- The Bacterial Community of Southern Lake Baikal in Winter
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Ahn, Tae Seok , Hong, Sun Hee , Kim, Dong Joo , Suck, Jung Hyun , Drucker, Valentin V.
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J. Microbiol. 1999;37(1):10-13.
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The bacterial abundance, proportion of respiring bacteria, and bacterial community of southern Lake Baikal were analyzed at 1 m and 400m depths during winter. The total bacterial numbers were 5.1×10^5 cells m^l-1 at 1 m and 2.5×10^5 cells ml^-1 at 400 m depth, which are about half and quarter of the numbers of other lakes. The proportion of respiring bacteria was as low as 2.5% at 1 m and 1.4% at 400 m depth. Considering the amount of organic carbon which need to be degraded and low proportion of respiring bacteria, the bacteria could be assumed to have high activities. The EUB/DAPI ratios were 77 and 89% at 1 m and 400 m depths, respectively. Of the bacterial community, the other group was dominant at both depths, and gamma group of proteobacteria followed next. But the beta group of proteobacteria and Cytophaga-Flavobacterium groups occupied very small proportions.
- Image analysis of bacterial cell size by diurnal changes in lake Soyang, Korea
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Choi, Seung Ik , Ahn, Tae Seok , Kato, Kenji
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J. Microbiol. 1996;34(4):300-304.
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To define the effects of zooplankton and phytoplankton to bacteria, bacterial numbers, frequency of dividing cells (FDC) and size distribution were performed with image analysis in the surface layer of Lake Soyang. In August 1992, when Anabaena was blooming, the bacterial number increased at daytime. Bacterial numbers and FDC value had a negative correlation (r = 0.83, P < 0.01). Bacterial size spectrums were dynamically changed during the day and night, especially the small bacteria less than 0.5 ㎛^3. Meanwhile, in October, after the bloom, the bacterial number was only one third of that in August, even though the FDC was higher than that in August. The bacterial numbers of small size class dropped at 13.00. But the size spectrums were relatively constant during the night time. These results suggest that the bacterial growth was tightly coupled with phytoplankton during Anabaena bloom. And after the bloom, the bacterial number was controlled grazing activity of zooplankton at daytime.
- Observation and Enumeration of Attached Bacteria on Cellulos Film
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Ahn, Tae Seok , Choi, Seung Ik , Byeon, Myeong Seop
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J. Microbiol. 1995;33(1):1-4.
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The DNA specific fluorochorome, Hoechst 33258, was used to enumerate the attached bacteria on cellulose film by epifluorescence microscope. Stainning with Hoechst dye gave fine features, whereas staining with acridine orange and DAPI gave poor contrast between background and bacterial cells. In Lake Uiam, Morphologically different two bacteria were detected after 3 days submerging in lake water. In Lake Soyang, the bacterial colonies appeared after 16 hours. This staining method had distinct advantages to enumerate the attached bacteria on surface.
- Incorpotation and production of glucose in Lake Soyang
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kwag, No Tae , Choi, Seung Ik , Ahn, Tae Young , Ahn, Tae Seok
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J. Microbiol. 1995;33(1):74-79.
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Kinetics of heterotrophic activity (glucose uptake) and extracellular enzyme activity(β-glucosidase, cellobiohydrolase) and cell numbers were measured in Lake Soyang during phytoplankton bloom development and after its breakdown. V_max for glucose was lower during Diatom bloom and that was higher after its breakdown. But the increase ion β-glucosidase activity was detected in late of Diatom bloom. Glucose uptake did not associated with β-glucosidase activity. The tight relationship between β-glucosidase and the incorporation of glucose by bacteria was not shown and the significance of depolymerization on the incorporation of glucose in lake water are discussed.
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