Structure And Function Of Microorganisms In Hangzhou Section Of The Grand Canal

The structure and function of microorganisms is an important study topic of the microbial ecology. Microorganisms in aquatic ecosystems play an important role in nutrient circulation and energy flow. Studying the structure and function of microorganisms was redound to reveal the mechanisms of carbon, nitrogen or phosphorus circulation in aquatic ecosystems. In order to more clearly understood the role of microorganisms in eutrophic aquatic ecosystems and offer some advise on pollution compositive control, we studied the physiological group struction and function of cultivable microorganisms in the water body of Hangzhou Section of the Grand Canal in 2004-2005.Water samples were collected seasonally. The bacterial physiological groups were counted by colony-forming unit (CFU) method or most probable number (MPN) method. Based on colony characteristics, predominant bacterial were further isolated and their partial 16S rDNA were sequenced and phyiogenetic relations were constructed.Results showed that, the annual average amount of heterotrophic bacteria (ammonifiers) is as high as 1.64×10~5 CFU/mL. Nitrogen fixers, ammonia oxidizers, nitrite oxidizers, nitrate reducers and denitrifiers were 1.39×10~4 CFU/mL, 143 MPN/mL, 1925 MPN/mL, 7.95×10~4MPN/mL and 9.35×l0~3MPN/mL, respectively; Inirganic phosphate solubilizing bacteria (IPB) and organic phosphorus mineralizing bacteria (OPB) were 2.75×10~4 CFU/mL and 5.72×10~3 MPN/mL, aerobic and anaerobic cellulose decomposers were 175 MPN/mL and 5 MPN/mL, respectively. The large amount of heterotrophic bacteria indicates that severe pollution still exists in the water body of canal. From spatial distribution, microorganisms are relatively lower in Yi Bridge and Tangqi Bridge, two locations far away from downtown, than those in Gongchen Bridge, a location inside Hangzhou city. However, there is no significant variation from seasonal distribution.