[目的]研究腹泻犊牛直肠细菌多样性,以及与健康犊牛直肠细菌多样性的差异.[方法]通过建立直肠菌群16S rRNA基因克隆文库,分别用限制性内切酶Msp Ⅰ和HhaⅠ对阳性克隆的PCR产物进行限制性酶切片段长度多态性(RFLP)分析,通过测定16S rRNA基因序列,绘制系统发育树,确定犊牛直肠菌群的组成.[结果]腹泻组克隆阳性率达98.75％ (474/480),优势菌群以乳杆菌属(14％)、肠球菌属(10％)和埃希菌属(8％)等需氧和兼性厌氧菌为主,健康组克隆阳性率达96.45％(488/506),优势菌群以梭菌属(13％)、双歧杆菌属(8％)和巨型球菌属(5％)等专性厌氧菌为主.[结论]2周龄犊牛直肠菌群复杂多样,并且具有自己的独特性菌群,且腹泻时乳杆菌属、肠球菌属、埃希氏菌属等显著增加.%[ Objective ] To analyze the diversity of bacterial community in rectum of diarrheic calves, and differences with health calves. [Methods] 16S rRNA clone libraries were constructed, positive clones were digested by Msp I and Hha I for restriction fragment length polymorphism (RFLP) , and then a phylogenetic tree was depicted based on the 16S rRNA sequencing, to confirm the compose of microbe in the diarrheic calf rectum. [ Results] The positive rate of clone was 98. 75% (474/480) in diarrheic calves, the dominant bacteria included Laetobacillus ( 14% ) , Enterocoeeus ( 10% ) and Escherichia (8% ) . The positive rate of clone was 96. 45% (488/506) in health samples, the dominant bacteria included Clostridium (13% ) , Bifidobacterium (8% ) , Megasphaera (5% ). [Conclusion] Complexity and diversity of bacterial community in rectum in 2 weeks old calves had their own features, and significant increase of Laetobacillus, Enterocoeeus and Escherichia was found in diarrhea calves.
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