterial culture (Pseudomonas fluorescens). WLI imaging facilitated monitoring the early stages of biofilm development and subtle variations in the structure of mature biofilms. Minimally-invasive imaging enabled monitoring of biofilm structure with surface metrology metrics (e.g., surface roughness). The system was used to observe a transition in biofilm structure that occurred in response to expsoure to a common antiseptic. In the future, WLI and the biofilm imaging cell described herein may be used to test the effectiveness of biofilm-specific therapies to combat common diseases associated with biofilm formation such as cystic fibrosis and periodontitis.

Biotreatment of Cr(VI) contaminated waters by sulphate reducing bacteria fed with ethanol

Energy Technology Data Exchange (ETDEWEB)

Pagnanelli, F., E-mail: francesca.pagnanelli@uniroma1.it [Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy); Cruz Viggi, C., E-mail: carolina.cruzviggi@uniroma1.it [Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy); Cibati, A., E-mail: alessio.cibati@uniroma1.it [Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy); Uccelletti, D., E-mail: daniela.uccelletti@uniroma1.it [Department of Biology and Biotechnology, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome (Italy); Toro, L., E-mail: luigi.toro@uniroma1.it [Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy); Palleschi, C., E-mail: claudio.palleschi@uniroma1.it [Department of Biology and Biotechnology, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome (Italy)

2012-01-15

Highlights: Black-Right-Pointing-Pointer Use of ethanol as electron donor for sulphate-reducing bacteria for the treatment of Cr(VI). Black-Right-Pointing-Pointer Isolation of contribution in Cr removal (adsorption vs. bioprecipitation). Black-Right-Pointing-Pointer Bioassessment of the process effectiveness by ecotoxicological in vivo tests using C. elegans. - Abstract: Biological treatment of Cr(VI) contaminated waters was performed in fixed bed reactors inoculated with SRB (sulphate-reducing bacteria) growing on ethanol. Treatment efficiency was evaluated by checking chemical abatement of Cr(VI) and by ecotoxicological tests using the nematode Caenorhabditis elegans. A preliminary comparison between ethanol and lactate was performed, denoting that using ethanol, the same values of final sulphate abatement were obtained. In addition ethanol showed to be a substrate more competitive than lactate in kinetic terms. Fixed bed column reactors were continuously fed with a solution containing sulphates (3 g L{sup -1}), ethanol (1.5 g L{sup -1}) and Cr(VI) (50 mg L{sup -1}). At steady state the column inoculated with SRB removed 65 {+-} 5% of sulphate and 95 {+-} 5% of chromium. Bioactive removal mechanisms predominated over biosorption. Diminution of Cr(VI) toxicity was assessed by using the nematode C. elegans as a test organism showing that the survival of nematodes was 20% in the presence of the untreated influent and raised up to 53% when the nematodes were exposed to the treated effluent.

New quantitative image analysis of staphylococcal biofilms on the surfaces of nontranslucent metallic biomaterials.

Science.gov (United States)

Adachi, Kouichi; Tsurumoto, Toshiyuki; Yonekura, Akihiko; Nishimura, Seisuke; Kajiyama, Shiro; Hirakata, Yoichi; Shindo, Hiroyuki

2007-03-01

Implant-related infection after orthopedic surgery is difficult to cure. One of the causes of infection is the bacterial biofilm that forms around biomaterials used during surgery. Therefore, it is necessary to investigate bacterial biofilms extensively to resolve the problems of these postoperative infections. However, no established culture method or quantification system exists for bacterial biofilms grown on the surface of the metallic biomaterials used in orthopedics, which are nonradiolucent. The purpose of this study was to develop a quantitative method to evaluate the difference in resistance of stainless steel versus titanium to staphylococcal biofilms and the efficacy of antibiotics against biofilms. The bacterial strains used in this study were three Staphylococcus aureus stains: strain Seattle 1945 and two clinical strains cultured from postoperative infections. Staphylococcal biofilms were formed on stainless steel washers (SUS304) and titanium washers (pure titanium). They were stained with crystal violet and were examined with a digital microscope to calculate the bacterial coverage rate (BCR) by NIH imaging. The BCR of S. aureus biofilms formed on stainless steel and titanium washers increased over time. At 24, 48, and 72 h after cultivation, the amount of biofilm on the surface of the stainless steel washers was significantly greater or tended to be greater than that on the titanium. Cefazolin was applied to the obtained biofilms of two clinically isolated S. aureus strains. Cefazolin did not eradicate the biofilms but significantly reduced the biofilm of one strain. The newly developed quantitative method (static microtube culture and measurement system) was useful for assessing the amount of bacterial biofilms on the surface of nontranslucent biomaterial. We found that titanium may be more resistant to bacterial infection than stainless steel. To control implant-related severe infections, the biomaterials should be assessed from the viewpoint of

Diversity and functions of bacterial community in drinking water biofilms revealed by high-throughput sequencing

Science.gov (United States)

Chao, Yuanqing; Mao, Yanping; Wang, Zhiping; Zhang, Tong

2015-06-01

The development of biofilms in drinking water (DW) systems may cause various problems to water quality. To investigate the community structure of biofilms on different pipe materials and the global/specific metabolic functions of DW biofilms, PCR-based 454 pyrosequencing data for 16S rRNA genes and Illumina metagenomic data were generated and analysed. Considerable differences in bacterial diversity and taxonomic structure were identified between biofilms formed on stainless steel and biofilms formed on plastics, indicating that the metallic materials facilitate the formation of higher diversity biofilms. Moreover, variations in several dominant genera were observed during biofilm formation. Based on PCA analysis, the global functions in the DW biofilms were similar to other DW metagenomes. Beyond the global functions, the occurrences and abundances of specific protective genes involved in the glutathione metabolism, the SoxRS system, the OxyR system, RpoS regulated genes, and the production/degradation of extracellular polymeric substances were also evaluated. A near-complete and low-contamination draft genome was constructed from the metagenome of the DW biofilm, based on the coverage and tetranucleotide frequencies, and identified as a Bradyrhizobiaceae-like bacterium according to a phylogenetic analysis. Our findings provide new insight into DW biofilms, especially in terms of their metabolic functions.

Identification of bacterial strains isolated from the Mediterranean Sea exhibiting different abilities of biofilm formation.

Science.gov (United States)

Brian-Jaisson, Florence; Ortalo-Magné, Annick; Guentas-Dombrowsky, Linda; Armougom, Fabrice; Blache, Yves; Molmeret, Maëlle

2014-07-01

The Mediterranean Sea has rarely been investigated for the characterization of marine bacteria as compared to other marine environments such as the Atlantic or Pacific Ocean. Bacteria recovered from inert surfaces are poorly studied in these environments, when it has been shown that the community structure of attached bacteria can be dissimilar from that of planktonic bacteria present in the water column. The objectives of this study were to identify and characterize marine bacteria isolated from biofilms developed on inert surfaces immersed in the Mediterranean Sea and to evaluate their capacity to form a biofilm in vitro. Here, 13 marine bacterial strains have been isolated from different supports immersed in seawater in the Bay of Toulon (France). Phylogenetic analysis and different biological and physico-chemical properties have been investigated. Among the 13 strains recovered, 8 different genera and 12 different species were identified including 2 isolates of a novel bacterial species that we named Persicivirga mediterranea and whose genus had never been isolated from the Mediterranean Sea. Shewanella sp. and Pseudoalteromonas sp. were the most preponderant genera recovered in our conditions. The phenotypical characterization revealed that one isolate belonging to the Polaribacter genus differed from all the other ones by its hydrophobic properties and poor ability to form biofilms in vitro. Identifying and characterizing species isolated from seawater including from Mediterranean ecosystems could be helpful for example, to understand some aspects of bacterial biodiversity and to further study the mechanisms of biofilm (and biofouling) development in conditions approaching those of the marine environment.

Microbial fuel cell based on electroactive sulfate-reducing biofilm

International Nuclear Information System (INIS)

Angelov, Anatoliy; Bratkova, Svetlana; Loukanov, Alexandre

2013-01-01

Highlights: ► Regulation and management of electricity generation by variation of residence time. ► Design of microbial fuel cell based on electroactive biofilm on zeolite. ► Engineering solution for removing of the obtained elemental sulfur. - abstract: A two chambered laboratory scale microbial fuel cell (MFC) has been developed, based on natural sulfate-reducing bacterium consortium in electroactive biofilm on zeolite. The MFC utilizes potassium ferricyanide in the cathode chamber as an electron acceptor that derives electrons from the obtained in anode chamber H 2 S. The molecular oxygen is finally used as a terminal electron acceptor at cathode compartment. The generated power density was 0.68 W m −2 with current density of 3.2 A m −2 at 150 Ω electrode resistivity. The hydrogen sulfide itself is produced by microbial dissimilative sulfate reduction process by utilizing various organic substrates. Finally, elemental sulfur was identified as the predominant final oxidation product in the anode chamber. It was removed from MFC through medium circulation and gathering in an external tank. This report reveals dependence relationship between the progress of general electrochemical parameters and bacterial sulfate-reduction rate. The presented MFC design can be used for simultaneous sulfate purification of mining drainage wastewater and generation of renewable electricity

Interspecific bacterial interactions are reflected in multispecies biofilm spatial organization

DEFF Research Database (Denmark)

Liu, Wenzheng; Røder, Henriette Lyng; Madsen, Jonas Stenløkke

2016-01-01

not only the enabling sub-populations. However, the specific molecular mechanisms of cellular processes affecting spatial organization, and vice versa, are poorly understood and very complex to unravel. Therefore, detailed description of the spatial organization of individual bacterial cells...... environments. Species residing in these complex bacterial communities usually interact both intra- and interspecifically. Such interactions are considered to not only be fundamental in shaping overall biomass and the spatial distribution of cells residing in multispecies biofilms, but also to result......, industrial, and clinical implications. This review briefly presents the state of the art of studying interspecies interactions and spatial organization of multispecies communities, aiming to support theoretical and practical arguments for further advancement of this field....

Effect of water hyacinth on distribution of sulphate-reducing bacteria ...

African Journals Online (AJOL)

The effect of the water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub, on the distribution of populations of sulphate-reducing bacteria (SRB) in sediments from various stations on the shores of Lake Victoria around Mwanza Municipality, Tanzania, was studied. Lactate-utilising SRB were observed to be the dominant ...

Biofilm structures (EPS and bacterial communities) in drinking water distribution systems are conditioned by hydraulics and influence discolouration.

Science.gov (United States)

Fish, K; Osborn, A M; Boxall, J B

2017-09-01

High-quality drinking water from treatment works is degraded during transport to customer taps through the Drinking Water Distribution System (DWDS). Interactions occurring at the pipe wall-water interface are central to this degradation and are often dominated by complex microbial biofilms that are not well understood. This study uses novel application of confocal microscopy techniques to quantify the composition of extracellular polymeric substances (EPS) and cells of DWDS biofilms together with concurrent evaluation of the bacterial community. An internationally unique, full-scale, experimental DWDS facility was used to investigate the impact of three different hydraulic patterns upon biofilms and subsequently assess their response to increases in shear stress, linking biofilms to water quality impacts such as discolouration. Greater flow variation during growth was associated with increased cell quantity but was inversely related to EPS-to-cell volume ratios and bacterial diversity. Discolouration was caused and EPS was mobilised during flushing of all conditions. Ultimately, biofilms developed under low-varied flow conditions had lowest amounts of biomass, the greatest EPS volumes per cell and the lowest discolouration response. This research shows that the interactions between hydraulics and biofilm physical and community structures are complex but critical to managing biofilms within ageing DWDS infrastructure to limit water quality degradation and protect public health. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

Energy Technology Data Exchange (ETDEWEB)

Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F; Hanley, Luke

2010-08-04

Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.

Cleaning and Disinfection of Bacillus cereus Biofilm.

Science.gov (United States)

Deal, Amanda; Klein, Dan; Lopolito, Paul; Schwarz, John Spencer

2016-01-01

Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to disassociated B. cereus spores and biofilm from a non-spore-forming species. Further, we assessed the impact that pre-cleaning has on increasing that susceptibility. Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to

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.

2015-01-01

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. PMID:26272750

Efficacy of silver/hydrophilic poly(p-xylylene) on preventing bacterial growth and biofilm formation in urinary catheters.

Science.gov (United States)

Heidari Zare, Hamideh; Juhart, Viktorija; Vass, Attila; Franz, Gerhard; Jocham, Dieter

2017-01-18

+ and Mg 2+ ions after exposure of the catheters to saturated urine for 24 h. The higher concentrations of Ca 2+ and Mg 2+ in the precipitates on the PPX-N catheters indicates that the hydrophilic PPX-N coating is superior to the simple PPX-N coating, with regard to the formation of a crystalline biofilm. Moreover, hydrophilic PPX-N as a cap layer may promote wettability and increase silver ion release rate and thus reduce the adhesion of suspended crystals to the catheter. Reduced bacterial growth and reduced adhesion may help to prevent CAUTI.

Comparing Methods of Separating Bacterial Biofilms on the Surface of Water Transportation Pipes and Equipment of Milking in the Farms

Directory of Open Access Journals (Sweden)

setareh nabizadeh

2016-08-01

Full Text Available Introduction Bacterial biofilms can be both useful and harmful based on their combination and locations. Biofilm formation occurs as a stepwise process. Their formation in liquid transportation pipes used for milking system and drinking water in animal farms may create some problems and is a potential source of pollution. Speed of biofilm formation depends on many factors including: construction and functional characteristics of bacteria, the composition and culture conditions such as temperature and substratum. In this research the Bacillus subtillis bacteria with special characteristics was selected due to its capability for biofilm creation. Bacillus subtillis bacteria is mobility and a stronger connection than other bacteria levels are created. In the research conducted in the biofilm there are many resources on biofilm formation by Bacillus subtillis bacteria. Bacillus subtillis is saprophytic in the soil, water and air. There is also the ability to form spores of Bacillus subtillis. Materials and Methods Firstly the possibility of creating biofilms on different Plastic (polyvinilchlorid, polypropylene, polyethylengelycole, alluminum and glass surfaces in three temperatures of 4°C, 30°C and 37°C were studied. Two different methods of biofilms separation including separating swap and vortex were tested and their efficienceies were calculated. After biofilm formation on parts of the vortex separation method after washing parts in sterile conditions in a tube containing normal saline for 4 minutes was vortex. The bacterial suspension decreasing dilution series was created. Pour plate in medium using agar plate count agar and was cultured at 30°C for 24-48 hours. Numbers of colonies were counted. The numbers of biofilm cells were calculated. In swap method after biofilm formation on parts using a cotton swap was isolated biofilms. The swap was transferred to tube containing normal saline and the bacterial suspension decreasing dilution

Bacterial sulphate reduction and the development of alklinity. III. Experiments under natural conditions in the Wadi Natrun

Energy Technology Data Exchange (ETDEWEB)

Abd-El-Malek, Y; Rizk, S G

1963-01-01

Evidence that microbial sulphate reduction is mainly responsible for the formation of the natron (hydrated Na/sub 2/CO/sub 3/) deposits in Wadi Natrun is presented. The sulphate in the infiltrating water is reduced during passage through the surrounding waterlogged soil and the bicarbonate formed is later concentrated by evaporation in the lakes.

Biomineralized diamond-like carbon films with incorporated titanium dioxide nanoparticles improved bioactivity properties and reduced biofilm formation.

Science.gov (United States)

Lopes, F S; Oliveira, J R; Milani, J; Oliveira, L D; Machado, J P B; Trava-Airoldi, V J; Lobo, A O; Marciano, F R

2017-12-01

Recently, the development of coatings to protect biomedical alloys from oxidation, passivation and to reduce the ability for a bacterial biofilm to form after implantation has emerged. Diamond-like carbon films are commonly used for implanted medical due to their physical and chemical characteristics, showing good interactions with the biological environment. However, these properties can be significantly improved when titanium dioxide nanoparticles are included, especially to enhance the bactericidal properties of the films. So far, the deposition of hydroxyapatite on the film surface has been studied in order to improve biocompatibility and bioactive behavior. Herein, we developed a new route to obtain a homogeneous and crystalline apatite coating on diamond-like carbon films grown on 304 biomedical stainless steel and evaluated its antibacterial effect. For this purpose, films containing two different concentrations of titanium dioxide (0.1 and 0.3g/L) were obtained by chemical vapor deposition. To obtain the apatite layer, the samples were soaked in simulated body fluid solution for up to 21days. The antibacterial activity of the films was evaluated by bacterial eradication tests using Staphylococcus aureus biofilm. Scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy, and goniometry showed that homogeneous, crystalline, and hydrophilic apatite films were formed independently of the titanium dioxide concentration. Interestingly, the diamond-like films containing titanium dioxide and hydroxyapatite reduced the biofilm formation compared to controls. A synergism between hydroxyapatite and titanium dioxide that provided an antimicrobial effect against opportunistic pathogens was clearly observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Human Tear Fluid Reduces Culturability of Contact Lens Associated Pseudomonas aeruginosa Biofilms but Induces Expression of the Virulence Associated Type III Secretion System

Science.gov (United States)

Wu, Yvonne T.; Tam, Connie; Zhu, Lucia S.; Evans, David J.; Fleiszig, Suzanne M. J.

2017-01-01

Purpose The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens (CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression. Methods P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured by RT-qPCR. Controls included trypticase soy broth, PBS and planktonic bacteria. Results With or without tear fluid, biofilms grew to ~108 cfu viable bacteria by 24 h. Exposing biofilms to tear fluid after they had formed without it on lenses reduced bacterial culturability ~180-fold (pbacteria [5.46 ± 0.24-fold for T3SS transcriptional activitor exsA (p=.02), and 3.76 ± 0.36-fold for T3SS effector toxin exoS (p=.01)]. Tear fluid further enhanced exsA and exoS expression in CL-grown biofilms, but not planktonic bacteria, by 2.09 ± 0.38-fold (p = 0.04) and 1.89 ± 0.26-fold (p<.001), respectively. Conclusions Considering the pivitol role of the T3SS in P. aeruginosa infections, its induction in CL-grown P. aeruginosa biofilms by tear fluid might contribute to the pathogenesis of CL-related P. aeruginosa keratitis. PMID:27670247

Effect of pulsed ultrasound in combination with gentamicin on bacterial killing of biofilms on bone cements in vivo

Science.gov (United States)

Ensing, G.T.; Roeder, B.L.; Nelson, J.L.; van Horn, J.R.; van der Mei, H.C.; Busscher, H.J.; Pitt, W.G.

