Dynamic transition of a methanogenic population in response to the concentration of volatile fatty acids in a thermophilic anaerobic digester
Dynamic transition of a methanogenic population in response to the concentration of volatile fatty acids in a thermophilic anaerobic digester
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DOI：
10.1128/aem.72.2.1623-1630.2006
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发表时间：
2006-02-01
影响因子：
4.4
通讯作者：
Igarashi, Y
中科院分区：
文献类型：
--
作者：
Hori, T;Haruta, S;Igarashi, Y
采用基于16S rRNA基因的PCR介导单链构象多态性（SSCP）、定量PCR和荧光原位杂交（FISH）技术，研究了酸化和中和分别诱导的高温产甲烷生物反应器中微生物群落退化和稳定条件下的群落演替。SSCP分析表明，古菌群落结构与挥发性脂肪酸（VFA）浓度密切相关，而细菌种群数量受pH值的影响。古菌群落主要由两种氢营养型产甲烷菌（即，和甲烷热杆菌属）和一种乙酸杆菌产甲烷菌（即，a甲烷八叠球菌属）。从每一个产甲烷菌的16S rRNA基因的定量PCR显示，在稳定的条件下，在VFA的情况下，在操作过程中的产甲烷菌中占主导地位的Methanoculleus sp。VFA的积累诱导氢营养型产甲烷菌的动态转变，特别是急剧变化（即，约10，000倍增加）。响应于VFA浓度，一种氢营养型产甲烷菌的优势被另一种氢营养型产甲烷菌的优势所取代，表明溶解氢浓度在优势中起决定性作用。氢营养型产甲烷菌以聚集体的形式存在于细菌附近，通过FISH分析也观察到了伴生细菌的转变。甲烷八叠球菌选择性增殖的同时降解了在恶劣条件下运行过程中积累的乙酸盐，表明乙酸杆菌产甲烷菌有效降解乙酸盐。高温厌氧消化池中的简单产甲烷菌群对环境条件，特别是挥发性脂肪酸的浓度有显著的响应。
In this study, the microbial community succession in a thermophilic methanogenic bioreactor under deteriorative and stable conditions that were induced by acidification and neutralization, respectively, was investigated using PCR-mediated single-strand conformation polymorphism (SSCP) based on the 16S rRNA gene, quantitative PCR, and fluorescence in situ hybridization (FISH). The SSCP analysis indicated that the archaeal community structure was closely correlated with the volatile fatty acid (VFA) concentration, while the bacterial population was impacted by pH. The archaeal community consisted mainly of two species of hydrogenotrophic methanogen (i.e., a Methanoculleus sp. and a Methanothermobacter sp.) and one species of aceticlastic methanogen (i.e., a Methanosarcina sp.). The quantitative PCR of the 16S rRNA gene from each methanogen revealed that the Methanoculleus sp. predominated among the methanogens during operation under stable conditions in the absence of VFAs. Accumulation of VFAs induced a dynamic transition of hydrogenotrophic methanogens, and in particular, a drastic change (i.e., an approximately 10,000-fold increase) in the amount of the 16S rRNA gene from the Methanothermobacter sp. The predominance of the one species of hydrogenotrophic methanogen was replaced by that of the other in response to the VFA concentration, suggesting that the dissolved hydrogen concentration played a decisive role in the predominance. The hydrogenotrophic methanogens existed close to bacteria in aggregates, and a transition of the associated bacteria was also observed by FISH analyses. The degradation of acetate accumulated during operation under deteriorative conditions was concomitant with the selective proliferation of the Methanosarcina sp., indicating effective acetate degradation by the aceticlastic methanogen. The simple methanogenic population in the thermophilic anaerobic digester significantly responded to the environmental conditions, especially to the concentration of VFAs.