K-060. Isolation of Novel (+)-Catechin Degrading Bacterium, Burkholderia sp. KTC-1, from Tropical Peat and Detection of Taxifolin as Intermediate of (+)-Catechin Metabolism

Y. Otsuka¹, M. Matsuda², M. Nakamura¹, S. Jin³, J. Wasaki³, J. Watanabe³, T. Watanabe², M. Osaki²;
¹Forestry and Forest Products Res. Inst., Tsukuba, JAPAN, ²Graduate Sch. of Agriculture, Hokkaido Univ., Sapporo, JAPAN, ³Creative Res. Inst., Sapporo, JAPAN.

Peat contains various persistent compounds derived from plant materials. We isolated a novel (+)-catechin degrading bacterium, Burkholderia sp. KTC-1 (KTC-1) as an example of a bacterium capable of degrading persistent aromatic compounds in tropical peat. This bacterium was isolated by enrichment technique and grew on (+)-catechin as sole carbon source under acidic condition. Crude enzyme reaction and structural study of its product showed that (+)-catechin is biotransformed into taxifolin during the preliminary stages of its metabolism by KTC-1. HPLC analysis indicated that a crude enzyme isolated from the bacterium transformed (+)-catechin into taxifolin in two oxidation steps: 4-hydroxylation and dehydrogenation. In addition, both catechin 4-hydroxylanase and leucocyanidin 4-dehydrogenase were localized in cytosol. Moreover, these enzymes require the 2R-flavan 3-ol structure and do not require the conformation of C-3 for C-4 oxidation. This is a first report on biotransformation of (+)-catechin into taxifolin via lucocyanidin by aerobic bacterium. This report suggests that tropical peat can become unique resource of natural aromatic compound degrading microorganisms.