关键词: 缩合单宁, 原花青素, 儿茶素, 肠杆菌, 生物降解

Abstract: The purpose of this study was to screen and isolate a condensed-tannin degrading bacteria, then identify the strain, and explore its degrading ability. In this study, from cattle and sheep feces, a strain of degrading bacteria which could utilize condensed tannin as a sole carbon source was obtained by gradient acclimation method. Through morphological characteristics observation, Biolog physiological, biochemical tests and 16S rRNA gene sequence analysis, strain B1 was identified as a gram-negative bacterium, which is belonging to the genus Enterobacter sp. and clustered with Enterobacter xiangfangensis 10-17T in a phylogenetic tree constructed. Comprehensive determination was detected by ultraviolet spectrophotometry and high performance liquid chromatography, the maximum OD600 value of B1 cultured for 24 hours was reached to 2.5. The degradation rate of larvae tannin by bacteria B1 was analyzed by the calculated changes in procyanidins and catechins, results showed that the degradation rate reached more than 90% at 72 hours and there was catechin generated. In addition, when explored the effects of additional nitrogen and carbon sources, the results showed that the addition of nitrogen source could slightly increase the degradation ability of bacterium B1, but the addition of carbon source would reduce the degradation rate. The results enriched the overall study of condensed tannins, enhanced the application value of condensed tannins, and further explored the mechanism of microbial degradation of condensed tannins.

Key words: condensed tannin, proanthocyanidins, (+)-catechin, enterobacter, biodegradation