Abstract:

L-arabinose isomerase catalyzes the isomerization reaction from D-galactose to D-tagatose, and has attracted more attention due to its importance in animal nutrition and food applied research. Animal rumen is a special anaerobic environment, and ruminal microorganisms contain large amounts of novel genes that code for polysaccharide-degrading enzymes. This study primarily analyzed the genetic diversity of L-arabinose isomerase in sheep rumen bacteria. Using the metagenome of rumen content extracted 4 h after feeding as template, 61 L-arabinose isomerase gene fragments with 68%~98% identities and known sequences were obtained by PCR amplification with specific degenerate primers and restriction enzyme digest. Of them, 38 distinct sequences (<95% identity) were subjected to clustering analysis. The results showed that the L-arabinose isomerase genes from Prevotella ruminicola were found to be predominant (36/38) in sheep rumen, and those from Catonella morbid and Marinilabilia salmonicolor (2/38) were minor. This study has not only enriched the genetic resources of L-arabinose isomerase, but also determined the importance of Prevotella in sheep rumen.

Key words: rumen, D-tagatose, L-arabinose isomerase, genetic diversity

摘要：

L-阿拉伯糖异构酶可以催化醛酮糖的异构化反应，将D-半乳糖转化为D-塔格糖，从而在动物营养与食品应用研究中获得重视。动物瘤胃是一个特殊的厌氧环境，而瘤胃微生物含有大量的多糖降解酶的新颖基因。初步分析了绵羊瘤胃液中细菌来源的阿拉伯糖异构酶基因的多样性。以饲喂后4h的瘤胃液的宏基因组为模板，通过兼并PCR技术和内切酶方法获得了61条与已知序列相似性达68%~98%的阿拉伯糖异构酶基因片段，并对38条差异片断(相似性低于95%)进行聚类分析。结果表明普雷氏菌来源的L-阿拉伯糖异构酶基因在绵羊瘤胃中占有绝对优势(36/38), 而来自于Catonella morbi和Marinilabilia salmonicolor的L-阿拉伯糖异构酶基因则数量稀少(2/38)。研究结果不但丰富了L-阿拉伯糖异构酶的基因资源，并确定了普雷氏菌在绵羊瘤胃的重要性。

关键词: 瘤胃；D-塔格糖；阿拉伯糖异构酶；基因多样性