Abstract: Alleviating the global climate change is one of the most important environmental challenges human faced. Autotrophic microbes have a strong adaptability to environmental changes and potential to CO2 fixation, thus it is important for researchers to study on molecular mechanisms of CO2 fixation by autotrophic microbes. Most of the autotrophic microbes fix CO2 via Calvin cycle, although there are another four alternative pathways. The crucial reaction of this pathway is catalyzed by the enzyme ribulose-1, 5-bisphos-phatecarboxylase/oxygenase (RubisCO). Therefore, the RubisCO and the encode gene can be used as functional gene markers to investigate the community and diversity of the CO2 fixation microorganisms in different ecological systems. The previous molecular analysis of microbial carbon fixation has emphasized on aquatic systems, revealing the characteristics of carbon fixation microbial communities and the response to the different habitats. Recent studies on the terrestrial systems have found out that CO2 fixation microorganism also numerous and widespread in soils whereas the functional implication of those autotrophies is not clear, and need to be future identified. Domestic researches on the molecular ecology of soil CO2 fixation microorganism as yet have not been reported. In the present paper, the species of carbon fixation microorganism, the dynamics of CO2 fixation and the current status concerning the carbon fixation by microorganism were reviewed, the main problems and further researches of the molecular ecology of carbon fixation in agricultural ecosystems were also discussed. The aim of this study is to provide useful information for Chinese molecular ecology research of CO2 fixation microorganism.

Key words: greenhouse effect, carbon fixation, molecular ecology, rubisCO