微氧折流反应器启动过程产甲烷菌群落结构变化特征

Structure characteristics of methanogenic community produced during the startup of microaerobic baffled reactor

采用实时荧光定量PCR和构建克隆文库的方法,对微氧折流反应器启动过程中产甲烷菌群落结构进行分析,以期了解反应器去除污染物机理.结果表明:随着反应器的运行,产甲烷菌丰度整体呈现增加趋势,化学需氧量(COD)去除率由启动初期的30%左右逐渐上升到75%左右,出水pH也从初期的弱酸性到后期稳定在7.3左右.其中,微氧曝气的1#格室产甲烷菌基因丰度先由第一阶段的1 580 copies ng-1(S1A)下降到第二阶段的1 355 copies ng-1(S2A),最后稳定阶段又升高到2 864 copies ng-1(S3A).2#格室的产甲烷菌基因丰度表现出与1#格室类似的趋势,但是相比1#格室变化幅度小,3个阶段的产甲烷基因丰度依次分别为2 024 copies ng-1(S1B)、1 970 copies ng-1(S2B)、2 282 copies ng-1(S3B).处于厌氧状态的3#格室的产甲烷菌基因丰度随着反应器的运行逐步上升,稳定后达到最大,为3 508 copies ng-1(S3C).1#格室中,产甲烷优势菌由第一阶段的Methanobacteriales目(占所得产甲烷菌序列群50%)变为第三阶段的Methanomicrobiales目(80%).2#格室中没有明显的优势产甲烷菌,群落结构相对稳定,隶属于Methanomicrobiales目的产甲烷菌序列比例在3个阶段分别为36.4%、36.4%和30%.3#格室稳定运行后有60%的产甲烷菌序列群属于Methanosarcinales目,成为优势菌.在反应器运行的不同阶段,2#格室的生物多样性均高于1#格室,3#格室的多样性在前两个阶段没有变化,而在第三阶段升高.因此,在启动过程中,微氧折流反应器不同格室产甲烷菌的基因丰度、群落结构和生物多样性表现出不同的变化特征.

The community structure of methanogens produced during operation of a microaerobic baffled reactor was analyzed by real-time quantitative PCR and clone library, with an aim to provide a reference basis for the research of the mechanism of pollutants removal. The results showed that the abundance of methanogens in the microaerobic baffled reactor increased generally. With the running of the reactor the removal rate of COD raised from about 30% to about 75%; and the effluent pH changed from weakly acid in the beginning to about 7.3. The abundance of methanogenic MCR gene of the cell 1# treated by micro-oxygen aeration decreased from 1 580 copies ng-1 （S1A） to 1 355 copies ng-1 （S2A） and then raised to 2 864 copies ng-1 （S3A）. The abundance of methanogenic MCR gene of the cell 2# showed similar trend with that of the cell 1#, with smaller variation from 2 024 copies ng-1 （S1B） to 1 970 copies ng-1 （S2B）, then to 2 282 copies ng-1 （S3B） respectively. The abundance of methanogenic MCR gene of the cell 3# maintained in anaerobic state increased gradually to 3 508 copies ng-1 （S3C） in the stable operational stage. The domination of methanogen in the cell 1# （50% of the sequences） was affiliated with the family of Methanobacteriales in the first stage. But the dominant methanogen turned into the family of Methanomicrobiales （80%） in the steady operation. There was no obvious dominant methanogen in the cell 2#, in which the community structure was relatively stable, and the methanogenic sequences affiliated with the family of Methanomicrobiales was 36.4%, 36.4% and 30% respectively in the three different stages. Methanosarcinales were the dominant methanogen （60% in the steady operation） in the cell 3#. At different stages of operation, the biodiversity was higher in the cell 2# than in cell 1#. The biodiversity of the cell 3# raised in the third stage but did not change abviously in the first two.