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Plant phenolic volatiles inhibit quorum sensing in pectobacteria and reduce their virulence by potential binding to ExpI and ExpR proteins. Center for Agricultural Biotechnology, The Robert H. Colanic acid polymer of Quorum sensing (QS) is a population density-dependent regulatory system in bacteria that couples gene expression to cell density through accumulation of diffusible signaling molecules. Pectobacteria are causal agents of soft rot disease in a range of economically important crops. They rely on QS to coordinate their main virulence factor, production of plant cell wall degrading enzymes (PCWDEs). Plants have evolved an array of antimicrobial compounds to anticipate and cope with pathogens, of which essential oils (EOs) are widely specifically interfere with QS, the master regulator of virulence in pectobacteria, resulting in strong inhibition of QS genes, biofilm formation and PCWDEs, thereby leading to impaired infection.

Accumulation of the signal molecule N-acylhomoserine lactone declined upon treatment with EOs, suggesting direct interaction of EOs with either homoserine lactone synthase (ExpI) or with the regulatory protein (ExpR). Homology models of both proteins were constructed and docking simulations were performed to test the above hypotheses. The resulting binding modes and docking scores of carvacrol and eugenol support potential binding to ExpI/ExpR, with stronger interactions than previously known inhibitors of both proteins. The results demonstrate the potential involvement of phytochemicals in the control of Pectobacterium. Regulatory Mutations Impacting Antibiotic Susceptibility in an Established Department of Pathology, University of Arkansas for Medical Sciences, Little We previously determined the extent to which mutations of different Staphylococcus aureus regulatory loci impact biofilm formation as assessed under in vitro conditions. Here we extend these studies to determine the extent to which those regulatory loci that had the greatest effect on biofilm formation also impact antibiotic susceptibility. The experiments were done under in vitro and in vivo conditions using two clinical isolates of S.

aureus (LAC and UAMS-1) and two functionally diverse antibiotics (daptomycin and ceftaroline). Mutation of the staphylococcal accessory regulator (sarA) or sigB was found to significantly increase susceptibilities to both antibiotics and in both strains in a manner that could not be explained by changes in the MICs. The impact of a mutation in sarA was comparable to that of a mutation in sigB and greater than the impact observed with any other mutant. These results suggest that therapeutic strategies targeting sarA and/or sigB have the greatest potential to facilitate the ability to overcome the intrinsic antibiotic resistance that defines S. aureus biofilm-associated infections. Associations of motility and auto-aggregation with biofilm-formation capacity Clostridioides difficile (C. difficile) is responsible for one of the most common nosocomial infections worldwide.

Seebio Colanic acid polymer assessed associations between flagella, motility and auto-aggregation in 118 clinical isolates. Biofilm production was assessed by the crystal violet method. Cell viability was determined by BacTiter-Glo™ Microbial Cell Viability Assay and live-imaging measured by real-time PCR. Motility was visually assessed in agar tubes. Auto-aggregation levels were determined by OD600 measurements. Out of 118 isolates, 66 (56 %) were biofilm producers, with most being strong or moderate producers. Cell viability, motility and auto-aggregation positively correlated with biofilm-production capacity (p = 0001, p = 036 and p < 0001, respectively).

Positive associations were found between pilA, fliC and luxS expression levels and biofilm-production capacity (p = 04, p = 01, p = 036, respectively). This is the first report of associations between expression, auto-aggregation and motility. These correlations should be further explored to expand knowledge on the regulation of C. difficile biofilm formation, and pathogenesis, which will have notable implications on treatment Conflict of interest statement: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this Effects of chlorine and hydrogen peroxide sanitation in low bacterial content water on biofilm formation model of poultry brooding house waterlines. University of Arkansas, Fayetteville 72701.