红壤稻田不同生育期土壤氨氧化微生物群落结构

以福建省红壤稻田土壤为对象,通过提取土壤总DNA,利用特异引物进行PCR(聚合酶链反应)扩增和DGGE(变性梯度凝胶电泳)并结合DNA克隆测序,研究了水稻生长过程中稻田土壤氨氧化细菌和氨氧化古菌群落结构的变化。结果显示:稻田土壤具有丰富的氨氧化细菌和氨氧化古菌资源。水稻生长过程中土壤氨氧化细菌群落组成较为稳定,只表现出水稻生长前期(苗期、分蘖期)和中后期(孕穗期、成熟期)间存在一定差异。而土壤氨氧化古菌群落组成变化较大,在水稻生长的苗期、分蘖期、孕穗期和成熟期4个时期间均存在一定差异。在水稻生长过程中,土壤氨氧化细菌群落多样性指数无显著性变化,但氨氧化古菌群落多样性指数随水稻生长明显提高,孕穗期后才达到平稳。水稻生长前期土壤硝化势也具有显著上升趋势,孕穗期时达到最高,而后有所下降。土壤硝化势与氨氧化古菌群落多样性指数具有显著正相关性,与氨氧化细菌没有相关性。研究表明,氨氧化古菌对红壤稻田土壤硝化作用的影响程度较大,证实了氨氧化微生物尤其是氨氧化古菌在稻田土壤微生物组成及其生态系统功能中的重要性。

Changes in community structures of ammonia-oxidizers and potential nitrification rates in red paddy soil at different growth stages of rice

Abstracts Community structures of ammonia-oxidizing bacteria and ammonia-oxidizing archaea in a red paddy soil were studied with aid of the denaturing gradient gel electrophoresis and DNA sequencing technologies. Results show that ammonia-oxidizing bacteria and ammonia-oxidizing archaea in red paddy soil were in abundance. Changes in community structures of ammonia-oxidizing archaea were more acute than of ammonia-oxidizing bacteria. With the former, changes were observed between all four stages, while with the latter, only some were between the early growth stages (seedling and tillering) and the late growth stages (booting and maturing) of rice. Shannon-wiener index of ammonia-oxidizing bacteria did not vary much during the entire rice growth season, while Shannon-Wiener index of ammonia-oxidizing archaea increased significant with the succession of the rice growth stages, and leveled off at the booting stage. Potential nitrification rate of the soil rose sharply during the early rice growth period, peaked at the booting stage and then declined somewhat. The potential nitrification rate appeared to be in significantly positive correlation with the Shannon-wiener index of ammonia-oxidizing archaea, but not with that of ammonia-oxidizing bacteria. The findings demonstrated that the effects of ammonia-oxidizing archaea on nitrification of red paddy soil are more pronounced than ammonia-oxidizing bacteria, and both of them, especially archaea, play an important role in the composition of paddy soil microbes and the function of the ecosystem of red paddy soil.