驯化对餐厨垃圾厌氧消化系统微生物群落结构的影响

为研究驯化对餐厨垃圾厌氧消化系统微生物群落结构的影响,在单相完全搅拌式(CSTR)反应器内,以农村户用沼气池污泥为接种污泥,进行了餐厨垃圾中温厌氧消化.反应器在3 g·L-1·d-1(以VS计)的负荷下成功启动,并连续45 d维持性能稳定,表明驯化成功.期间采用454焦磷酸测序技术分析了驯化前后系统内的微生物群落结构.结果表明,微生物群落结构与底物密切相关,驯化后细菌及古菌群落都发生明显变化.从细菌群落看,与复杂有机物降解相关的菌类显著下降(如梭菌纲(Clostridia)和(vadin HA17),而易降解碳水化合物发酵菌(如Petrimonas)和脂肪降解菌(如Erysipelotrichia)显著增加.这与餐厨垃圾易降解有机物含量高,且富含淀粉和脂肪相关.丰富的易降解有机物还使得反应器内总挥发性脂肪酸(VFA)浓度((2203±174)mg·L-1)远高于种泥水平((222.0±0.3)mg·L-1),这导致了产甲烷菌由乙酸型的甲烷鬃菌属(Methanosaeta,占85.01%)绝对主导转向氢营养型的甲烷螺菌属(Methanospirillum,占35.35%)、甲烷囊菌属(Methanoculleus,占9.89%)与之(46.97%)共同主导的局面.然而,驯化后Methanosaeta在非最优条件下依然保持主导地位,可见接种污泥的群落组成对厌氧消化系统群落结构的塑造也具有重大影响.

Influence of inoculum acclimation on microbial community structure in anaerobic digesters treating food waste

To investigate the influence of inoculum acclimation on microbial community structure during the mesophilic anaerobic digestion of food waste (FW), a continuous stirred tank reactor (CSTR) was set up to treat FW with inoculum collected from a household biogas digester. Initially, the reactor was started up at an organic loading rate (OLR) of 3 g·L^-1·d^-1, and the reactor performance (i.e., methane production) maintained stable for 45 d, which suggests that the microbial community in the reactor was established well for effective conversion of FW to biogas. The results on microbial community structure obtained by using 454 pyrosequence approach show that the microbial community structure was closely related to the composition and quantity of substrate. Both bacterial and archaeal communities had significantly transited after the acclimation of feeding FW rich in readily degradable organics such as starches and fats. The quantity of bacteria associated with complex organic matter degradation, such as Clostridia and vadin HA17, decreased significantly, while the quantity of bacteria for degradation of carbohydrates and fats remarkably increased. The readily degradable organic compounds in FW contributed to the elevated volatile fatty acids (VFAs) from (222.0±0.3) mg·L^-1 to (2203±174)mg·L^-1 and resulted in the shift of the dominant methanogen structure. The acetate-utilization methanogen Methanosaeta (85.01%) dominanted in the initial inoculum, while after acclimation, it decreased to 46.97% along with hydrogen-utilization methanogens, Methanospirillum and Methanoculleus, reached to 35.35% and 9.89%, respectively. Nevertheless, Methanosaeta remained dominant even when the system was not operated under optimum conditions, which suggests that the microbial community composition of inoculum had significant influence on the community structure in anaerobic digesters treating FW.