Biochemical characterization of three tannases from Clostridium butyricum

Conference poster, 2021

Bark is the outer tissue of the tree, shielding the wood from microbial attack. The compounds present in bark which gives the bark this ability to hamper microbial attack are the secondary metabolites called extractives, such as tannins. Biochemical degradation of tannins is known to be conducted by tannase enzymes (EC 3.1.1.20), which are serine-esterases able to separate gallic acid from the aromatic-sugar complexes. In this study we investigated three tannases from the bacterium Clostridium butyricum, named CbTan1-3, both on model substrates but also on oak bark extract. The enzymes were tested on a range of galloyl ester model substrates and display different substrate preferences, with CbTan1-3 preferring galloyl moiety linked to glucose and CbTan2 not displaying preference towards any model substrate tested in this study. On oak bark extract, the three enzymes act on different molecules, with CbTan2 degrading all identified substrates and CbTan3 and CbTan1 able to degrade similar substrates, however, CbTan3 was also able to liberate additional glucose from the oak bark extract.