Journal articles on the topic 'Biofilms – Research'
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1
Rittmann, B. E. "Where are we with biofilms now? Where are we going?" Water Science and Technology 55, no. 8-9 (April 1, 2007): 1–7. http://dx.doi.org/10.2166/wst.2007.235.
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The IWA's BiofilmVI conference presented a wide range of research on biofilm systems. Particularly popular themes were nitrogen removal, mathematical modelling and microbial ecology. Emerging themes included biofilms with membranes, pathogens in biofilms, biofouling and detachment. Within microbial ecology and mathematical modelling, emphasis was given to N-removal systems, particularly involving nitrifiers and Anammox bacteria. Both themes also recognised the importance of biofilm detachment. Although biofilms on membranes gained attention, little interest was exhibited towards linking biofilms with other advanced materials, such as ceramics, conductors, semi-conductors or nano-materials. Research presented at BiofilmVI marked major advances in improving water sustainability towards removing BOD and N, but did not address many emerging contaminants, such as oxidised contaminants and endocrine disruptors. Attention to energy sustainability, such as with bio-hydrogen or microbial fuel cells, was minimal. Thus, research reported at BiofilmVI was strong towards “improving the expected” with regard to BOD and N removal, but not yet focused on “exploiting the unexpected” to deal with emerging pollutants and bio-energy.
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Jiang, Yu, Mengxin Geng, and Liping Bai. "Targeting Biofilms Therapy: Current Research Strategies and Development Hurdles." Microorganisms 8, no. 8 (August 11, 2020): 1222. http://dx.doi.org/10.3390/microorganisms8081222.
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Biofilms are aggregate of microorganisms in which cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS) and adhere to each other and/or to a surface. The development of biofilm affords pathogens significantly increased tolerances to antibiotics and antimicrobials. Up to 80% of human bacterial infections are biofilm-associated. Dispersal of biofilms can turn microbial cells into their more vulnerable planktonic phenotype and improve the therapeutic effect of antimicrobials. In this review, we focus on multiple therapeutic strategies that are currently being developed to target important structural and functional characteristics and drug resistance mechanisms of biofilms. We thoroughly discuss the current biofilm targeting strategies from four major aspects—targeting EPS, dispersal molecules, targeting quorum sensing, and targeting dormant cells. We explain each aspect with examples and discuss the main hurdles in the development of biofilm dispersal agents in order to provide a rationale for multi-targeted therapy strategies that target the complicated biofilms. Biofilm dispersal is a promising research direction to treat biofilm-associated infections in the future, and more in vivo experiments should be performed to ensure the efficacy of these therapeutic agents before being used in clinic.
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Keir, J., L. Pedelty, and A. C. Swift. "Biofilms in chronic rhinosinusitis: systematic review and suggestions for future research." Journal of Laryngology & Otology 125, no. 4 (February 11, 2011): 331–37. http://dx.doi.org/10.1017/s0022215111000016.
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AbstractBackground:A biofilm is a community of micro-organisms encased within a self-produced, extracellular, polymeric substance. The role of biofilms as a major pathological aetiology in chronic rhinosinusitis would help explain the clinical manifestation of the disease.Objectives:To examine the current evidence, and to discuss possible future research directions, in relation to biofilms and chronic rhinosinusitis.Study design:Systematic literature review.Evaluation method:Two assessors independently undertook critical appraisal of the studies identified by the literature search. Significant findings were incorporated into this review. The primary outcome assessed was the presence of biofilm in human mucosal biopsy samples taken from patients with chronic rhinosinusitis, and from healthy controls.Results:We identified 11 studies examining biofilm formation in human mucosal biopsy samples taken from patients with chronic rhinosinusitis.Conclusion:It is unlikely that biofilms occur in every case of chronic rhinosinusitis; consequently, the significance of ‘biofilm detection’ in some series should be considered carefully. Several authors have argued strongly for the use of confocal scanning laser microscopy with fluorescent in situ hybridisation probes as the ‘gold standard’ for biofilm imaging. This imaging modality should be combined with further investigation of the microbiology of chronic rhinosinusitis, and of the efficacy of traditional culture techniques used for pathogen identification.
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Rocco, Christopher J., Lauren O. Bakaletz, and Steven D. Goodman. "Targeting the HUβ Protein PreventsPorphyromonas gingivalisfrom Entering into Preexisting Biofilms." Journal of Bacteriology 200, no. 11 (February 5, 2018): e00790-17. http://dx.doi.org/10.1128/jb.00790-17.
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ABSTRACTThe oral cavity is home to a wide variety of bacterial species, both commensal, such as various streptococcal species, and pathogenic, such asPorphyromonas gingivalis, one of the main etiological agents of periodontal disease. Our understanding of how these bacteria ultimately cause disease is highly dependent upon understanding how they coexist and interact with one another in biofilm communities and the mechanisms by which biofilms are formed. Our research has demonstrated that the DNABII family of DNA-binding proteins are important components of the extracellular DNA (eDNA)-dependent matrix of bacterial biofilms and that sequestering these proteins via protein-specific antibodies results in the collapse of the biofilm structure and release of the resident bacteria. While the high degree of similarity among the DNABII family of proteins has allowed antibodies derived against specific DNABII proteins to disrupt biofilms formed by a wide range of bacterial pathogens, the DNABII proteins ofP. gingivalishave proven to be antigenically distinct, allowing us to determine if we can use anti-P. gingivalisHUβ antibodies to specifically target this species for removal from a mixed-species biofilm. Importantly, despite forming homotypic biofilmsin vitro,P. gingivalismust enter preexisting biofilmsin vivoin order to persist within the oral cavity. The data presented here indicate that antibodies derived against theP. gingivalisDNABII protein, HUβ, reduce by half the amount ofP. gingivalisorganisms entering into preexisting biofilm formed by four oral streptococcal species. These results support our efforts to develop methods for preventing and treating periodontal disease.IMPORTANCEPeriodontitis is one of the most prevalent chronic infections, affecting 40 to 50% of the population of the United States. The root cause of periodontitis is the presence of bacterial biofilms within the gingival space, withPorphyromonas gingivalisbeing strongly associated with the development of the disease. Periodontitis also increases the risk of secondary conditions and infections such as atherosclerosis and infective endocarditis caused by oral streptococci. To induce periodontitis,P. gingivalisneeds to incorporate into preformed biofilms, with oral streptococci being important binding partners. Our research demonstrates that targeting DNABII proteins with an antibody disperses oral streptococcus biofilm and preventsP. gingivalisentry into oral streptococcus biofilm. These results suggest potential therapeutic treatments for endocarditis caused by streptococci as well as periodontitis.
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Ise, Kotaro, Tomofumi Sato, Yoshito Sasaki, and Hideki Yoshikawa. "Development of simplified biofilm sorption and diffusion experiment method using Bacillus sp. isolated from Horonobe Underground Research Laboratory." MRS Proceedings 1665 (2014): 171–77. http://dx.doi.org/10.1557/opl.2014.643.
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ABSTRACTWe developed a simplified biofilm sorption and diffusion experiment method. The biofilms of the Bacillus cereus were incubated on cellulose acetate membrane filters (pore size 0.2 µm, diameter 47 mm) placed on thick NB broth agar medium (thickness was about 30 mm) to support sufficient biofilm growth of the Bacillus cereus. The thickness of the formed biofilms was about 1 mm. The formed biofilms were applied to through-diffusion method, which has been used to measure diffusion coefficient of crystalline and sedimentary rocks and clay minerals. The obtained copper sorption coefficient by batch experiments was about 100 ml/g (wet weight) at the case of the concentration of cupper ion was over 0.074mmol/L. And diffusion coefficients by through diffusion experiment was De=1.1 x 10-10 (m2/s). From these results, this simplified biofilm sorption and diffusion experiment may make possible to obtain these parameters with ease.
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Yin, Wen, Yiting Wang, Lu Liu, and Jin He. "Biofilms: The Microbial “Protective Clothing” in Extreme Environments." International Journal of Molecular Sciences 20, no. 14 (July 12, 2019): 3423. http://dx.doi.org/10.3390/ijms20143423.
