The Identification Of Intestinal Tannin Degrading Bacteria And The Characterization Of Their Tannase In Plateau Pikas (Ochotona Curzoniae) And Root Voles (Microtus Oeconomus)

Tannins are polyphenolic secondary compounds, which exist in many kinds of plants. 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.Plateau pika (Ochtona curzoniae) and root vole (Mictotus oeconomus) are small herbivorous mammals survive in Qinghai-Tibet plateau for many years. So they forage on plants with high second compounds. In order to explore their utilization mechanism of tannins, we isolated and identified the tannins degrading bacteria in their intestine, studied the enzymatic characterization of tannase in different bacteria and assayed the tannin acid degrading ability of these bacteria in different conditions. The results were as follows.The amplification and blast of the sequences of 16srDNA in the bacteria isolated from animal fences suggested that both of pikas and voles had at least six kinds of tannins degrading bacteria in their intestine. They were bacillus licheniformis, Acetobacterium, Sporosarcina ureae, Klebsiella pneumoniae, Shigella, Bacillaceae in pikas and Enterobacter cancerogenus, Pantone, Bacillus cereus, Pseudomonas, Bacillus thuringiensis, Klebsiella in voles, respectively.It seemed that except bacillus licheniformis in piaks, which had higher tannase activity, there were no differences of the enzymatic activity among all of the other bacteria. The change of temperature and pH had similar effect on the tannin degradation ability of all of the bacteria.In field, the tannin acid degrading ability of the intestinal bacteria varied significantly from June to September, and they had highest tannase activity in August, in both of pikas and voles.When the voles were administrated 5,10 and 20 mg·(kg·BW·d)–1 tannin acid for 5 days,continuously,their tannin degrading bacteria had higher tannase activity than the bacteria in control group. The more the dosage was,the more intensive of the change. The highest enzymatic activity appeared 3 days after administration of 5 and 10 mg·(kg·BW·d)–1 tannin acid and 2 days after 20 mg·(kg·BW·d)–1 administration, respectively. But when pikas were given same dosage of tannin acid, the tannase activity of their intestinal bacteria was inhibited significantly. In both of 5 and 10 mg·(kg·BW·d)–1 groups, activity of the bacteria tannase inhibited 4 days after administration,while in 20 mg·(kg·BW·d)–1 group,the enzymatic activity inhibited even 1 day after administration.So, it could be concluded that both of pikas and voles could decompose the unabsorbed tannins by the intestinal bacteria. And the tannase activity of these bacteria was influenced by the amount of tannins in their food.