Contribution of a tannase from Atopobium parvulum DSM 20469T in the oral processing of food tannins

During oral passage, food tannins interact with the microbiota present in the oral cavity. Atopobium parvulum strains are inhabitants of the human oral cavity. A gene encoding a protein similar to bacterial tannases is present in A. parvulum strains. The tanAAp (apar_1020) gene was cloned and expressed in Escherichia coli BL21 (DE3). The overproduced TanAAp protein was purified to homogeneity. It exhibited optimal activity at pH 6.0 and broad temperature range, being these properties compatible with its action during food oral processing. However, purified TanAAp protein presented the lowest specific activity among bacterial tannases (3.5 U/mg) and was unable to hydrolyze complex tannin, such as tannic acid. These biochemical properties discard a main role of TanAAp in the breakdown of complex food tannins during oral processing.