Journal of Microbiology

Distribution and activity of sulfate-reducing bacteria in lake soyang sediments: Jin, Ho Yong , Lee, Dong Hun , Zo, Young Gun , Kang Chan Su , Kim Sang Jong; J. Microbiol. 1996;34(2):131-136.

Abstract: In order to known the extend of contribution to the degradation of organic materials and nutrient recycling by sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB) in sediment, the distribution and activity of these two groups of microorganisms were studied montly in 1994 at two sites, one littoral (Sanggulri) and the other profundal (DAM), in Lake Soyang. In the seasonal distribution of two microorganisms, SRB were 1.07 × 10^3 - 2.42 × 10^5 cells/g-dry weight at Sanggulri, 2.40 × 10^5 - 1.29 × 10^6 at Dam and MPB were 0.52 × 10^3 cells/g-dry weight at Sangguri and 1.44 × 10^3 - 6.89 × 10^3 at Dam. In these results, the density of SRB in Lake Soyang is much higher than other lakes. These high values might be due to higher sulfate concentration, 0.69-4.05 mM, than normal freshwater, 0.01-1.2 mM. And a good correlation of SRB and chlorophyll a concentration implied that the important environmental factor on distribution of SRB might be the concentration of available organic matter. In a comparison of sulfate-reducing rate and methane producing rate in 1995, the activity of SRB for the degradation of organic matter was higher than MPB by factor of 359. Conclusively SRB superior to MPB in the distribution and activity are more important anaerobic bacteria in Lake Soyang sediments.

Image analysis of bacterial cell size by diurnal changes in lake Soyang, Korea: Choi, Seung Ik , Ahn, Tae Seok , Kato, Kenji; J. Microbiol. 1996;34(4):300-304.

Abstract: 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.

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