Central metabolism is a key player in < i > E < /i > . < i > coli < /i > biofilm stimulation by sub-MIC antibiotics

by Luke N. Yaeger, Shawn French, Eric D. Brown, Jean Philippe C ôté, Lori L. Burrows Exposure ofEscherichia coli to sub-inhibitory antibiotics stimulates biofilm formation through poorly characterized mechanisms. Using a high-throughput Congo Red binding assay to report on biofilm matrix production, we screened ~4000E.coli K12 deletion mutants for deficiencies in this biofilm stimulation response. We screened using three different antibiotics to identify core components of the biofilm stimulation response. Mutants lackingacnA,nuoE, orlpdA failed to respond to sub-MIC cefixime and novobiocin, implicating central metabolism and aerobic respiration in biofilm stimulation. These genes are members of the ArcA/B regulon –controlled by a respiration-sensitive two-component system. Mutants ofarcA andarcB had a ‘pre-activated’ phenotype, where biofilm formation was already high relative to wild type in vehicle control conditions, and failed to increase further with the addition of sub-MIC cefixime. Using a tetrazolium dye and anin vivo NADH sensor, we showed spatial co-localization of increased metabolic activity with sub-lethal concentrations of the bactericidal antibiotics cefixime and novobiocin. Supporting a role for respiratory stress, the biofilm stimulation response to cefixime and novobiocin was inhibited when nitrate was provided as an alternative electron acceptor. Deletion of a gene encoding part of the machinery for respiring nitrate abolished its ameliorating eff...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research