纤维素降解复合菌系的微生物多样性及关键功能菌解析

Microbial diversity analysis of a cellulolytic microbial consortium and the key functional bacteria

为分析纤维素降解复合菌系中微生物多样性及关键功能菌,本研究通过梯度稀释法观察不同梯度下滤纸降解及酶活变化情况,确定复合菌系实现滤纸有效降解的临界点为10-5;在此基础上结合高通量测序技术对不同稀释度下的稀释液进行测序.研究结果表明,具有降解能力的稀释液(稀释度≤10-5)与无降解能力的稀释液(稀释度>10-5)微生物组成差异显著.从门水平热图看,Firmicutes和Proteobacteria为复合菌系的优势菌门;在属水平上,复合菌系中协同降解纤维素的菌株主要属于Clostridium、Petrobacter、Defluviitalea等属,Clostridium属在有降解能力(稀释度≤10-5)的稀释液中丰度较高,而随着稀释度的增大,在无降解能力(稀释度>10-5)的稀释液中几乎消失.经分析判断梭菌属Clostridium是纤维素降解复合菌系的关键功能属,它们与Petrobacter、Defluviitalea等菌属协同作用从而实现纤维素的高效降解.

In order to analyze the microbial diversity and key functional bacteria in a cellulolytic microbial consortium,a dilution-to-extinction method was used to investigate the degradation of filter paper and enzyme activities under different dilution gradients. It was found that 10-5 is the critical dilution point of the cellulolytic microbial consortium for effective filter-paper degradation. Samples with different dilutions were further sequenced with high-throughput sequencing technology. Diversity analysis results show the microbial diversity of the samples with degradation capability（ dilution gradient ≤10-5） and non-degradable samples（ dilution gradient 〉10-5） are significantly different. Firmicutes and Proteobacteria are found as the dominant bacteria of all samples at phylum level; and the bacteria can synergically degrade cellulose mainly belong to Clostridium,Petrobacter and Defluviitalea et al in the microbial consortium. The abundance of Clostridium sp. was higher in the samples with degradation ability（ dilution gradient ≤10-5）,but no detected in non-degradable samples（ dilution gradient 〉10-5）. Thus,Clostridium sp. was regarded as the key functional strains in the cellulose-degrading microbial consortium,and these strains can effectively degrade cellulose with the cooperation Petrobacter and Defluviitalea sp. etc.