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Microbial biofilms are communities of aggregated microbial cells embedded in a self-produced matrix of extracellular polymeric substances (EPS). Biofilms are recalcitrant to extreme environments, and can protect microorganisms from ultraviolet (UV) radiation, extreme temperature, extreme pH, high salinity, high pressure, poor nutrients, antibiotics, etc., by acting as “protective clothing”. In recent years, research works on biofilms have been mainly focused on biofilm-associated infections and strategies for combating microbial biofilms. In this review, we focus instead on the contemporary perspectives of biofilm formation in extreme environments, and describe the fundamental roles of biofilm in protecting microbial exposure to extreme environmental stresses and the regulatory factors involved in biofilm formation. Understanding the mechanisms of biofilm formation in extreme environments is essential for the employment of beneficial microorganisms and prevention of harmful microorganisms.
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FOLSOM, JAMES P., and JOSEPH F. FRANK. "Chlorine Resistance of Listeria monocytogenes Biofilms and Relationship to Subtype, Cell Density, and Planktonic Cell Chlorine Resistance." Journal of Food Protection 69, no. 6 (June 1, 2006): 1292–96. http://dx.doi.org/10.4315/0362-028x-69.6.1292.
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Strains of Listeria monocytogenes vary in their ability to produce biofilms. This research determined if cell density, planktonic chlorine resistance, or subtype are associated with the resistance of L. monocytogenes biofilms to chlorine. Thirteen strains of L. monocytogenes were selected for this research based on biofilm accumulation on stainless steel and rep-PCR subtyping. These strains were challenged with chlorine to determine the resistance of individual strains of L. monocytogenes. Planktonic cells were exposed to 20 to 80 ppm sodium hypochlorite in 20 ppm increments for 5 min in triplicate per replication, and the experiment was replicated three times. The number of tubes with surviving L. monocytogenes was recorded for each isolate at each level of chlorine. Biofilms of each strain were grown on stainless steel coupons. The biofilms were exposed 60 ppm of sodium hypochlorite. When in planktonic culture, four strains were able to survive exposure to 40 ppm of chlorine, whereas four strains were able to survive 80 ppm of chlorine in at least one of three tubes. The remaining five strains survived exposure to 60 ppm of chlorine. Biofilms of 11 strains survived exposure to 60 ppm of chlorine. No association of biofilm chlorine resistance and planktonic chlorine resistance was observed; however, biofilm chorine resistance was similar for strains of the same subtype. Biofilm cell density was not associated with chlorine resistance. In addition, biofilms that survived chlorine treatment exhibited different biofilm morphologies. These data suggest that chlorine resistance mechanisms of planktonic cells and biofilms differ, with planktonic chlorine resistance being more affected by inducible traits, and biofilm chlorine resistance being more affected by traits not determined in this study.
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Xu, Tao, Yue Xiao, Hongchao Wang, Jinlin Zhu, Yuankun Lee, Jianxin Zhao, Wenwei Lu, and Hao Zhang. "Characterization of Mixed-Species Biofilms Formed by Four Gut Microbiota." Microorganisms 10, no. 12 (November 25, 2022): 2332. http://dx.doi.org/10.3390/microorganisms10122332.
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In natural settings, approximately 40–80% of bacteria exist as biofilms, most of which are mixed-species biofilms. Previous studies have typically focused on single- or dual-species biofilms. To expand the field of study on gut biofilms, we found a group of gut microbiota that can form biofilms well in vitro: Bifidobacterium longum subsp. infantis, Enterococcus faecalis, Bacteroides ovatus, and Lactobacillus gasseri. The increase in biomass and bio-volume of the mixed-species biofilm was confirmed via crystal violet staining, field emission scanning electron microscopy, and confocal laser scanning microscopy, revealing a strong synergistic relationship in these communities, with B. longum being the key biofilm-contributing species. This interaction may be related to changes in the cell number, biofilm-related genes, and metabolic activities. After quantifying the cell number using quantitative polymerase chain reaction, B. longum and L. gasseri were found to be the dominant flora in the mixed-species biofilm. In addition, this study analyzed biological properties of mixed-species biofilms, such as antibiotic resistance, cell metabolic activity, and concentration of water-insoluble polysaccharides. Compared with single-species biofilms, mixed-species biofilms had higher metabolic activity, more extracellular matrix, and greater antibiotic resistance. From these results, we can see that the formation of biofilms is a self-protection mechanism of gut microbiota, and the formation of mixed-species biofilms can greatly improve the survival rate of different strains. Finally, this study is a preliminary exploration of the biological characteristics of gut biofilms, and the molecular mechanisms underlying the formation of biofilms warrant further research.
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van Loosdrecht, M. C. M., D. Eikelboom, A. Gjaltema, A. Mulder, L. Tijhuis, and J. J. Heijnen. "Biofilm structures." Water Science and Technology 32, no. 8 (October 1, 1995): 35–43. http://dx.doi.org/10.2166/wst.1995.0258.
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The influences of reactor conditions (substrate loading rate and shear) and microbial characteristics (yield and growth rate) on the structure of biofilms is discussed. Based on research on the formation of biofilms in Biofilm Airlift Suspension (BAS) reactors a hypothesis is postulated that the ratio between biofilm surface loading and shear rate determines the biofilm structure. When shear forces are relatively high only a patchy biofilm will develop, whereas at low shear rates the biofilm becomes highly heterogeneous with many pores and protuberances. In case of a right balance smooth and stable biofilms can be obtained. A hypothesis for the evolution of biofilm structures as a function of process conditions is formulated.
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Lewandowski, Z., H. Beyenal, and D. Stookey. "Reproducibility of biofilm processes and the meaning of steady state in biofilm reactors." Water Science and Technology 49, no. 11-12 (June 1, 2004): 359–64. http://dx.doi.org/10.2166/wst.2004.0880.
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The need for reproducing biofilm processes is undisputable - the quality of biofilm research depends on this reproducibility. However, as many biofilm researchers know, long-term biofilm processes are notoriously difficult to reproduce. To avoid problems related to biofilm reproducibility two strategies are used: (1) to study very young biofilms that have accumulated for a few hours to a few days only, and (2) to run biofilm experiments only once. The first approach trades reproducibility for relevance because natural biofilms are usually older, often much older than a few days. This approach can be applied to answer questions relevant to initial events of biofilm formation but not questions relevant to long-term biofilm accumulation. The second approach conceals the problem of biofilm reproducibility. To assure reproducibility of biofilm processes, we methodically followed a procedure for growing biofilms in terms of microbial makeup, media composition, temperature, surface preparation, etc. Despite all this effort the reproducibility of our results for long term growth is unimpressive. Consequently, the question had to be asked: Are biofilm processes reproducible? The experiments described in this paper address this question. Biofilms grown in two identical and identically operated biofilm reactors had comparable structure only until the first sloughing event. After that, biofilms had different patterns of accumulation.
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Thi, Minh Tam Tran, David Wibowo, and Bernd H. A. Rehm. "Pseudomonas aeruginosa Biofilms." International Journal of Molecular Sciences 21, no. 22 (November 17, 2020): 8671. http://dx.doi.org/10.3390/ijms21228671.
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Pseudomonas aeruginosa is an opportunistic human pathogen causing devastating acute and chronic infections in individuals with compromised immune systems. Its highly notorious persistence in clinical settings is attributed to its ability to form antibiotic-resistant biofilms. Biofilm is an architecture built mostly by autogenic extracellular polymeric substances which function as a scaffold to encase the bacteria together on surfaces, and to protect them from environmental stresses, impedes phagocytosis and thereby conferring the capacity for colonization and long-term persistence. Here we review the current knowledge on P. aeruginosa biofilms, its development stages, and molecular mechanisms of invasion and persistence conferred by biofilms. Explosive cell lysis within bacterial biofilm to produce essential communal materials, and interspecies biofilms of P. aeruginosa and commensal Streptococcus which impedes P. aeruginosa virulence and possibly improves disease conditions will also be discussed. Recent research on diagnostics of P. aeruginosa infections will be investigated. Finally, therapeutic strategies for the treatment of P. aeruginosa biofilms along with their advantages and limitations will be compiled.
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Xu, Xiang Rong, Qi Wang, Hao Xu, and Liang Liang Li. "Development of Mathematical Modeling and Dynamics for Biofilms." Advanced Materials Research 749 (August 2013): 93–98. http://dx.doi.org/10.4028/www.scientific.net/amr.749.93.
