渭北旱塬长期施肥试验中氨氧化细菌的多样性及群落结构分析

以中国科学院长武黄土高原农业生态试验站23 a长期施肥定位试验的土壤样品为研究对象,通过构建氨氧化细菌的amoA基因克隆文库,采用PCR-RFLP方法分析了裸地（LD）、种植不施肥（CK）、单施氮肥（N）、单施磷肥（P）和氮磷共施（NP）这5个处理条件下土壤中氨氧化细菌的多样性及其群落结构。结果表明,N处理的土壤中氨氧化细菌的Shannon-Wiene（rH′）和Margalef（dM）a指数均最高,其次是CK、NP、P,而LD处理中最低,表明长期单施氮肥后增加了土壤中氨氧化细菌的多样性和丰富度,长期种植作物后也同样会增加土壤中氨氧化细菌的多样性和丰富度,但单施磷肥和氮磷共施后土壤中氨氧化细菌的多样性和丰富度都有所降低。基于amoA基因建立的系统进化树显示,所有来自于各处理条件下土壤中氨氧化细菌的优势种群都是属于Nitrosospira和Nitrosospira-like,与Nitrosospira cluster 3聚为一组,但优势菌种在克隆文库中所占的比例不同,表明不同的施肥处理下土壤中氨氧化细菌的群落结构发生了改变。

Effects of Long-term Fertilization on Diversity and Composition of Ammonia-oxidizing Bacterium Communities in Weibei Dry-land

Ammonia-oxidizing microbes play an important role in the biogeochemical cycle of N element and it is also the limited rate of ni-trification.The diversity and composition of soil ammonia-oxidizing bacteria were analyzed through constructing its amoA gene（amoA en-codes ammonia monooxygenase）clone library and by PCR-based Restriction Fragment Length Polymorphism analysis（RFLP）.The soil sim-ple which had received 23 years continuous fertilization treatments,include fallow（LD）,control without fertilizers（CK）、nitrogen inpu（tN）、 phosphorus inpu（tP）and combination of fertilizer nitrogen and phosphorus（NP）.They derived from Changwu Agro-ecological Eexperimen-tal Station on the Loess Plateau,Chinese Academy of Sciences.About 150 positive clones from five different ammonia-oxidizing bacteria li-braries were digested by Rsa I and Hha I,respectively.According to the statistics of diversity index,Shannon-Wiene（rH′）and Margale（fdM）a in the N treatment were the highest,followed by CK,NP and P treatments,and the lowest appeared in the CK.These results demonstrated that the diversity and abundance of soil ammonium-oxidizing bacteria were improved after long-term fertilizers N,but after fertilizers P and com-binations of fertilizer N and P,the diversity and abundance of soil ammonium-oxidizing bacteria were both reduced.Phylogenetic tree based on analysis of amoA gene sequences showed that the sequences of soil ammonia-oxidizing bacteria affiliated with Nitrosospira or Nitrosospi-ra-like,and grouped with Nitrosospira cluster 3.The proportion of the distribution of sequence types affiliated with amoA clusters in the clone libraries were different,which indicated that the composition of soil ammonia-oxidizing bacteria were affected by treatments became changed.Our results also indicated the sequences related to Nitrosomonas were predominant in these of five treatments,as well as P was important ef-fects of ammonia-oxidizing bacteria diversity and community.These findings could be fundamental to improve our understanding of the im-portance of ammonia-oxidizing bacteria in the cycling of nitrogen and other nutrients in terrestrial ecosystems.