PL-200 (JTK):

Endogenous hydrogen peroxide increases biofilm formation by inducing exopolysaccharide production in Acinetobacter oleivorans DR1

We investigated the proteins that were differentially expressed in Acinetobacter oleivorans cells during planktonic and biofilm growth using two-dimensional gel electrophoresis combined with MALDI-TOF mass spectrometry. We focused on the role of oxidative stress resistance in biofilm formation by using mutants defective in alkyl hydroperoxide reductase (AhpC) because its production in aged biofilms was enhanced compared to that in planktonic cells. The ahpC promoter-gfp reporter alanlysis also showed that aged biofilms had higher ahpC expression than planktonic cells at 48 h. However, at 24 h, ahpC expression was higher in planktonic cells than in biofilms. Deletion of the ahpC gene led to a severe growth defect in rich media that was not observed in minimal media, and the ahpC deletion promoted early biofilm formation through increased production of exopolysaccharide (EPS) and EPS gene expression. Increased production of endogenous H{2}O{2} in the ahpC mutant in rich media enhanced biofilm formation, and this enhancement was not observed in the presence of antioxidants. Exogenous addition of H{2}O{2} promoted early biofilm formation in wild type cells, which suggested that biofilm development is linked to defense against H{2}O{2}. Collectively, maintenance of low level endogenous H{2}O{2} inside cells determines the timing of biofilm formation.

keywords:Biofilm,hydrogen peroxide,exopolysaccharide,Proteomics