Analysis Of Microbial Community Structure In The Rhizosphere Of Eichhornia Crassipes In Eutrophic Water

With the rapid development of industry and agriculture, water contamination is appearing to be a serious problem, especially because of excess nitrogen and phosphorus caused eutrophication of water, has become a global water quality issues of most concern. Using higher aquatic plant management and restoration of eutrophic water has a significant effect,less investment and high efficiency. Eichhornia crassipes research is the most in-depth study in earliest days,and it also gets broader application of ecological restoration project compare to other aquatic plants.On the one hand, eutrophic water restoration depends on the absorption and utilization by E. crassipes itself, on the other hand, uptake and utilization of rhizosphere microorganisms and the removal of nitrogen by ammonification- nitrification-denitrification also play an important role on it.Therefore,rhizosphere microbial community structure of E. crassipes was studied in ths paper. Traditional culture, molecular biology tools (T-RFLP technique and clone library method) were used to study rhizosphere microbial community structure of E. crassipes so that we can know more about it and realize the relationships between microbial community structure diversity in the rhizosphere of E. crassipes and eutrophic water environment, that we can build a water hyacinth-microbial degradation coupled system to strengthen water hyacinth water features providing a theoretical basis.In this paper, denitrifying bacteria culturing medium was used to separate 8 bacteria from the sample of the rhizosphere of E. crassipes. For the first part among them,5 bacteria which can resist to 203mg/L of NO2--N were separated from autotrophic medium,3 of which are Pseudomonas putida,1 of which is Montessori aeruginosa and 1 of which is belonged to Comamonas. For the second part,3 bacteria which can resist to 237mg/L of NH4+-N were separated from heterotrophic medium, and 3 bacteria are Acinetobacter sp.16S rRNA gene as a molecular marker, the rnicrobial community structure diversity of the rhizosphere of E. crassipes.(R), water samples nearJ E. crassipes(WN) and water samples far from E. crassipes(WF) were analyzed by T-RFLP technique. The results showed that in the same period, the microbial community structure diversity index of R was the highest, followed by the sample WN and WF. According to the T-RFLP patterns, bacteria 159bp was the most dominat strain in R, and we can find that Acinetobacter sp Yll-5 which is by cultured correspons with bacteria 159bp according enzyme digestion simulation analysis by online software (SMS).16S rRNA gene clone library was established by RO(sample R collected in October). The result showed that Proteobacteria was the major group in RO, which accounted for 65.1% of the entire groups, and Bacteroidetes accounted for 11.6%, Acidobacteria for 7%, Verrucomicrobia for 7%, Hydrogenedentes for 2.3% and unclassified bacteria for 7%.amoA gene as a molecular marker, the ammonia oxidizing bacterial community structure diversity of RO and WNO(sample WN collected in October) were analyzed by T-RFLP technique. The results showed that ammonia oxidizing bacterial community diversity index of RO was higher than WNO, but these two samples have very similar dominant species. amoA gene clone library was also established by RO, and based on the amoA gene phyfogeny, ammonia-oxidizing bacteria in rhizosphere of E. crassipes can be divided into three groups. According to the enzyme digestion simulation analysis., we can find that clone C25 correspons with bacteria 402bp which is found to be the dominant bacteria from the T-RFLP patterns.