College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Environ Microbiol Rep. 2009 Oct;1(5):362-9. doi: 10.1111/j.1758-2229.2009.00065.x. Epub 2009 Aug 13.
Addition of nitrate strongly inhibits CH4 production from anoxic soil. The main mechanisms were considered to be the substrate competition and the toxic effect of denitrification intermediates on the methanogenesis. However, it is unclear whether these inhibitory effects are reflected in the structure and dynamics of methanogenic community in the soil. In the present study, the response of methanogenic archaeal community to nitrate addition was determined using terminal restriction fragment length polymorphisms in combination with cloning and sequencing of archaeal 16S rRNA genes. When nitrate was added at the beginning of an anoxic incubation of rice field soil, denitrification occurred rapidly and the denitrification intermediates were detected only for a short time. Total production of CH4 was reduced, but no obvious effect on the structure of methanogenic community was observed. In contrast, when nitrate was added 20 days after the anoxic incubation, the denitrification intermediates obviously accumulated. CH4 production was completely suppressed for 7 and 16 days from treatments of 5 and 10 mM nitrate respectively. The dynamics of methanogenic community also diverged greatly from the control. While the hydrogenotrophic methanogens increased and the acetoclastic methanogens decreased with the incubation in the control soil, the structure and abundance of the methanogenic community remained unchanged after the addition of nitrate. Methanogenesis resumed when the denitrification intermediates were depleted in soil. The analysis of carbon isotopic signals revealed that hydrogenotrophic methanogenesis recovered faster than acetoclastic methanogenesis. Our study suggests that the accumulation of denitrification intermediates has a strong inhibitory effect on the activity but not the structure of methanogenic community.
添加硝酸盐强烈抑制缺氧土壤中的 CH4 生成。主要机制被认为是底物竞争和反硝化中间产物对产甲烷作用的毒性作用。然而，这些抑制作用是否反映在土壤中产甲烷微生物群落的结构和动态中尚不清楚。在本研究中，通过末端限制性片段长度多态性（T-RFLP）结合克隆和测序古菌 16S rRNA 基因，确定了硝酸盐添加对产甲烷古菌群落的响应。当硝酸盐在缺氧培养稻田土壤的开始时添加时，反硝化作用迅速发生，仅短时间检测到反硝化中间产物。总 CH4 产量减少，但未观察到产甲烷群落结构的明显变化。相比之下，当硝酸盐在缺氧培养 20 天后添加时，反硝化中间产物明显积累。分别添加 5 和 10 mM 硝酸盐处理时，CH4 生成分别完全抑制了 7 和 16 天。产甲烷微生物群落的动态也与对照有很大差异。在对照土壤中，随着培养时间的增加，氢营养型产甲烷菌增加，乙酸营养型产甲烷菌减少，而添加硝酸盐后，产甲烷微生物群落的结构和丰度保持不变。当土壤中反硝化中间产物耗尽时，甲烷生成恢复。碳同位素信号的分析表明，氢营养型产甲烷作用比乙酸营养型产甲烷作用恢复得更快。我们的研究表明，反硝化中间产物的积累对产甲烷微生物群落的活性有很强的抑制作用，但对其结构没有影响。
