家蚕肠道细菌群体调查与分析

Investigation and analysis of the bacteria community in silkworm intestine

目前,环境微生物中绝大部分是无法获得纯培养的。为了比较全面地了解家蚕肠道的细菌群体结构,研究采用了非培养法和传统培养法相结合的方法进行调查分析。非培养法是先直接提取家蚕肠道中的微生物群体基因组DNA,用PCR法扩增细菌16S rRNA基因,建立16S rDNA文库;再以限制性片段长度多态性(RFLP)方法从文库中筛选可能不同细菌来源的克隆,并测定其核苷酸序列。将所获得的序列与GenBank数据库进行BLAST比对分析,并通过系统发育分析,推测它们可能代表的细菌种属,以及对家蚕生长发育所起的作用。结果表明,家蚕肠道中的细菌主要是节杆菌属、乳杆菌属、大肠杆菌属、芽胞杆菌属、葡萄球菌属、假单胞菌属。它们在家蚕消化利用桑叶和疾病预防中可能有着重要意义。非培养法和培养法均有各自的长处和不足,两者具有较强的互补性。

Majority of the environmental microorganisms are still unculturable. To shed a light on the bacteria community in the silkworm intestine more completely, culture-dependent and culture-independent methods were used to perform the investigation. As the latter, 16s rRNA gene was amplified and a library was constructed by using the meta-genomic DNA extracted from the bacteria in the silkworm intestine as template. Restriction fragment length polymorphism （RFLP） method was used to screen recombinants originated from different bacteria, and the nucleotide sequences were determined. A BLAST searching in the GenBank and an analysis on phylogenesis were performed. The taxonomy of these bacteria and their physiological function to silkworm were speculated. Results showed that the bacteria in silkworm intestine are mainly belong to the genera Arthrobacter, Lactobacillus, Pseudomonas, Escherichia, Micrococcus, Bacillus, and Staphylococcus. They may play important roles to the host silkworm in the utilization of their food mulberry and disease prevention. Both the culture-dependent and culture-independent methods have their advantages and disadvantages, and they are complemented with each other.