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Characterization of Monospecies Biofilm Formation by Helicobacter pylori. Sheri P. Cole, 2004.As all bacteria studied to date, the gastric pathogen Helicobacter pylori has an alternate lifestyle as a biofilm . H . pylori forms biofilms on glass surfaces at the air-liquid interface in stationary or shaking batch cultures . By light microscopy, we have observed attachment of individual, spiral H . pylori to glass surfaces, followed by division to form microcolonies, merging of individual microcolonies, and growth in the third dimension . Scanning electron micrographs showed H . pylori arranged in a matrix on the glass with channels for nutrient flow, typical of other bacterial biofilms . To understand the importance of biofilms to the H . pylori life cycle, we tested the effect of mucin on biofilm formation . Our results showed that 10% mucin greatly increased the number of planktonic H . pylori while not affecting biofilm bacteria, resulting in a decline in percent adherence to the glass . This suggests that in the mucus-rich stomach, H . pylori planktonic growth is favored over biofilm formation . We also investigated the effect of specific mutations in several genes, including the quorum-sensing gene, luxS, and the cagE type IV secretion gene . Both of these mutants were found to form biofilms approximately twofold more efficiently than the wild type in both assays . These results indicate the relative importance of these genes to the production of biofilms by H . pylori and the selective enhancement of planktonic growth in the presence of gastric mucin .
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