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Biofilm formation, structure and dynamics properties play an important role in the effective performance of biofilm wastewater treatment reactors. Biofilm models are commonly used as simulation tools in engineering applications and as research tools to study biofilm formation and dynamics. This paper briefly outlines the present and past status of research on biofilm modeling, dynamics and experimental results. Biofilms constitute a spectrum of dynamical microorganisms, whose interaction with the surrounding environment and thereby induced dynamics dominates the complex properties of the living microorganism. Modeling of biofilms began with a low dimensional continuum description first based on kinematics and translational diffusions; later, more sophisticated microscopic dynamical mechanisms are introduced leading to the anomalous diffusion and dissipation encountered by various components in biofilms. We classify the models into roughly four classes: the reaction-diffusion dynamics model, the Capdeville biofilm growth dynamics model, the Cellular automata (CA) model, and the Phase field biofilm dynamical model.
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Ntarlagiannis, Dimitrios, and Andrew Ferguson. "SIP response of artificial biofilms." GEOPHYSICS 74, no. 1 (January 2009): A1—A5. http://dx.doi.org/10.1190/1.3031514.
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In recent years, research into the use of geophysical methods for monitoring microbial activity within the subsurface has advanced. One of the most promising methods, induced polarization (IP), has indirectly shown sensitivity to changes in the presence of microbial cells and especially biofilms. The aim of this study is to conclusively show, and quantify if possible, the effect of biofilm accumulation on IP signals. To ensure the controlled formation of biofilm we created an “artificial” alginate gel biofilm, which was introduced into an experimental column at varying amounts. The IP response was measured throughout. Our initial results showed that the IP method is sensitive to biofilm accumulation, after a certain point, and could potentially be used to monitor such microbial structures remotely. Further research with real biofilms under more natural conditions is needed to validate our results.
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Bishop, Paul L. "Biofilm structire and kinetics." Water Science and Technology 36, no. 1 (July 1, 1997): 287–94. http://dx.doi.org/10.2166/wst.1997.0066.
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Recently, conventional concepts concerning the internal structure of wastewater biofilms have been brought into question. Most existing biofilm kinetic models assume that biofilms can be modeled in a one-dimensional (perpendicular to the substratum) fashion. There is much evidence indicating that mature biofilms may adequately be considered as growing as a continuum, although heterogeneously stratified with depth, and thus can be modeled in this way. However, there is recent evidence indicating that at least some biofilms grow in a much more heterogeneous format, with a highly channelized structure. This paper reviews the research on biofilm structure and the implications for substrate and nutient mass transport into biofilms. It then discusses the impact of the various growth models on biodegradation kinetics.
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Khalil, Maha A., Jamal A. Alorabi, Lamya M. Al-Otaibi, Sameh S. Ali, and Sobhy E. Elsilk. "Antibiotic Resistance and Biofilm Formation in Enterococcus spp. Isolated from Urinary Tract Infections." Pathogens 12, no. 1 (December 25, 2022): 34. http://dx.doi.org/10.3390/pathogens12010034.
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Background: A urinary tract infection (UTI) resulting from multidrug-resistant (MDR) enterococci is a common disease with few therapeutic options. About 15% of urinary tract infections are caused by biofilm-producing Enterococcus spp. Therefore, the objective of this study was to identify the MDR enterococci associated with UTIs and assess their potential to produce biofilms. Methods: Thirty Enterococcus isolates were obtained from urine samples collected from UTI patients at King Abdulaziz Specialist Hospital in Taif, Saudi Arabia. The antimicrobial resistance profiles of the isolates were evaluated using disk diffusion techniques against 15 antimicrobial agents. Two techniques, Congo red agar (CRA) and a microtiter plate (MTP), were used to assess the potential of the isolates to produce biofilms. The enterococcal isolates were screened for biofilm-related genes, esp; ebpA; and ebpB, using the PCR method. Results: The molecular identification of the collected bacteria revealed the presence of 73.3% Enterococcus faecalis and 26.6% Enterococcus faecium. The antibiotic susceptibility test revealed that all the tested Enterococcus spp. were resistant to all antimicrobials except for linezolid and tigecycline. Additionally, by employing the CRA and MTP techniques, 76.6% and 100% of the Enterococcus isolates were able to generate biofilms, respectively. In terms of the association between the antibiotic resistance and biofilm’s formation, it was observed that isolates capable of creating strong biofilms were extremely resistant to most of the antibiotics tested. The obtained data showed that all the tested isolates had biofilm-encoding genes. Conclusions: Our research revealed that the biofilm-producing enterococci bacteria that causes urinary tract infections were resistant to antibiotics. Therefore, it is necessary to seek other pharmacological treatments if antibiotic medicine fails.
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Caruso, Gabriella. "Microbial Colonization in Marine Environments: Overview of Current Knowledge and Emerging Research Topics." Journal of Marine Science and Engineering 8, no. 2 (January 24, 2020): 78. http://dx.doi.org/10.3390/jmse8020078.
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Microbial biofilms are biological structures composed of surface-attached microbial communities embedded in an extracellular polymeric matrix. In aquatic environments, the microbial colonization of submerged surfaces is a complex process involving several factors, related to both environmental conditions and to the physical-chemical nature of the substrates. Several studies have addressed this issue; however, more research is still needed on microbial biofilms in marine ecosystems. After a brief report on environmental drivers of biofilm formation, this study reviews current knowledge of microbial community attached to artificial substrates, as obtained by experiments performed on several material types deployed in temperate and extreme polar marine ecosystems. Depending on the substrate, different microbial communities were found, sometimes highlighting the occurrence of species-specificity. Future research challenges and concluding remarks are also considered. Emphasis is given to future perspectives in biofilm studies and their potential applications, related to biofouling prevention (such as cell-to-cell communication by quorum sensing or improved knowledge of drivers/signals affecting biological settlement) as well as to the potential use of microbial biofilms as sentinels of environmental changes and new candidates for bioremediation purposes.
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Cruz, Adriana, Manuel Condinho, Beatriz Carvalho, Cecília M. Arraiano, Vânia Pobre, and Sandra N. Pinto. "The Two Weapons against Bacterial Biofilms: Detection and Treatment." Antibiotics 10, no. 12 (December 3, 2021): 1482. http://dx.doi.org/10.3390/antibiotics10121482.
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Bacterial biofilms are defined as complex aggregates of bacteria that grow attached to surfaces or are associated with interfaces. Bacteria within biofilms are embedded in a self-produced extracellular matrix made of polysaccharides, nucleic acids, and proteins. It is recognized that bacterial biofilms are responsible for the majority of microbial infections that occur in the human body, and that biofilm-related infections are extremely difficult to treat. This is related with the fact that microbial cells in biofilms exhibit increased resistance levels to antibiotics in comparison with planktonic (free-floating) cells. In the last years, the introduction into the market of novel compounds that can overcome the resistance to antimicrobial agents associated with biofilm infection has slowed down. If this situation is not altered, millions of lives are at risk, and this will also strongly affect the world economy. As such, research into the identification and eradication of biofilms is important for the future of human health. In this sense, this article provides an overview of techniques developed to detect and imaging biofilms as well as recent strategies that can be applied to treat biofilms during the several biofilm formation steps.
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Roldán, Mónica, Ester Clavero, Susanna Castel, and Mariona Hernández-Mariné. "Biofilms fluorescence and image analysis in hypogean monuments research." Algological Studies/Archiv für Hydrobiologie, Supplement Volumes 111 (February 1, 2004): 127–43. http://dx.doi.org/10.1127/1864-1318/2004/0111-0127.
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Schlafer, Sebastian, Rikke L. Meyer, Irene Dige, and Viduthalai R. Regina. "Extracellular DNA Contributes to Dental Biofilm Stability." Caries Research 51, no. 4 (2017): 436–42. http://dx.doi.org/10.1159/000477447.
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Extracellular DNA (eDNA) is a major matrix component of many bacterial biofilms. While the presence of eDNA and its role in biofilm stability have been demonstrated for several laboratory biofilms of oral bacteria, there is no data available on the presence and function of eDNA in in vivo grown dental biofilms. This study aimed to determine whether eDNA was part of the matrix in biofilms grown in situ in the absence of sucrose and whether treatment with DNase dispersed biofilms grown for 2.5, 5, 7.5, 16.5, or 24 h. Three hundred biofilms from 10 study participants were collected and treated with either DNase or heat-inactivated DNase for 1 h. The bacterial biovolume was determined with digital image analysis. Staining with TOTO®-1 allowed visualization of eDNA both on bacterial cell surfaces and, with a cloud-like appearance, in the intercellular space. DNase treatment strongly reduced the amount of biofilm in very early stages of growth (up to 7.5 h), but the treatment effect decreased with increasing biofilm age. This study proves the involvement of eDNA in dental biofilm formation and its importance for biofilm stability in the earliest stages. Further research is required to uncover the interplay of eDNA and other matrix components and to explore the therapeutic potential of DNase treatment for biofilm control.
