• Korean Journal of Microbiology
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• v.31 no.1
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• pp.93-98
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• 1993

To investigate the organic matter transformation in aquatic environment, seasonal fluctuations of heterotrophic activity and microbia] extracellular enzyme activity were studied in Paldang Lake, Korea. The turnover time in the water column and the sediment at the station I fluctuated between 3 -I ,300 hrs and 17-170 hrs for glucose, 5 -1.900 hrs and 15-240 hrs for protein hydrolysate and 4-350 hrs and 15-230 hrs for acetic acid, respectively, indicating that the seasonal turnover time of organic substrates fluctuated drastically. The respiration ratios of glucose. protein hydrolysate and acetate were 23-32%, 38-41% and 22-28% in the water column and 34%, 61% and 41% in the sediment. respectively. These results showed that the respiration ratios in the sediment were higher than those in the water column regardless of kinds of organic substrates. The bacterial extracellular enzyme activities of $\alpha$-glucosidase. $\beta$-glucosidase, N-acetyl-$\beta$-D-glucosaminidase and aminopeptidase were 32-44%. 31-32%, 18-34% and 61-67% in the water column, and 34%. 40%, 23% and 65% in the sediment. respectively.