The Screening Of Intestinal Anaerobic Tannin Degrading Bac-teria And The Characterization Of Their Enzymes In Mammals Inhabiting In Alpine Meadow Ecosystem

Qinghai-Tibet plateau is the highest plateau in the world. The plants there exposed to special environment such as hypoxia, low temperature, and intense ultraviolet, etc. during all of their lifespan. Most of them have large amount of secondary compounds, including tannins. Tannins are polyphenolic secondary compounds having wide prevalence in plants. The presence of a large number of phenolic hydroxyl groups enables them to form large complexes with dietary proteins. These compounds are difficult to be degraded in the mammal’s digestive tract. It will affect food digestion and the utilization of food proteins. Some microbes inhabiting in animals digestive tract are, however, resistant to tannins, and have developed various mechanisms and pathways for tannin degradation in their natural milieu. It makes dietary protein to be absorbed by animals, thereby improving the utilization of forage.Plateau pika (Ochotona Curzoniae), root vole (Microtus Oeconomus) and zokor (Eospalax Baile) are native of Qinghai-Tibetan plateau. In order to explore their utilization mechanism of tannins, we isolated and identified their intestinal anaerobic tannin degrading bacteria, studied the enzymatic characterization of tannase and cellulase in different bacteria and assayed the tannin acid degrading ability of bacteria in feces of zokors in different months. The results were as follows.The amplification and blast of the sequences of16S rDNA in the bacteria suggested that there were different tannin degrading bacteria in caecum of these mammals. They were Enterobacter kobei, Klebsiella oxytoca, Klebsiella sp.,Shigella sp., Shigella dysenteriae, Shigella flexneri,Staphylococcus haemolyticus in pikas; Enterobacter sp., Pantoea sp., Gamma proteobacterium, Enterobacter cloacae, Shigella dysenteriae, Staphylococcus haemolyticus, Bacillus pumilus in voles and Enterococcus gallinarum, Bacillus pumilus, Bacillus cereus, Bacillus licheniformis in zokor, respectively.It seemed that except bacillus licheniformis in zokors, which had higher tannase activity, there were no differences of the enzymatic activity among all of the other bacteria. All of the tannase had good stability in the range of25-75℃. At50℃, all strains retained more than90%catalytic activity. In addition, the maximum tannase activity was achieved at pH6.0.Furthermore, all of the strains had cellulase activity. Except of Bacillus licheniformis, the optimum temperatures for the cellulase of the other strains were lower than60℃. The cellulose of all strains had more than80%enzyme activity at30-40℃and they also had stability at pH6-7.In the fields, the tannin acid degrading ability of the intestinal bacteria in zokors was on the rise from May to August.So, it could be concluded that all of pikas, voles and zokors could decompose the unabsorbed tannins by the intestinal bacteria. But three Tibetan animals, which lived in different habitats, had different types of tannin-degrading anaerobic bacteria within the caecum.