非光合CO_2同化微生物菌群的选育/优化及其群落结构分析

Breeding,Optimization and Community Structure Analysis of Non-photosynthetic CO_2 Assimilation Microbial Flora

通过从海水及其沉积物中分离、筛选,并结合电子供体和无机碳源结构的优化以期获得不用光照与供氢的高效固碳微生物菌群;通过16S rDNA序列分析、比对等手段研究非光合固碳微生物菌群的结构,以期为优化群落配置,进一步提升固碳效率提供理论依据.结果显示,通过分离和长期驯化可从海洋中得到在普通好氧、厌氧条件下具有固碳能力的非光合微生物菌群.添加硫代硫酸钠、硫化钠和氢气作为电子供体可有效提升菌群的固碳效率,在以硫代硫酸钠为电子供体的好氧、厌氧条件下,该菌群的CO2同化效率分别可达10.44 mg/L和12.56 mg/L.该固碳菌群对混合无机碳源的同化效率显著高于单一碳源,在以CO2、碳酸氢钠及碳酸钠为混合碳源情况下,菌群好氧、厌氧固碳效率(以CO2计)分别可达110 mg.(L.d)-1,和72mg.(L.d)-1,接近氢氧化细菌的水平.微生物群落结构分析结果表明,添加不同电子供体后,固碳微生物菌群的优势种发生了显著变化,在发现的16个优势菌种中,11个是不可培养微生物,即其只能以共生方式存在.菌群混合培养时的固碳效率可能是多种菌共同作用的结果,因此优化固碳微生物菌群的结构和配比将有利于其固碳效率的进一步提升.

Isolation and screening from sea water and sediments, and the optimization of electron donor and inorganic carbon source structure were performed for obtaining microbial flora with high efficient inorganic carbon fixation without the light and hydrogen. In addition, the structure of the microbial flora was studied through 16S rDNA sequence analysis and contrast for providing theoretical basis to improve carbon fixation efficiency through optimizing microbial flora structure. The resuh showed that non-photosynthetic microbial flora with the capacity of inorganic carbon fixation under the general aerobic and anaerobic conditions could be obtained from the sea by long-term domestication and isolation. Inorganic carbon fixation efficiency of the microbial flora was enhanced significantly by adding of sodium thiosulfate, sodium sulfide and hydrogen as electron donor. Under the aerobic and anaerobic conditions with sodium thiosulfate as electron donor, the efficiency of inorganic carbon assimilation was 10.44 mg/L and 12.56 mg/L respectively. The assimilation efficiency of the microbial flora with mixed inorganic carbon source was higher than that with single carbon source. When C02, sodium bicarbonate and sodium carbonate were added as carbon sources, carbon fixation efficiency of the microbial flora under the aerobic and anaerobic condition was 110 mg·（L·d）^-1 and 72 mg·（L·d）^-1 respectively which had been closed to the efficiency of hydrogen-oxidizing bacteria. The analysis results showed that the predominant species of the microbial flora varied significantly after the adding of different electron donor. And 11 species of the 16 predominant species in the microbial flora was uncultured. It means that the microbial flora could only exist in symbiotic manner. The inorganic carbon fixation effect of the microbial flora may be the results of co-function of muhi-mierobial species. Therefore, the optimization of microbial flora structure and proportion is benefit for the further improvement of carbon fixation efficiency.