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Chapek, Sergey, Sergey Golovin, Michael Chikindas, Svetlana Ponomareva, Dmitry Rudoy, and Anastasiya Olshevskaya. "Application of 3D bioprinting in the study of bacterial biofilms." E3S Web of Conferences 273 (2021): 13010. http://dx.doi.org/10.1051/e3sconf/202127313010.
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The article presents an overview of the main methods of obtaining biofilms in vitro, used in research. The technology of 3D-bioprinting is described – a new method in the modeling of bacterial biofilms, which solves one of the main problems in the study of biofilms- the heterogeneity of biomass, and opens up new opportunities for the study of various aspects of biofilm formation.
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Alvarez-Ordóñez, Avelino, Laura M. Coughlan, Romain Briandet, and Paul D. Cotter. "Biofilms in Food Processing Environments: Challenges and Opportunities." Annual Review of Food Science and Technology 10, no. 1 (March 25, 2019): 173–95. http://dx.doi.org/10.1146/annurev-food-032818-121805.
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This review examines the impact of microbial communities colonizing food processing environments in the form of biofilms on food safety and food quality. The focus is both on biofilms formed by pathogenic and spoilage microorganisms and on those formed by harmless or beneficial microbes, which are of particular relevance in the processing of fermented foods. Information is presented on intraspecies variability in biofilm formation, interspecies relationships of cooperativism or competition within biofilms, the factors influencing biofilm ecology and architecture, and how these factors may influence removal. The effect on the biofilm formation ability of particular food components and different environmental conditions that commonly prevail during food processing is discussed. Available tools for the in situ monitoring and characterization of wild microbial biofilms in food processing facilities are explored. Finally, research on novel agents or strategies for the control of biofilm formation or removal is summarized.
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Zhang, Xiao-Yan, Kai Sun, Aliya Abulimiti, Pian-Pian Xu, and Zhe-Yu Li. "Microfluidic System for Observation of Bacterial Culture and Effects on Biofilm Formation at Microscale." Micromachines 10, no. 9 (September 12, 2019): 606. http://dx.doi.org/10.3390/mi10090606.
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Biofilms exist in the natural world and applied to many industries. However, due to the variety of characteristics caused by their complex components, biofilms can also lead to membrane fouling and recurrent infections which pose threats to human health. So, to make the best use of their advantages and avoid their disadvantages, knowing the best time and methods for improving or preventing biofilm formation is important. In situ observation without fluorescence labeling in microscale and according to a time scale is useful to research biofilm and confine its formation. In this study, we developed a microfluidic system for real-time observation of bacteria culture and biofilms development at microscale. We cultured E. coli ATCC 25922 on a chip at continuous flow of the velocity, which could promote bacterial formation. Biofilms formation under the condition of adding amoxicillin at different times is also discussed. In addition, the mixed strains from sludge were also cultured on chip, and possible factors in biofilm formation are discussed. Our results show that a microfluidic device could culture microorganisms in continuous flow and accelerate them to adhere to the surface, thereby promoting biofilm formation. Overall, this platform is a useful tool in research on initial biofilm formation, which can contribute to preventing biofouling and infections.
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Nagaoka, Hiroshi. "Mass transfer mechanism in biofilms under oscillatory flow conditions." Water Science and Technology 36, no. 1 (July 1, 1997): 329–36. http://dx.doi.org/10.2166/wst.1997.0071.
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The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions, which provides valuable information for the understanding of self-purification by biofilms under oscillatory flow conditions like in coastal areas. A mathematical model was developed to describe substrate profiles in biofilms under oscillatory flow conditions, which suggested that substrate uptake rate by biofilms is proportional to the square root of the Reynolds number. A laboratory-scale channel with a wave generator was prepared, in which plastic plates were used as substratum for biofilms. Glucose was used as a substrate. Velocity and turbulence profiles near the biofilm were measured by a laser Doppler velocimeter. The cycle of the wave generator was changed and its short-term effect on the substrate uptake rate by the biofilm was measured. The substrate uptake rate decreased with the decrease of the Reynolds number of the wave motion according to a power law with a coefficient of 0.6, which suggests that substrate transport in biofilms under oscillatory flow conditions is carried out by turbulent diffusion caused by oscillatory flow motions over biofilms.
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Sabba, Fabrizio, Cristian Picioreanu, Joshua P. Boltz, and Robert Nerenberg. "Predicting N2O emissions from nitrifying and denitrifying biofilms: a modeling study." Water Science and Technology 75, no. 3 (October 14, 2016): 530–38. http://dx.doi.org/10.2166/wst.2016.484.
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Wastewater treatment plants can be significant sources of nitrous oxide (N2O), a potent greenhouse gas. While our understanding of N2O emissions from suspended-growth processes has advanced significantly, less is known about emissions from biofilm processes. Biofilms may behave differently due to their substrate gradients and microbial stratification. In this study, we used mathematical modeling to explore the mechanisms of N2O emissions from nitrifying and denitrifying biofilms. Our ammonia-oxidizing bacteria biofilm model suggests that N2O emissions from biofilm can be significantly greater than from suspended-growth systems. The driving factor is the diffusion of hydroxylamine, a nitrification intermediate, from the aerobic to the anoxic regions of the biofilm. The presence of nitrite-oxidizing bacteria further increased emissions. For denitrifying biofilms, our results suggest that emissions are generally greater than for suspended-growth systems. However, the magnitude of the difference depends on the bulk dissolved oxygen, chemical oxygen demand, and nitrate concentrations, as well as the biofilm thickness. Overall, the accumulation and diffusion of key intermediates, i.e. hydroxylamine and nitrite, distinguish biofilms from suspended-growth systems. Our research suggests that the mechanisms of N2O emissions from biofilms are much more complex than suspended-growth systems, and that emissions may be higher in many cases.
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Mishra, Sonal, Amit Gupta, Vijay Upadhye, Suresh C. Singh, Rajeshwar P. Sinha, and Donat-P. Häder. "Therapeutic Strategies against Biofilm Infections." Life 13, no. 1 (January 6, 2023): 172. http://dx.doi.org/10.3390/life13010172.
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A biofilm is an aggregation of surface-associated microbial cells that is confined in an extracellular polymeric substance (EPS) matrix. Infections caused by microbes that form biofilms are linked to a variety of animals, including insects and humans. Antibiotics and other antimicrobials can be used to remove or eradicate biofilms in order to treat infections. However, due to biofilm resistance to antibiotics and antimicrobials, clinical observations and experimental research clearly demonstrates that antibiotic and antimicrobial therapies alone are frequently insufficient to completely eradicate biofilm infections. Therefore, it becomes crucial and urgent for clinicians to properly treat biofilm infections with currently available antimicrobials and analyze the results. Numerous biofilm-fighting strategies have been developed as a result of advancements in nanoparticle synthesis with an emphasis on metal oxide np. This review focuses on several therapeutic strategies that are currently being used and also those that could be developed in the future. These strategies aim to address important structural and functional aspects of microbial biofilms as well as biofilms’ mechanisms for drug resistance, including the EPS matrix, quorum sensing (QS), and dormant cell targeting. The NPs have demonstrated significant efficacy against bacterial biofilms in a variety of bacterial species. To overcome resistance, treatments such as nanotechnology, quorum sensing, and photodynamic therapy could be used.
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Pugliese, Gina, and Martin S. Favero. "Biofilms: New Research at CDC." Infection Control & Hospital Epidemiology 19, no. 12 (December 1998): 929–30. http://dx.doi.org/10.1017/s0195941700092213.
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Chew, Siang-Siang, Loh Teng-Hern Tan, Jodi Woan-Fei Law, Priyia Pusparajah, Bey-Hing Goh, Nurul Syakima Ab Mutalib, and Learn-Han Lee. "Targeting Gut Microbial Biofilms—A Key to Hinder Colon Carcinogenesis?" Cancers 12, no. 8 (August 13, 2020): 2272. http://dx.doi.org/10.3390/cancers12082272.
