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.