水稻土甲烷氧化菌对镉胁迫的响应

Response of methanotrophic community structure and oxidation potential to cadmium stress in a Chinese paddy soil

重金属污染影响土壤微生物群落结构与活性,间接影响土壤碳(如CO2、CH4)的生物地球化学循环和全球气候变化。甲烷氧化菌氧化消耗CH4,降低大气中CH4含量,在缓解由温室气体导致的全球温暖化方面起着重要作用。本研究通过短期土壤培养实验,比较研究了不同强度重金属镉(Cd)胁迫下,水稻土中甲烷氧化菌的多度、群落组成及其氧化CH4潜势的差异。结果表明,添加Cd含量越大,水稻土氧化CH4潜势越弱,甲烷氧化菌pmoA基因拷贝数显著减少;甲烷氧化菌多度与水稻土氧化CH4潜势之间存在显著正相关关系(P<0.001)。群落组成分析发现,在相对低含量Cd(1 mg.kg-1)条件下,有新的甲烷氧化菌菌属出现,而添加较高含量Cd(10 mg.kg-1)时甲烷氧化菌种类减少。总之,Cd胁迫降低水稻土中甲烷氧化菌多样性及其氧化CH4潜势,可能导致原位CH4消耗减少,从而增加稻田CH4排放。

Heavy metal contamination has strong effect on the soil microbial community and activities,and also affects the biogeochemical cycling of soil carbon（e.g.CO2 and CH4） and global climate change.Fortunately,methane-oxidizing bacteria（methanotrophs） can consume CH4 and therefore play a critical role in the mitigation of global warming.Here,a short-term,laboratory-based incubation experiment was conducted to examine the effects of cadmium（Cd） amendments on the abundance,community composition and oxidation potential of methanotrophs in a southern China paddy soil.The results showed that there were significantly lower methanotrophic oxidation potential and abundance in the treatment of Cd amendment of 10 mg kg-1（high-Cd） than those in the treatment of Cd amendment of 1 mg.kg-1（low-Cd） dry weight soil and the Control.Correlation analyses indicated that the methanotrophic oxidation potentials were significantly positively correlated with the abundance of methanotrophs（P 0.001）.For the community in rice soil after incubation,some novel methanotrophic genera/species were found in the low-Cd addition.However,much less genera/species were found in the high-Cd treatment.In conclusion,the methanotrophic community diversity and activity of the rice soil were decreased under Cd stress,which could probably inhibit the consumption of CH4 in situ and thus enhance the CH4emission from the rice paddy.