2008-01-01

Aim The aim of this study is to investigate whether pulsed ultrasound in combination with gentamicin yields increased killing of bacterial biofilms on bone cements in vivo. Methods and Results Bacterial survival on bone cement in the presence and absence of ultrasound was compared in a rabbit model. Two bone cement samples with E. coli ATCC 10798 biofilm were implanted in a total of nine rabbits. In two groups bone cement disks loaded with gentamicin were used, and in one group unloaded bone cement disks in combination with systemically administered gentamicin were used. Pulsed ultrasound with a mean acoustic intensity of 167 mW cm−2 and a maximum acoustic intensity of 500 mW cm−2 was applied from 24 h till 72 h post surgery on one of the two implanted disks. After euthanization, the bacteria removed from the disk were quantified. Application of ultrasound, combined with gentamicin, reduced the biofilm in all three groups varying between 58 to 69% compared to the negative control. Ultrasound proved to be safe with respect to creating skin lesions. Conclusions Ultrasound resulted in an tendency of improved efficacy of gentamicin, either applied locally or systemically. Significance and impact of Study This study implies that ultrasound could improve the prevention of infection, especially because the biomaterials, gentamicin and ultrasound used in this model are all in clinical usage, but not yet combined in clinical practice. PMID:16108785

Inhibition of Bio corrosion of steel coupon by sulphate reducing ...

African Journals Online (AJOL)

ADOWIE PERE

Inhibition of Bio corrosion of steel coupon by sulphate reducing bacteria and Iron oxidizing bacteria using .... Ethanol for 24 h. The extract was ... with distilled water to get a zero reading from the meter before .... Ethanol extract of musa species peels as a green corrosion ... Eco friendly extract of banana peel as corrosion ...

Microbial biofilm study by synchrotron X-ray microscopy

International Nuclear Information System (INIS)

Pennafirme, S.; Lima, I.; Bitencourt, J.A.; Crapez, M.A.C.; Lopes, R.T.

2015-01-01

Microbial biofilm has already being used to remove metals and other pollutants from wastewater. In this sense, our proposal was to isolate and cultivate bacteria consortia from mangrove’s sediment resistant to Zn (II) and Cu (II) at 50 mg L −1 and to observe, through synchrotron X-ray fluorescence microscopy (microXRF), whether the biofilm sequestered the metal. The biofilm area analyzed was 1 mm 2 and a 2D map was generated (pixel size 20×20 μm 2 , counting time 5 s/point). The biofilm formation and retention followed the sequence Zn>Cu. Bacterial consortium zinc resistant formed dense biofilm and retained 63.83% of zinc, while the bacterial consortium copper resistant retained 3.21% of copper, with lower biofilm formation. Dehydrogenase activity of Zn resistant bacterial consortium was not negatively affect by 50 mg ml −1 zinc input, whereas copper resistant bacterial consortium showed a significant decrease on dehydrogenase activity (50 mg mL −1 of Cu input). In conclusion, biofilm may protect bacterial cells, acting as barrier against metal toxicity. The bacterial consortia Zn resistant, composed by Nitratireductor spp. and Pseudomonas spp formed dense biofilm and sequestered metal from water, decreasing the metal bioavailability. These bacterial consortia can be used in bioreactors and in bioremediation programs. - Highlights: • We studied bacterial bioremediation by microXRF. • Dense biofilm may act sequestering metal while protecting bacterial metabolism. • Nitratireductor spp. and Pseudomonas spp decreased seawater metal bioavailability. • Bacterial consortia from polluted areas may be used in bioremediation programs.

Effect of Punica granatum L. Flower Water Extract on Five Common Oral Bacteria and Bacterial Biofilm Formation on Orthodontic Wire.

Science.gov (United States)

Vahid Dastjerdi, Elahe; Abdolazimi, Zahra; Ghazanfarian, Marzieh; Amdjadi, Parisa; Kamalinejad, Mohammad; Mahboubi, Arash

2014-12-01

Use of herbal extracts and essences as natural antibacterial compounds has become increasingly popular for the control of oral infectious diseases. Therefore, finding natural antimicrobial products with the lowest side effects seems necessary. The present study sought to assess the effect of Punica granatum L. water extract on five oral bacteria and bacterial biofilm formation on orthodontic wire. Antibacterial property of P. granatum L. water extract was primarily evaluated in brain heart infusion agar medium using well-plate method. The minimum inhibitory concentration and minimum bactericidal concentration were determined by macro-dilution method. The inhibitory effect on orthodontic wire bacterial biofilm formation was evaluated using viable cell count in biofilm medium. At the final phase, samples were fixed and analyzed by Scanning Electron Microscopy. The growth inhibition zone diameter was proportional to the extract concentration. The water extract demonstrated the maximum antibacterial effect on Streptococcus sanguinis ATCC 10556 with a minimum inhibitory concentration of 6.25 mg/ml and maximum bactericidal effect on S. sanguinis ATCC 10556 and S. sobrinus ATCC 27607 with minimum bactericidal concentration of 25 mg/ml. The water extract decreased bacterial biofilm formation by S. sanguinis, S. sobrinus, S. salivarius, S. mutans ATCC 35608 and E. faecalis CIP 55142 by 93.7-100%, 40.6-99.9%, 85.2-86.5%, 66.4-84.4% and 35.5-56.3% respectively. Punica granatum L. water extract had significant antibacterial properties against 5 oral bacteria and prevented orthodontic wire bacterial biofilm formation. However, further investigations are required to generalize these results to the clinical setting.

Comparative assessment of antibiotic susceptibility of coagulase-negative staphylococci in biofilm versus planktonic culture as assessed by bacterial enumeration or rapid XTT colorimetry.

Science.gov (United States)

Cerca, Nuno; Martins, Silvia; Cerca, Filipe; Jefferson, Kimberly K; Pier, Gerald B; Oliveira, Rosário; Azeredo, Joana

2005-08-01

To quantitatively compare the antibiotic susceptibility of biofilms formed by the coagulase-negative staphylococci (CoNS) Staphylococcus epidermidis and Staphylococcus haemolyticus with the susceptibility of planktonic cultures. Several CoNS strains were grown planktonically or as biofilms to determine the effect of the mode of growth on the level of susceptibility to antibiotics with different mechanisms of action. The utility of a new, rapid colorimetric method that is based on the reduction of a tetrazolium salt (XTT) to measure cell viability was tested by comparison with standard bacterial enumeration techniques. A 6 h kinetic study was performed using dicloxacillin, cefazolin, vancomycin, tetracycline and rifampicin at the peak serum concentration of each antibiotic. In planktonic cells, inhibitors of cell wall synthesis were highly effective over a 3 h period. Biofilms were much less susceptible than planktonic cultures to all antibiotics tested, particularly inhibitors of cell wall synthesis. The susceptibility to inhibitors of protein and RNA synthesis was affected by the biofilm phenotype to a lesser degree. Standard bacterial enumeration techniques and the XTT method produced equivalent results both in biofilms and planktonic assays. This study provides a more accurate comparison between the antibiotic susceptibilities of planktonic versus biofilm populations, because the cell densities in the two populations were similar and because we measured the concentration required to inhibit bacterial metabolism rather than to eradicate the entire bacterial population. While the biofilm phenotype is highly resistant to antibiotics that target cell wall synthesis, it is fairly susceptible to antibiotics that target RNA and protein synthesis.

Surface-Adaptive, Antimicrobially Loaded, Micellar Nanocarriers with Enhanced Penetration and Killing Efficiency in Staphylococcal Biofilms

NARCIS (Netherlands)

Liu, Yong; Busscher, Henk J; Zhao, Bingran; Li, Yuanfeng; Zhang, Zhenkun; van der Mei, Henny C; Ren, Yijin; Shi, Linqi

Biofilms cause persistent bacterial infections and are extremely recalcitrant to antimicrobials, due in part to reduced penetration of antimicrobials into biofilms that allows bacteria residing in the depth of a biofilm to survive antimicrobial treatment. Here, we describe the preparation of

Early canine plaque biofilms: characterization of key bacterial interactions involved in initial colonization of enamel.

Directory of Open Access Journals (Sweden)

Lucy J Holcombe

Full Text Available Periodontal disease (PD is a significant problem in dogs affecting between 44% and 63.6% of the population. The main etiological agent for PD is plaque, a microbial biofilm that colonizes teeth and causes inflammation of the gingiva. Understanding how this biofilm initiates on the tooth surface is of central importance in developing interventions against PD. Although the stages of plaque development on human teeth have been well characterized little is known about how canine plaque develops. Recent studies of the canine oral microbiome have revealed distinct differences between the canine and human oral environments and the bacterial communities they support, particularly with respect to healthy plaque. These differences mean knowledge about the nature of plaque formation in humans may not be directly translatable to dogs. The aim of this study was to identify the bacterial species important in the early stages of canine plaque formation in vivo and then use isolates of these species in a laboratory biofilm model to develop an understanding of the sequential processes which take place during the initial colonization of enamel. Supra-gingival plaque samples were collected from 12 dogs at 24 and 48 hour time points following a full mouth descale and polish. Pyrosequencing of the 16S rDNA identified 134 operational taxonomic units after statistical analysis. The species with the highest relative abundance were Bergeyella zoohelcum, Neisseria shayeganii and a Moraxella species. Streptococcal species, which tend to dominate early human plaque biofilms, had very low relative abundance. In vitro testing of biofilm formation identified five primary colonizer species, three of which belonged to the genus Neisseria. Using these pioneer bacteria as a starting point, viable two and three species communities were developed. Combining in vivo and in vitro data has led us to construct novel models of how the early canine plaque biofilm develops.

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.

The bioactivation procedure for increasing the sulphate-reducing bacteria in a UASB reactor

Directory of Open Access Journals (Sweden)

M. M. M. Gonçalves

2005-12-01

Full Text Available Bioactivation, a procedure to obtain anaerobic sulphidogenic sludge, was developed in order to increase sulphate reduction and, consequently, sulphide production to remove metals from effluents. This procedure, in which the source of carbon/energy (lactate is gradually replaced, consisted of three operational conditions. It was observed that bioactivation took six months so there was a 100-fold increase in the population of sulphate-reducing bacteria estimated by the most-probable-number (MPN when molasses was employed as a new source.

Synergistic Antibacterial Effects of Nanoparticles Encapsulated with Scutellaria baicalensis and Pure Chlorhexidine on Oral Bacterial Biofilms

Directory of Open Access Journals (Sweden)

Ken Cham-Fai Leung

2016-04-01

Full Text Available Scutellaria baicalensis (SB is a traditional Chinese medicine for treating infectious and inflammatory diseases. Our recent study shows potent antibacterial effects of nanoparticle-encapsulated chlorhexidine (Nano-CHX. Herein, we explored the synergistic effects of the nanoparticle-encapsulated SB (Nano-SB and Nano-CHX on oral bacterial biofilms. Loading efficiency of Nano-SB was determined by thermogravimetric analysis, and its releasing profile was assessed by high-performance liquid chromatographyusing baicalin (a flavonoid compound of SB as the marker. The mucosal diffusion assay on Nano-SB was undertaken in a porcine model. The antibacterial effects of the mixed nanoparticles (Nano-MIX of Nano-SB and Nano-CHX at 9:1 (w/w ratio were analyzed in both planktonic and biofilm modes of representative oral bacteria. The Nano-MIX was effective on the mono-species biofilms of Streptococcus (S. mutans, S. sobrinus, Fusobacterium (F. nucleatum, and Aggregatibacter (A. actinomycetemcomitans (MIC 50 μg/mL at 24 h, and exhibited an enhanced effect against the multi-species biofilms such as S. mutans, F. nucleatum, A. actinomycetemcomitans, and Porphyromonas (P. gingivalis (MIC 12.5 μg/mL at 24 h that was supported by the findings of both scanning electron microscopy (SEM and confocal scanning laser microscopy (CLSM. This study shows enhanced synergistic antibacterial effects of the Nano-MIX on common oral bacterial biofilms, which could be potentially developed as a novel antimicrobial agent for clinical oral/periodontal care.

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.

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

It has become evident that aggregation or biofilm formation is an important survival mechanism for bacteria in almost any environment. In this review, we summarize recent visualizations of bacterial aggregates in several chronic infections (chronic otitis media, cystic fibrosis, infection due...... 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...

Bacterial surface adaptation

Science.gov (United States)

Utada, Andrew

2014-03-01

Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

Bacterial adhesion on direct and indirect dental restorative composite resins: An in vitro study on a natural biofilm.

Science.gov (United States)

Derchi, Giacomo; Vano, Michele; Barone, Antonio; Covani, Ugo; Diaspro, Alberto; Salerno, Marco

2017-05-01

Both direct and indirect techniques are used for dental restorations. Which technique should be preferred or whether they are equivalent with respect to bacterial adhesion is unclear. The purpose of this in vitro study was to determine the affinity of bacterial biofilm to dental restorative composite resins placed directly and indirectly. Five direct composite resins for restorations (Venus Diamond, Adonis, Optifil, Enamel Plus HRi, Clearfil Majesty Esthetic) and 3 indirect composite resins (Gradia, Estenia, Signum) were selected. The materials were incubated in unstimulated whole saliva for 1 day. The biofilms grown were collected and their bacterial cells counted. In parallel, the composite resin surface morphology was analyzed with atomic force microscopy. Both bacterial cell count and surface topography parameters were subjected to statistical analysis (α=.05). Indirect composite resins showed significantly lower levels than direct composite resins for bacterial cell adhesion, (Pcomposite resins (P>.05). However, within the indirect composite resins a significantly lower level was found for Gradia than Estenia or Signum (Pcomposite resin roughness and bacterial adhesion when the second and particularly the third-order statistical moments of the composite resin height distributions were considered. Indirect dental restorative composite resins were found to be less prone to biofilm adhesion than direct composite resins. A correlation of bacterial adhesion to surface morphology exists that is described by kurtosis; thus, advanced data analysis is required to discover possible insights into the biologic effects of morphology. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Sulphate in Pregnancy

Directory of Open Access Journals (Sweden)

Paul A. Dawson

2015-03-01

Full Text Available Sulphate is an obligate nutrient for healthy growth and development. Sulphate conjugation (sulphonation of proteoglycans maintains the structure and function of tissues. Sulphonation also regulates the bioactivity of steroids, thyroid hormone, bile acids, catecholamines and cholecystokinin, and detoxifies certain xenobiotics and pharmacological drugs. In adults and children, sulphate is obtained from the diet and from the intracellular metabolism of sulphur-containing amino acids. Dietary sulphate intake can vary greatly and is dependent on the type of food consumed and source of drinking water. Once ingested, sulphate is absorbed into circulation where its level is maintained at approximately 300 μmol/L, making sulphate the fourth most abundant anion in plasma. In pregnant women, circulating sulphate concentrations increase by twofold with levels peaking in late gestation. This increased sulphataemia, which is mediated by up-regulation of sulphate reabsorption in the maternal kidneys, provides a reservoir of sulphate to meet the gestational needs of the developing foetus. The foetus has negligible capacity to generate sulphate and thereby, is completely reliant on sulphate supply from the maternal circulation. Maternal hyposulphataemia leads to foetal sulphate deficiency and late gestational foetal death in mice. In humans, reduced sulphonation capacity has been linked to skeletal dysplasias, ranging from the mildest form, multiple epiphyseal dysplasia, to achondrogenesis Type IB, which results in severe skeletal underdevelopment and death in utero or shortly after birth. Despite being essential for numerous cellular and metabolic functions, the nutrient sulphate is largely unappreciated in clinical settings. This article will review the physiological roles and regulation of sulphate during pregnancy, with a particular focus on animal models of disturbed sulphate homeostasis and links to human pathophysiology.

Effective biofilm removal and changes in bacterial biofilm building capacity after wound debridement with low-frequency ultrasound as part of wound bed preparation before skin grafting

Directory of Open Access Journals (Sweden)

Yarets Y

2017-03-01

Full Text Available Yuliya Yarets Clinical Laboratory Medicine Department, The Republican Scientific Centre for Radiation Medicine and Human Ecology, Gomel, Belarus Abstract: The aim of the study was to evaluate the efficacy of ultrasonic-assisted wound debridement (UAW used for wound bed preparation of chronic wounds prior to skin grafting. Initially, 140 patients were enrolled into study. Group 1 patients (n=53 with critically colonized wounds underwent a single UAW procedure before skin grafting. Group 2 patients (n=87 with colonized wounds received two UAW sessions, skin grafting followed by the second UAW treatment. Initial wound classification in colonized and critically colonized wounds did not correlate with results from microbiological analysis of wound swab samples. Hence, comparison of efficacy of one or two debridement sessions was conducted solely for a similar group of patients, that is, patients with colonized wounds of group 1 (n=40 and group 2 (n=47. In wounds of group 1 patients, a single debridement session resulted in reduction of bacteria from >104 to <104 CFU/mL. However, bacteria remaining at wound site showed minor differences in biofilm slime production, with skin graft failure being observed in 25% cases. In wounds of group 2 patients, two debridement sessions significantly reduced bacterial presence up to <102 CFU/mL. Bacteria remaining at wound site showed low capacity for biofilm slime production and high accumulation of biomass; a complete graft healing was observed in all patients. We suggest two to three debridement sessions with UAW to be most effective in wound bed preparation before skin grafting of chronic wounds. UAW showed to be effective in cleaning the wound bed, destroying the extracellular substances in biofilms, and influencing biofilm slime building capacity of bacteria left at wound site. Keywords: wound debridement, wound bed preparation, biofilm, low-frequency ultrasound, skin grafting, biofilm assay

Imaging biofilm in porous media using X-ray computed microtomography.

