不同C/N值下亚硝酸盐氧化菌和异养菌混合体系的微生物多样性

采用PCR-RFLP技术研究了不同C/N比下亚硝酸盐氧化菌及异养菌混合体系的微牛物多样性,并探讨了微生物菌群结构与其功能(硝化件能)的关系.C/N=0时,混合体系主要由自养菌和寡营养菌(85.1%)组成,包括亚硝酸盐氧化菌(NOB)、拟杆菌门、α-变形菌纲、浮霉菌门和绿色非硫细菌中的一些菌株.C/N=0.44时,混合体系中的自养菌减少,异养菌(主要是γ-变形菌纲的成员)大量出现.C/N=8.82时,γ-变形菌纲的菌株尤其是反硝化菌Pseudomonas sp.占主导(93.8%),与此同时,随着C/N升高,该混合体系的硝化性能也由专一的亚硝酸盐氧化过程转变为同时硝化反硝化过程.微生物菌群结构的转变较好地解释了其硝化性能的改变.本研究揭示了微生物菌群结构与其功能的内在联系,同时表明PCR-RFLP技术与化学分析相结合是研究微生物菌群结构与功能的有力工具.图3表2参13

Microbial Diversity of Nitrite-oxidizing and Heterotrophic Bacterial Communities under Different C/N Ratios

The microbial diversity of nitrite-oxidizing and heterotrophic bacterial communities at three C/N ratios of feed solutions was experimentally investigated using PCR- restriction fragment length polymorphism (RFLP) technique and correlated with nitrification performances of the mixture. At C/N = 0, the dominant populations were mainly autotrophic and oligotrophic bacteria (85.1%), including nitrite-oxidizing bacteria (NOB), and some strains of Bacteroidetes, Alphaproteobacteria, Actinobacteria, and green nonsulfur bacteria. At C/N = 0.44, autotrophic bacteria reduced, while heterotrophic bacteria (members of Gammaproteobacteria) increased. At C/N =8.82, members of Gammaproteobacteria dominated (93.8%), especially denitrifiers, i.e., Pseudomonas sp. And on the other side, a striking shift of nitrification performance occurred from a normal nitrite oxidation process to a simultaneous nitrification and denitrification process along with increasing C/N. The nitrification performances at the three C/N ratios could be well explained by the obtained microbial diversities. This study demonstrated the linkage between the functional performance (nitrification performance) and the microbial diversity, suggesting that PCR- RFLP technique together with functional parameter analysis has potential as a tool for relating functional variety to bacterial community shifts. Fig 3, Tab 2, Ref 13