Effect evaluation of different electron donors on CO2 fixation by a non-photosynthetic microbial community under aerobic conditions using factorial design
混合电子供体对好氧非光合微生物菌群固碳效率影响的析因实验分析

Carbon dioxide is one of the main greenhouse gases, but it is also the most abundant carbon source, so that its recycle and reuse has become an important issue. In our experiment, a factorial design was used to demonstrate the interaction effects of different electron donors on CO2 fixation by a non-photosynthetic microbial community under aerobic conditions, and PCR-DGGE technology was applied to analyze the changes of microbial community structure during CO2 fixing with different electron donors. The results showed that the factorial design models were of high quality to predict the CO2 fixation efficiency of the non-photosynthetic microbial community. Na2S and Na2S2O3 could each enhance its CO2 fixation efficiency, and the positive effect was reinforced when both were present. NaNO2 as added electron donor could significantly enhance CO2 fixation, but this effect was competitively inhibited when Na2S2O3 or Na2S was added to the medium. The DGGE patterns revealed significant differences among microbial communities cultivated with various electron donors, demonstrating changes of CO2 fixation efficiency at the molecular level. Nitrobacteria, which were predominant when pre-incubated under conditions in which NH+4 was sole electron donor, disappeared in general when other electron donors were added, but many other strains which grow well in the medium with different electron donors appeared. Some of them might fix CO2 efficiently, but some of them might compete with the bacteria which can fix CO2.