中文摘要：

真核生物、细菌和古菌三者共同构成了生命的三域系统.古菌作为第3种生命形式,不仅能在高温、强酸和高盐等极端环境下生存,而且在海洋、湖泊和土壤等生境中也广泛分布,预示其在整个生态系统中有着不可估量的作用.本文以2个农田剖面土壤和2个长期施肥试验站祁阳（QY）和封丘（FQ）的土壤为对象,以实时定量PCR方法为主要研究手段,对土壤中古菌（包括泉古菌）和细菌的16SrRNA基因拷贝数丰度变化进行了研究.结果表明：土壤泉古菌16SrRNA基因拷贝数要低于古菌1～2个数量级,两者与细菌相比,16SrRNA基因拷贝数大小顺序为土壤泉古菌〈古菌〈细菌,而古菌和泉古菌16SrRNA基因拷贝数与细菌的比值均随土壤深度加深而增大.不同施肥处理对土壤古菌和泉古菌的数量有显著影响.QY试验站土壤古菌和细菌的数量与土壤pH值显著相关（分别为r=0.850,P〈0.01和r=0.676,P〈0.05）.FQ古菌、泉古菌和细菌与土壤pH值相关性不显著,与土壤有机质含量相关性均达显著水平（分别为r=0.783,P〈0.05;r=0.827,P〈0.05;r=0.767,P〈0.05）.了解古菌包括泉古菌在农田土壤中的分布,可为评价其在生态系统和物质循环中的作用提供重要的理论依据.

英文摘要：

Eukaryota,bacteria and archaea are the three domains of life.As the third domain of life,archaea has been found not only in extreme environments such as high-temperature,high-saline,and extremely acid habitats,but also in moderate environments including ocean,lake and soil,which implies that archaea may contribute greatly to various ecosystems.By targeting the 16S rRNA gene with real-time PCR approaches,this paper studied the abundance of archaea,crenarchaea and bacteria from two agricultural soil profiles and two long-term fertilization stations Qiyang（QY） and Fengqiu（FQ）.The 16S rRNA gene copy number of crenarchaea was 1-2 orders of magnitude lower than that of archaea,and the order of these three groups was crenarchaea archaea bacteria.The ratios of both archaea and crenarchaea to bacteria increased with soil depth.The abundance of archaea and crenarchaea had significantly different responses to different fertilization treatments.In QY station,the copy numbers of archaeal and bacterial 16S rRNA gene had significant positive correlations with soil pH（r=0.850,P0.01 and r=0.676,P0.05,respectively）;in FQ station,all the 16S rRNA gene copy numbers of archaea,crenarchaea and bacteria had no significant correlations with soil pH,but significantly correlated with soil organic matter（r=0.783,P0.05;r=0.827,P0.05;r=0.767,P0.05,respectively）.To understand the distribution of archaea and crenarchaea in agricultural soil could provide important information to evaluate their ecological functions in soil ecosystem and element cycling.