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Colorectal cancer (CRC) is a global public health issue which poses a substantial humanistic and economic burden on patients, healthcare systems and society. In recent years, intestinal dysbiosis has been suggested to be involved in the pathogenesis of CRC, with specific pathogens exhibiting oncogenic potentials such as Fusobacterium nucleatum, Escherichia coli and enterotoxigenic Bacteroides fragilis having been found to contribute to CRC development. More recently, it has been shown that initiation of CRC development by these microorganisms requires the formation of biofilms. Gut microbial biofilm forms in the inner colonic mucus layer and is composed of polymicrobial communities. Biofilm results in the redistribution of colonic epithelial cell E-cadherin, increases permeability of the gut and causes a loss of function of the intestinal barrier, all of which enhance intestinal dysbiosis. This literature review aims to compile the various strategies that target these pathogenic biofilms and could potentially play a role in the prevention of CRC. We explore the potential use of natural products, silver nanoparticles, upconverting nanoparticles, thiosalicylate complexes, anti-rheumatic agent (Auranofin), probiotics and quorum-sensing inhibitors as strategies to hinder colon carcinogenesis via targeting colon-associated biofilms.
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Høiby, Niels. "A personal history of research on microbial biofilms and biofilm infections." Pathogens and Disease 70, no. 3 (April 2014): 205–11. http://dx.doi.org/10.1111/2049-632x.12165.
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Mamatarkova, V., L. Nikolov, and D. Karamanev. "Biofilms: Problems and Trends in Research Activity. Part I: Biofilm Carriers." Biotechnology & Biotechnological Equipment 16, no. 1 (January 2002): 170–76. http://dx.doi.org/10.1080/13102818.2002.10819176.
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Hrynchuk, N. I., N. O. Vrynchanu, and L. G. Stepura. "Influence of diclofenac sodium on antibiofilm activity of azithromycin." Farmatsevtychnyi zhurnal, no. 3-4 (September 4, 2018): 47–55. http://dx.doi.org/10.32352/0367-3057.3-4.18.07.
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Nowadays bacterial biofilms are the major problem in the medical practice, that can lead to chronic infections and decline of antimicrobial therapy efficacy. Therefore, combined use of drugs of various pharmacotherapeutic groups may offer significant benefits in the research of new ways of treatment infections associated with biofilms. The data of the literature shows that non-steroidal anti-inflammatory drugs have antimicrobial activity and they can be improved antimicrobial action of antibiotics.
The aim of the study was to establish specific antibiofilm activity of azithromycin in the combined treatment with diclofenac sodium.
Strain S. epidermidis 2265 susceptibility to azithromycin was evaluated by microdilution method and assessed by minimum inhibitory concentration (MIC). Action of azithromycin and diclofenac sodium on biofilm formation and preformed biofilms of S. epidermidis was determined by the crystal violet assay.
Our results of study have shown that azithromycin and diclofenac sodium reduced of biofilm formation to abiotic surface. Dose-depending low antibiofilm effect was found under treatment preformed S. epidermidis biofilms with macrolide antibiotic. Diclofenac sodium possessed antibiofilm activity against the preformed 1-day staphylococcal biofilms (reducing biomass 68.5%). Also diclofenac sodium stimulated biofilms formation and increased biomass accumulation of preformed 12-hour and 2-day staphylococcal biofilms to 12.4%. The data obtained of experiments have shown that combined treatment with both azithromycin and diclofenac sodium lead to reduce activity of macrolide against biofilm formation (to 69.5%) and S. epidermidis mature biofilms (2-day) at therapeutic concentrations (increasing biomass accumulation on 10.4% in comparison with controls). Antibiofilm activity of macrolide antibiotic become higher only against preformed 1-day biofilms.
The data obtained suggest the possibility of using of azithromycin with diclofenac sodium for treatment of acute purulent-inflammatory processes. Because of diclofenac sodium exhibited antibiofilm activity and increased the antibiotic specific activity, that lead to prevention of development of chronic infections. The issue of combined treatment of azithromycin with diclofenac sodium of chronic infections remains open and requires in-depth research.
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PARK, YOEN JU, and JINRU CHEN. "Control of the Biofilms Formed by Curli- and Cellulose-Expressing Shiga Toxin–Producing Escherichia coli Using Treatments with Organic Acids and Commercial Sanitizers." Journal of Food Protection 78, no. 5 (May 1, 2015): 990–95. http://dx.doi.org/10.4315/0362-028x.jfp-14-382.
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Biofilms are a mixture of bacteria and extracellular products secreted by bacterial cells and are of great concern to the food industry because they offer physical, mechanical, and biological protection to bacterial cells. This study was conducted to quantify biofilms formed by different Shiga toxin–producing Escherichia coli (STEC) strains on polystyrene and stainless steel surfaces and to determine the effectiveness of sanitizing treatments in control of these biofilms. STEC producing various amounts of cellulose (n = 6) or curli (n = 6) were allowed to develop biofilms on polystyrene and stainless steel surfaces at 28°C for 7 days. The biofilms were treated with 2% acetic or lactic acid and manufacturer-recommended concentrations of acidic or alkaline sanitizers, and residual biofilms were quantified. Treatments with the acidic and alkaline sanitizers were more effective than those with the organic acids for removing the biofilms. Compared with their counterparts, cells expressing a greater amount of cellulose or curli formed more biofilm mass and had greater residual mass after sanitizing treatments on polystyrene than on stainless steel. Research suggests that the organic acids and sanitizers used in the present study differed in their ability to control biofilms. Bacterial surface components and cell contact surfaces can influence both biofilm formation and the efficacy of sanitizing treatments. These results provide additional information on control of biofilms formed by STEC.
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Cloete, T. E., and M. R. Maluleke. "The use of the Rotoscope as an online, real-time, non-destructive biofilm monitor." Water Science and Technology 52, no. 7 (October 1, 2005): 211–16. http://dx.doi.org/10.2166/wst.2005.0203.
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Biofilms are involved in all kinds of biofouling and cause a significant economic loss of billions of dollars annually, worldwide. In order to effectively control the growth of biofilms, it is necessary to investigate the structure of biofilms grown under different conditions. Several methods are available to monitor biofilm progression, but their applications are limited by low intensity, high labour intensity, intrusive sampling, and long time lags from sampling to results. The goal of this research was to monitor biofilm growth using a biological rotating contact disc, based on the total plate count, scanning electron microscopy and the light reflection. Light reflected changed with biofilm thickness and the thicker the biofilm, the less light was reflected. Addition of NaCl anolyte caused some detachment of the microbial cells as was indicated by a slight increase in light reflection. This was supported by SEM micrographs.
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Flemming, H. C., S. L. Percival, and J. T. Walker. "Contamination potential of biofilms in water distribution systems." Water Supply 2, no. 1 (January 1, 2002): 271–80. http://dx.doi.org/10.2166/ws.2002.0032.
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Biofilms are ubiquitous in drinking water systems, either in the form of thin and patchy colonies or as surface-covering multiple layers. In biofilters they are used for the elimination of biologically degradable substances. However, they occur in other sites, e.g., on the walls of containers and pipes, on sediment and on suspended particles. They can rise problems by contamination of the water phase by detaching biofilm organisms. Biofilms provide a possible habitat for hygienically relevant microbes in which they can persist and even multiply. Here they are protected against disinfectants, in particular if located in corrosion products, sediments or ingested by protozoa which feed on biofilm cells. Biofilms are related to the occurrence of “black water” and malodours. They are involved in the corrosion of metals, mineral materials and synthetic polymers. The limiting factor for biofilm growth is usually the availability of nutrients, mainly provided either by biodegradable substances leaching from materials or from by the water phase. The extent of biofilm growth and of the occurrence of hygienically relevant organisms is still unknown and to be investigated. However, latest research indicates that such organisms do not multiply in large numbers in drinking water biofilms; it is possible that drinking water biofilms can inhibit the propagation of invading pathogens.
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Gupta, Tripti Thapa, Niraj K. Gupta, Peter Burback, and Paul Stoodley. "Free-Floating Aggregate and Single-Cell-Initiated Biofilms of Staphylococcus aureus." Antibiotics 10, no. 8 (July 21, 2021): 889. http://dx.doi.org/10.3390/antibiotics10080889.
