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The force-deflection and removal characteristics of bacterial biofilm were measured by two different techniques before and after chemical, or enzymatic, treatment. The first technique involved time lapse imaging of a biofilm grown...
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The force-deflection and removal characteristics of bacterial biofilm were measured by two different techniques before and after chemical, or enzymatic, treatment. The first technique involved time lapse imaging of a biofilm grown in a capillary flow cell and subjected to a brief shear stress challenge imparted through increased fluid flow. Biofilm removal was determined by calculating the reduction in biofilm area from quantitative analysis of transmission images. The second technique was based on micro-indentation using an atomic force microscope. In both cases, biofilms formed by Staphylococcus epidermidis were exposed to buffer (untreated control), urea, chlorhexidine, iron chloride, or DispersinB. In control experiments, the biofilm exhibited force-deflection responses that were similar before and after the same treatment. The biofilm structure was stable during the post-treatment shear challenge (1% loss). Biofilms treated with chlorhexidine became less deformable after treatment and no increase in biomass removal was seen during the post-treatment shear challenge (2% loss). In contrast, biofilms treated with urea or DispersinB became more deformable and exhibited significant biofilm loss during the post-treatment flow challenge (71% and 40%, respectively). During the treatment soak phase, biofilms exposed to urea swelled. Biofilms exposed to iron chloride showed little difference from the control other than slight contraction during the treatment soak. These observations suggest the following interpretations: (1) chemical or enzymatic treatments, including those that are not frankly antimicrobial, can alter the cohesion of bacterial biofilm; (2) biocidal treatments (e.g., chlorhexidine) do not necessarily weaken the biofilm; and (3) biofilm removal following treatment with agents that make the biofilm more deformable (e.g., urea, DispersinB) depend on interaction between the moving fluid and the biofilm structure. Measurements such as those reported here open the door to development of new technologies for controlling detrimental biofilms by targeting biofilm cohesion rather than killing microorganisms.
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The negative impact of biofilms in both the industry and the human health, demands the development of strategies for the in situ and early detection of biofilm formation. In this review we describe potentiometric, voltammetric and...
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The negative impact of biofilms in both the industry and the human health, demands the development of strategies for the in situ and early detection of biofilm formation. In this review we describe potentiometric, voltammetric and impedance-based sensors as to provide an overview of the different electrochemical techniques applied in biofilm detection and monitoring. (C) 2020 Elsevier B.V. All rights reserved.
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Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed...
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Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms.
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Candida albicans is a normal member of the human microbiota that asymptomaticallycolonizes healthy individuals, however it is also an opportunisticpathogen that can cause severe infections, especially in immunocompromisedindividua...
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Candida albicans is a normal member of the human microbiota that asymptomaticallycolonizes healthy individuals, however it is also an opportunisticpathogen that can cause severe infections, especially in immunocompromisedindividuals. The medical impact of C. albicans depends, in part, on its abilityto form biofilms, communities of adhered cells encased in an extracellularmatrix. Biofilms can form on both biotic and abiotic surfaces, such as tissuesand implanted medical devices. Once formed, biofilms are highly resistant toantifungal agents and the host immune system, and can act as a protected reservoirto seed disseminated infections. Here, we present several in vitro biofilmprotocols, including protocols that are optimized for high-throughput screeningof mutant libraries and antifungal compounds. We also present protocolsto examine specific stages of biofilm development and protocols to evaluateinterspecies biofilms that C. albicans forms with interactingmicrobial partners.
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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 ...
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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.
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Candida albicans biofilms have a significant medical impact due to their rapid growth on implanted medical devices, their resistance to antifungal drugs, and their ability to seed disseminated infections. Biofilm assays performed ...
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Candida albicans biofilms have a significant medical impact due to their rapid growth on implanted medical devices, their resistance to antifungal drugs, and their ability to seed disseminated infections. Biofilm assays performed in vitro allow for rapid, high-throughput screening of gene deletion libraries or antifungal compounds and typically serve as precursors to in vivo studies. Here, we compile and discuss the protocols for several recently published C. albicans in vitro biofilm assays. We also describe improved versions of these protocols as well as novel in vitro assays. Finally, we consider some of the advantages and disadvantages of these different types of assays.