Science.gov (United States)

Davit, Y; Iltis, G; Debenest, G; Veran-Tissoires, S; Wildenschild, D; Gerino, M; Quintard, M

2011-04-01

In this study, a new technique for three-dimensional imaging of biofilm within porous media using X-ray computed microtomography is presented. Due to the similarity in X-ray absorption coefficients for the porous media (plastic), biofilm and aqueous phase, an X-ray contrast agent is required to image biofilm within the experimental matrix using X-ray computed tomography. The presented technique utilizes a medical suspension of barium sulphate to differentiate between the aqueous phase and the biofilm. Potassium iodide is added to the suspension to aid in delineation between the biofilm and the experimental porous medium. The iodide readily diffuses into the biofilm while the barium sulphate suspension remains in the aqueous phase. This allows for effective differentiation of the three phases within the experimental systems utilized in this study. The behaviour of the two contrast agents, in particular of the barium sulphate, is addressed by comparing two-dimensional images of biofilm within a pore network obtained by (1) optical visualization and (2) X-ray absorption radiography. We show that the contrast mixture provides contrast between the biofilm, the aqueous-phase and the solid-phase (beads). The imaging method is then applied to two three-dimensional packed-bead columns within which biofilm was grown. Examples of reconstructed images are provided to illustrate the effectiveness of the method. Limitations and applications of the technique are discussed. A key benefit, associated with the presented method, is that it captures a substantial amount of information regarding the topology of the pore-scale transport processes. For example, the quantification of changes in porous media effective parameters, such as dispersion or permeability, induced by biofilm growth, is possible using specific upscaling techniques and numerical analysis. We emphasize that the results presented here serve as a first test of this novel approach; issues with accurate segmentation of

Effect of Punica granatum L. Flower Water Extract on Five Common Oral Bacteria and Bacterial Biofilm Formation on Orthodontic Wire

Science.gov (United States)

VAHID DASTJERDI, Elahe; ABDOLAZIMI, Zahra; GHAZANFARIAN, Marzieh; AMDJADI, Parisa; KAMALINEJAD, Mohammad; MAHBOUBI, Arash

2014-01-01

Background: Use of herbal extracts and essences as natural antibacterial compounds has become increasingly popular for the control of oral infectious diseases. Therefore, finding natural antimicrobial products with the lowest side effects seems necessary. The present study sought to assess the effect of Punica granatum L. water extract on five oral bacteria and bacterial biofilm formation on orthodontic wire. Methods: Antibacterial property of P. granatum L. water extract was primarily evaluated in brain heart infusion agar medium using well-plate method. The minimum inhibitory concentration and minimum bactericidal concentration were determined by macro-dilution method. The inhibitory effect on orthodontic wire bacterial biofilm formation was evaluated using viable cell count in biofilm medium. At the final phase, samples were fixed and analyzed by Scanning Electron Microscopy. Results: The growth inhibition zone diameter was proportional to the extract concentration. The water extract demonstrated the maximum antibacterial effect on Streptococcus sanguinis ATCC 10556 with a minimum inhibitory concentration of 6.25 mg/ml and maximum bactericidal effect on S. sanguinis ATCC 10556 and S. sobrinus ATCC 27607 with minimum bactericidal concentration of 25 mg/ml. The water extract decreased bacterial biofilm formation by S. sanguinis, S. sobrinus, S. salivarius, S. mutans ATCC 35608 and E. faecalis CIP 55142 by 93.7–100%, 40.6–99.9%, 85.2–86.5%, 66.4–84.4% and 35.5–56.3% respectively. Conclusion: Punica granatum L. water extract had significant antibacterial properties against 5 oral bacteria and prevented orthodontic wire bacterial biofilm formation. However, further investigations are required to generalize these results to the clinical setting. PMID:26171362

Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

DEFF Research Database (Denmark)

Knoblauch, C.; Jørgensen, BB

1999-01-01

and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields......Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... for growth (T(opt)) were 7 degrees C (PSv29), 10 degrees C (ASv26, LSv54) and 18 degrees C (LSv21, LSv514), Although T(opt) was considerably above the in situ temperatures of their habitats (-1.7 degrees C and 2.6 degrees C), relative growth rates were still high at 0 degrees C, accounting for 25...

Anti-infective effects of Brazilian Caatinga plants against pathogenic bacterial biofilm formation.

Science.gov (United States)

Silva, Laura Nunes; Trentin, Danielle da Silva; Zimmer, Karine Rigon; Treter, Janine; Brandelli, Clara Lia Costa; Frasson, Amanda Piccoli; Tasca, Tiana; da Silva, Alexandre Gomes; da Silva, Márcia Vanusa; Macedo, Alexandre José

2015-03-01

The local communities living in the Brazilian Caatinga biome have a significant body of traditional knowledge on a considerable number of medicinal plants used to heal several maladies. Based on ethnopharmacological data, this study screened 23 aqueous plant extracts against two well-known models of biofilm-forming bacteria: Staphylococcus epidermidis and Pseudomonas aeruginosa. Crystal violet assay and scanning electron microscopy (SEM) were used to evaluate the effect of extracts on biofilm formation and measurements of the absorbance at 600 nm to assess bacterial growth. Selected extracts were investigated regarding the cytotoxicity by MTT assay using mammal cells and the qualitative phytochemical fingerprint by thin layer chromatography. Harpochilus neesianus Mart. ex Nees. (Acanthaceae) leaves, Apuleia leiocarpa Vogel J. F. Macbr. (Fabaceae), and Poincianella microphylla Mart. ex G. Don L. P. Queiroz (Fabaceae) fruits showed non-biocidal antibiofilm action against S. epidermidis with activities of 69, 52, and 63%, respectively. SEM confirmed that biofilm structure was strongly prevented and that extracts promoted overproduction of the matrix and/or bacterial morphology modification. Poincianella microphylla demonstrated toxicity at 4.0 mg/mL and 2.0 mg/mL, A. leiocarpa presented toxicity only at 4.0 mg/mL, whereas H. neesianus presented the absence of toxicity against Vero cell line. Preliminary phytochemical analysis revealed the presence of flavonoids, terpenoids, steroids, amines, and polyphenols. This work provides a scientific basis which may justify the ethnopharmacological use of the plants herein studied, indicating extracts that possess limited mammal cytotoxicity in vitro and a high potential as a source of antibiofilm drugs prototypes.

Sulfate Reducing Bacteria and Mycobacteria Dominate the Biofilm Communities in a Chloraminated Drinking Water Distribution System.

Science.gov (United States)

Gomez-Smith, C Kimloi; LaPara, Timothy M; Hozalski, Raymond M

2015-07-21

The quantity and composition of bacterial biofilms growing on 10 water mains from a full-scale chloraminated water distribution system were analyzed using real-time PCR targeting the 16S rRNA gene and next-generation, high-throughput Illumina sequencing. Water mains with corrosion tubercles supported the greatest amount of bacterial biomass (n = 25; geometric mean = 2.5 × 10(7) copies cm(-2)), which was significantly higher (P = 0.04) than cement-lined cast-iron mains (n = 6; geometric mean = 2.0 × 10(6) copies cm(-2)). Despite spatial variation of community composition and bacterial abundance in water main biofilms, the communities on the interior main surfaces were surprisingly similar, containing a core group of operational taxonomic units (OTUs) assigned to only 17 different genera. Bacteria from the genus Mycobacterium dominated all communities at the main wall-bulk water interface (25-78% of the community), regardless of main age, estimated water age, main material, and the presence of corrosion products. Further sequencing of the mycobacterial heat shock protein gene (hsp65) provided species-level taxonomic resolution of mycobacteria. The two dominant Mycobacteria present, M. frederiksbergense (arithmetic mean = 85.7% of hsp65 sequences) and M. aurum (arithmetic mean = 6.5% of hsp65 sequences), are generally considered to be nonpathogenic. Two opportunistic pathogens, however, were detected at low numbers: M. hemophilum (arithmetic mean = 1.5% of hsp65 sequences) and M. abscessus (arithmetic mean = 0.006% of hsp65 sequences). Sulfate-reducing bacteria from the genus Desulfovibrio, which have been implicated in microbially influenced corrosion, dominated all communities located underneath corrosion tubercules (arithmetic mean = 67.5% of the community). This research provides novel insights into the quantity and composition of biofilms in full-scale drinking water distribution systems, which is critical for assessing the risks to public health and to the

Effect of nanoemulsion on dental unit waterline biofilm

Directory of Open Access Journals (Sweden)

Karthikeyan Ramalingam

2013-09-01

Full Text Available Bacterial biofilm in dental unit waterlines (DUWLs is a widespread problem and poses a potentially significant risk of infection to dental staff and patients. The present study investigates the level and composition of bacterial contamination of dental chair syringe waterlines and investigates the efficacy of a cetylpyridinium chloride-containing nanoemulsion disinfectant in reducing bacterial loads. Waterline biofilms exposed to nanoemulsion for 1 hour, 6 hours, 12 hours, 24 hours, 48 hours, and 72 hours showed high reduction of colonies, and very low counts after 12 hours and 24 hours (67 colony-forming units/mL were observed. Exposures for 48 hours and 72 hours showed no or few visible colonies (2 colony-forming units/mL. The nanoemulsion employed improves efficacy against microorganisms more than unemulsified components. DNA sequencing showed that the organisms in the waterline biofilm are primarily of soil or water origin. The findings indicate that nanoemulsion effectively disinfects waterlines to consistently meet the American Dental Association (ADA recommendation.

Effect of flow on bacterial transport and biofilm formation in saturated porous media

Science.gov (United States)

Rusconi, R.

2016-12-01

Understanding the transport of bacteria in saturated porous media is crucial for many applications ranging from the management of pumping wells subject to bio-clogging to the design of new bioremediation schemes for subsurface contamination. However, little is known about the spatial distribution of bacteria at the pore scale, particularly when small-scale heterogeneities - always present even in seemingly homogeneous aquifers - lead to preferential pathways for groundwater flow. In particular, the coupling of flow and motility has recently been shown to strongly affect bacterial transport1, and this leads us to predict that subsurface flow may strongly affect the dispersal of bacteria and the formation of biofilms in saturated aquifers. I present here microfluidic experiments combined with numerical simulations to show how the topological features of the flow correlate with bacterial concentration and promote the attachment of bacteria to specific regions of the pore network, which will ultimately influence the formations of biofilms. These results highlight the intimate link between small-scale biological processes and transport in porous media.

Efficacy of NVC-422 against Staphylococcus aureus biofilms in a sheep biofilm model of sinusitis.

Science.gov (United States)

Singhal, Deepti; Jekle, Andreas; Debabov, Dmitri; Wang, Lu; Khosrovi, Bez; Anderson, Mark; Foreman, Andrew; Wormald, Peter-John

2012-01-01

Bacterial biofilms are a major obstacle in management of recalcitrant chronic rhinosinusitis. NVC-422 is a potent, fast-acting, broad-spectrum, nonantibiotic, antimicrobial with a new mechanism of action effective against biofilm bacteria in in vitro conditions. The aim of this study was to investigate the safety and efficacy of NVC-422 as local antibiofilm treatment in a sheep model of rhinosinusitis. After accessing and occluding frontal sinus ostia in 24 merino sheep via staged endoscopic procedures, S. aureus clinical isolate was instilled in frontal sinuses. Following biofilm formation, ostial obstruction was removed and sinuses irrigated with 0.1% and 0.5% NVC-422 in 5 mM acetate isotonic saline at pH 4.0. Sheep were monitored for adverse effects and euthanized 24 hours after treatment. Frontal sinuses were assessed for infection and changes in mucosa after the treatment. S. aureus biofilms were identified with Baclight-confocal scanning microscopy protocol and the biofilm biomass assayed by applying the COMSTAT2 program to recorded image stacks. After 2 irrigations with 0.1% NVC-422, S. aureus biofilm biomass was reduced when compared to control sinuses (p = 0.0001), though this effect was variable in samples. NVC-422 0.5% solution irrigations reduced biofilm even more significantly and consistently over all samples (p biofilm biomass (p biofilms, with dose-dependent efficacy in this animal model of biofilm-associated sinusitis. Copyright © 2012 American Rhinologic Society-American Academy of Otolaryngic Allergy, LLC.

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 di.......International Journal of Oral Science advance online publication, 12 December 2014; doi:10.1038/ijos.2014.65....

Observations on the development of the crystalline bacterial biofilms that encrust and block Foley catheters.

Science.gov (United States)

Stickler, D J; Morgan, S D

2008-08-01

The care of many patients undergoing long-term bladder catheterisation is complicated when the flow of urine through the catheter is blocked by encrustation. The problem results from infection by urease-producing bacteria, especially Proteus mirabilis, and the subsequent formation of crystalline biofilms on the catheter. The aim of this study was to discover how P. mirabilis initiates the development of these crystalline biofilms. The early stages in the formation of the biofilms were observed on a range of Foley catheters in a laboratory model of the catheterised bladder. Scanning electron micrographs revealed that when all-silicone, silicone-coated latex, hydrogel-coated latex, hydrogel/silver-coated latex and nitrofurazone silicone catheters were inserted into bladder models containing P. mirabilis and alkaline urine, their surfaces were rapidly coated with a microcrystalline foundation layer. X-ray microanalysis showed that this material was composed of calcium phosphate. Bacterial colonisation of the foundation layer followed and by 18h the catheters were encrusted by densely populated crystalline P. mirabilis biofilms. These observations have important implications for the development of encrustation-resistant catheters. In the case of silver catheters for example, bacterial cells can attach to the crystalline foundation layer and continue to grow, protected from contact with the underlying silver. If antimicrobials are to be incorporated into catheters to prevent encrustation, it is important that they diffuse into the urine and prevent the rise in pH that triggers crystal formation.

Pseudomonas chlororaphis Produces Two Distinct R-Tailocins That Contribute to Bacterial Competition in Biofilms and on Roots.

Science.gov (United States)

Dorosky, Robert J; Yu, Jun Myoung; Pierson, Leland S; Pierson, Elizabeth A

2017-08-01

R-type tailocins are high-molecular-weight bacteriocins that resemble bacteriophage tails and are encoded within the genomes of many Pseudomonas species. In this study, analysis of the P. chlororaphis 30-84 R-tailocin gene cluster revealed that it contains the structural components to produce two R-tailocins of different ancestral origins. Two distinct R-tailocin populations differing in length were observed in UV-induced lysates of P. chlororaphis 30-84 via transmission electron microscopy. Mutants defective in the production of one or both R-tailocins demonstrated that the killing spectrum of each tailocin is limited to Pseudomonas species. The spectra of pseudomonads killed by the two R-tailocins differed, although a few Pseudomonas species were either killed by or insusceptible to both tailocins. Tailocin release was disrupted by deletion of the holin gene within the tailocin gene cluster, demonstrating that the lysis cassette is required for the release of both R-tailocins. The loss of functional tailocin production reduced the ability of P. chlororaphis 30-84 to compete with an R-tailocin-sensitive strain within biofilms and rhizosphere communities. Our study demonstrates that Pseudomonas species can produce more than one functional R-tailocin particle sharing the same lysis cassette but differing in their killing spectra. This study provides evidence for the role of R-tailocins as determinants of bacterial competition among plant-associated Pseudomonas in biofilms and the rhizosphere. IMPORTANCE Recent studies have identified R-tailocin gene clusters potentially encoding more than one R-tailocin within the genomes of plant-associated Pseudomonas but have not demonstrated that more than one particle is produced or the ecological significance of the production of multiple R-tailocins. This study demonstrates for the first time that Pseudomonas strains can produce two distinct R-tailocins with different killing spectra, both of which contribute to bacterial

Modeling of Mesoscale Variability in Biofilm Shear Behavior.

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Pallab Barai

Full Text Available 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 regimes: a initial increase in stiffness due to strain stiffening of polymer matrix, and b eventual reduction in stiffness because of tear in polymeric substrate.

Evidence of Bacterial Biofilms among Infected and Hypertrophied Tonsils in Correlation with the Microbiology, Histopathology, and Clinical Symptoms of Tonsillar Diseases

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Saad Musbah Alasil

2013-01-01

Full Text Available Diseases of the tonsils are becoming more resistant to antibiotics due to the persistence of bacteria through the formation of biofilms. Therefore, understanding the microbiology and pathophysiology of such diseases represent an important step in the management of biofilm-related infections. We have isolated the microorganisms, evaluated their antimicrobial susceptibility, and detected the presence of bacterial biofilms in tonsillar specimens in correlation with the clinical manifestations of tonsillar diseases. Therefore, a total of 140 palatine tonsils were collected from 70 patients undergoing tonsillectomy at University Malaya Medical Centre. The most recovered isolate was Staphylococcus aureus (39.65% followed by Haemophilus influenzae (18.53%. There was high susceptibility against all selected antibiotics except for cotrimoxazole. Bacterial biofilms were detected in 60% of patients and a significant percentage of patients demonstrated infection manifestation rather than obstruction. In addition, an association between clinical symptoms like snore, apnea, nasal obstruction, and tonsillar hypertrophy was found to be related to the microbiology of tonsils particularly to the presence of biofilms. In conclusion, evidence of biofilms in tonsils in correlation with the demonstrated clinical symptoms explains the recalcitrant nature of tonsillar diseases and highlights the importance of biofilm’s early detection and prevention towards better therapeutic management of biofilm-related infections.

Synergistic Interactions within a Multispecies Biofilm Enhance Individual Species Protection against Grazing by a Pelagic Protozoan

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Prem K. Raghupathi

2018-01-01

Full Text Available Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were constructed and subjected to grazing by the ciliate Tetrahymena pyriformis. In monocultures, grazing strongly reduced planktonic cell numbers in P. amylolyticus and S. rhizophila and also X. retroflexus. At the same time, cell numbers in the underlying biofilms increased in S. rhizophila and X. retroflexus, but not in P. amylolyticus. This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by P. amylolyticus in monoculture, either with or without grazing. In four-species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of X. retroflexus, S. rhizophila, and P. amylolyticus in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a “shared grazing protection” within the four-species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and

Anti-Biofilm Compounds Derived from Marine Sponges

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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.

Combined treatment of Pseudomonas aeruginosa biofilms with bacteriophages and chlorine.

Science.gov (United States)

Zhang, Yanyan; Hu, Zhiqiang

2013-01-01

Bacterial biofilms are a growing concern in a broad range of areas. In this study, a mixture of RNA bacteriophages isolated from municipal wastewater was used to control and remove biofilms. At the concentrations of 400 and 4 × 10(7) PFU/mL, the phages inhibited Pseudomonas aeruginosa biofilm formation by 45 ± 15% and 73 ± 8%, respectively. At the concentrations of 6,000 and 6 × 10(7) PFU/mL, the phages removed 45 ± 9% and 75 ± 5% of pre-existing P. aeruginosa biofilms, respectively. Chlorine reduced biofilm growth by 86 ± 3% at the concentration of 210 mg/L, but it did not remove pre-existing biofilms. However, a combination of phages (3 × 10(7) PFU/mL) and chlorine at this concentration reduced biofilm growth by 94 ± 2% and removed 88 ± 6% of existing biofilms. In a continuous flow system with continued biofilm growth, a combination of phages (a one-time treatment at the concentration of 1.9 × 10(8) PFU/mL for 1 h first) with chlorine removed 97 ± 1% of biofilms after Day 5 while phage and chlorine treatment alone removed 89 ± 1% and 40 ± 5%, respectively. For existing biofilms, a combined use of a lower phage concentration (3.8 × 10(5) PFU/mL) and chlorination with a shorter time duration (12 h) followed by continuous water flushing removed 96 ± 1% of biofilms in less than 2 days. Laser scanning confocal microscopy supplemented with electron microscopy indicated that the combination treatment resulted in biofilms with lowest cell density and viability. These results suggest that the combination treatment of phages and chlorine is a promising method to control and remove bacterial biofilms from various surfaces. Copyright © 2012 Wiley Periodicals, Inc.

