Ultraviolet-C light-emitting diodes (UV-C LEDs) are an emerging technology for decontamination applications in different sectors. In this study, the inactivation of bacterial biofilms was investigated by applying an UV-C LED emitting at 280 nm and by measuring both the influence of the initial cell density (load) and presence of an extracellular matrix (biofilm). Two bacterial strains exposing diverging matrix structures and biochemical compositions were used: Pseudomonas aeruginosa and Leuconostoc citreum.
View Article and Find Full Text PDFThe valorization of biological aggregates through the extraction of hydrogel-forming polymers can enhance the economics and sustainability of various processes in which bacteria are involved in organic waste transformation, such as wastewater treatment. Achieving these goals requires the development of a method capable of detecting the presence of gel-forming polymers in complex mixtures containing biopolymers that are most often unknown and uncharacterized. A miniaturized screening method capable of detecting gelation via ionic crosslinking using only 1 to 3 mg of the tested samples (commercial molecules or extracellular polymeric substances, EPSs) is proposed.
View Article and Find Full Text PDFL-17 strain was isolated from a sample of chicken feathers. Here, we report complete genome sequence data of L-17. The size of the genome is 3,933,788 bp which harbours 4001 coding Sequences.
View Article and Find Full Text PDFPhototrophic biofilms are exposed to multiple stressors that can affect them both directly and indirectly. By modifying either the composition of the community or the physiology of the microorganisms, press stressors may indirectly impact the ability of the biofilms to cope with disturbances. Extracellular polymeric substances (EPS) produced by the biofilm are known to play an important role in its resilience to various stresses.
View Article and Find Full Text PDFBacillus amyloliquefaciens is a ubiquitous soil and plant-associated bacterial species which shows structural and adaptative responses to the environment. This present paper explores the ability of the strain L-17 to form subaerial biofilms on a liquid surface. Hydrophobic and non-wetting properties were observed for the rough top biofilm layer in contact with the air, which are quite different to the hydrophilic properties which were observed for the smooth biofilm layer in contact with the liquid.
View Article and Find Full Text PDFAim: Study of the biocidal effect of a cold atmospheric-pressure plasma in ambient air on single-species bacterial biofilms with controlled cell density, characterized by different extracellular matrices.
Methods And Results: Two bacterial strains were chosen to present different Gram properties and contrasted extracellular matrices: ATCC 15442 (Gram-negative), and NRRL B-1299 (Gram-positive). biofilm exhibits a complex matrix, rich in proteins while presents the specificity to produce glucan-type exopolysaccharides when grown in the presence of sucrose.
The influence of wastewater (WW) composition and the bioaggregates types (floccular vs. aerobic granular sludge - AGS) on the content, physical-chemical, hydrogel and rheological properties of Alginate-Like Exopolymers (ALE) was studied. Results showed that ALE are a complex mixture of proteins, humic acids and polysaccharides.
View Article and Find Full Text PDFIn freshwater ecosystem, phototrophic biofilms play a crucial role through adsorption and sequestration of organic and inorganic pollutants. However, extracellular polymeric substance (EPS) secretion by phototrophic biofilms exposed to metals is poorly documented. This work evaluated the physiological responses of phototrophic biofilms by exposing three microorganisms (cyanobacterium Phormidium autumnale, diatom Nitzschia palea and green alga Uronema confervicolum) to 20 and 200 μg L of Cu or 60 and 600 μg L of Zn, both individually and in combination.
View Article and Find Full Text PDFMicrobial biofilms can be both cause and cure to a range of emerging societal problems including antimicrobial tolerance, water sanitation, water scarcity and pollution. The identities of extracellular polymeric substances (EPS) responsible for the establishment and function of biofilms are poorly understood. The lack of information on the chemical and physical identities of EPS limits the potential to rationally engineer biofilm processes, and impedes progress within the water and wastewater sector towards a circular economy and resource recovery.
