Tannin Degradation by a Novel Tannase Enzyme Present in Some Lactobacillus plantarum Strains

摘要

Lactobacillus plantarum is frequently isolated from the fermentation of plant material where tannins are abundant. L. plantarum strains possess tannase activity to degrade plant tannins. An L. plantarum tannase (TanB_(Lp), formerly called TanLp1) was previously identified and biochemically characterized. In this study, we report the identification and characterization of a novel tannase (TanA_(Lp)). While all 29 L. plantarum strains analyzed in the study possess the tanB_(Lp) gene, the gene tanA_(Lp) was present in only four strains. Upon methyl gallate exposure, the expression of tanB_(Lp) was induced, whereas tanA_(Lp) expression was not affected. TanA_(Lp) showed only 27% sequence identity to TanB_(Lp), but the residues involved in tannase activity are conserved. Optimum activity for TanA_(Lp) was observed at 30°C and pH 6 in the presence of Ca~(2+) ions. TanA_(Lp) was able to hydrolyze gallate and protocatechuate esters with a short aliphatic alcohol substituent. Moreover, TanA_(Lp) was able to fully hydrolyze complex gallotannins, such as tannic acid. The presence of the extracellular TanA_(Lp) tannase in some L. plantarum strains provides them an advantage for the initial degradation of complex tannins present in plant environments.