Using optical coherence tomography to detect bacterial biofilms on foley catheters (Conference Presentation)

Science.gov (United States)

Heidari, Andrew E.; Oh, Kyungjin; Chen, Zhongping

2017-02-01

Urinary tract infections(UTI) pose a serious problem for hospital patients accounting for 33% of all hospital acquired(nosocomial) infections with indwelling foley catheters. The presence of an indwelling foley catheter provides a scaffolding for circulating planktonic bacteria to adhere to and to form microbial biofilm communities that would typically be hindered by the body's innate immune system response. It is these biofilm communities that form on the inner lumen of foley catheters that provide a reservoir of pathogenic bacteria that could dislodge or disperse from the biofilm and infect urethra or bladder mucosal tissue in the urinary tract. Current diagnostic techniques of urine microbiological cultures are lacking in differentiating asymptomatic bacteriuria and symptomatic catheter-associated urinary tract infection(CAUTI) since almost all patients with chronic indwelling catheters are almost universally bacteriuruic. There is an unmet need of a diagnostic tool to assess the difference between the pathogenesis of asymptomatic bacteriuria and CAUTI, specifically at the site of the native biofilm formation. Optical Coherence Tomography(OCT) is an emerging high resolution, minimally invasive tomographic imaging technique that has shown promise in imaging biofilm structures previously in an endoscopic setting of the airway in-vivo and in microfluidic chambers. OCT can be adapted to image various sized biological surfaces and orifices such as airway branches and blood vessels by using a variety of minature endoscopic probes. In this work OCT will be used to image biofilm structure in-vitro on the inner lumen of extravasated critical care patient's foley catheters. Scanning electron microscopy will be conducted post OCT to confirm the presence of bacterial biofilm in OCT images.

Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

NARCIS (Netherlands)

Elving, GJ; van der Mei, HC; Busscher, HJ; van Weissenbruch, R; Albers, FWJ

Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses by causing leakage or an increased air-flow resistance and the prosthesis has to be replaced. To determine which bacterial or yeast strains,

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.

Spatial transcriptomes within the Pseudomonas aeruginosa biofilm architecture.

Science.gov (United States)

Heacock-Kang, Yun; Sun, Zhenxin; Zarzycki-Siek, Jan; McMillan, Ian A; Norris, Michael H; Bluhm, Andrew P; Cabanas, Darlene; Fogen, Dawson; Vo, Hung; Donachie, Stuart P; Borlee, Bradley R; Sibley, Christopher D; Lewenza, Shawn; Schurr, Michael J; Schweizer, Herbert P; Hoang, Tung T

2017-12-01

Bacterial cooperative associations and dynamics in biofilm microenvironments are of special interest in recent years. Knowledge of localized gene-expression and corresponding bacterial behaviors within the biofilm architecture at a global scale has been limited, due to a lack of robust technology to study limited number of cells in stratified layers of biofilms. With our recent pioneering developments in single bacterial cell transcriptomic analysis technology, we generated herein an unprecedented spatial transcriptome map of the mature in vitro Pseudomonas aeruginosa biofilm model, revealing contemporaneous yet altered bacterial behaviors at different layers within the biofilm architecture (i.e., surface, middle and interior of the biofilm). Many genes encoding unknown functions were highly expressed at the biofilm-solid interphase, exposing a critical gap in the knowledge of their activities that may be unique to this interior niche. Several genes of unknown functions are critical for biofilm formation. The in vivo importance of these unknown proteins was validated in invertebrate (fruit fly) and vertebrate (mouse) models. We envisage the future value of this report to the community, in aiding the further pathophysiological understanding of P. aeruginosa biofilms. Our approach will open doors to the study of bacterial functional genomics of different species in numerous settings. © 2017 The Authors. Molecular Microbiology Published by John Wiley & Sons Ltd.

Biofilm characteristics and evaluation of the sanitation procedures of thermophilic Aeribacillus pallidus E334 biofilms.

Science.gov (United States)

Kilic, Tugba; Karaca, Basar; Ozel, Beste Piril; Ozcan, Birgul; Cokmus, Cumhur; Coleri Cihan, Arzu

2017-04-01

The ability of Aeribacillus pallidus E334 to produce pellicle and form a biofilm was studied. Optimal biofilm formation occurred at 60 °C, pH 7.5 and 1.5% NaCl. Extra polymeric substances (EPS) were composed of proteins and eDNA (21.4 kb). E334 formed biofilm on many surfaces, but mostly preferred polypropylene and glass. Using CLSM analysis, the network-like structure of the EPS was observed. The A. pallidus biofilm had a novel eDNA content. DNaseI susceptibility (86.8% removal) of eDNA revealed its importance in mature biofilms, but the purified eDNA was resistant to DNaseI, probably due to its extended folding outside the matrix. Among 15 cleaning agents, biofilms could be removed with alkaline protease and sodium dodecyl sulphate (SDS). The removal of cells from polypropylene and biomass on glass was achieved with combined SDS/alkaline protease treatment. Strong A. pallidus biofilms could cause risks for industrial processes and abiotic surfaces must be taken into consideration in terms of sanitation procedures.

One-step purification and characterization of alginate lyase from a clinical Pseudomonas aeruginosa with destructive activity on bacterial biofilm

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Parinaz Ghadam

2017-05-01

Full Text Available Objective(s: Pseudomonas aeruginosais a Gram-negative and aerobic rod bacterium that displays mucoid and non-mucoid phenotype. Mucoid strains secrete alginate, which is the main agent of biofilms in chronic P. aeruginosa infections, show high resistance to antibiotics; consequently, the biological disruption of mucoid P. aeruginosa biofilms is an attractive area of study for researchers. Alginate lyase gene (algl is a member of alginate producing operon which by glycosidase activity produces primer for other enzymes in this cluster. Also this activity can destroy the extracellular alginate; therefore this enzyme participates in alginate production and destruction pathway. Alginate lyase causes detachment of a biofilm by reducing its adhesion to the surfaces, and increases phagocytosis and antibiotic susceptibility. In this study, alginate lyase was purified in just one step and its properties were investigated. Materials and Methods: The purification was done by affinity chromatography, analysed by SDS-PAGE, and its effect on P. aeruginosa biofilms was surveyed by micro titer plate assay and SEM. The substrate specificity of the enzyme was determined by PCR. Results: Alginate lyase from isolate 48 was purified in one step. It is more thermally resistant than alginate lyase from Pseudomonas aeruginosa PAO1 and poly M, poly G and poly MG alginate were the substrate of this enzyme. Moreover, it has an eradication effect on biofilms from P. aeruginosa 48 and PAO1. Conclusion: In this study an alginate lyase with many characteristics suitable in medicine such as thermal stability, effective on poly M alginate, and bacterial biofilm destructive was introduced and purified.

Abolition of Biofilm Formation in Urinary Tract Escherichia coli and Klebsiella Isolates by Metal Interference through Competition for Fur

DEFF Research Database (Denmark)

Hancock, Viktoria; Dahl, Malin; Klemm, Per

2010-01-01

Bacterial biofilms are associated with a large number of persistent and chronic infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics and immune defenses, which makes it hard if not impossible to eradicate biofilm-associated infections. In the urinary tract, free iron...... is strictly limited but is critical for bacterial growth. Biofilm-associated Escherichia coli cells are particularly desperate for iron. An attractive way of inhibiting biofilm formation is to fool the bacterial regulatory system for iron uptake. Here, we demonstrate that biofilm formation can be impaired...... by the addition of divalent metal ions, such as Zn(II) and Co(II), which inhibit iron uptake by virtue of their higher-than-iron affinity for the master controller protein of iron uptake, Fur. Reduced biofilm formation of urinary tract-infectious E. coli strains in the presence of Zn(II) was observed...

Sulphate reduction in the Aespoe HRL tunnel

International Nuclear Information System (INIS)

Gustafson, G.; Pedersen, K.; Tullborg, E.L.; Wallin, B.; Wikberg, P.

1995-12-01

Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl - concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs

Current understanding of multi-species biofilms

DEFF Research Database (Denmark)

Yang, Liang; Liu, Yang; Wu, Hong

2011-01-01

every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi......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 actually......-species biofilm formation will facilitate the development of methods for combating bacterial biofilms in clinical, environmental, industrial, and agricultural areas. The most recent advances in the understanding of multi-species biofilms are summarized and discussed in the review....

Killing of Serratia marcescens biofilms with chloramphenicol.

Science.gov (United States)

Ray, Christopher; Shenoy, Anukul T; Orihuela, Carlos J; González-Juarbe, Norberto

2017-03-29

Serratia marcescens is a Gram-negative bacterium with proven resistance to multiple antibiotics and causative of catheter-associated infections. Bacterial colonization of catheters mainly involves the formation of biofilm. The objectives of this study were to explore the susceptibility of S. marcescens biofilms to high doses of common antibiotics and non-antimicrobial agents. Biofilms formed by a clinical isolate of S. marcescens were treated with ceftriaxone, kanamycin, gentamicin, and chloramphenicol at doses corresponding to 10, 100 and 1000 times their planktonic minimum inhibitory concentration. In addition, biofilms were also treated with chemical compounds such as polysorbate-80 and ursolic acid. S. marcescens demonstrated susceptibility to ceftriaxone, kanamycin, gentamicin, and chloramphenicol in its planktonic form, however, only chloramphenicol reduced both biofilm biomass and biofilm viability. Polysorbate-80 and ursolic acid had minimal to no effect on either planktonic and biofilm grown S. marcescens. Our results suggest that supratherapeutic doses of chloramphenicol can be used effectively against established S. marcescens biofilms.

Bacterial biofilms utilization of low concentrations of organic matter on hydrophile surfaces submerged in seawater

Directory of Open Access Journals (Sweden)

Aurelia Manuela Moldoveanu

2011-12-01

Full Text Available A series of experiments were designed to determine the effect and the metabolic rate utilization of various types of organic matter in low concentration by heterotrophic marine bacteria using as Henrici slide technique as culture method and “in vitro” static conditions in sterile containers in order to obtain bacterial biofilms on the hydrophile surface of glass. The bacteria attachment and biofilm formation was analyzed for a period from 2 hours to 72 hours in order to observe de first phase of biofilm formation in condition of seawater supplied  with organic matter and noninvasive optic microscopy analysis. The utilization of five different  types of organic substances (amino-acid mixture, yeast extract, tryptone, glucose and starch reveled that bacteria multiply and are otherwise physiologically active in this very dilute nutrient solutions of 0.1% and also the results revealed that the bacterial growth was considerable in the case of the substances like amino-acid mixture with a total density of 30.9∙103 cells/mm2  and tryptone with a total density of 28.85∙103 cells/mm2  comparable to the other types of organic matter used to supply the seawater

Biofilm Surface Density Determines Biocide Effectiveness

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Sara Bas

2017-12-01

Full Text Available High resistance of biofilms for chemical challenges is a serious industrial and medical problem. In this work a gradient of surface covered with biofilm has been produced and correlated to the effectiveness of different commercially available oxidative biocides. The results for thin Escherichia coli biofilms grown in rich media supplemented with glucose or lactose on glass or poly methyl methacrylate surfaces indicate that the effectiveness of hydrogen peroxide or chlorine dioxide and quaternary ammonium compounds is inversely proportional to the fraction of the surface covered with the biofilm. In areas where biofilm covered more than 90% of the available surface the biocide treatment was inefficient after 60 min of incubation. The combined effect of oxidant and surfactant increased the effectiveness of the biocide. On the other hand, the increased biofilm viscoelasticity reduced biocide effectiveness. The results emphasize differential biocide effectiveness depending on the fraction of the attached bacterial cells. The results suggest that biofilm biocide resistance is an acquired property that increases with biofilm maturation. The more dense sessile structures present lower log reductions compared to less dense ones.

Novel synthetic organic compounds inspired from antifeedant marine alkaloids as potent bacterial biofilm inhibitors.

Science.gov (United States)

Rane, Rajesh A; Karpoormath, Rajshekhar; Naphade, Shital S; Bangalore, Pavankumar; Shaikh, Mahamadhanif; Hampannavar, Girish

2015-08-01

In this paper, we have reported seventeen novel synthetic organic compounds derived from marine bromopyrrole alkaloids, exhibiting potential inhibition of biofilm produced by Gram-positive bacteria. Compound 5f with minimumbiofilm inhibitory concentration(MBIC) of 0.39, 0.78 and 3.125 μg/mL against MSSA, MRSA and SE respectively, emerged as promising anti-biofilm lead compounds. In addition, compounds 5b, 5c, 5d, 5e, 5f, 5h, 5i and 5j revealed equal potency as that of the standard drug Vancomycin (MBIC = 3.125 μg/mL) against Streptococcus epidermidis. Notably, most of the synthesized compounds displayed better potency than Vancomycin indicating their potential as inhibitors of bacterial biofilm. The cell viability assay for the most active hybrid confirms its anti-virulence properties which need to be further researched. Copyright © 2015 Elsevier Inc. All rights reserved.

CHRONIC Cd TOXICITY OF BEAN PLANTS CAN BE PARTIALLY REDUCED BY SUPPLY OF AMMONIUM SULPHATE

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Andon VASSILEV

2006-05-01

Full Text Available The effect of ammonium sulphate supply on plant Cd uptake, growth and photosynthesis of bean plants (cv. Limburgse vroege grown in Cd-contaminated artifi cial soil was studied. The experiments were performed at controlled conditions in absence or presence of Cd (0 or 50 mg Cd kg-1 soil and with or without supply of ammonium sulphate [0 or 0.687 g (NH42SO4 kg-1]. Cadmium inhibited both growth and photosynthetic activity of bean plants. The supply of ammonium sulphate had no signifi cant effect on plant Cd uptake and growth inhibition, but to some extend, reduced Cd-induced stress and its negative impact on the photosynthetic performance.

The role of biofilms in persistent infections and factors involved in ica-independent biofilm development and gene regulation in Staphylococcus aureus.

Science.gov (United States)

Figueiredo, Agnes Marie Sá; Ferreira, Fabienne Antunes; Beltrame, Cristiana Ossaille; Côrtes, Marina Farrel

2017-09-01

Staphylococcus aureus biofilms represent a unique micro-environment that directly contribute to the bacterial fitness within hospital settings. The accumulation of this structure on implanted medical devices has frequently caused the development of persistent and chronic S. aureus-associated infections, which represent an important social and economic burden worldwide. ica-independent biofilms are composed of an assortment of bacterial products and modulated by a multifaceted and overlapping regulatory network; therefore, biofilm composition can vary among S. aureus strains. In the microniches formed by biofilms-produced by a number of bacterial species and composed by different structural components-drug refractory cell subpopulations with distinct physiological characteristics can emerge and result in therapeutic failures in patients with recalcitrant bacterial infections. In this review, we highlight the importance of biofilms in the development of persistence and chronicity in some S. aureus diseases, the main molecules associated with ica-independent biofilm development and the regulatory mechanisms that modulate ica-independent biofilm production, accumulation, and dispersion.

Norlichexanthone Reduces Virulence Gene Expression and Biofilm Formation in Staphylococcus aureus

DEFF Research Database (Denmark)

Baldry, Mara; Nielsen, Anita; Bojer, Martin S.

2016-01-01

characterise the mode of action of norlichexanthone and its effect on biofilm formation. We find that norlichexanthone reduces expression of both hla and RNAIII also in strain USA300. Structurally, norlichexanthone resembles ω-hydroxyemodin that recently was shown to bind the agr two component response......-hydroxyemodin however, norlichexanthone reduces staphylococcal biofilm formation. Transcriptomic analysis revealed that genes regulated by the SaeRS two-component system are repressed by norlichexanthone when compared to untreated cells, an effect that was mitigated in strain Newman carrying a partially constitutive...... SaeRS system. Our data show that norlichexanthone treatment reduces expression of key virulence factors in CA-MRSA strain USA300 via AgrA binding and represses biofilm formation....

Direct analysis of bacterial viability in endotracheal tube biofilm from a pig model of methicillin-resistant Staphylococcus aureus pneumonia following antimicrobial therapy.

Science.gov (United States)

Fernández-Barat, Laia; Li Bassi, Gianluigi; Ferrer, Miquel; Bosch, Anna; Calvo, Maria; Vila, Jordi; Gabarrús, Albert; Martínez-Olondris, Pilar; Rigol, Montse; Esperatti, Mariano; Luque, Néstor; Torres, Antoni

2012-07-01

Confocal laser scanning microscopy (CLSM) helps to observe the biofilms formed in the endotracheal tube (ETT) of ventilated subjects and to determine its structure and bacterial viability using specific dyes. We compared the effect of three different treatments (placebo, linezolid, and vancomycin) on the bacterial biofilm viability captured by CLSM. Eight pigs with pneumonia induced by methicillin-resistant Staphylococcus aureus (MRSA) were ventilated up to 96 h and treated with linezolid, vancomycin, or placebo (controls). ETT images were microscopically examined after staining with the live/dead(®) BacLight(™) Kit (Invitrogen, Barcelona, Spain) with a confocal laser scanning microscope. We analyzed 127 images obtained by CLSM. The median ratio of live/dead bacteria was 0.51, 0.74, and 1 for the linezolid, vancomycin, and control groups, respectively (P = 0.002 for the three groups); this ratio was significantly lower for the linezolid group, compared with the control group (P = 0.001). Images showed bacterial biofilm attached and non-attached to the ETT surface but growing within secretions accumulated inside ETT. Systemic treatment with linezolid is associated with a higher proportion of dead bacteria in the ETT biofilm of animals with MRSA pneumonia. Biofilm clusters not necessarily attach to the ETT surface. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Fundamental Studies on the Electrochemical Behaviour of Carbon Steel Exposed in Sulphide and Sulphate-Reducing Environments

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

The aim of the report is to give a fundamental understanding of the response of different electrochemical techniques on carbon steel in a sulphide environment as well as in a biologically active sulphate-reducing environment (SRB). This will form the basis for further studies and for recommendati......The aim of the report is to give a fundamental understanding of the response of different electrochemical techniques on carbon steel in a sulphide environment as well as in a biologically active sulphate-reducing environment (SRB). This will form the basis for further studies...

