Search results for "biofilm."

Microbial Adaptation to Boreal Saturated Subsurface: Implications in Bioremediation of Polychlorophenols

2008

Saturated subsurface environments pose challenges to the intrinsic microbiology. Prevailing environmental conditions (temperature, pH, bioavailability of substrates and nutrients) affect microbial biodegradation activity, which is often favored by certain redox conditions. Microbial adaptation in each redox environment proceeds by selection and enrichment of indigenous bacteria, evolution of novel catabolic pathways and horizontal gene transfer (Wilson et al. 1985; van der Meer et al. 1998; Tiirola et al. 2002b). Formation of biofilms enables microbial retainment, co-operation among microorganisms and enhanced gene transfer among organisms (Singh et al. 2006). Chlorophenols are toxic and pe…

Total mercury and methyl-mercury contents and accumulation in polar microbial mats.

2014

Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them…

TOWARD POTENT ANTIBIOFILM DEGRADABLE MEDICAL DEVICES: GENERIC METHODOLOGIES FOR THE SURFACE MODIfiCATION OF POLYLACTIDE

2014

When Functionalization of PLA Surfaces Meets Thiol−Yne Photochemistry: Case Study with Antibacterial PolyaspartamideDerivatives

2014

International audience; In this work we wish to report on the covalent functionalization of polylactide (PLA) surfaces by photoradical thiol–yne to yield antibacterial surfaces. At first, hydrophilic and hydrophobic thiol fluorescent probes are synthesized and used to study and optimize the conditions of ligation on alkyne-PLA surfaces. In a second part, a new antibacterial polyaspartamide copolymer is covalently grafted. The covalent surface modification and the density of surface functionalization are evaluated by SEC and XPS analyses. No degradation of PLA chains is observed, whereas covalent grafting is confirmed by the presence of S2p and N1s signals. Antiadherence and antibiofilm acti…

Modeling in Microbial Ecology

2014

SPE IPM; International audience; The bases and the principles of modeling in microbial community ecology and biogeochemistry are presented and discussed. Several examples are given. Among them, the fermentation process is largely developed, thus demonstrating how the model allows determining the microbial population growth rate, the death rate, and the maintenance rate. More generally, these models have been used to increase the development of bioenergetic formulations which are presently used in biogeochemical models (Monod, Droop, DEB models). Different types of interactions (competition, predation, and virus–bacteria) are also developed. For each topic, a complete view of the models used…

Association of colony morphotypes with virulence, growth and resistance against protozoan predation in the fish pathogen Flavobacterium columnare.

2014

Many opportunistic pathogens can alternate between inside- and outside-host environments during their life cycle. The opportunistic fish pathogen Flavobacterium columnare is an inhabitant of the natural microbial community and causes significant yearly losses in aquaculture worldwide. The bacterium grows in varying colony morphotypes that are associated with either virulence (rhizoid type) or resistance to starvation and phages (rough type). Rough type strains can arise spontaneously or can be induced by phage infection. To identify the determinants of morphotype fitness, we measured virulence, growth parameters, biofilm-forming ability and resistance to amoeba and ciliate predation of both…

Grapefruit essential oils inhibit quorum sensing of Pseudomonas aeruginosa.

2019

Citrus essential oils are used in food to confer flavor and aromas. The citrus essential oils have been granted as GRAS and could be used as antimicrobial additives to control bacterial quorum sensing from potential food bacterial pathogens. The chemical composition and inhibitory activity of Citrus paradisi (grapefruit) essential oils obtained by cold-pressed method (EOP) and cold-pressed method followed by steam distillation, against Pseudomonas aeruginosa were determined . The GC-MS analyses of the oil indicated the amount of the essential oil components was highest with D-limonene in both cases. However, the extraction method modified the chemical composition. EOP had higher amount of …

Biogenesis and roles of Lacticaseibacillus casei BL23 membrane vesicles

2023

Gram-positive bacteria of the species Lacticaseibacillus casei (formerly known as Lactobacillus casei) are fermentative bacilli found in dairy products that are known for their anti-inflammatory properties and beneficial effects against pathogens. Like all living organisms, L. casei produces nanostructures of 20 to 400 nm in diameter bounded by a lipid membrane called membrane vesicles (MVs). MVs have been shown to contain various cellular constituents and exert multiple functions. However, despite the growing interest in Gram-positive MVs over the past 10 years, the mechanisms of biogenesis and the roles played by these vesicles remain poorly characterized. In this context, the objectives …

Dominant role of paraoxonases in inactivation of the Pseudomonas aeruginosa quorum-sensing signal N-(3-oxododecanoyl)-L-homoserine lactone.

2008

Pseudomonas aeruginosa is an opportunistic bacterium which causes serious infections in immunocompromised and cystic fibrosis patients (10). As with many gram-negative bacteria, P. aeruginosa produces acyl-homoserine lactone (AHL) quorum-sensing (QS) signaling molecules termed autoinducers which allow the single-celled organisms to coordinate their actions (36). N-(3-Oxododecanoyl)-l-homoserine lactone (3OC12-HSL) is a key autoinducer synthesized by P. aeruginosa which regulates the expression of extracellular virulence factors and biofilm formation (5, 36). Rats and mice experimentally infected with P. aeruginosa mutants deficient in the ability to produce or respond to 3OC12-HSL exhibited…

Biological properties of extracellular vesicles and their physiological functions

2015

The authors wish to thank Dr R Simpson and Dr D Taylor for critical reading of the manuscript and acknowledge the Horizon 2020 European Cooperation in Science and Technology programme and its support of our European Network on Microvesicles and Exosomes in Health & Disease (ME-HaD; BM1202 www.cost.eu/COST_Actions/bmbs/Actions/BM1202). In the past decade, extracellular vesicles (EVs) have been recognized as potent vehicles of intercellular communication, both in prokaryotes and eukaryotes. This is due to their capacity to transfer proteins, lipids and nucleic acids, thereby influencing various physiological and pathological functions of both recipient and parent cells. While intensive invest…