Response of a Lactobacillus plantarum human isolate to tannic acid challenge assessed by proteomic analyses

Scope: To gain insight on the mechanisms used by intestinal bacteria to adapt and resist the antimicrobial action of dietary tannins and identify targets for tannic acid in Lactobacillus plantarum. Methods and results: A proteomic analysis of an L. plantarum human isolate exposed to the tannic acid challenge was undertaken. Tannic acid targeted proteins involved in outstanding processes for bacterial stress resistance including cyclopropanation of membrane lipids, stress response at population scale and maintenance of cell shape. To respond to this aggression, tannic acid-misfit cells of L. plantarum challenged with tannic acid reorganized their metabolic capacity to economize energy and express proteins involved in oxidative stress defense and cell wall biogenesis, indicating that the injury incurred by tannic acid was based on oxidative damage and disruption of the cell envelope. The induction of 3-octaprenyl-4-hydroxybenzoate carboxy-lyase, which is sensitive to changes in redox conditions and involved in ubiquinone biosynthesis in other bacteria, suggests for a tannic acid-induced redox imbalance. Conclusion: The results reveal the adaptation of a gastrointestinal isolate of L. plantarum to tannic acid and identify antibacterial targets for this dietary compound. This provides the basis for the selection of tannin-resistant microorganisms and their use to obtain health benefits from tannin-containing diets.