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The authors have proposed a novel water treatment process in which nitrifying bacteria are fixed on the surface of rotating membrane disks. This biofilm-membrane process can perform strict solid-liquid separation and oxidation of ...
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The authors have proposed a novel water treatment process in which nitrifying bacteria are fixed on the surface of rotating membrane disks. This biofilm-membrane process can perform strict solid-liquid separation and oxidation of ammonia nitrogen simulataneously. In this research, applicability of the conventional biofilm model (assuming the biofilm structure to be flat, homogeneous and continuous) to analysis of the biofilm developing in the proposed process was examined.
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The review includes literature published during the year 2011 regarding the use of biofilm and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular poly...
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The review includes literature published during the year 2011 regarding the use of biofilm and bioreactors to treat wastewater. Topics considered are: biofilm formation and factors that impact biofilm formation; extracellular polymeric substance and its extraction from biofilms; biofilm consortia and quorum sensing; biofilm imaging techniques; biofilm reactors and modeling.
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A novel biofilm reactor—alternating pumped sequencing batch biofilm reactor (APSBBR)— was developed to treat synthetic dairy wastewater at a volumetric chemical oxygen demand (COD) loading rate of 487 g COD m~(-3) d~(-1) and an ...
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A novel biofilm reactor—alternating pumped sequencing batch biofilm reactor (APSBBR)— was developed to treat synthetic dairy wastewater at a volumetric chemical oxygen demand (COD) loading rate of 487 g COD m~(-3) d~(-1) and an areal loading rate of 5.4 g COD m~(-2) d~(-1). This biofilm reactor comprised two tanks, Tanks 1 and 2, with two identical plastic biofilm modules in each tank. The maximum volume of bulk fluid in the two-tank reactor was the volume of one tank. The APSBBR was operated as a sequencing batch biofilm reactor with five operational phases—fill (25 min), anoxic (9h), aerobic (9h), settle (6h) and draw (5min). The fill, anoxic, settle and draw phases occurred in Tank 1. In the aerobic phase, the wastewater was circulated between the two tanks with centrifugal pumps and aeration was mainly achieved through oxygen absorption by micro-organisms in the biofilms when they were exposed to the air. In this paper, the biofilm growth and characteristics in the APSBBR were studied in a 98-day laboratory-scale experiment. During the course of the study, it was found that the biofilm thickness (δ) in Tank 1 ranged from 1.2 to 7.2 mm and that in Tank 2 from 0.5 to 2.2 mm; the biofilm growth against time (t) can be simulated as δ = 0.07t~(0.99) (R~2 = 0.97, P = 0.002) in Tank 1 and δ = 0.08t~(0.66) (R~2 = 0.81, P = 0.04) in Tank 2. The biomass yield coefficient, Y, was 0.18 g volatile solids (VS) g~(-1) COD removal. The biofilm density in both tanks, X, decreased as the biofilm thickness increased and can be correlated to the biofilm thickness, δ .
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With the discovery that 48% of cholera infections in rural Bangladesh villages could be prevented by simple filtration of unpurified waters and the detection of Vibrio cholerae aggregates in stools from cholera patients it was rea...
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With the discovery that 48% of cholera infections in rural Bangladesh villages could be prevented by simple filtration of unpurified waters and the detection of Vibrio cholerae aggregates in stools from cholera patients it was realized V. cholerae biofilms had a central function in cholera pathogenesis. We are currently in the seventh cholera pandemic, caused by 01 serotypes of the El Tor biotypes strains, which initiated in 1961. It is estimated that V. cholerae annually causes millions of infections and over 100,000 deaths. Given the continued emergence of cholera in areas that lack access to clean water, such as Haiti after the 2010 earthquake or the ongoing Yemen civil war, increasing our understanding of cholera disease remains a worldwide public health priority. The surveillance and treatment of cholera is also affected as the world is impacted by the COVID-19 pandemic, raising significant concerns in Africa. In addition to the importance of biofilm formation in its life cycle, V. cholerae has become a key model system for understanding bacterial signal transduction networks that regulate biofilm formation and discovering fundamental principles about bacterial surface attachment and biofilm maturation. This chapter will highlight recent insights into V. cholerae biofilms including their structure, ecological role in environmental survival and infection, regulatory systems that control them, and bio-mechanical insights into the nature of V. cholerae biofilms.
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