농업용 저수지에서의 질화세균의 계절적인 변화 = Seasonal Variations of Nitrifying Bacteria in Agricultural Reservoir

다국어 초록 (Multilingual Abstract)

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chl-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of 0.8∼1.5×10 exp (6) cells/㎖ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only 1.0∼7.4%. The variations of ammonia-oxidizing bacteria ranged from 1.1×10 exp (4) to 3.0×10 exp (4) cells/㎖ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in 1.3∼5.7×10 exp (4) cells/㎖ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature(r=0.355, p<0.05) and DOC(r=0.586, p<0.05) and pH(r=-0.568, p=0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers(r=0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.