产氢细菌FSC-15对稻草秸秆厌氧发酵产甲烷的影响

Effect of the hydrogen-producing bacterium FSC-15 on methanogenesis during rice straw anaerobic fermentation

产氢细菌是厌氧发酵过程中重要的功能微生物.将分离自纤维素降解产甲烷复合菌系FSC的产氢细菌FSC-15回补至复合菌系,通过监测氢气产量、甲烷产量、脂肪酸浓度及秸秆降解效率,探究产氢细菌对水稻秸秆水解产甲烷代谢及微生物群落结构的影响.结果显示:添加菌株FSC-15使FSC中纤维素、半纤维素和木质素降解率分别提高了17.33%、28.61%和47.21%,对复合菌系FSC中秸秆降解效率有一定促进作用.培养第3天,氢气产量相比复合菌系FSC提高了41.18%,为产甲烷菌提供更充足的底物,使甲烷产量提高1倍.高通量测序结果显示,Ruminococcaceae和Methanobacteriaceae分别是水稻秸秆厌氧发酵产甲烷体系中水解纤维素和产甲烷的主要类群,Methanobacteriaceae是厌氧发酵体系挥发酸含量较高时产甲烷的主要物种,补加产氢细菌FSC-15对厌氧降解纤维素产甲烷菌系中的细菌群落结构无明显影响,但可以改变古菌的物种多样性及丰度.本研究证明向水稻秸秆厌氧发酵体系补加功能微生物能有效提高体系甲烷产量,可为调控水稻秸秆厌氧消化技术提供理论支撑.

Hydrogen-producing bacteria play an important role in the anaerobic fermentation process. In this study, the hydrogen-producing bacterium FSC-15 was added back to a cellulose-degrading methanogenic community （FSC） from which it was isolated, to explore the effect of hydrogen-producing bacteria on the methanogenesis and microbial community structure in rice straw degradation. We determined the composition of the rice straw before and after degradation by the Van Soest method, and calculated the degradation rates. We monitored the hydrogen yield and methane yield by gas chromatography. We measured organic acid metabolism by liquid chromatography. We monitored the composition changes of microbiota in straw degradation by 16S rDNA sequence analysis. FSC-15 increased the degradation rates of cellulose, hemicellulose, and lignin by 17.33%, 28.61%, and 47.21%, respectively. Therefore, FSC-15 promoted the straw degradation rates of FSC, and accelerated organic matter hydrolysis and hydrogen production in the initial stage. On the 3rd day, the hydrogen yield increased by 41.18% compared with FSC, which could provide an adequate substrate for methanogens and enhance the rate of straw anaerobic digestion and methanogenesis, and the methane yield doubled. The result of high-throughput sequencing showed that Ruminococcaceae and Methanobacteriaceae dominated in the FSC community, which functions in cellulose degradation and methanogenesis, respectively. Furthermore, Methanobacteriaceae prevailed in the high-acid condition. FSC-15 had no obvious effect on the microbial community structure of bacteria in the composite system, but could influence the abundance and variety of Archaea. FSC-15 was expected to boost the rate and yield of methane in the anaerobic digester and it also had an effect on the microbial community structure of Archaea. These results showed that the yield of methane was effectively improved by adding functional microorganisms to the rice straw anaerobic fermentation system, providing theoretical support for the technology of rice straw anaerobic digestion.