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Periprosthetic joint infection (PJI) occurring after artificial joint replacement is a major clinical issue requiring multiple surgeries and antibiotic interventions. Staphylococcus aureus is the common bacteria responsible for PJI. Recent in vitro research has shown that staphylococcal strains rapidly form free-floating aggregates in the presence of synovial fluid (SF) with biofilm-like resistance to antimicrobial agents. However, the development of biofilms formed from these aggregates under shear have not been widely investigated. Thus, in this study, we examined the progression of attached biofilms from free-floating aggregates. Biofilms were grown for 24 h in flow cells on titanium discs after inoculation with either pre-aggregated or single planktonic cells. Image analysis showed no significant difference between the biofilm formed from aggregates vs. the planktonic cells in terms of biomass, surface area, and thickness. Regarding antibiotic susceptibility, there were 1 and 2 log reductions in biofilms formed from single cells and aggregates, respectively, when treated with vancomycin for 24 h. Thus, this study demonstrates the formation of biofilm from free-floating aggregates and follows a similar developmental time period and shows similar antibiotic tolerance to more traditionally inoculated in vitro flow cell biofilms.
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Achinas, Spyridon, Stijn Keimpe Yska, Nikolaos Charalampogiannis, Janneke Krooneman, and Gerrit Jan Willem Euverink. "A Technological Understanding of Biofilm Detection Techniques: A Review." Materials 13, no. 14 (July 15, 2020): 3147. http://dx.doi.org/10.3390/ma13143147.
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Biofouling is a persistent problem in almost any water-based application in several industries. To eradicate biofouling-related problems in bioreactors, the detection of biofilms is necessary. The current literature does not provide clear supportive information on selecting biofilm detection techniques that can be applied to detect biofouling within bioreactors. Therefore, this research aims to review all available biofilm detection techniques and analyze their characteristic properties to provide a comparative assessment that researchers can use to find a suitable biofilm detection technique to investigate their biofilms. In addition, it discusses the confluence of common bioreactor fabrication materials in biofilm formation.
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Sharma, Ankur, Dhruv Kumar, Kajal Dahiya, Susan Hawthorne, Saurabh Kumar Jha, Niraj Kumar Jha, Parma Nand, et al. "Advances in pulmonary drug delivery targeting microbial biofilms in respiratory diseases." Nanomedicine 16, no. 21 (September 2021): 1905–23. http://dx.doi.org/10.2217/nnm-2021-0057.
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The increasing burden of respiratory diseases caused by microbial infections poses an immense threat to global health. This review focuses on the various types of biofilms that affect the respiratory system and cause pulmonary infections, specifically bacterial biofilms. The article also sheds light on the current strategies employed for the treatment of such pulmonary infection-causing biofilms. The potential of nanocarriers as an effective treatment modality for pulmonary infections is discussed, along with the challenges faced during treatment and the measures that may be implemented to overcome these. Understanding the primary approaches of treatment against biofilm infection and applications of drug-delivery systems that employ nanoparticle-based approaches in the disruption of biofilms are of utmost interest which may guide scientists to explore the vistas of biofilm research while determining suitable treatment modalities for pulmonary respiratory infections.
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Zabielska, Julia, Agnieszka Tyfa, and Alina Kunicka-Styczyńska. "Methods for eradication of the biofilms formed by opportunistic pathogens using novel techniques – A review." Folia Biologica et Oecologica 12 (January 7, 2016): 26–37. http://dx.doi.org/10.1515/fobio-2016-0003.
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The inconvenient environmental conditions force microorganisms to colonize either abiotic surfaces or animal and plant tissues and, therefore, form more resistant structures – biofilms. The phenomenon of microbial adherence, opportunistic pathogens in particular, is of a great concern. Colonization of medical devices and biofilm formation on their surface, may lead to severe infections mainly in humans with impaired immune system. Although, current research consider various methods for prevention of microbial biofilms formation, still, once a biofilm is formed, its elimination is almost impossible. This study focuses on the overview of novel methods applied for eradication of mature opportunistic pathogens' biofilms. Among various techniques the following: cold plasma, electric field, ultrasounds, ozonated water treatment, phagotherapy, matrix targeting enzymes, bacteriocins, synthetic chemicals and natural origin compounds used for biofilm matrix disruption were briefly described.
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Schönborn, Sarah, Nicole Wente, Jan-Hendrik Paduch, and Volker Krömker. "In vitro ability of mastitis causing pathogens to form biofilms." Journal of Dairy Research 84, no. 2 (May 2017): 198–201. http://dx.doi.org/10.1017/s0022029917000218.
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This Research Communication describes the study of in vitro biofilm formation of mastitis causing pathogens. Biofilms are communities of bacteria that are attached to a surface and to each other and are embedded in a self-produced matrix of extracellular polymeric substances. Biofilm formation is an important virulence factor that may result in recurrent or persistent udder infections and treatment failure through increased resistance to antibiotics and protection against host defences. In the present study 252 bacterial isolates from milk samples from bovine udder quarters with intramammary infections were examined with Congo Red agar (CRA) method and tube method (TM) for their ability to form biofilms. Both tests revealed a high number of biofilm-positive strains. Literature reports that the cure rates for Staphylococcus aureus infected udders are lower (27%) in comparison to cure rates of Streptococcus uberis (64–81%) or coagulase-negative staphylococci (CNS) mastitis (80–90%). The findings of the present study suggest that biofilm formation is not the main factor for the differences in cure rates of the various bacteria genera, because all tested pathogen groups showed a similarly high proportion of biofilm formation. Further research is needed to detect microbial biofilms on bovine udder epithelia.
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Joshi, Abhayraj S., Priyanka Singh, and Ivan Mijakovic. "Interactions of Gold and Silver Nanoparticles with Bacterial Biofilms: Molecular Interactions behind Inhibition and Resistance." International Journal of Molecular Sciences 21, no. 20 (October 16, 2020): 7658. http://dx.doi.org/10.3390/ijms21207658.
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Many bacteria have the capability to form a three-dimensional, strongly adherent network called ‘biofilm’. Biofilms provide adherence, resourcing nutrients and offer protection to bacterial cells. They are involved in pathogenesis, disease progression and resistance to almost all classical antibiotics. The need for new antimicrobial therapies has led to exploring applications of gold and silver nanoparticles against bacterial biofilms. These nanoparticles and their respective ions exert antimicrobial action by damaging the biofilm structure, biofilm components and hampering bacterial metabolism via various mechanisms. While exerting the antimicrobial activity, these nanoparticles approach the biofilm, penetrate it, migrate internally and interact with key components of biofilm such as polysaccharides, proteins, nucleic acids and lipids via electrostatic, hydrophobic, hydrogen-bonding, Van der Waals and ionic interactions. Few bacterial biofilms also show resistance to these nanoparticles through similar interactions. The nature of these interactions and overall antimicrobial effect depend on the physicochemical properties of biofilm and nanoparticles. Hence, study of these interactions and participating molecular players is of prime importance, with which one can modulate properties of nanoparticles to get maximal antibacterial effects against a wide spectrum of bacterial pathogens. This article provides a comprehensive review of research specifically directed to understand the molecular interactions of gold and silver nanoparticles with various bacterial biofilms.
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Tsarev, V. N., E. N. Nikolaeva, M. V. Vitovich, M. S. Podporin, and E. V. Ippolitov. "Morphological aspects of microbial biofilm formation on atherosclerotic plaque fragments." Bacteriology 5, no. 2 (2020): 8–17. http://dx.doi.org/10.20953/2500-1027-2020-2-8-17.
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Modern research indicates the presence of living bacteria in atherosclerotic plaques. However, the potential of microbes in the formation of biofilms in arterial plaques has not been studied. Purpose of the study. Identification of biofilms on fragments of arterial vessels with atherosclerotic plaques. Materials and methods. Fragments of atherosclerotic plaques isolated during coronary artery bypass grafting in patients with coronary artery disease were cultured in an exhaustive fluid system under anaerobic conditions in vitro for 1 or 14 days. The presence of biofilms was evaluated using scanning electron microscopy. Results. Mixed biofilms, represented by rod-shaped bacteria and cocci, were identified after in vitro cultivation in all fragments of atherosclerotic plaques. The characteristic ultrastructure revealed the main stages of the biofilm life cycle. Conclusions. Modeling biofilms on biotic surfaces in a system of exhausted fluids under anaerobic conditions will allow us to study in detail the phenotype of biofilms and provide a significant understanding of the pathophysiology of infectious processes in blood vessels and atherosclerotic plaques. Key words: atherosclerotic plaque, chronic periodontitis, biofilm-forming microbes, periodontal pathogens, causative agents of nosocomial infections, fluid technology
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Subroto, Eefje, Jacq van Neer, Ivan Valdes, and Hans de Cock. "Growth of Aspergillus fumigatus in Biofilms in Comparison to Candida albicans." Journal of Fungi 8, no. 1 (January 4, 2022): 48. http://dx.doi.org/10.3390/jof8010048.
