猪粪厌氧发酵消化液回流体系微生物群落结构特征与产气关系研究

为明确厌氧发酵消化液回流体系中微生物群落结构的特征,采用Miseq高通量测序技术,研究回流过程中微生物的多样性和群落结构变化,并分析其与产气性能的关系。结果表明:消化液回流体系中,细菌的丰富度、多样性均高于产甲烷古菌,并随回流时间的延长明显增加,而产甲烷古菌无明显变化;细菌群落主要分为厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)和变形菌门(Proteobacteria)等8个不同的门类,厚壁菌门、梭菌纲(Clostridia)、梭菌属(Clostridium)是不同水平上的优势细菌,相对丰度分别从初期的62.79%、58.62%、35.44%上升到81.46%、68.19%、39.10%;产甲烷古菌中,广古菌门(Euryarchaeota)占绝对优势,在接种物中,第68 d和第219 d相对丰度分别为94.76%、99.89%、99.59%,属分类上主要有7种,其中甲烷八叠球菌属(Methanosarcina)的相对丰度由23.99%升高到72.28%,而甲烷短杆菌属(Methanobrevibacter)和甲烷球菌属(Methanosphaera)分别由16.34%、21.71%降低至3.70%、12.93%;日平均产气率由初期的409 m L·g~(-1)升高至477 m L·g~(-1),在219 d的试验中,氨氮和有机酸浓度均呈升高趋势,但并未对厌氧发酵产生抑制作用。研究表明:厌氧发酵回流体系中微生物以梭菌属和甲烷八叠球菌属为优势菌属,产气率随其相对丰度的增大而升高,而与甲烷短杆菌属和甲烷球菌属呈负相关。

Study of microbial community and biogas production in anaerobic digestion of pig manure with digested slurry recirculation

In order to investigate the characteristics of microbial community and its relationship with biogas production in an anaerobic digestion reactor with digested slurry recirculation, a continuous stirred-tank reactor(CSTR) was operated and the microbial community was analyzed by Miseq high-throughput sequencing. Results indicated that the richness and diversity of bacteria were higher than that of archaea, and they increased in bacteria, but no obvious difference could be observed in archaea, even by prolonging the experiment time. The bacterial structures consisted of eight categories, such as Firmicutes, Bacteroidetes, and Proteobacteria at phylum level. Firmicute was the most prevalent in the reactor; its relative abundance increased from 62.79% to 81.46%. The main class and genus were Clostridia and Clostridium, whose relative abundance changed from 58.62% and 35.44% to 68.19% and 39.10%, respectively. For archaeal communities, Euryarchaeota showed an absolute predominance, accounting for 94.76%, 99.89%, and 99.59% at inoculation, 68 d, and 219 d, respectively. This phylum included seven genera, of which the relative abundance of Methanosarcina increased from 23.99% to 72.28%, but that of Methanobrevibacter and Methanosphaera decreased from 16.34% and 21.71% to 3.70% and 12.93%, respectively. Specific methane yield increased from 409 mL·g^-1 to 477 mL·g^-1. The concentration of ammonia and VFA increased gradually, and the biogas yield was maintained at a relatively high level without any inhibition. The results indicated that Clostridium and Methanosarcina were the dominant genera in the reactor, and the relative abundance increased with an increase in recirculation time. The specific methane yield showed positive correlations with the relative abundance of Clostridium and Methanosarcina, whereas it showed negative correlations with Methanobrevibacter and Methanosphaera.