广西水牛瘤胃中的细菌多样性

Bacterial diversity in Guangxi buffalo rumen

摘要:

[目的]了解广西水牛瘤胃中细菌的组成及其可能的降解纤维素细菌的主要类群。[方法]提取水牛瘤胃内容物和高效降解滤纸的水牛瘤胃内容物的富集培养物的宏基因组DNA，以宏基因组DNA为模板，扩增16S rRNA基因序列，构建该两种样品的细菌的16S rRNA基因文库。通过对16S rRNA基因序列的分析，了解这两种样品的细菌群体种类及数量。 [结果] 水牛瘤胃内容物与其富集培养物中均主要含有LGCGPB (low G+C Gram-Positive Bacteria)、CFB (Cytophaga-Flexibacter-Bacteroides)两大类菌群和少数的螺旋体菌（Spirochaetes），且LGCGPB所占的比例都是最高的，LGCGPB在水牛瘤胃内容物细菌中的比例为56.66%，而在富集培养物细菌中的比例升高为73.33%。在水牛瘤胃内容物中，丝状杆菌（Fibrobacteres）占3.33%，但在富集培养物中未被检测到。而在富集培养物中占13.33%的变形杆菌（Proteobacteria），在水牛瘤胃内容物中未被检测到。本研究还发现了分类地位尚未明确的一菌群（R46）。[结论]细菌类群LGCGPB、Proteobacteria可能在水牛瘤胃中的纤维素降解过程中起重要作用。此外，水牛瘤胃中的细菌组成和牦牛、牛、羊瘤胃中的细菌组成较相似但比例有所不同。

Abstract:

[Objective] To analyze the diversity of bacterial community in Guangxi buffalo rumen and to identify the possible cellulolytic bacterial group. [Methods] Metagenomic DNAs were isolated directly from a buffalo rumen and its enriched culture, and were used as PCR templates to amplify 16S rRNA genes. Two libraries carrying 16S rRNA genes of bacteria in the two samples were constructed. The bacterial community composition was revealed by the constructed phylogenetic tree of known sequences and the sequences randomly selected from the libraries. [Results] We found that both samples contained low G+C Gram-positive bacteria (LGCGPB) and Cytophaga-Flexibacter-Bacteroides (CFB) phyla as the majorities, and Spirochaetes as the minorities. LGCGPB accounts for 56.66% and 73.33% of the bacterial communities in buffalo rumen and its enriched culture. We detected Fibrobacteres in the rumen sample (3.33%) but not in the enriched sample. Furthermore, we found Proteobacteria as a major component in the enrichment (13.33%) but not in the rumen sample. Clone R46 was not clustered into any known phyla and might belong to a novel taxonomic group. [Conclusion] The LGCGPB and Proteobacteria may play important roles in the hydrolysis of cellulose in buffalo rumen. The bacterial composition in the rumen of buffalo is quite similar to those in the rumen of yak, cattle and sheep.