土壤自养微生物对二氧化碳的同化是土壤碳循环中的重要环节，对减少大气二氧化碳浓度，提高土壤碳储量起到十分重要的作用。本研究立足我国西南地区，选择本区域独有的紫色土为研究对象，以编码开尔文循环的关键酶，1,5-二磷酸核酮糖羧化酶大亚基的cbbL基因为分子标识，拟通过现代分子生物方法来研究长期定位施肥对紫色土自养微生物活性及群落结构的影响。之后，结合土壤微宇宙培养试验，利用稳定同位素探测（SIP）技术进一步深入研究pH、含水量、温度等环境因子及能源、碳源对紫色土自养微生物活性及群落组成的影响。进而探讨影响紫色土自养微生物活性和群落结构的关键因子，阐明影响紫色土自养微生物活性的微生物机理。本研究将为揭示土壤碳循环过程的微生物机理打下基础，同时为本区域制定合理的耕作措施，以增加土壤碳储量、减少二氧化碳排放提供一定的理论依据。

Carbondioxide fixation by soil autotrophic microorganism, one of the most important biological processes involved in the soil carbon cycle, could decrease the carbondioxide concentration in the atmosphere and increase the content of soil carbon pool. In this project, the purple soil, which is unique in the world and the main soil type in the Southwest China, will be selected as target. Using the large subunit of RubiosCo gene (cbbL gene) as biomarker, the effects of soil environmental factors, such as long-term fertilization on the community composition and activity of soil autotrophic microorganism will be investigated through modern molecular techniques. Then, in order to study the mechanism affecting soil autotrophic organism and explore the active autotrophic microorganism in the purple soil, through microcosm culture experiment, using the combined method of molecular technology and DNA-SIP, the responses of soil alive autotrophic microorganism to some key soil factors, such as energy sources, pH, water content, light, and carbondioxide concentration, will be examined. This study will clarify the main factors affecting the activity and community structure of autotrophic microorganism, and main active population in the purple soil, which should be very important for the discovery of the microbiological mechanism of soil carbon cycle. On the other hand, this study also can afford some useful basic theories for the drawing up of the reasonable farmland management measure aimed at increasing the soil carbon pool and decreasing soil carbon emission.