【摘要】 【目的】研究不同p H缓冲液对乙酸产甲烷过程及对细菌和古菌群落结构的影响。【方法】分别添加磷酸盐(PB)、4-羟乙基哌嗪乙磺酸(HEPES)、哌嗪-1,4-二乙磺酸(PIPES)和Na HCO3/CO2缓冲液到乙酸产甲烷菌系中,定期监测甲烷产生趋势,到稳定期后收集菌体,进行16S rRNA基因的末端限制性片段多态性分析(T-RFLP)。【结果】发现PB组的乙酸产甲烷菌系延滞期约为40d,显著高于其他组的20-24 d(P<0.05);Na HCO3/CO2组乙酸转化为甲烷的比例为(88.3±0.5)%,显著高于其他组的77%-81%(P<0.05);不同缓冲液组的最大甲烷比生长速率为0.46-0.57 d-1(P>0.05);Na HCO3/CO2组的细菌群落变化最明显,主要是未培养细菌(unclassified bacteria)、螺旋菌科细菌(Spirochaetaceae)和未培养WWE1类群的丰度较其他组分别增加到(15.5±9.4)%、(7.3±4.6)%和(17.6±6.3)%,而互养菌科(Synergistaceae)的细菌丰度降低到(8.9±8.1)%。AC+PB组中的古菌类群发生了明显变化,以竹节状甲烷鬃毛菌(Methanosaeta harundinacea)相关的产甲烷古菌占主导(97±2%),而在HEPES、PIPES和Na HCO3/CO2组和不加缓冲液组中同时存在两类乙酸营养型产甲烷古菌M.harundinacea和联合鬃毛甲烷菌(Methanosaeta concilii),以及属于甲烷杆菌目(Methanobacteriales)的氢营养型产甲烷古菌。【结论】在乙酸产甲烷菌系中加入PB增加了甲烷产生的延滞期,加入Na HCO3/CO2增加了甲烷产量,但是添加p H缓冲液不会影响到菌系的最大甲烷比生长速率。加入PB和Na HCO3/CO2都会显著改变微生物的菌群结构。这些研究为设计适宜的产甲烷菌系生长条件提供了参考。更多还原

【Abstract】 [Objective]To evaluate the effects of p H on methane production from acetate and the methanogenic community structures. [Methods] Solutions of phosphate( PB),2-hydroxyethyl( HEPES),Na HCO3/ CO2 or piperazine-1,4-bisethanesulfonic acid( PIPES) were added into the methanogenic cultures,separately. The substrate consumption was determined by monitoring cumulative methane production,the methanogenic community structuresin the stationary-phase cultures were analyzed using terminal restriction fragment length polymorphism( T-RFLP) of 16 S rRNA gene fragments.[Results]The period of lag phase of methane production in the PB addition culture( ca. 40 d) was much longer than that in other p H buffer cultures( 20- 24 d,P < 0. 05). Approximate 88. 3% of acetate was converted into methane in the Na HCO3/ CO2 addition culture,while the value decreased to 77%- 81% in other p H buffer cultures( P < 0. 05). The maximum specific methane production rate was similar between different p H buffer cultures( P > 0. 05). The relative abundance of members of unclassified bacteria,Spirochaetaceae and uncultured WWE1 increased to( 15. 5 ± 9. 4) %,( 7. 3 ± 4. 6) % and( 17. 6 ± 6. 3) %,respectively,in the Na HCO3/ CO2 addition culture,while synergistaceae decreased to( 8. 9 ± 8. 1) %. In archaeal domain,the acetotrophic methanogen related with Methanosaeta harundinacea became predominant( 97 ± 2%) in the PB buffer culture,on the contrary,the concurrence of M. harundinacea,M.concilii and hydrogenotrophic methanogen related with Methanobacteriales were detected in the cultures amended with HEPES,PIPES and Na HCO3/ CO2. [Conclusion] PB retarded the methane production in the acetatemethanogenic culture,Na HCO3/ CO2 addition improve methane production from acetate,the p H buffers had not obvious effects on the maximum specific methane production rate of the cultures,the microbial community structures obviously changed along with PB and Na HCO3/ CO2 addition. The research would help us to design suitable condition for the growth of methanogenic culture.更多还原