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Biofilm formation during infections with the opportunistic pathogen Aspergillus fumigatus can be very problematic in clinical settings, since it provides the fungal cells with a protective environment. Resistance against drug treatments, immune recognition as well as adaptation to the host environment allows fungal survival in the host. The exact molecular mechanisms behind most processes in the formation of biofilms are unclear. In general, the formation of biofilms can be categorized roughly in a few stages; adhesion, conidial germination and development of hyphae, biofilm maturation and cell dispersion. Fungi in biofilms can adapt to the in-host environment. These adaptations can occur on a level of phenotypic plasticity via gene regulation. However, also more substantial genetic changes of the genome can result in increased resistance and adaptation in the host, enhancing the survival chances of fungi in biofilms. Most research has focused on the development of biofilms. However, to tackle developing microbial resistance and adaptation in biofilms, more insight in mechanisms behind genetic adaptations is required to predict which defense mechanisms can be expected. This can be helpful in the development of novel and more targeted antifungal treatments to combat fungal infections.
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Maggio, Francesca, Chiara Rossi, Clemencia Chaves-López, Annalisa Serio, Luca Valbonetti, Francesco Pomilio, Alessio Pio Chiavaroli, and Antonello Paparella. "Interactions between L. monocytogenes and P. fluorescens in Dual-Species Biofilms under Simulated Dairy Processing Conditions." Foods 10, no. 1 (January 16, 2021): 176. http://dx.doi.org/10.3390/foods10010176.
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In dairy processing environments, many bacterial species adhere and form biofilms on surfaces and equipment, leading to foodborne illness and food spoilage. Among them, Listeria monocytogenes and Pseudomonas spp. could be present in mixed-species biofilms. This study aimed to evaluate the interactions between L. monocytogenes and P. fluorescens in biofilms simulating dairy processing conditions, as well as the capability of P. fluorescens in co-culture to produce the blue pigment in a Ricotta-based model system. The biofilm-forming capability of single- and mixed-cultures was evaluated on polystyrene (PS) and stainless steel (SS) surfaces at 12 °C for 168 h. The biofilm biomass was measured, the planktonic and sessile cells and the carbohydrates in biofilms were quantified. The biofilms were also observed through Confocal Laser Scanning Microscopy analysis. Results showed that only P. fluorescens was able to form biofilms on PS. Moreover, in dual-species biofilms at the end of the incubation time (168 h at 12 °C), a lower biomass compared to P. fluorescens mono-species was observed on PS. On SS, the biofilm cell population of L. monocytogenes was higher in the dual-species than in mono-species, particularly after 48 h. Carbohydrates quantity in the dual-species system was higher than in mono-species and was revealed also at 168 h. The production of blue pigment by P. fluorescens was revealed both in single- and co-culture after 72 h of incubation (12 °C). This work highlights the interactions between the two species, under the experimental conditions studied in the present research, which can influence biofilm formation (biomass and sessile cells) but not the capability of P. fluorescens to produce blue pigment.
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Horiuk, Y. V., M. D. Kukhtyn, Y. S. Stravskyy, S. I. Klymnyuk, K. M. Vergeles, and V. V. Horiuk. "Influence of staphylococcal Phage SAvB14 on biofilms, formed by Staphylococcus aureus variant bovis." Regulatory Mechanisms in Biosystems 10, no. 3 (August 22, 2019): 314–18. http://dx.doi.org/10.15421/021948.
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The use of bacteriophages for the treatment of chronic inflammatory processes has proved to be relevant, especially during isolation of antibiotic-resistant pathogens formed in biofilms. The article presents the results of research on the influence of Phage SAvB14 on young and mature biofilms formed by Staphylococcus aureus variant bovis. In the experiments we used cultures of S. aureus and a specific Phage SAvB14 isolated from the secretion of the mammary gland of cows suffering from chronic mastitis. In the study of the influence of bacteriophage on formed biofilms we determined the optical density of the dye solution that was washed from the biofilm photometrically on a spectrophotometer PE-5400UV (Ecroskhim, Russia) and the number of staphylococcal cells in the biofilm after the action of the bacteriophage on 24-hour and 72-hour biofilms by a ten-fold dilution on beef-extract agar. It was determined that under the influence of the bacteriophage on young 24-hour biofilms of S. aureus var. bovis, the optical density of the dye solution from biofilm increased within 4 hours up to 10% and the number of microbial cells increased by 1.8 times. After 32 hours of bacteriophage action, the optical density of the dye solution decreased on average by 34% compared to the initial density and the number of S. aureus cells in the biofilm decreased by 30 times. This indicates that microbial cells of young biofilms are not subject to complete lysis during the action of even this specific bacteriophage. Degradation of 77.5% of biofilm under the influence of the bacteriophage was observed on mature 72-hour biofilm within 32 hours at 37 °C. At the same time, viable cells of S. aureus were not isolated from the biofilm. This indicates the high lytic activity of the bacteriophage against mature biofilm bacteria and the possibility of its use in chronic staphylococcal infections caused by S. aureus var. bovis. Thus, the obtained data indicate that when mature 72-hour biofilms are exposed to the researched bacteriophage, their degradation is more intense compared with the young 24-hour biofilms, and the amount of destroyed biofilm was on average 2 times higher. This suggests that the use of specific staphylococcal Phage SAvB14 isolated by us for the destruction of biofilm, formed by S. aureus var. bovis, is promising.
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Peruč, Dolores, Dalibor Broznić, Željka Maglica, Zvonimir Marijanović, Ljerka Karleuša, and Ivana Gobin. "Biofilm Degradation of Nontuberculous Mycobacteria Formed on Stainless Steel Following Treatment with Immortelle (Helichrysum italicum) and Common Juniper (Juniperus communis) Essential Oils." Processes 9, no. 2 (February 16, 2021): 362. http://dx.doi.org/10.3390/pr9020362.
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Nontuberculous mycobacteria, like other opportunistic premise plumbing pathogens, produce resistant biofilms on various surfaces in the plumbing system including pipes, tanks, and fittings. Since standard methods of water disinfection are ineffective in eradicating biofilms, research into new agents is necessary. Essential oils (EOs) have great potential as anti-biofilm agents. Therefore, the purpose of this research was to investigate the potential anti-biofilm effect of common juniper (Juniperus communis) and immortelle (Helichrysum italicum) EOs. Minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), and minimum effective concentrations of EOs on Mycobacterium avium, M. intracellulare, and M. gordonae were tested. Additionally, biofilms on the surface of a stainless steel disc were treated with single or mixed concentration of EOs, in order to investigate their degeneration via the bacterial count and confocal laser scanning microscopy (CLSM). H. italicum EO showed the strongest biofilm degradation ability against all Mycobacteria strains that were tested. The strongest effect in the biofilm degradation after the single or mixed applications of EOs was observed against M. gordonae, followed by M. avium. The most resistant was the M. intracellulare biofilm. Synergistic combinations of J. communis and H. italicum EOs therefore seem to be an effective substance in biofilm degradation for use in small water systems such as baths or hot tubs.
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Zhao, Jing Guo, Yu Long Yang, and Cong Li. "The Laboratory Study of Drinking Water Biofilms." Applied Mechanics and Materials 535 (February 2014): 455–59. http://dx.doi.org/10.4028/www.scientific.net/amm.535.455.
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Due to the existence of some kinds of minim organic matters in drinking water distribution systems, biofilms are commonly found on the inner walls of pipe networks, and it can contribute to the deterioration to water quality and influence water supply security. The current situations of the study of the biofilm are summarized. Two typical kinds of reactors often used in laboratories are stated. And numerous environmental factors influencing biofilm formation, including hydraulic condition, water temperature, pipe material, water temperature, disinfectant residuals and nutrient element, are reviewed. Furthermore, some key aspects for future research to control the development of biofilms are proposed. Keywords: drinking water distribution system; biofilm; simulation system; disinfectant residual
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Webb, Jeremy S., Mathew Lau, and Staffan Kjelleberg. "Bacteriophage and Phenotypic Variation in Pseudomonas aeruginosa Biofilm Development." Journal of Bacteriology 186, no. 23 (December 1, 2004): 8066–73. http://dx.doi.org/10.1128/jb.186.23.8066-8073.2004.
