Search

Abstract The overuse of antibiotics and biofilm formation ability has led to the emergence of bacterial resistant strains. The combined use of several antibiotics has been found as an efficient strategy to overcome this resistance. In this study, two exopolysaccharides (EPS) obtained from Lactobacillus plantarum (EPS-Lp) and Bacillus spp. (EPS-B), isolated from a traditional Tunisian food "ricotta cheese" and hypersaline environment respectively, were used to counteract the biofilm formation and efflux pumps activities in Escherichia coli ATCC35218. The obtained results revealed that the tested EPSs can be effective against E. coli at a concentration > 1 mg/ml and were able to modulate biofilm formation by 50%. Moreover, at a concentration of 512 μg/ml, the tested EPSs inhibit the EtBr efflux in the tested bacteria and no significant difference was shown compared to cells treated with reserpine (P > 0.05). The positive effect of the tested EPSs may be due to the decrease of Indole production level proposed as a signal involved in quorum sensing and through the significant reduction of the hydrophobicity percentage between the treated and untreated cells. Overall, EPS-Lp and EPS-B, when used at appropriate concentration, may inhibit biofilm formation and reduce efflux pumps implicated in bacterial adhesion and antimicrobial resistance. These results make them an interesting candidate in the design of a new strategies to control bacterial biofilm-associated infections. Highlights • EPSs were extracted from Lactobacillus plantarum and halophilic Bacillus spp. • Both EPS-LP and EPS-b showed antibacterial activity. • Both EPS-LP and EPS-b induced the inhibition of biofilm and efflux pumps Escherichia coli ATCC35218. • The tested EPSs inhibit the indole production. [ABSTRACT FROM AUTHOR]

In this work, polyethylene terephthalate (PET) was chemically modified by covalent co-immobilization of two separate layers of bioactive polymers composed of chitosan and a new dermatan sulfate isolated fromRaja montaguiskin. The new materials obtained were characterized by determination of carboxyl groups, ATR-FTIR spectroscopy, drop water contact angle, SEM, and TGA measurements. The different immobilizations modified the surface characteristics; especially when the first layer was dermatan sulfate (PET–DS–Chito) which presented the best surface wettability (71 ± 3°). It also reduced the ability ofStaphylococcus epidermidisto form biofilm on PET surfaces which could decrease the virulence of vascular prosthesis infections. [ABSTRACT FROM AUTHOR]

Because of their functional diversity, bioactive compounds are becoming a new biocontrol agent to limit biofilm formation by pathogens. In this study, the physico-chemical characterization of an exopolysaccharide (EPS) isolated from Lactobacillus plantarum (EPLB) was characterized and its in vitro effect on biofilm formation was studied. The EPS had a molecular weight of 36 kDa and polydispersity index estimated to be 1.2. The tested EPLB had an antibacterial activity, with a Minimal Inhibition Concentration (MIC) values ranging between 1 mg/ml and 10 mg/ml, displayed an antibiofilm effect concentration dependent on Gram positive and negative strains. Among the pathogenic strains, 2 out of 4 appeared to be more than 50% inhibited in their biofilm development by the EPS. The antibiofilm activity can be due to the ability of the EPS to influence the function of biological membranes like hydrophobicity that decreased (P < 0.05) when the EPS was used at a concentration of 512 μg/ml. This EPS without cytotoxic effect, showed an antioxidant effect on the quenching of DPPH radicals and the inhibition of lipid peroxidation with a percentage of 64% and 66%, respectively. Taken together these biological properties, EPLB can be considered as a potential prebiotic agent in the design of new therapeutic strategies for bacterial biofilm-associated infections. [ABSTRACT FROM AUTHOR]