pH调控对瘤胃液接种稻秸厌氧消化中水解菌及产甲烷菌的影响

为了研究pH值调控对瘤胃液接种厌氧消化体系的影响,在半连续条件下考察了稻秆水解和产甲烷特性,并分别利用相对定量PCR(Q-PCR)和Mi Seq高通量测序技术分析了微生物菌群的变化。结果表明:有机负荷为1.5、3.5 g·L-1·d-1和7 g·L-1·d-1时,调控体系中甲烷产率分别比对照提高了1.98、1.99倍和1.53倍;沼气中的甲烷含量明显提高(P0.05),在24%~32%之间变动。pH调控使乙酸和丙酸之间比例逐渐增大,体系中pH值维持在6.24~7.77之间,适宜稻秸产甲烷代谢;滤纸酶和羧甲基纤维素酶活性呈增加趋势。厌氧消化后GH 5水解菌群结构变化明显,梭状芽孢杆菌属(Clostridium)占主导地位,瘤胃球菌属(Ruminococcus)相对丰度提高了12.47倍;来源于瘤胃的纤维杆菌属(Fibrobacter)从体系中消逝。甲烷短杆菌属(Methanobrevibacter)相对丰度提高到3.73%,同时甲烷八叠球菌属(Methanosarcina)相对丰度增加。研究表明,pH调控体系通过强化水解和产甲烷菌活性提高了稻秸厌氧消化的效率。

The effect of pH adjustment on hydrolytic bacteria and methanogens during rumen fluid derived anaerobic digestion of rice straw

In order to evaluate the influence of pH adjustment on rumen-enhanced anaerobic digestion, this study investigates the hydrolytic and methanogenic characteristics in the semi-continuous mode. Microbial consortia were analyzed by relative quantitative PCR(Q-PCR) and MiSeq high-throughput sequencing technology. Compared with the control system, the methane yields after pH adjustment increases by 1.98-, 1.99-and 1.53-fold with three organic loading rates of 1.5, 3.5 g·L^-1·d^-1 and 7 g·L^-1·d^-1, respectively. The methane contents are significantly different from the control reactor(P<0.05), varying from 24% to 32%. Additionally, pH adjustment increases the ratios of acetate and propionate. The pH values vary from 6.24 to 7.77 in the digestion process, which are within the optimal range of methanogenesis from rice straw. Moreover, the FPase and CMCase activities show an increasing trend in the adjustment system. Microbial compositions of GH 5 hydrolytic consortia change significantly after anaerobic digestion. The relative abundances of Ruminococcus genus increase 12.47-fold compared with the ruminal inoculum, even though Clostridium was the predominant genus. The proportion of hydrogenotrophic Methanobrevibacter reaches 3.73% and the relative abundance of acetotrophic Methanosarcina also increases. Our results indicate that pH adjustment increases the efficiency of anaerobic digestion from rice straw through the enhancement of hydrolytic and methanogenic activities.