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ABSTRACT A current question in biofilm research is whether biofilm-specific genetic processes can lead to differentiation in physiology and function among biofilm cells. In Pseudomonas aeruginosa, phenotypic variants which exhibit a small-colony phenotype on agar media and a markedly accelerated pattern of biofilm development compared to that of the parental strain are often isolated from biofilms. We grew P. aeruginosa biofilms in glass flow cell reactors and observed that the emergence of small-colony variants (SCVs) in the effluent runoff from the biofilms correlated with the emergence of plaque-forming Pf1-like filamentous phage (designated Pf4) from the biofilm. Because several recent studies have shown that bacteriophage genes are among the most highly upregulated groups of genes during biofilm development, we investigated whether Pf4 plays a role in SCV formation during P. aeruginosa biofilm development. We carried out immunoelectron microscopy using anti-Pf4 antibodies and observed that SCV cells, but not parental-type cells, exhibited high densities of Pf4 filaments on the cell surface and that these filaments were often tightly interwoven into complex latticeworks surrounding the cells. Moreover, infection of P. aeruginosa planktonic cultures with Pf4 caused the emergence of SCVs within the culture. These SCVs exhibited enhanced attachment, accelerated biofilm development, and large regions of dead and lysed cells inside microcolonies in a manner identical to that of SCVs obtained from biofilms. We concluded that Pf4 can mediate phenotypic variation in P. aeruginosa biofilms. We also performed partial sequencing and analysis of the Pf4 replicative form and identified a number of open reading frames not previously recognized in the genome of P. aeruginosa, including a putative postsegregational killing operon.
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Liehr, Sarah K., Hui-Jung Chen, and Shun-Hung Lin. "Metals removal by algal biofilms." Water Science and Technology 30, no. 11 (December 1, 1994): 59–68. http://dx.doi.org/10.2166/wst.1994.0546.
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The objective of this research is to evaluate the possibility of enhanced metal precipitation inside algal biofilms. The pH environment surrounding microorganisms growing in biofilms is frequently different than the environment of the bulk liquid because products of metabolic reactions are limited in their ability to diffuse out of the biofilm. This occurs with algal biofilms, in which CO2 utilization during photosynthesis results in an increase in the pH. The pH inside algal biofilms can be several units higher than the pH of the surrounding liquid. This higher pH favors removal of metals by precipitation and possibly adsorption. Laboratory studies were conducted in which biofilms of Cladophora glomerata were grown in buffered nutrient media. Copper or nickel was added to the media to study short term metal removals. Experimental results were compared to predictions of solubility based on a theoretical model of pH inside algal biofilms. Results provide evidence to support the theory that higher internal pH can result in greater metal removal by the biofilms.
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Leonhard, Matthias, Beata Zatorska, Doris Moser, and Berit Schneider-Stickler. "Growth Media for Mixed Multispecies Oropharyngeal Biofilm Compositions on Silicone." BioMed Research International 2019 (July 9, 2019): 1–8. http://dx.doi.org/10.1155/2019/8051270.
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Aims. Microbial colonization of silicone voice prostheses by bacteria and Candida species limits the device lifetime of modern voice prostheses in laryngectomized patients. Thus, research focuses on biofilm inhibitive properties of novel materials, coatings, and surface enhancements. Goal of this in vitro study was the evaluation of seven commonly used growth media to simulate growth of mixed oropharyngeal species as mesoscale biofilms on prosthetic silicone for future research purposes. Methods and Results. Yeast Peptone Dextrose medium (YPD), Yeast Nitrogen Base medium (YNB), M199 medium, Spider medium, RPMI 1640 medium, Tryptic Soy Broth (TSB), and Fetal Bovine Serum (FBS) were used to culture combined mixed Candida strains and mixed bacterial-fungal compositions on silicone over the period of 22 days. The biofilm surface spread and the microscopic growth showed variations from in vivo biofilms depending on the microbial composition and growth medium. Conclusion. YPD and FBS prove to support continuous in vitro growth of mixed bacterial-fungal oropharyngeal biofilms deposits over weeks as needed for longterm in vitro testing with oropharyngeal biofilm compositions. Significance and Impact of Study. The study provides data on culture conditions for mixed multispecies biofilm compositions that can be used for future prosthesis designs.
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Sari, Ika Rhisty Cendana, Rini Devijanti Ridwan, and Diah Savitri Ernawati. "Inhibitory effects of siwak (Salvadora persica. L) extract on the growth of Enterococcus faecalis planktonics and biofilms by in vitro." Dental Journal (Majalah Kedokteran Gigi) 49, no. 3 (September 30, 2016): 158. http://dx.doi.org/10.20473/j.djmkg.v49.i3.p158-162.
Full textAbstract:
Background: Enterococcus faecalis (E. faecalis) is one of the most persistent gram positive bacteria in root canal, resulting in secondary infection after endodontic treatment. E. faecalis pathogenicity is caused by overgrowth of E. faecalis planktonics and biofilms. E. faecalis planktonics produce lipoteichoid acid (LTA) as a virulence factor that can defend their permeability cell. On the other hand, E. faecalis biofilms produce protease, such as Esp (enterococcal surface protein), GelE (gelatinase), and SprE (serin protease), that have quorum-sensing mechanism as an adhesion factor to form extracellular polysaccharide substance (EPS) and increase the growth of the biofilms themselves. Siwak (Salvadora persica L.) has active components, namely benzylisothio-cyanate, trimethylamine, and salvadorine that can inhibit the growth of E. faecalis planktonics and biofilms. Purpose: This study aimed to measure inhibitory effects of siwak extract on the growth of E. faecalis planktonics and biofilms. Method: This research was an antimicrobial research on the culture of E.faecalis incubated in a TSB medium. Siwak extract was diluted into different concentrations, namely 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, and 100%. The extract then was placed into the E. faecalis’s colony and planted into Trypticase Soy Agar medium. After incubated for 24 hours at 37°C, the colony would be measured and compared with the control (+) and control (-). As an antibiofilm research, this research used biofilm microtitter assay method to form E. faecalis biofilms incubated in a well-plate medium containing TSB and 0.1 % glucose. Siwak extract then was diluted into the same range concentration as in first method, and placed into the colony of E. faecalis to form biofilms. The biofilms were measured and compared to the control (+) given siwak extract and the control (-) given 0.1% chlorhexidine. After the incubation, they were washed three times, and staining process was conducted using Chrystal violet. The optical density then was measured by ELISA Reader 595 nm. Result: Siwak extract could inhibit the growth of E. faecalis planktonics at the concentration of 35% as a minimum inhibitory concentration as well as the growth of E. faecalis biofilms at the concentration of 45% as a minimum biofilm inhibitory concentration. Conclusion: Siwak extract has an inhibitory effect, particularly at a concentration of 35% on the growth of E. faecalis planktonics and at the concentration of 45% on the growth of E. faecalis biofilms.
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Jang, A., P. L. Bishop, S. Okabe, S. G. Lee, and I. S. Kim. "Effect of dissolved oxygen concentration on the biofilm and in situ analysis by fluorescence in situ hybridization (FISH) and microelectrodes." Water Science and Technology 47, no. 1 (January 1, 2003): 49–57. http://dx.doi.org/10.2166/wst.2003.0014.
Full textAbstract:
A better understanding of microbiology and ecology of nitrifying bacteria in inner biofilms is an important part of improving process performance and control. Microelectrodes and fluorescent in situ hybridization (FISH) in biofilm research have been used to investigate the spatial distributions of various microbial activities in biofilms and have led to new experimental findings as well as modifications of the homogeneous assumptions in the biofilm kinetic models. The objective of this study is to try the combination of two methods, both FISH and microelectrode measurements, and to provide reliable and in situ information on nitrifying bacterial activity in biofilms. The characteristics of biofilm developed on tygon slides were different according to the change of dissolved oxygen (DO). When the DO increased from 2 to 10 μg DO/L, the rate of the biofilm thickness increased and its dry density changed from 50-70 to 25-90 mg/cm3. Ammonia oxidizing bacteria were not uniformly distributed in biofilm, and were found at the deeper layer where oxygen is depleted, they were detected primarily in the upper and middle layers of the biofilm.