AtlA Mediates Extracellular DNA Release, Which Contributes to Streptococcus mutans Biofilm Formation in an Experimental Rat Model of Infective Endocarditis.

Science.gov (United States)

Jung, Chiau-Jing; Hsu, Ron-Bin; Shun, Chia-Tung; Hsu, Chih-Chieh; Chia, Jean-San

2017-09-01

Host factors, such as platelets, have been shown to enhance biofilm formation by oral commensal streptococci, inducing infective endocarditis (IE), but how bacterial components contribute to biofilm formation in vivo is still not clear. We demonstrated previously that an isogenic mutant strain of Streptococcus mutans deficient in autolysin AtlA (Δ atlA ) showed a reduced ability to cause vegetation in a rat model of bacterial endocarditis. However, the role of AtlA in bacterial biofilm formation is unclear. In this study, confocal laser scanning microscopy analysis showed that extracellular DNA (eDNA) was embedded in S. mutans GS5 floes during biofilm formation on damaged heart valves, but an Δ atlA strain could not form bacterial aggregates. Semiquantification of eDNA by PCR with bacterial 16S rRNA primers demonstrated that the Δ atlA mutant strain produced dramatically less eDNA than the wild type. Similar results were observed with in vitro biofilm models. The addition of polyanethol sulfonate, a chemical lysis inhibitor, revealed that eDNA release mediated by bacterial cell lysis is required for biofilm initiation and maturation in the wild-type strain. Supplementation of cultures with calcium ions reduced wild-type growth but increased eDNA release and biofilm mass. The effect of calcium ions on biofilm formation was abolished in Δ atlA cultures and by the addition of polyanethol sulfonate. The VicK sensor, but not CiaH, was found to be required for the induction of eDNA release or the stimulation of biofilm formation by calcium ions. These data suggest that calcium ion-regulated AtlA maturation mediates the release of eDNA by S. mutans , which contributes to biofilm formation in infective endocarditis. Copyright © 2017 American Society for Microbiology.

Ratiometric Imaging of Extracellular pH in Dental Biofilms

DEFF Research Database (Denmark)

Schlafer, Sebastian; Dige, Irene

2016-01-01

The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces...... the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms...... allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6...

AzaSite® inhibits Staphylococcus aureus and coagulase-negative Staphylococcus biofilm formation in vitro.

Science.gov (United States)

Wu, Eric C; Kowalski, Regis P; Romanowski, Eric G; Mah, Francis S; Gordon, Y Jerold; Shanks, Robert M Q

2010-12-01

The aim of this study was to analyze the effect of azithromycin (AZM) 1% ophthalmic solution in DuraSite® (AzaSite®) on biofilm formation by Staphylococcus aureus and coagulase-negative staphylococci in vitro. Susceptible and resistant clinical strains (n = 8) of S. aureus and coagulase-negative staphylococci were challenged with serial dilutions of AzaSite® and its components: AZM, benzalkonium chloride (BAK), and the DuraSite drug delivery vehicle. After 20 h of incubation, bacterial growth was quantified using a spectrophotometer (A = 600 nm). Plates were stained with crystal violet and biofilm formation was quantified spectrophotometrically at A = 590 nm. AzaSite® and AZM inhibited bacterial growth (P reduction in biofilm formation (P reduction in biofilm formation at concentrations from 1.25 to 10 mg/mL in most strains. DuraSite® inhibited biofilm formation at concentrations between 10% and 2.5% in all studied strains (P < 0.05), without affecting bacterial growth. BAK inhibited bacterial growth and biofilm formation in all strains between concentrations of 0.042 and 0.375 mg/mL (P < 0.05). AzaSite®, AZM, or BAK prevented biofilm formation by inhibiting growth of AZM-susceptible strains. AzaSite®, AZM, and DuraSite® also reduced biofilm formation at subinhibitory concentrations for growth. Our data indicate that AZM has a moderate inhibitory effect on biofilm formation, whereas DuraSite® appears to play a greater role in the inhibition of staphylococcal biofilm formation by AzaSite®.

Bacterial Adhesion & Blocking Bacterial Adhesion

DEFF Research Database (Denmark)

Vejborg, Rebecca Munk

2008-01-01

, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...... tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters...

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...

Arsenic Transfer from As-Rich Sediments to River Water in the Presence of Biofilms

Directory of Open Access Journals (Sweden)

Diego Martiñá Prieto

2016-01-01

Full Text Available The influence of epipsammic biofilms on As release from river sediments was evaluated in a microcosm experiment where biofilms were grown on sediments containing 106 mg kg−1 As, collected in the Anllóns River, and compared with control systems without biofilms. The As transfer to the water column was low (<0.11% of total As in the sediment and was further reduced by 64% in the presence of biofilms. AsV was the predominant species in the overlying water in both systems. AsIII concentration was higher (up to 12% of total dissolved As in the control systems than in the systems with biofilms, where this species was almost absent. This fact is of toxicological relevance due to the usually higher mobility and toxicity of the reduced AsIII species. Control systems exhibited higher As mobility in water, in sulphate solution, and in weak acid medium and higher bioavailability in diffusive gradient in thin films (DGT devices. Arsenic retained by the biofilm was equally distributed between extracellular and intracellular compartments. Inside the cells, significant concentrations of AsIII, monomethylarsonic acid (MMAV, and dimethylarsinic acid (DMAV were detected, suggesting that active methylation (detoxification processes are occurring in the intracellular compartment.

Kaempferol Inhibits the Primary Attachment Phase of Biofilm Formation in Staphylococcus aureus.

Science.gov (United States)

Ming, Di; Wang, Dacheng; Cao, Fengjiao; Xiang, Hua; Mu, Dan; Cao, Junjie; Li, Bangbang; Zhong, Ling; Dong, Xiaoyun; Zhong, Xiaobo; Wang, Lin; Wang, Tiedong

2017-01-01

The ability to form biofilms on surfaces makes Staphylococcus aureus the main pathogenic factor in implanted medical device infections. The aim of this study was to discover a biofilm inhibitor distinct from the antibiotics used to prevent infections resulting from S. aureus biofilms. Here, we describe kaempferol, a small molecule with anti-biofilm activity that specifically inhibited the formation of S. aureus biofilms. Crystal violet (CV) staining and fluorescence microscopy clearly showed that 64 μg/ml kaempferol inhibited biofilm formation by 80%. Meanwhile, the minimum inhibitory concentration (MIC) and growth curve results indicated that kaempferol had no antibacterial activity against the tested bacterial strain. Kaempferol inhibited the primary attachment phase of biofilm formation, as determined by a fibrinogen-binding assay. Moreover, a fluorescence resonance energy transfer (FRET) assay and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analyses revealed that kaempferol reduced the activity of S. aureus sortaseA (SrtA) and the expression of adhesion-related genes. Based on these results, kaempferol provides a starting point for the development of novel anti-biofilm drugs, which may decrease the risk of bacterial drug resistance, to prevent S. aureus biofilm-related infections.

Monitoring of Multilayered Bacterial Biofilm Morphology by Cryo-SEM for Raman Spectroscopy Measurements

Czech Academy of Sciences Publication Activity Database

Hrubanová, Kamila; Bernatová, Silvie; Samek, Ota; Šerý, Mojmír; Zemánek, Pavel; Nebesářová, Jana; Růžička, F.; Krzyžánek, Vladislav

2015-01-01

Roč. 21, S3 (2015), s. 187-188 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA ČR(CZ) GA14-20012S Institutional support: RVO:68081731 ; RVO:60077344 Keywords : multilayered bacterial biofilm * morphology by Cryo-SEM * Raman spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

Inhibited Bacterial Adhesion and Biofilm Formation on Quaternized Chitosan-Loaded Titania Nanotubes with Various Diameters

Directory of Open Access Journals (Sweden)

Wen-tao Lin

2016-03-01

Full Text Available Titania nanotube-based local drug delivery is an attractive strategy for combating implant-associated infection. In our previous study, we demonstrated that the gentamicin-loaded nanotubes could dramatically inhibit bacterial adhesion and biofilm formation on implant surfaces. Considering the overuse of antibiotics may lead to the evolution of antibiotic-resistant bacteria, we synthesized a new quaternized chitosan derivative (hydroxypropyltrimethyl ammonium chloride chitosan, HACC with a 27% degree of substitution (DS; referred to as 27% HACC that had a strong antibacterial activity and simultaneously good biocompatibility with osteogenic cells. Titania nanotubes with various diameters (80, 120, 160, and 200 nm and 200 nm length were loaded with 2 mg of HACC using a lyophilization method and vacuum drying. Two standard strain, methicillin-resistant Staphylococcus aureus (American Type Culture Collection 43300 and Staphylococcus epidermidis (American Type Culture Collection 35984, and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the bacterial adhesion at 6 h and biofilm formation at 24, 48, and 72 h on the HACC-loaded nanotubes (NT-H using the spread plate method, confocal laser scanning microscopy (CLSM, and scanning electron microscopy (SEM. Smooth titanium (Smooth Ti was also investigated and compared. We found that NT-H could significantly inhibit bacterial adhesion and biofilm formation on its surface compared with Smooth Ti, and the NT-H with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended HACC release time of NT-H with larger diameters. Therefore, NT-H can significantly improve the antibacterial ability of orthopedic implants and provide a promising strategy to prevent implant-associated infections.

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems.

Science.gov (United States)

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P; Packman, Aaron

2009-01-01

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study (6 days) to observe the initial bacterial colonization of the cooling tower, and a long-term study (3 months) to observe the ecological dynamics with repeated introduction of the test strains. An additional set of batch experiments (6 days) was carried out to evaluate the adhesion of each strain to steel surfaces under similar conditions to those found in the cooling tower experiments. Substantial differences were observed in the microbial communities that developed in the batch systems and cooling towers. P. aeruginosa showed a low degree of adherence to steel surfaces both in batch and in the cooling towers, but grew much faster than K. pneumoniae and Flavobacterium in mixed-species biofilms and ultimately became the dominant organism in the closed batch systems. However, the low degree of adherence caused P. aeruginosa to be rapidly washed out of the open cooling tower systems, and Flavobacterium became the dominant microorganism in the cooling towers in both the short-term and long-term experiments. These results indicate that adhesion, retention and growth on solid surfaces play important roles in the bacterial community that develops in cooling tower systems.

EIS Response of MIC on Carbon Steel

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel; Maahn, Ernst

1998-01-01

Abstract Microbially influenced corrosion of carbon steel under sulphate reducing (sulphide-producing) bacterial activity (SRB) results in the formation of both ferrous sulphides as well as biofilm on the metal surface. The electrochemical characteristics of the ferrous sulphide/steel interface...... as compared to the biofilm/ferrous sulphide/steel interface has been studied with EIS, DC polarisations (Tafel, LPR) and a potentiostatic step technique. The electrochemical response is related to a threshold sulphide concentration above which very characteristic changes such as indications of finite...

Susceptibility of Staphylococcus aureus biofilms to reactive discharge gases.

Science.gov (United States)

Traba, Christian; Liang, Jun F

2011-08-01

Formation of bacterial biofilms at solid-liquid interfaces creates numerous problems in both industrial and biomedical sciences. In this study, the susceptibility of Staphylococcus aureus biofilms to discharge gas generated from plasma was tested. It was found that despite distinct chemical/physical properties, discharge gases from oxygen, nitrogen, and argon demonstrated very potent and almost the same anti-biofilm activity. The bacterial cells in S. aureus biofilms were killed (>99.9%) by discharge gas within minutes of exposure. Under optimal experimental conditions, no bacteria and biofilm re-growth from discharge gas treated biofilms was found. Further studies revealed that the anti-biofilm activity of the discharge gas occurred by two distinct mechanisms: (1) killing bacteria in biofilms by causing severe cell membrane damage, and (2) damaging the extracellular polymeric matrix in the architecture of the biofilm to release biofilm from the surface of the solid substratum. Information gathered from this study provides an insight into the anti-biofilm mechanisms of plasma and confirms the applications of discharge gas in the treatment of biofilms and biofilm related bacterial infections.

Lipid shell-enveloped polymeric nanoparticles with high integrity of lipid shells improve mucus penetration and interaction with cystic fibrosis-related bacterial biofilms

DEFF Research Database (Denmark)

Wan, Feng; Nylander, Tommy; Klodzinska, Sylvia Natalie

2018-01-01

, we describe facile methods to prepare Lipid@NPs with high integrity of lipid shells and demonstrate the potential of Lipid@NPs in effective mucus penetration and interaction with cystic fibrosis-related bacterial biofilms. Lipid shell-enveloped polystyrene NPs with high integrity of lipid shells (c...... mediated layer-by layer approach. Our results suggest that the integrity of the lipid envelopes is crucial for enabling the diffusion of Lipid@PSNPs into the mucus layer and promoting the interaction of Lipid@PSNPs with a bacterial biofilm....

An In Vitro Study of the Effect of Fluoridated Milk on Oral Bacterial Biofilms

Science.gov (United States)

Pratten, J.; Bedi, R.; Wilson, M.

2000-01-01

Microcosmic dental plaques were grown in artificial saliva and supplemented with either milk or fluoridated milk. The presence of fluoride in the milk increased the pH of the biofilms and reduced the proportions of streptococci, demonstrating that in this model, fluoridation of milk produces biofilms with reduced cariogenic potential. PMID:10742268

Effects of amine fluoride on biofilm growth and salivary pellicles.

Science.gov (United States)

van der Mei, H C; Engels, E; de Vries, J; Busscher, H J

2008-01-01

The amine fluoride (AmF) N'-octadecyl-trimethylene-diamine-N,N,N'-tris(2-ethanol)-dihydro-fluoride is a cationic antimicrobial which can have beneficial effects on plaque formation. Here, we determine changes in pellicle and bacterial cell surface properties of the strains Actinomyces naeslundii HM1, Streptococcus mutans NS, S.mutans ATCC 700610, S. sobrinus HG1025 and S. oralis HM1 upon adsorption of this AmF and accompanying effects on bacterial adhesion and biofilm growth. In vitro pellicles had a zeta potential of -12 mV that became less negative upon adsorption of AmF. The chemical functionalities in which carbon and oxygen were involved changed after AmF adsorption and AmF-treated pellicles had a greater surface roughness than untreated pellicles. Water contact angles in vitro decreased from 56 to 45 degrees upon AmF treatment, which corresponded with water contact angles (44 degrees ) measured intraorally on the front incisors of volunteers immediately after using an AmF-containing toothpaste. All bacterial strains were negatively charged and their isoelectric points (IEP) increased upon AmF adsorption. Minimal inhibitory concentrations were smallest for strains exhibiting the largest increase in IEP. Adhesion to salivary pellicles and biofilm growth of the mutans streptococcal strains were significantly reduced after AmF treatment, but not of A. naeslundii or S. oralis. However, regardless of the strain involved, biofilm viability decreased significantly after AmF treatment. The electrostatic interaction between cationic AmF and negatively charged bacterial cell surfaces is pivotal in establishing reduced biofilm formation by AmF through a combination of effects on initial adhesion and killing. The major effect of AmF treatment, however, was a reduction brought about in biofilm viability.

Mixed species biofilms of Fusobacterium necrophorum and Porphyromonas levii impair the oxidative response of bovine neutrophils in vitro.

Science.gov (United States)

Lockhart, Joey S; Buret, Andre G; Ceri, Howard; Storey, Douglas G; Anderson, Stefanie J; Morck, Douglas W

2017-10-01

Biofilms composed of anaerobic bacteria can result in persistent infections and chronic inflammation. Host immune cells have difficulties clearing biofilm-related infections and this can result in tissue damage. Neutrophils are a vital component of the innate immune system and help clear biofilms. The comparative neutrophilic response to biofilms versus planktonic bacteria remains incompletely understood, particularly in the context of mixed infections. The objective of this study was to generate mixed species anaerobic bacterial biofilms composed of two opportunistic pathogens, Fusobacterium necrophorum and Porphyromonas levii, and evaluate neutrophil responses to extracellular fractions from both biofilms and planktonic cell co-cultures of the same bacteria. Purified bovine neutrophils exposed to culture supernatants from mixed species planktonic bacteria showed elevated oxidative activity compared to neutrophils exposed to biofilms composed of the same bacteria. Bacterial lipopolysaccharide plays a significant role in the stimulation of neutrophils; biofilms produced substantially more lipopolysaccharide than planktonic bacteria under these experimental conditions. Removal of lipopolysaccharide significantly reduced neutrophil oxidative response to culture supernatants of planktonic bacteria. Oxidative responses to LPS-removed biofilm supernatants and LPS-removed planktonic cell supernatants were similar. The limited neutrophil response to biofilm bacteria observed in this study supports the reduced ability of the innate immune system to eradicate biofilm-associated infections. Lipopolysaccharide is likely important in neutrophil response; however, the presence of other extracellular, immune modifying molecules in the bacterial media also appears to be important in altering neutrophil function. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distinct roles of extracellular polymeric substances in Pseudomonas aeruginosa biofilm development

DEFF Research Database (Denmark)

Yang, Liang; Hu, Yifan; Liu, Yang

2011-01-01

Bacteria form surface attached biofilm communities as one of the most important survival strategies in nature. Biofilms consist of water, bacterial cells and a wide range of self‐generated extracellular polymeric substances (EPS). Biofilm formation is a dynamic self‐assembly process and several d...... polysaccharide is more important than Pel polysaccharide in P. aeruginosa PAO1 biofilm formation and antibiotic resistance. Our study thus suggests that different EPS materials play distinct roles during bacterial biofilm formation.......Bacteria form surface attached biofilm communities as one of the most important survival strategies in nature. Biofilms consist of water, bacterial cells and a wide range of self‐generated extracellular polymeric substances (EPS). Biofilm formation is a dynamic self‐assembly process and several...... distinguishable stages are observed during bacterial biofilm development. Biofilm formation is shown to be coordinated by EPS production, cell migration, subpopulation differentiation and interactions. However, the ways these different factors affect each other and contribute to community structural...

Feasibility of lead removal from industrial effluents by sulphate reducing bacteria

International Nuclear Information System (INIS)

Nunez, L. A.; Diez, M.; Rodriguez, F. J.