View Article and Find Full Text PDFCan J Microbiol
November 2018
This paper aims to define a robust procedure to extract extracellular polymeric substances (EPS) from aggregates of three benthic phototrophic microorganisms: the cyanobacterium Phormidium autumnale, the diatom Nitzschia palea, and the green alga Uronema confervicolum. This study focuses on the extraction efficiency of polysaccharide and protein EPS by using two physical methods (sonication, cation exchange resin) and three chemical methods (formamide, EDTA, Tween 20) with minimum cell lysis. Cell lysis was evaluated by monitoring chlorophyll a release.
View Article and Find Full Text PDFBackground: Sugarcane distillery waste water (SDW) or vinasse is the residual liquid waste generated during sugarcane molasses fermentation and alcohol distillation. Worldwide, this effluent is responsible for serious environmental issues. In Reunion Island, between 100 and 200 thousand tons of SDW are produced each year by the three local distilleries.
View Article and Find Full Text PDFAn amyloid fibrils investigation within biofilm samples requires distinguishing the amyloid β-sheet structure of these proteins and quantifying them. In this study, the property of amyloids to incorporate the fluorescent dye Thioflavin T has been exploited to propose a method of quantification. The experimental protocol includes the preparation of amyloids from commercial κ-casein (κCN) and their fractionation through size exclusion chromatography (SEC) to provide calibration curves from fluorescence and absorbance signals.
View Article and Find Full Text PDFThis study aims to clarify the biochemical nature and interactions of Extracellular Polymeric Substances (EPS) involved in the structure and cohesive properties of aerobic granules. Granules were incubated with selective hydrolytic enzymes or with chemicals and the resistance of digested granules to shear stress was evaluated. After α-amylase digestion, the hydrodynamic stress released macro-particles (>315 μm) while soluble molecules (<1.
View Article and Find Full Text PDFA colorimetric assay based on the conventional anthrone reaction was investigated for specific quantification of uronic acids (UA) in the presence of neutral sugars and/or proteins. Scanning of glucose (Glu) and glucuronic acid (GlA) was performed after the reaction with anthrone and a double absorbance reading was made, at 560 nm and at 620 nm, in order to quantify the UA and neutral sugars separately. The assay was implemented on binary or ternary solutions containing Glu, GlA and bovine serum albumin (BSA) in order to validate its specificity towards sugars and check possible interference with other biochemical components such as proteins.
View Article and Find Full Text PDFA multi-method protocol previously proposed for the extraction of extracellular polymeric substances (EPS) from flocculated sludges was investigated on dense aerobic granules. The protocol combines mechanical disruption by sonication and chemical extraction using the Tween detergent and the cation chelator, EDTA. Polysaccharides were mainly recovered during the first sonication step while proteins were recovered all along the extractive procedure with a high prevalence in the EDTA step.
View Article and Find Full Text PDFExtracellular Polymeric Substances (EPS) analysis was undertaken on three biofilms grown under different feeding conditions and offering diverging microbial activities and structural characteristics. EPS were extracted by a multi-method protocol including sonication, Tween and EDTA treatments and were characterized by size exclusion chromatography (SEC). Tween and sonication extracts presented higher EPS size diversity compared to EDTA extracts.
View Article and Find Full Text PDFThe search of new pharmacological targets with original mechanism of action within the ubiquitin-proteasome pathway is still a goal to be reached in oncopharmacology. Modification by phosphorylation/dephosphorylation has been found to be involved in cancer and to regulate functional activity of proteasome. Until now, phosphorylated forms of alpha subunits of the 20S human proteasome have been mostly reported.
View Article and Find Full Text PDFA multi-method extraction protocol based on mechanical, ionic and hydrophobic methods was investigated on two types of activated sludge samples. Extraction methods were chosen with regards to optimal protein yield without cell disruption. Sonication, EDTA and Tween extraction methods were selected and combined.
View Article and Find Full Text PDFThe pharmacologic properties of ajoene, the major sulfur-containing compound purified from garlic, and its possible role in the prevention and treatment of cancer has received increasing attention. Several studies demonstrated that induction of apoptosis and cell cycle blockade are typical biologic effects observed in tumor cells after proteasome inhibition. The proteasome is responsible for the degradation of a variety of intracellular proteins and plays a key role in the regulation of many cellular processes.
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