高温下两种不同pH水稻土甲烷产生及古菌群落的比较

Comparison of methane production and archaeal community of two rice paddy soils with different pH under high temperature

水稻土甲烷产生及相关古菌群落受到环境因子和土壤理化性质的影响。为比较高温下2种不同p H水稻土的甲烷产生及古菌群落结构的差异,本研究在50℃下将2种不同p H水稻土S1(p H 7.88)和S2(p H 4.67)进行了为期100 d的厌氧培养,测定了培养过程中甲烷气体的产生和土壤p H、有机碳以及铵氮等土壤理化性质的变化,并运用基于16S rRNA基因的T-RFLP(末端限制性片段多态性分析)技术分析了产甲烷过程中古菌群落结构随时间的变化情况。结果表明,2种水稻土在厌氧培养过程中土壤有机碳含量下降,铵氮浓度变化趋势相似,且甲烷累积总量无差异,但两者p H的变化趋势和甲烷产生速率显著不同。土壤p H的升高会加快甲烷产生的速率,且甲烷八叠球菌(Methanosarcinaceae)和Methanocellaceae是50℃高温下2种水稻土中主要的产甲烷菌群,随着培养时间推移,不同水稻土有不同的群落发展方向,酸性水稻土更有利于Methanocellaceae的生长。

Production of methane from paddy fields and the related archaeal community are both influenced by environmental factors and soil characteristics of the field（ e.g. p H,carbon and nitrogen contents）. To study the effect of soil p H on methane production and community structure of the methanogenic archaea at high temperature,two soil samples S1（ p H 7. 88） and S2（ p H4.67） developed from different matrices were anaerobically incubated at 50 ℃ for 100 days.Methane production was measured continually by gas chromatography during the incubation. Soil characteristics,such as p H,organic carbon and ammonium nitrogen contents were also evaluated in the supernatant or the soil itself. The variations in the microbial structure with incubation time in the two soils were studied by terminal restriction fragment length polymorphism（ T-RFLP）analysis based on archaeal 16 S ribosomal RNA gene. The results showed that the organic carbon content decreased with the formation of methane during incubation,whereas the variation of ammonium was similar in both the supernatants and soil samples S1 and S2. Although the final amount of methane produced was same for S1 and S2,the changes in p H and methane production rates were significantly different between the two soils. It was found that the rate of methane formation increased with the increase of p H. The T-RFLP profiles showed that Methanosarcinaceae and Methanocellaceae were the primary active methanogenic groups in paddy soil at 50 ℃. Analysis of the entire T-RFLP profiles via two-dimensional plots of PCA（ principal component analysis） revealed that the developmental direction of structures of the archaeal populations in the two soils were different. Acidic paddy soil was more suitable for enhancing the activity of Methanocel-laceae.