2009-01-01

Battery manufacturing wastewater contains high concentration of sulphate and lead at low pH values. Biogical treatment by anaerobic reduction of sulphate to sulphite, with organic matter as electron donor, increases alkalinity and allow precipitating lead as sulphide. the type of organic matter, COD/SO 4 ratio and lead concentration over sulphate reduction rate are investigated in this work. (Author)

Influence of biofilm lubricity on shear-induced transmission of staphylococcal biofilms from stainless steel to silicone rubber.

Science.gov (United States)

Gusnaniar, Niar; Sjollema, Jelmer; Jong, Ed D; Woudstra, Willem; de Vries, Joop; Nuryastuti, Titik; van der Mei, Henny C; Busscher, Henk J

2017-11-01

In real-life situations, bacteria are often transmitted from biofilms growing on donor surfaces to receiver ones. Bacterial transmission is more complex than adhesion, involving bacterial detachment from donor and subsequent adhesion to receiver surfaces. Here, we describe a new device to study shear-induced bacterial transmission from a (stainless steel) pipe to a (silicone rubber) tube and compare transmission of EPS-producing and non-EPS-producing staphylococci. Transmission of an entire biofilm from the donor to the receiver tube did not occur, indicative of cohesive failure in the biofilm rather than of adhesive failure at the donor-biofilm interface. Biofilm was gradually transmitted over an increasing length of receiver tube, occurring mostly to the first 50 cm of the receiver tube. Under high-shearing velocity, transmission of non-EPS-producing bacteria to the second half decreased non-linearly, likely due to rapid thinning of the lowly lubricious biofilm. Oppositely, transmission of EPS-producing strains to the second tube half was not affected by higher shearing velocity due to the high lubricity and stress relaxation of the EPS-rich biofilms, ensuring continued contact with the receiver. The non-linear decrease of ongoing bacterial transmission under high-shearing velocity is new and of relevance in for instance, high-speed food slicers and food packaging. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Amide side chain amphiphilic polymers disrupt surface established bacterial bio-films and protect mice from chronic Acinetobacter baumannii infection.

Science.gov (United States)

Uppu, Divakara S S M; Samaddar, Sandip; Ghosh, Chandradhish; Paramanandham, Krishnamoorthy; Shome, Bibek R; Haldar, Jayanta

2016-01-01

Bacterial biofilms represent the root-cause of chronic or persistent infections in humans. Gram-negative bacterial infections due to nosocomial and opportunistic pathogens such as Acinetobacter baumannii are more difficult to treat because of their inherent and rapidly acquiring resistance to antibiotics. Due to biofilm formation, A. baumannii has been noted for its apparent ability to survive on artificial surfaces for an extended period of time, therefore allowing it to persist in the hospital environment. Here we report, maleic anhydride based novel cationic polymers appended with amide side chains that disrupt surface established multi-drug resistant A. baumannii biofilms. More importantly, these polymers significantly (p polymers also show potent antibacterial efficacy against methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococci (VRE) and multi-drug resistant clinical isolates of A. baumannii with minimal toxicity to mammalian cells. We observe that optimal hydrophobicity dependent on the side chain chemical structure of these polymers dictate the selective toxicity to bacteria. Polymers interact with the bacterial cell membranes by causing membrane depolarization, permeabilization and energy depletion. Bacteria develop rapid resistance to erythromycin and colistin whereas no detectable development of resistance occurs against these polymers even after several passages. These results suggest the potential use of these polymeric biomaterials in disinfecting biomedical device surfaces after the infection has become established and also for the topical treatment of chronic bacterial infections. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecular Characterization of the Bacterial Community in Biofilms for Degradation of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate) Films in Seawater.

Science.gov (United States)

Morohoshi, Tomohiro; Ogata, Kento; Okura, Tetsuo; Sato, Shunsuke

2018-03-29

Microplastics are fragmented pieces of plastic in marine environments, and have become a serious environmental issue. However, the dynamics of the biodegradation of plastic in marine environments have not yet been elucidated in detail. Polyhydroxyalkanoates (PHAs) are biodegradable polymers that are synthesized by a wide range of microorganisms. One of the PHA derivatives, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) has flexible material properties and a low melting temperature. After an incubation in seawater samples, a significant amount of biofilms were observed on the surfaces of PHBH films, and some PHBH films were mostly or partially degraded. In the biofilms that formed on the surfaces of unbroken PHBH films, the most dominant operational taxonomic units (OTUs) showed high similarity with the genus Glaciecola in the family Alteromonadaceae. On the other hand, the dominant OTUs in the biofilms that formed on the surfaces of broken PHBH films were assigned to the families Rhodobacteraceae, Rhodospirillaceae, and Oceanospirillaceae, and the genus Glaciecola mostly disappeared. The bacterial community in the biofilms on PHBH films was assumed to have dynamically changed according to the progression of degradation. Approximately 50 colonies were isolated from the biofilm samples that formed on the PHBH films and their PHBH-degrading activities were assessed. Two out of three PHBH-degrading isolates showed high similarities to Glaciecola lipolytica and Aestuariibacter halophilus in the family Alteromonadaceae. These results suggest that bacterial strains belonging to the family Alteromonadaceae function as the principal PHBH-degrading bacteria in these biofilms.

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.

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

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

Phototrophic biofilms of restored fields in the Rhenish lignite mining area: development of soil algal, bacterial, and fungal biomasses

Energy Technology Data Exchange (ETDEWEB)

Jahnke, K.; Priefer, U.B. [Rhein Westfal TH Aachen, Aachen (Germany)

2002-07-01

The formation of phototrophic biofilms in three fields under restoration of a lignite-mining area was recorded over 3 years of lucerne cultivation in terms of biomass carbon from algae, bacteria and fungi. The primary phase of biofilm development on the humus- and nitrogen deficient uppermost soil surfaces was dominated by algae. The ratio of algal carbon to heterotrophic bacterial and fungal carbon ranged from 1:0.4 to 1:2. Only during this initial developmental stage did the total microfloral carbon exceed 10% of the overall organic carbon content. With time, the ratios between algal and heterotrophic microbial carbon increased to 1:10 which was mainly due to decomposed plant residues and humus accumulation supporting the growth of bacteria and fungi. At this later stage of field development the calculated amount of bacterial and fungal carbon associated with the algae was still at least 8% of total heterotrophic microbial carbon and could even reach 20%. Bacterial and fungal biomasses were primarily governed by the organic carbon content (r = 0.81), but fluctuations-up to 50% and occurring mostly simultaneously for the three microfloral members-were observed in response to temperature and moisture conditions. The calculated in situ doubling times were 8 days (algae), 9 days (bacteria) and 14 days (fungi), respectively. Insight is given into the dynamics of phototrophic biofilm development and the abiotic factors affecting them during early phases of arable soil restoration. The results indicate that biomass changes expressed as the respective ratios between their microfloral members are a useful tool to characterise the different developmental stages of terrestrial biofilms.

Delivery of cyclodextrin polymers to bacterial biofilms - An exploratory study using rhodamine labelled cyclodextrins and multiphoton microscopy.

Science.gov (United States)

Thomsen, Hanna; Benkovics, Gábor; Fenyvesi, Éva; Farewell, Anne; Malanga, Milo; Ericson, Marica B

2017-10-15

Cyclodextrin (CD) polymers are interesting nanoparticulate systems for pharmaceutical delivery; however, knowledge regarding their applications towards delivery into complex microbial biofilm structures is so far limited. The challenge is to demonstrate penetration and transport through the biofilm and its exopolysaccharide matrix. The ideal functionalization for penetration into mature biofilms is unexplored. In this paper, we present a novel set of rhodamine labelled βCD-polymers, with different charge moieties, i.e., neutral, anionic, and cationic, and explore their potential delivery into mature Staphylococcus epidermidis biofilms using multiphoton laser scanning microscopy (MPM). The S. epidermidis biofilms, being a medically relevant model organism, were stained with SYTO9. By using MPM, three-dimensional imaging and spectral investigation of the distribution of the βCD-polymers could be obtained. It was found that the cationic βCD-polymers showed significantly higher integration into the biofilms, compared to neutral and anionic functionalized βCDs. None of the carriers presented any inherent toxicity to the biofilms, meaning that the addition of rhodamine moiety does not affect the inertness of the delivery system. Taken together, this study demonstrates a novel approach by which delivery of fluorescently labelled CD nanoparticles to bacterial biofilms can be explored using MPM. Future studies should be undertaken investigating the potential in using cationic functionalization of CD based delivery systems for targeting anti-microbial effects in biofilms. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Quorum-sensing regulation governs bacterial adhesion, biofilm development, and host colonization in Pantoea stewartii subspecies stewartii.

Science.gov (United States)

Koutsoudis, Maria D; Tsaltas, Dimitrios; Minogue, Timothy D; von Bodman, Susanne B

2006-04-11

The phytopathogenic bacterium Pantoea stewartii subsp. stewartii synthesizes stewartan exo/capsular polysaccharide (EPS) in a cell density-dependent manner governed by the EsaI/EsaR quorum-sensing (QS) system. This study analyzes biofilm development and host colonization of the WT and QS regulatory mutant strains of P. stewartii. First, we show that the cell density-dependent synthesis of stewartan EPS, governed by the EsaI/EsaR QS system, is required for proper bacterial adhesion and development of spatially defined, 3D biofilms. Second, a nonvirulent mutant lacking the esaI gene adheres strongly to surfaces and develops densely packed, less structurally defined biofilms in vitro. This strain appears to be arrested in a low cell density developmental mode. Exposure of this strain to exogenous N-acyl-homoserine lactone counteracts this adhesion phenotype. Third, QS mutants lacking the EsaR repressor attach poorly to surfaces and form amorphous biofilms heavily enmeshed in excess EPS. Fourth, the WT strain disseminates efficiently within the xylem, primarily in a basipetal direction. In contrast, the two QS mutant strains remain largely localized at the site of infection. Fifth, and most significantly, epifluorescence microscopic imaging of infected leaf tissue and excised xylem vessels reveals that the bacteria colonize the xylem with unexpected specificity, particularly toward the annular rings and spiral secondary wall thickenings of protoxylem, as opposed to indiscriminate growth to fill the xylem lumen. These observations are significant to bacterial plant pathogenesis in general and may reveal targets for disease control.

Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

Science.gov (United States)

Dashper, Stuart G; Catmull, Deanne V; Liu, Sze-Wei; Myroforidis, Helen; Zalizniak, Ilya; Palamara, Joseph E A; Huq, N Laila; Reynolds, Eric C

2016-01-01

Glass ionomer cements (GIC) are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm) formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

[Effect of compound Chinese traditional medicine on infected root canal bacteria biofilm].

Science.gov (United States)

Ma, Rui; Huang, Li-li; Xia, Wen-wei; Zhu, Cai-lian; Ye, Dong-xia

2010-08-01

To assess the efficacy of compound Chinese traditional medicine(CTM), which composed of gallic acid, magnolol and polysaccharide of Blettila striata, against the infected root canal bacterial biofilm. Actinomyces viscosus (Av), Enterococcus faecalis (Ef), Fusobacterium nucleatum (Fn) were composed to form biofilm, then confocal laser scan microscope (CLSM) was used to observe and study the bacterial activity. SAS6.12 software package was used for statistical analysis. The biofilm thickness reduced after treatment by both CTM and ZnO (P>0.05),while there was a significant decrease of the percentage of vital bacterias after treatment by CTM (Pcompound Chinese traditional medicine is effective on biofilm control, so that it would be an effective disinfecting drug for root canal sealers. Supported by Research Fund of Bureau of Traditional Chinese Medicine of Shanghai Municipality (Grant No.2008L008A).

Poly-N-acetylglucosamine matrix polysaccharide impedes fluid convection and transport of the cationic surfactant cetylpyridinium chloride through bacterial biofilms.

Science.gov (United States)

Ganeshnarayan, Krishnaraj; Shah, Suhagi M; Libera, Matthew R; Santostefano, Anthony; Kaplan, Jeffrey B

2009-03-01

Biofilms are composed of bacterial cells encased in a self-synthesized, extracellular polymeric matrix. Poly-beta(1,6)-N-acetyl-d-glucosamine (PNAG) is a major biofilm matrix component in phylogenetically diverse bacteria. In this study we investigated the physical and chemical properties of the PNAG matrix in biofilms produced in vitro by the gram-negative porcine respiratory pathogen Actinobacillus pleuropneumoniae and the gram-positive device-associated pathogen Staphylococcus epidermidis. The effect of PNAG on bulk fluid flow was determined by measuring the rate of fluid convection through biofilms cultured in centrifugal filter devices. The rate of fluid convection was significantly higher in biofilms cultured in the presence of the PNAG-degrading enzyme dispersin B than in biofilms cultured without the enzyme, indicating that PNAG decreases bulk fluid flow. PNAG also blocked transport of the quaternary ammonium compound cetylpyridinium chloride (CPC) through the biofilms. Binding of CPC to biofilms further impeded fluid convection and blocked transport of the azo dye Allura red. Bioactive CPC was efficiently eluted from biofilms by treatment with 1 M sodium chloride. Taken together, these findings suggest that CPC reacts directly with the PNAG matrix and alters its physical and chemical properties. Our results indicate that PNAG plays an important role in controlling the physiological state of biofilms and may contribute to additional biofilm-associated processes such as biocide resistance.

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.

Exploiting social evolution in biofilms

DEFF Research Database (Denmark)

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

2013-01-01

Bacteria are highly social organisms that communicate via signaling molecules, move collectively over surfaces and make biofilm communities. Nonetheless, our main line of defense against pathogenic bacteria consists of antibiotics-drugs that target individual-level traits of bacterial cells...... 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...... the molecular mechanisms and the evolutionary pressures underpinning bacterial sociality. This exciting new research can ultimately lead to new therapies against biofilm infections that exploit evolutionary cheating or the trade-off between biofilm formation and dispersal....

Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

Directory of Open Access Journals (Sweden)

Stuart G Dashper

Full Text Available Glass ionomer cements (GIC are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

Modulating bacterial and gut mucosal interactions with engineered biofilm matrix proteins.

Science.gov (United States)

Duraj-Thatte, Anna M; Praveschotinunt, Pichet; Nash, Trevor R; Ward, Frederick R; Joshi, Neel S

2018-02-22

Extracellular appendages play a significant role in mediating communication between bacteria and their host. Curli fibers are a class of bacterial fimbria that is highly amenable to engineering. We demonstrate the use of engineered curli fibers to rationally program interactions between bacteria and components of the mucosal epithelium. Commensal E. coli strains were engineered to produce recombinant curli fibers fused to the trefoil family of human cytokines. Biofilms formed from these strains bound more mucins than those producing wild-type curli fibers, and modulated mucin rheology as well. When treated with bacteria producing the curli-trefoil fusions mammalian cells behaved identically in terms of their migration behavior as when they were treated with the corresponding soluble trefoil factors. Overall, this demonstrates the potential utility of curli fibers as a scaffold for the display of bioactive domains and an untapped approach to rationally modulating host-microbe interactions using bacterial matrix proteins.

Hybrid combinations containing natural products and antimicrobial drugs that interfere with bacterial and fungal biofilms.

Science.gov (United States)

Zacchino, Susana A; Butassi, Estefanía; Cordisco, Estefanía; Svetaz, Laura A

2017-12-15

works respectively. Regarding combinations against bacterial biofilms, in vitro studies were performed in all works by using several different methods of higher variety than the used against fungal biofilms. Biofilms of both the gram (+) and gram (-) bacteria were prepared, although biofilm of Staphylococcus spp. were the most used in the collected works. Among the discovered potentiators of antibacterial drugs, 75% were terpenes, including mono, di- and triterpenes, and, among the atibacterial drugs, several structurally diverse types were used in the combinations: aminoglycosides, β-lactams, glucopeptides and fluoroquinolones. The potentiating capacity of natural products, mainly terpenes, on the antibiofilm effect of antimicrobial drugs opens a wide range of possibilities for the combination antimicrobial therapy. More in vivo studies on combinations of natural products with antimicrobial drugs acting against biofilms are highly required to cope the difficult to treat biofilm-associated infections. Copyright © 2017 Elsevier GmbH. All rights reserved.

Role of bacterial efflux pumps in biofilm formation.

Science.gov (United States)

Alav, Ilyas; Sutton, J Mark; Rahman, Khondaker Miraz

2018-02-28

Efflux pumps are widely implicated in antibiotic resistance because they can extrude the majority of clinically relevant antibiotics from within cells to the extracellular environment. However, there is increasing evidence from many studies to suggest that the pumps also play a role in biofilm formation. These studies have involved investigating the effects of efflux pump gene mutagenesis and efflux pump inhibitors on biofilm formation, and measuring the levels of efflux pump gene expression in biofilms. In particular, several key pathogenic species associated with increasing multidrug resistance, such as Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, have been investigated, whilst other studies have focused on Salmonella enterica serovar Typhimurium as a model organism and problematic pathogen. Studies have shown that efflux pumps, including AcrAB-TolC of E. coli, MexAB-OprM of P. aeruginosa, AdeFGH of A. baumannii and AcrD of S. enterica, play important roles in biofilm formation. The substrates for such pumps, and whether changes in their efflux activity affect biofilm formation directly or indirectly, remain to be determined. By understanding the roles that efflux pumps play in biofilm formation, novel therapeutic strategies can be developed to inhibit their function, to help disrupt biofilms and improve the treatment of infections. This review will discuss and evaluate the evidence for the roles of efflux pumps in biofilm formation and the potential approaches to overcome the increasing problem of biofilm-based infections.

Toxic anterior segment syndrome caused by autoclave reservoir wall biofilms and their residual toxins.

