Study Guide for Biofilms and Quorum Sensing We covered this stuff quickly and briefly, so the expectations are similar. Biofilms - communities of bacteria usually at surface-liquid interfaces. Usually are mixtures of different bacteria. Free (individual) bacteria are called planktonic. Steps in biofilm development (from review article on food biofilms): Stage 1: reversible attachment of bacterial cells to a surface. Stage 2: irreversible attachment - exopolymeric material Stage 3: formation of microcolonies. Stage 4: mature biofilm with a 3-dimensional structure containing cells packed in clusters with channels between the clusters that allow transport of water and nutrients and waste removal Stage 5: detachment and dispersion of cells from the biofilm. Because of limited nutrients, most cells in the biofilms are not replicating. Therefore, they are resistant to antibiotics, environmental stress, host defenses, etc. Biofilms are a form of developmental biology for organisms.
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