Science.gov (United States)

Sorenson, Andrew L; Sorenson, Robert L; Evans, David J

2016-11-01

To identify etiology of toxic anterior segment syndrome (TASS) after uneventful phacoemulsification. EyeMD Laser and Surgery Center, Oakland, California. Retrospective case series. Patient charts with TASS were reviewed. Reservoirs of 2 autoclaves associated with these cases were cultured for bacterial contamination. Cultures were performed on 23 other autoclave reservoirs at surgery centers in the local area. The main outcome measures were the incidence of TASS and prevalence of bacterial biofilm contamination of autoclave reservoirs. From 2010 to 2013, 11 935 consecutive cataract surgeries were performed at 1 center by multiple surgeons with no reported TASS. Between January 1, 2014, and January 15, 2015, 10 cases of TASS occurred out of 3003 cataract surgeries; these patients' charts were reviewed. Cultures of 2 Statim autoclave reservoir walls grew Bacillus species, Williamsia species, Mycobacterium mucogenicum, and Candida parapsilosis. Scanning electron microscopy of reservoir wall sections showed prominent biofilm. The 2 autoclaves were replaced in January 2015. Subsequently, 2875 cataract surgeries were performed with no reported TASS (P autoclaves were also contaminated with bacterial biofilms. Toxic anterior segment syndrome was strongly associated with bacterial biofilm contamination of autoclave reservoirs. An etiological mechanism might involve transport of heat-stable bacterial cell antigens in the steam with deposition on surgical instrumentation. Data suggest widespread prevalence of bacterial biofilms on fluid-reservoir walls, despite adherence to manufacturer guidelines for cleaning and maintenance. Prevention or elimination of autoclave fluid-reservoir biofilms might reduce the risk for postoperative TASS. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The natural antimicrobial carvacrol inhibits quorum sensing in Chromobacterium violaceum and reduces bacterial biofilm formation at sub-lethal concentrations

NARCIS (Netherlands)

Burt, Sara A|info:eu-repo/dai/nl/140114432; Ojo-Fakunle, Victoria T A; Woertman, Jenifer; Veldhuizen, Edwin J A|info:eu-repo/dai/nl/19545264X

2014-01-01

The formation of biofilm by bacteria confers resistance to biocides and presents problems in medical and veterinary clinical settings. Here we report the effect of carvacrol, one of the major antimicrobial components of oregano oil, on the formation of biofilms and its activity on existing biofilms.

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.

Anti-adhesion and Anti-biofilm Potential of Organosilane Nanoparticles against Foodborne Pathogens

Directory of Open Access Journals (Sweden)

Eleni N. Gkana

2017-07-01

Full Text Available Nowadays, modification of surfaces by nanoparticulate coatings is a simple process that may have applications in reducing the prevalence of bacterial cells both on medical devices and food processing surfaces. To this direction, biofilm biological cycle of Salmonella Typhimurium, Listeria monocytogenes, Escherichia coli O157:H7, Staphylococcus aureus, and Yersinia enterocolitica on stainless steel and glass surfaces, with or without nanocoating was monitored. To achieve this, four different commercial nanoparticle compounds (two for each surface based on organo-functionalized silanes were selected. In total 10 strains of above species (two for each species were selected to form biofilms on modified or not, stainless steel or glass surfaces, incubated at 37°C for 72 h. Biofilm population was enumerated by bead vortexing-plate counting method at four time intervals (3, 24, 48, and 72 h. Organosilane based products seemed to affect bacterial attachment on the inert surfaces and/or subsequent biofilm formation, but it was highly dependent on the species and material of surfaces involved. Specifically, reduced bacterial adhesion (at 3 h of Salmonella and E. coli was observed (P < 0.05 in nanocoating glass surfaces in comparison with the control ones. Moreover, fewer Salmonella and Yersinia biofilm cells were enumerated on stainless steel coupons coated with organosilanes, than on non-coated surfaces at 24 h (P < 0.05. This study gives an insight to the efficacy of organosilanes based coatings against biofilm formation of foodborne pathogens, however, further studies are needed to better understand the impact of surface modification and the underlying mechanisms which are involved in this phenomenon.

Biofilm-forming activity of bacteria isolated from toilet bowl biofilms and the bactericidal activity of disinfectants against the isolates.

Science.gov (United States)

Mori, Miho; Gomi, Mitsuhiro; Matsumune, Norihiko; Niizeki, Kazuma; Sakagami, Yoshikazu

2013-01-01

To evaluate the sanitary conditions of toilets, the bacterial counts of the toilet bowl biofilms in 5 Kansai area and 11 Kansai and Kanto area homes in Japan were measured in winter and summer seasons, respectively. Isolates (128 strains) were identified by analyzing 16S ribosomal RNA sequences. The number of colonies and bacterial species from biofilms sampled in winter tended to be higher and lower, respectively, than those in summer. Moreover, the composition of bacterial communities in summer and winter samples differed considerably. In summer samples, biofilms in Kansai and Kanto areas were dominated by Blastomonas sp. and Mycobacterium sp., respectively. Methylobacterium sp. was detected in all toilet bowl biofilms except for one sample. Methylobacterium sp. constituted the major presence in biofilms along with Brevundimonas sp., Sphingomonas sp., and/or Pseudomonas sp. The composition ratio of the sum of their genera was 88.0 from 42.9% of the total bacterial flora. The biofilm formation abilities of 128 isolates were investigated, and results suggested that Methylobacterium sp. and Sphingomonas sp. were involved in biofilm formation in toilet bowls. The biofilm formation of a mixed bacteria system that included bacteria with the highest biofilm-forming ability in a winter sample was greater than mixture without such bacteria. This result suggests that isolates possessing a high biofilm-forming activity are involved in the biofilm formation in the actual toilet bowl. A bactericidal test against 25 strains indicated that the bactericidal activities of didecyldimethylammonium chloride (DDAC) tended to be higher than those of polyhexamethylene biguanide (PHMB) and N-benzyl-N,N-dimethyldodecylammonium chloride (ADBAC). In particular, DDAC showed high bactericidal activity against approximately 90% of tested strains under the 5 h treatment.

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...

Sodium Dodecyl Sulfate (SDS-Loaded Nanoporous Polymer as Anti-Biofilm Surface Coating Material

Directory of Open Access Journals (Sweden)

Sokol Ndoni

2013-02-01

Full Text Available Biofilms cause extensive damage to industrial settings. Thus, it is important to improve the existing techniques and develop new strategies to prevent bacterial biofilm formation. In the present study, we have prepared nanoporous polymer films from a self-assembled 1,2-polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS block copolymer via chemical cross-linking of the 1,2-PB block followed by quantitative removal of the PDMS block. Sodium dodecyl sulfate (SDS was loaded into the nanoporous 1,2-PB from aqueous solution. The SDS-loaded nanoporous polymer films were shown to block bacterial attachment in short-term (3 h and significantly reduce biofilm formation in long-term (1 week by gram-negative bacterium Escherichia coli. Tuning the thickness or surface morphology of the nanoporous polymer films allowed to extent the anti-biofilm capability.

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

NARCIS (Netherlands)

Molhoek, E.M.; van Dijk, A.; 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

Cranberry-derived proanthocyanidins prevent formation of Candida albicans biofilms in artificial urine through biofilm- and adherence-specific mechanisms.

Science.gov (United States)

Rane, Hallie S; Bernardo, Stella M; Howell, Amy B; Lee, Samuel A

2014-02-01

Candida albicans is a common cause of nosocomial urinary tract infections (UTIs) and is responsible for increased morbidity and healthcare costs. Moreover, the US Centers for Medicare & Medicaid Services no longer reimburse for hospital-acquired catheter-associated UTIs. Thus, development of specific approaches for the prevention of Candida urinary infections is needed. Cranberry juice-derived proanthocyanidins (PACs) have efficacy in the prevention of bacterial UTIs, partially due to anti-adherence properties, but there are limited data on their use for the prevention and/or treatment of Candida UTIs. Therefore, we sought to systematically assess the in vitro effect of cranberry-derived PACs on C. albicans biofilm formation in artificial urine. C. albicans biofilms in artificial urine were coincubated with cranberry PACs at serially increasing concentrations and biofilm metabolic activity was assessed using the XTT assay in static microplate and silicone disc models. Cranberry PAC concentrations of ≥16 mg/L significantly reduced biofilm formation in all C. albicans strains tested, with a paradoxical effect observed at high concentrations in two clinical isolates. Further, cranberry PACs were additive in combination with traditional antifungals. Cranberry PACs reduced C. albicans adherence to both polystyrene and silicone. Supplementation of the medium with iron reduced the efficacy of cranberry PACs against biofilms. These findings indicate that cranberry PACs have excellent in vitro activity against C. albicans biofilm formation in artificial urine. We present preliminary evidence that cranberry PAC activity against C. albicans biofilm formation is due to anti-adherence properties and/or iron chelation.

Evidence of extensive diversity in bacterial adherence mechanisms that exploit unanticipated stainless steel surface structural complexity for biofilm formation.

Science.gov (United States)

Davis, Elisabeth M; Li, Dongyang; Shahrooei, Mohammad; Yu, Bin; Muruve, Daniel; Irvin, Randall T

2013-04-01

Three protease-resistant bioorganic 304 stainless steel surfaces were created through the reaction of synthetic peptides consisting of the D-enantiomeric isomer (D-K122-4), the retro-inverso D-enantiomeric isomer (RI-K122-4), and a combination of the two peptides (D+RI) of the Pseudomonas aeruginosa PilA receptor binding domain with steel surfaces. The peptides used to produce the new materials differ only in handedness of their three-dimensional structure, but they reacted with the steel to yield materials that differed in their surface electron work function (EWF) while displaying an identical chemical composition and equivalent surface adhesive force properties. These surfaces allowed for an assessment of the relative role of surface EWF in initial biofilm formation. We examined the ability of various bacteria (selected strains of Listeria monocytogenes, L. innocua, Staphylococcus aureus and S. epidermidis) to initiate biofilm formation. The D-K1224 generated surface displayed the lowest EWF (classically associated with greater molecular interactions and more extensive biofilm formation) but was observed to be least effectively colonized by bacteria (>50% decrease in bacterial adherence of all strains). The highest surface EWF with the lowest surface free energy (RI-K122-4 generated) was more extensively colonized by bacteria, with the binding of some strains being equivalent to unmodified steel. The D+RI generated surface was least effective in minimizing biofilm formation, where some strains displayed enhanced bacterial colonization. Fluorescent microscopy revealed that the D and RI peptides displayed similar but clearly different binding patterns, suggesting that the peptides recognized different sites on the steel, and that differential binding of the peptides to the steel surfaces influences the binding of different bacterial strains and species. We have demonstrated that stainless steel surfaces can be easily modified by peptides to generate surfaces with

The soil sulphate effect and maize plant (Zea mays L.) growth of sulphate reducing bacteria (SRB) inoculation in acid sulfate soils with the different soil water condition

Science.gov (United States)

Asmarlaili, S.; Rauf, A.; Hanafiah, D. S.; Sudarno, Y.; Abdi, P.

2018-02-01

The objective of the study was to determine the potential application of sulphate reducing bacteria on acid sulfate soil with different water content in the green house. The research was carried out in the Laboratory and Green House, Faculty of Agriculture, Universitas Sumatera Utara. This research used Randomized Block Design with two treatments factors, ie sulphate reducing bacteria (SRB) isolate (control, LK4, LK6, TSM4, TSM3, AP4, AP3, LK4 + TSM3, LK4 + AP4, LK4 + AP3, LK6 + TSM3, LK6 + AP4, LK6 + AP3, TSM4 + TSM3, TSM4 + AP4, TSM4 + AP3) and water condition (100% field capacity and 110% field capacity). The results showed that application of isolate LK4 + AP4 with water condition 110% field capacity decreased the soil sulphate content (27.38 ppm) significantly after 6 weeks. Application of isolate LK4 + AP3 with water condition 110% field capacity increased soil pH (5.58) after-week efficacy 6. Application of isolate LK4 with water condition 110% field capacity increased plant growth (140 cm; 25.74 g) significantly after week 6. The best treatment was application isolate LK4 with water condition 110% field Capacity (SRB population 2.5x108; soil sulphate content 29.10ppm; soil acidity 4.78; plant height 140cm; plant weight 25.74g).

Eradication of the corrosion-causing bacterial strains Desulfovibrio vulgaris and Desulfovibrio desulfuricans using photodisinfection

Energy Technology Data Exchange (ETDEWEB)

Street, C.N.; Gibbs, A.J. [Biocorrosion Solutions Inc., Edmonton, AB (Canada)

2010-07-01

Microbiologically influenced corrosion (MIC) can cause oil and gas pipelines to fail prematurely. The free-floating bacteria collects on the inner pipeline surface to form complex adherent biofilms. This study evaluated the use of photodisinfection as a means of treating 2 sulfate-reducing bacterial strains known to contribute to MIC. The sulfate-reducing strains Desulfovibrio vulgaris and Desulfovibrio desulfuricans were studied experimentally to a concentration of 10{sup 7} colony-forming units per millimeter. Bacterial inocula was made to an optical density of 0.150 at 420 nm in order to assess biofilm growth. The study showed that photodisinfection was able to eradicate more than 99 per cent of the bacterial populations prepared in the study. The method was highly effective in removing the biofilms known to cause MIC in oil and gas pipelines. A close-loop dynamic flow system model will be prepared to evaluate the ability of photodisinfection to inhibit bacterially-influenced corrosion of steel coupons. 24 refs., 3 tabs., 1 fig.

Inhibition of Staphylococcus epidermidis Biofilm by Trimethylsilane Plasma Coating

Science.gov (United States)

Ma, Yibao; Jones, John E.; Ritts, Andrew C.; Yu, Qingsong

2012-01-01

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. PMID:22964248

Biofilm-specific extracellular matrix proteins of non-typeable Haemophilus influenzae

Science.gov (United States)

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

2014-01-01

Non-typeable 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 hr and 96 hr NTHi biofilms contained polysaccharides and proteinaceous components as detected by NMR and 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 hr biofilms, two were found only in 96 hr biofilms, and fifteen were present in the ECM of both 24 hr and 96 hr NTHi biofilms. All proteins identified were either associated with bacterial membranes or were 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. PMID:24942343

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

International Nuclear Information System (INIS)

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

2014-01-01

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. (paper)

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

Directory of Open Access Journals (Sweden)

A Al-Ahmad

Full Text Available 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.

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.

Lactobacilli : Important in biofilm formation on voice prostheses

NARCIS (Netherlands)

Buijssen, Kevin J. D. A.; Harmsen, Hermie J. M.; van der Mei, Henny C.; Busscher, Henk J.; van der Laan, Bernard F. A. M.

OBJECTIVE: We sought to identify bacterial strains responsible for biofilm formation on silicone rubber voice prostheses. STUDY DESIGN: We conducted an analysis of the bacterial population in biofilms on used silicone rubber voice prostheses by using new microbiological methods. METHODS: Two

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...

Dynamic Dispersal of Surface Layer Biofilm Induced by Nanosized TiO2 Based on Surface Plasmon Resonance and Waveguide.

Science.gov (United States)

Zhang, Peng; Guo, Jin-Song; Yan, Peng; Chen, You-Peng; Wang, Wei; Dai, You-Zhi; Fang, Fang; Wang, Gui-Xue; Shen, Yu

2018-05-01

Pollutant degradation is present mainly in the surface layer of biofilms, and the surface layer is the most vulnerable to impairment by toxic pollutants. In this work, the effects of nanosized TiO 2 (n-TiO 2 ) on the average thicknesses of Bacillus subtilis biofilm and on bacterial attachment on different surfaces were investigated. The binding mechanism of n-TiO 2 to the cell surface was also probed. The results revealed that n-TiO 2 caused biofilm dispersal and the thicknesses decreased by 2.0 to 2.6 μm after several hours of exposure. The attachment abilities of bacteria with extracellular polymeric substances (EPS) on hydrophilic surfaces were significantly reduced by 31% and 81% under 10 and 100 mg/liter of n-TiO 2 , respectively, whereas those of bacteria without EPS were significantly reduced by 43% and 87%, respectively. The attachment abilities of bacteria with and without EPS on hydrophobic surfaces were significantly reduced by 50% and 56%, respectively, under 100 mg/liter of n-TiO 2 The results demonstrated that biofilm dispersal can be attributed to the changes in the cell surface structure and the reduction of microbial attachment ability. IMPORTANCE Nanoparticles can penetrate into the outer layer of biofilm in a relatively short period and can bind onto EPS and bacterial surfaces. The current work probed the effects of nanosized TiO 2 (n-TiO 2 ) on biofilm thickness, bacterial migration, and surface properties of the cell in the early stage using the surface plasmon resonance waveguide mode. The results demonstrated that n-TiO 2 decreased the adhesive ability of both cell and EPS and induced bacterial migration and biofilm detachment in several hours. The decreased adhesive ability of microbes and EPS worked against microbial aggregation, reducing the effluent quality in the biological wastewater treatment process. Copyright © 2018 American Society for Microbiology.

A morphological study of the changes in the ultrastructure of a bacterial biofilm disrupted by an ac corona discharge in air

International Nuclear Information System (INIS)

Stepanova, Olga; Astafiev, Alexander; Kudryavtsev, Anatoly; Rybalchenko, Oksana; Orlova, Olga; Kapustina, Valentina

2016-01-01

The morphology of bacterial cells and biofilms subjected to a low frequency (∼10"5 Hz) ac (∼10"−"1 A) corona discharge was investigated using electron microscopy. A low-frequency ac corona discharge in air is shown to have a bactericidal and bacteriostatic effect on Escherichia coli M17 culture at both the cellular and population levels. Corona exposure inhibits the formation of a microbial community and results in the destruction of formed biofilms. This paper presents data on changes in the ultrastructure of cells and biofilms after corona treatment. Our results suggest that the E. coli M17 cells inside biofilms are affected with results similar to sub-lethal and lethal thermal exposure. Some of the biological aspects of colony and biofilm cells death are evaluated. Morphological changes in the ultrastructure of the biofilms under corona treatment are described. Our results indicate that the heating effect is the main factor responsible for the corona-induced inactivation of bacteria.

A morphological study of the changes in the ultrastructure of a bacterial biofilm disrupted by an ac corona discharge in air

Energy Technology Data Exchange (ETDEWEB)

Stepanova, Olga, E-mail: o.m.stepanova@spbu.ru; Astafiev, Alexander; Kudryavtsev, Anatoly [Physical Faculty, Saint Petersburg State University, St. Petersburg (Russian Federation); Rybalchenko, Oksana; Orlova, Olga; Kapustina, Valentina [Faculty of Medicine, Saint Petersburg State University, St. Petersburg (Russian Federation)

2016-08-14

The morphology of bacterial cells and biofilms subjected to a low frequency (∼10{sup 5} Hz) ac (∼10{sup −1} A) corona discharge was investigated using electron microscopy. A low-frequency ac corona discharge in air is shown to have a bactericidal and bacteriostatic effect on Escherichia coli M17 culture at both the cellular and population levels. Corona exposure inhibits the formation of a microbial community and results in the destruction of formed biofilms. This paper presents data on changes in the ultrastructure of cells and biofilms after corona treatment. Our results suggest that the E. coli M17 cells inside biofilms are affected with results similar to sub-lethal and lethal thermal exposure. Some of the biological aspects of colony and biofilm cells death are evaluated. Morphological changes in the ultrastructure of the biofilms under corona treatment are described. Our results indicate that the heating effect is the main factor responsible for the corona-induced inactivation of bacteria.

Microbiology and biogeochemistry of sediments and rhizosphere of mangroves: bacterial production, sulphate-reduction and methylation of mercury with methodological focus on incubation-extraction of 14C-leucine

International Nuclear Information System (INIS)

Feijo, Issabella Vitoria Abduche

2015-01-01

located at Sepetiba bay. We also estimated the contribution for BP of different groups using metabolic inhibitors: prokaryotic, eukaryotic, sulphate-reducing bacteria (SRB) and methanogenic. Our results showed that bacteria are the major group in carbon cycling in all location and sulfate-reducing bacteria would not be the main group involved in the degradation of organic matter in the studied mangroves. Regarding the formation of MeHg in mangrove sediment, this work is the first to assess mercury methylation in the rhizosphere (pneumatophores and feeding roots) of a mangrove tree (Avicennia schaueriana). Our results showed that mercury methylation and sulphate reduction were significantly higher in the rhizosphere of feeding roots (p <0.05). Bacterial production as also higher in rhizosphere but with no significant difference with bulk sediment (p>0.05). There was a significant positive correlation between sulfate-reducing and PB (r 2 = 0.29, p <0.05). No significant correlation was found neither with BP and %MeHg, nor with SRR and %MeHg. Sites where sulfate reduction was higher, %MeHg decreased. Our data suggested that other groups in addition to the SRB may be involved in methylation of mercury in mangrove rhizosphere. (author)

Antimicrobial photodynamic therapy combined with conventional endodontic treatment to eliminate root canal biofilm infection.

Science.gov (United States)

Garcez, Aguinaldo S; Ribeiro, Martha S; Tegos, George P; Núñez, Silvia C; Jorge, Antonio O C; Hamblin, Michael R

2007-01-01

To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. Ten single-rooted freshly extracted human teeth were inoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laser light delivered into the root canal via a 200-micro fiber, and this was compared and combined with standard endodontic treatment using mechanical debridement and antiseptic irrigation. Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (Ptreatment. Bioluminescence imaging is an efficient way to monitor endodontic therapy. Antimicrobial PDT may have a role to play in optimized endodontic therapy. (c) 2006 Wiley-Liss, Inc.

Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

Energy Technology Data Exchange (ETDEWEB)

Pusch, R. [Geodevelopment AB, Lund (Sweden)

1999-12-01

Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m{sup 3}. Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter.

Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

International Nuclear Information System (INIS)

Pusch, R.

1999-12-01

Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m 3 . Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter

Pseudomonas aeruginosa forms Biofilms in Acute InfectionIndependent of Cell-to-Cell Signaling

Energy Technology Data Exchange (ETDEWEB)

Schaber, J. Andy; Triffo, W.J.; Suh, Sang J.; Oliver, Jeffrey W.; Hastert, Mary C.; Griswold, John A.; Auer, Manfred; Hamood, Abdul N.; Rumbaugh, Kendra P.

2006-09-20

Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 hours of infection in thermally-injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections. P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild type and QS-deficient P. aeruginosa formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independent of QS.

Serrulatane Diterpenoid from Eremophila neglecta Exhibits Bacterial Biofilm Dispersion and Inhibits Release of Pro-inflammatory Cytokines from Activated Macrophages.

Science.gov (United States)

Mon, Htwe H; Christo, Susan N; Ndi, Chi P; Jasieniak, Marek; Rickard, Heather; Hayball, John D; Griesser, Hans J; Semple, Susan J

2015-12-24

The purpose of this study was to assess the biofilm-removing efficacy and inflammatory activity of a serrulatane diterpenoid, 8-hydroxyserrulat-14-en-19-oic acid (1), isolated from the Australian medicinal plant Eremophila neglecta. Biofilm breakup activity of compound 1 on established Staphylococcus epidermidis and Staphylococcus aureus biofilms was compared to the antiseptic chlorhexidine and antibiotic levofloxacin. In a time-course study, 1 was deposited onto polypropylene mesh to mimic a wound dressing and tested for biofilm removal. The ex-vivo cytotoxicity and effect on lipopolysaccharide-induced pro-inflammatory cytokine release were studied in mouse primary bone-marrow-derived macrophage (BMDM) cells. Compound 1 was effective in dispersing 12 h pre-established biofilms with a 7 log10 reduction of viable bacterial cell counts, but was less active against 24 h biofilms (approximately 2 log10 reduction). Compound-loaded mesh showed dosage-dependent biofilm-removing capability. In addition, compound 1 displayed a significant inhibitory effect on tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) secretion from BMDM cells, but interleukin-1 beta (IL-1β) secretion was not significant. The compound was not cytotoxic to BMDM cells at concentrations effective in removing biofilm and lowering cytokine release. These findings highlight the potential of this serrulatane diterpenoid to be further developed for applications in wound management.

Effects of meat juice on biofilm formation of Campylobacter and Salmonella.

Science.gov (United States)

Li, Jiaqi; Feng, Jinsong; Ma, Lina; de la Fuente Núñez, César; Gölz, Greta; Lu, Xiaonan

2017-07-17

Campylobacter and Salmonella are leading causes of foodborne illnesses worldwide, vastly harboured by raw meat as their common food reservoir. Both microbes are prevalent in meat processing environments in the form of biofilms that contribute to cross-contamination and foodborne infection. This study applied raw meat juice (chicken juice and pork juice) as a minimally processed food model to study its effects on bacterial biofilm formation. Meat juice was collected during the freeze-thaw process of raw meat and sterilized by filtration. In 96-well polystyrene plates and glass chambers, supplementation of over 25% meat juice (v/v) in laboratory media led to an increase in biofilm formation of Campylobacter and Salmonella. During the initial attachment stage of biofilm development, more bacterial cells were present on surfaces treated with meat juice residues compared to control surfaces. Meat juice particulates on abiotic surfaces facilitated biofilm formation of Campylobacter and Salmonella under both static and flow conditions, with the latter being assessed using a microfluidic platform. Further, the deficiency in biofilm formation of selected Campylobacter and Salmonella mutant strains was restored in the presence of meat juice particulates. These results suggested that meat juice residues on the abiotic surfaces might act as a surface conditioner to support initial attachment and biofilm formation of Campylobacter and Salmonella. This study sheds light on a possible survival mechanism of Campylobacter and Salmonella in meat processing environments, and indicates that thorough cleaning of meat residues during meat production and handling is critical to reduce the bacterial load of Campylobacter and Salmonella. Copyright © 2017 Elsevier B.V. All rights reserved.

Biofilm biomass disruption by natural substances with potential for endodontic use

Directory of Open Access Journals (Sweden)

Flávio Rodrigues Ferreira Alves

2013-02-01

Full Text Available This study evaluated the in vitro effects of four natural substances on the biomass of bacterial biofilms to assess their potential use as root canal irrigants. The following substances and their combinations were tested: 0.2% farnesol; 5% xylitol; 20% xylitol; 0.2% farnesol and 5% xylitol; 0.2% farnesol, 5% xylitol, and 0.1% lactoferrin; 5% xylitol and 0.1% lactoferrin; and 20 mM salicylic acid. The crystal violet assay was used to evaluate the effects of these substances on the biomass of biofilms formed by Enterococcus faecalis and Staphylococcus epidermidis. All substances except for 20 mM salicylic acid and 20% xylitol reduced biofilm mass when compared to controls. The combination of farnesol and xylitol was the most effective agent against E. faecalis ATCC 29212 (p < 0.05. Farnesol combined with xylitol and lactoferrin was the most effective against biofilms of the endodontic strain of E. faecalis MB35 (p < 0.05. Similarly, combinations involving farnesol, xylitol, and lactoferrin reduced the biomass of S. epidermidis biofilms. In general, farnesol, xylitol, and lactoferrin or farnesol and xylitol reduced biofilm biomass most effectively. Therefore, it was concluded that combinations of antibiofilm substances have potential use in endodontic treatment to combat biofilms.

Detection of biofilm production of Yersinia enterocolitica strains isolated from infected children and comparative antimicrobial susceptibility of biofilm versus planktonic forms.

Science.gov (United States)

Ioannidis, A; Kyratsa, A; Ioannidou, V; Bersimis, S; Chatzipanagiotou, S

2014-06-01

The ability of Yersinia species to produce biofilms has not been hitherto systematically studied, although there is evidence, that Y. enterocolitica is able to form biofilms on inanimate surfaces. The present study aimed to detect the production of biofilms by 60 clinical strains of Y. enterocolitica and to compare the antimicrobial susceptibility of planktonic versus biofilm-forming bacteria. Y. enterocolitica strains were collected from stool and blood cultures collected from β-thalassaemic children, with gastroenteritis and/or septicemia. The isolated bacterial strains were grouped by biotyping and serotyping and the antimicrobial susceptibility of the planktonic forms was investigated by MIC determination. Biofilm formation was detected by the use of silicone disks and for the biofilm forming strains the minimum inhibitory concentration for bacterial regrowth (MICBR) of 11 clinically important antimicrobials was determined. The presence of the waaE, a gene reported to be related with biofilm formation was investigated in all the strains. All of 60 strains were positive for biofilm production by the use of silicone disks. The great majority of the biofilm forms were resistant to all the antimicrobials. In antimicrobial concentrations far higher than the CLSI breakpoints, bacterial regrowth from the biofilms was still possible. None of the strains bore the waaE gene. These results, indicate that biofilm formation by Y. enterocolitica might be an inherent feature. The presence of biofilms increased dramatically the MICBR in all antimicrobials. The way in which biofilms could contribute to Y. enterocolitica pathogenicity in humans is a matter needing further investigation.

Decontamination Efficiency of Fish Bacterial Flora from Processing Surfaces

Directory of Open Access Journals (Sweden)

Birna Guðbjörnsdóttir

2009-01-01

Full Text Available There are numerous parameters that can influence bacterial decontamination during washing of machinery and equipment in a food processing establishment. Incomplete decontamination of bacteria will increase the risk of biofilm formation and consequently increase the risk of pathogen contamination or prevalence of other undesirable microorganisms such as spoilage bacteria in the processing line. The efficiency of a typical washing protocol has been determined by testing three critical parameters and their effects on bacterial decontamination. Two surface materials (plastic and stainless steel, water temperatures (7 and 25 °C and detergent concentrations (2 and 4 % were used for this purpose in combination with two types of detergents. Biofilm was prepared on the surfaces with undefined bacterial flora obtained from minced cod fillets. The bacterial flora of the biofilm was characterised by cultivation and molecular analysis of 16S rRNA genes. All different combinations of washing protocols tested were able to remove more than 99.9 % of the bacteria in the biofilm and reduce the cell number from 7 to 0 or 2 log units of bacteria/cm2. The results show that it is possible to use less diluted detergents than recommended with comparable success, and it is easier to clean surface material made of stainless steel compared to polyethylene plastic.

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. Copyright © 2012 Elsevier B.V. All rights reserved.

Water-limiting conditions alter the structure and biofilm-forming ability of bacterial multispecies communities in the alfalfa rhizosphere.

Directory of Open Access Journals (Sweden)

Pablo Bogino

Full Text Available Biofilms are microbial communities that adhere to biotic or abiotic surfaces and are enclosed in a protective matrix of extracellular compounds. An important advantage of the biofilm lifestyle for soil bacteria (rhizobacteria is protection against water deprivation (desiccation or osmotic effect. The rhizosphere is a crucial microhabitat for ecological, interactive, and agricultural production processes. The composition and functions of bacterial biofilms in soil microniches are poorly understood. We studied multibacterial communities established as biofilm-like structures in the rhizosphere of Medicago sativa (alfalfa exposed to 3 experimental conditions of water limitation. The whole biofilm-forming ability (WBFA for rhizospheric communities exposed to desiccation was higher than that of communities exposed to saline or nonstressful conditions. A culture-dependent ribotyping analysis indicated that communities exposed to desiccation or saline conditions were more diverse than those under the nonstressful condition. 16S rRNA gene sequencing of selected strains showed that the rhizospheric communities consisted primarily of members of the Actinobacteria and α- and γ-Proteobacteria, regardless of the water-limiting condition. Our findings contribute to improved understanding of the effects of environmental stress factors on plant-bacteria interaction processes and have potential application to agricultural management practices.

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...

Composite Biofilms grown in Acidic Mining Lakes and assessed by Electron Microscopy and Molecular Techniques

International Nuclear Information System (INIS)

Luensdorf, Heinrich; Wenderoth, Dirk F.; Abraham, Wolf-Rainer

2002-01-01

Microbial consortia of composite biofilms, grown in surface water of acidicmining lakes near Lauchhammer, Germany, were investigated. The red-brown colored lake water was acidic (pH 2.5), had high concentrations of Fe(III), Al(III), and sulphate and low concentrations of dissolved organic matter. As a result the abundance of bacteria in the lake is with 10 4 cells mL -1 rather low. One input of organic material into the lake are autumnal leaves from trees, growing in the lakeside area. From aliquots of unfixed birch leave biofilms the 16S rRNA genes were amplified by PCR and community fingerprints were determined by single-strand conformation polymorphism (SSCP) analysis. Specific bands within the fingerprints were extracted from SSCP gels and sequenced for the taxonomical affiliation.These results were compared with those from the second type of biofilms which were grown on sterile substrata, floating submersed in surface waters of the lakes. By excising the bands from the gel and sequencing the individual bands bacterial taxa, common to both types of biofilms, were found but also some, which were only present in one type of biofilm. Ultrathin sectioned biofilms often showed bacteria associated with electron dense particles as main inorganic constituents. Elemental microanalysis by energy dispersive X-ray analysis (EDX) revealed them to contain iron, sulfur and oxygen as main elemental fractions and electron diffraction ring pattern analysis classified them to be schwertmannite. These bacteria and their interactions with each other as well as with the inorganic minerals formed in this lake generally is of great interest, in order to use these results for bioremediation applications

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. PMID:24086697

A characterization of DNA release in Pseudomonas aeruginosa cultures and biofilms

DEFF Research Database (Denmark)

Allesen-Holm, Marie; Barken, Kim Bundvig; Yang, Liang

2006-01-01

-type P. aeruginosa biofilms stained with different DNA stains suggested that the extracellular DNA is located primarily in the stalks of mushroom-shaped multicellular structures, with a high concentration especially in the outer part of the stalks forming a border between the stalk-forming bacteria...... to whole-genome DNA. Evidence that the extracellular DNA in P. aeruginosa biofilms and cultures is generated via lysis of a subpopulation of the bacteria was obtained through experiments where extracellular beta-galactosidase released from lacZ-containing P. aeruginosa strains was assessed. Experiments...... and the cap-forming bacteria. Biofilms formed by lasIrhlI, pqsA and fliMpilA mutants contained less extracellular DNA than biofilms formed by the wild type, and the mutant biofilms were more susceptible to treatment with sodium dodecyl sulphate than the wild-type biofilm....

Microbiologically influenced corrosion of sa106 gr.b carbon steel in raw water

International Nuclear Information System (INIS)

Tunaru, M.; Velciu, L.; Stancu, M.; Popa, L.

2015-01-01

This paper presents the evaluation of microbiological corrosion susceptibility of carbon steel SA106gr.B in raw water. The experiment consisted of a series of electrochemical accelerated tests which evaluated the pitting corrosion susceptibility and determined corrosion rates before and after the immersion. The microbiological analysis of the water determined the types of bacteria and bacterial concentration present in water and in biofilms. Microbiological analysis of the water sample emphasized the existence, in small numbers (10-101 ml-1), of heterotrophic aerobic bacteria, sulphate-reducing bacteria and iron-oxidizing microorganisms. Along with sulphate-reducing bacteria, the heterotrophic aerobic bacteria and the iron-oxidizing microorganisms are categorized as having an important role in the corrosion of metals, including steel. The surfaces of the tested samples were analysed using the optical and electronic microscope, and emphasized the role of bacteria in the development of biofilms under which appeared characteristics of corrosion attack. (authors)

Short communication: Evaluation of a sol-gel-based stainless steel surface modification to reduce fouling and biofilm formation during pasteurization of milk.

Science.gov (United States)

Liu, Dylan Zhe; Jindal, Shivali; Amamcharla, Jayendra; Anand, Sanjeev; Metzger, Lloyd

2017-04-01

Milk fouling and biofilms are common problems in the dairy industry across many types of processing equipment. One way to reduce milk fouling and biofilms is to modify the characteristics of milk contact surfaces. This study examines the viability of using Thermolon (Porcelain Industries Inc., Dickson, TN), a sol-gel-based surface modification of stainless steel, during thermal processing of milk. We used stainless steel 316L (control) and sol-gel-modified coupons in this study to evaluate fouling behavior and bacterial adhesion. The surface roughness as measured by an optical profiler indicated that the control coupons had a slightly smoother finish. Contact angle measurements showed that the modified surface led to a higher water contact angle, suggesting a more hydrophobic surface. The modified surface also had a lower surface energy (32.4 ± 1.4 mN/m) than the control surface (41.36 ± 2.7 mN/m). We evaluated the susceptibility of control and modified stainless steel coupons to fouling in a benchtop plate heat exchanger. We observed a significant reduction in the amount of fouled layer on modified surfaces. We found an average fouling weight of 19.21 mg/cm 2 and 0.37 mg/cm 2 on the control and modified stainless steel coupons, respectively. We also examined the adhesion of Bacillus and biofilm formation, and observed that the modified stainless steel surface offered greater resistance to biofilm formation. Overall, the Thermolon-modified surface showed potential in the thermal processing of milk, offering significantly lower fouling and bacterial attachment than the control surface. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

In vitro and in vivo generation and characterization of Pseudomonas aeruginosa biofilm-dispersed cells via c-di-GMP manipulation

DEFF Research Database (Denmark)

Chua, Song Lin; Hultqvist, Louise D; Yuan, Mingjun

2015-01-01

Bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) is a global secondary bacterial messenger that controls the formation of drug-resistant multicellular biofilms. Lowering the intracellular c-di-GMP content can disperse biofilms, and it is proposed as a biofilm eradication strategy...... biofilms by reducing the intracellular c-di-GMP content through modulation of phosphodiesterases (PDEs). Unlike conventional protocols that demonstrate biofilm dispersal by biomass quantification, our protocols enable physiological characterization of the dispersed cells. Biomarkers of dispersed cells...