• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.149-179
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• 2004

In order to understand the taxonomic and ecologic characteristics on ciliates plankton, surface water samples were collected once a weekly from March 2001 to December 2001 except once a monthly from December 2001 to January 2001 and twice a monttdy at February 2001 at Pal'tang reservoir in Korea. Totally 12 species belonging to 10 genera in 7 families of 6 order, were identified and all species new record in Korea. All of them had been recorded in eutrophic water bodies. Succession of dominant species occurred obviously according to seasonality. Large -sized Codonella cratera, Rimostrombidium lacustris, Strobilidium caudatum, Limnostrombidium viride, Pelagostrombidium fallax, Stylonychia sp., Pseudostrombidium plaktonticum and Phascolodon vorticella dominated during the period of outbreak of nanophytoplankton in winter to spring. However, small-sized Rimostrombidium hyalinum, rimostrombidium brachykinetum, Halteria gradinella and Vorticella convallaria occurred when the bacteria abundance increased in summer to autumn.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2003.06a
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• pp.7-8
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• 2003

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.47-56
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• 2004

To understand the effect of nutrient deficiency on the plankton community in three stations with different water qualities in Pal'tang Reservoir, Korea, phytoplanktons(> 10 ${\mu}m$) were cultured in nutrient enrichment Allen's media (AM) and nutrient-deficient Allen's media. A distinct shift in the species composition and biomass of phytoplankton (as chlorophyll- a) showed in all treatments. In particular, it was very interesting that the new development of cyanobacterium Microcystis aeruginosa occurred by the Fe-deficient AM. Except for Si, a community growth (as chlorophyll- a) was inhibited in all nutrient deficient treatments. Species diversity after nutrient deficiency was changed to below 2.0; slightly increased in N and P-deficiency, while decreased in Si and Fe, respectively. As suggested, dominance was entirely opposite to diversity. Therefore, the nutrient deficient effectively induced the succession of species and biomass, phytoplankton community, suggesting a possibility as a reliable tool to control the algal bloom in eutrophic lakes and reservoirs.

• Korean Journal of Ecology and Environment
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• v.35 no.1 s.97
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• pp.1-9
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• 2002

In order to understand the relationship between succession of phytoplankton community structure and inorganic nutrients and particulate organic matters, a one station in Kyungan stream in Korea during the dry season was chosen. Water samplings were carried out once a week from 18 August to 13 November 1993. The DIN concentration distributed always abundantly, however, phosphate and silicate gradually reduced during the period. Phytoplankton community had a peak chlorophyll a concentration of $90.6\;{\mu}g/l$ in late summer (21 August 1993) and a second peak of $29.7\;{\mu}g/l$ in autumn (2 October 1993). After then late autumn was characterined by relatively low chlorophyll a concentration of $15{\sim}16\;{\mu}g/l$. Seasonal fluctuation of chlorophyll a concentrations were correlated with measured POC and PON concentrations: phytoplankton blooming may be a major factor controlling POC and PON concentrations in this ecosystem. Phosphate plays an most important role as a limiting factor of phytoplankton growth. However, when Si/P ratio low, silicate may be a more critical limiting factor than phosphate. Shifts of P-limitation to Si- limitation the succession of dominant phytoplankton can in duce: diatom to cyanobacteria such as Anabaena, Microcystis and Oscillatoria.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.23-29
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• 2004

An algicidal effect of endemic algicidal bacterium (Pseudomonas putida) and rotifer zooplankton (Brachionus calyciflorus) on diatom Stephanodiscus hantzschii were examined in the filtered water, and were compared with those of bacterium plus ciliate. Bacteria removed as 80% of the diatom within 3.5 days, while ciliate and zooplankton suppressed 57% and 40% of diatom during the same period, respectively. Mixed treatment of bacteria plus ciliate removed as 54% of diatoms, while that of bacteria plus zooplankton decreased as 85%. Although single bacteria and mixed treatment of bacteria plus zooplankton quickly decreased the diatom in the initial of experiment, bacteria plus ciliate perfectly removed the diatom in culture flask within 5.5 days of the study. On the other hand, other single and mixed treatments did not clear the diatom during the same period, and over 10% of them still remain in culture flask. Predator biomass in the presence of algicidal bacteria showed the growth patterns; zooplankton gradually decreased, and ciliate sustained over 0.5 cells/ml. These results indicated that the addition of ciliate to the algicidal bacterium in controlling the diatom Stephanodiscus hantzschii is more effective than that of zooplankton. Therefore, this synergistic interaction relationship between the bacterium and ciliate play an important role in the bio-manipulation using bio-agents to control the diatomal bloom in freshwater lakes and streams.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.236-240
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• 2004

To examine the algicidal effect of co-treatment of biological control agent on centric diatom Stephanodiscus hantzschii in the filtered water, an endemic algicidal bacterium (Pseudomonas putida) and a heterotrich ciliate (Stentor roselli) were iso-lated from Pal'tang reservoir, Korea. Bacterial isolate and ciliate removed 98% and 80% of the diatom for 7 days of cultivation. Co-treatments of these two agents perfectly inhibited the diatom growth, compared to the single treatment of each agent. This synergistic interaction of the bacterium and ciliate could provide an effective tool in the biomanipulation to control the diatom bloom in freshwater lakes and streams.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.107-112
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• 2002

To isolate the bacteria lysing cyanobacteria, the sediment samples were collected from Dochang and Pal'tang Reservoir and Seokchon Lake. Each sample was smeared on the Anabaena cylindrica lawn and incubated in light chamber for 11 days. Bacteria having cyanobacteria-Iysing activity were isolated from the samples of Seokchon reservoir. Confirmation of cyanobacteria-Iysing activity was carried out to measure chlorophyll a and bacterial cell counting in mixed culture of Anabaena cylindrica and bacteria. Lysis was detected when extracellular meterials was added to the Anabaena cylindrica culture. The isolate was identified by analysis based on 16S rDNA sequence and morphological and physiological properties. The bacterial strain was taxonomically studied by the phylogenetic analysis based on 165 rDNA sequence. This strain was identified as a member of the genus Bacillus and designated as Bacillus sp. CHS1.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.194-202
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• 2003

To isolate alga-lytic bacteria, a number of samples were collected from Lake of Sukchon and Pal'tang reservoir where cyanobacteria blooming occurred. HY0210-AK1, which exhibited high alga-lytic activity, was isolated using Anabaena cylindrica lawn. The morphological and biochemical characteristics of the isolate HY0210-AK1 were very similar to that of the genus Rhizobium. Taxonomic identification including 16S rDNA base sequencing and phylogenetic analysis indicated that the isolate Hy0210-AK1 had a 99.1% homology in its 16S rDNA babe sequence with Sphingobium herbicidovorans. A. cylindrica NIES-19 was susceptible to the alga-lytic bacterial attack. The growth-inhibiting offset of the bacterium was not different on A. cylindrica NIES-19 when Sphingobium herbicidovorans HY0210-AK1 was in the lag, exponential, and stationary growth phase, although the alga-Iytic effect of S. herbici-dovorans HY0210-AK1 that in stationary growth phase was somewhat pronounced at the first time of inoculation. When S. herbicidovorans HY0210-AK1 was inoculated was inoculated with $1\times 10^{8}$ CFU $ml^{-1}$ together with A cylindrica NIES-19, the bacterium proliferated and caused algal lysis. A. cylindrica NIES-19 died when S. herbicidovorans HY0210 AKl was added to the algal culture but not when duly the filtrates from the bacterial culture was added. This suggests that extracellular substances are not responsible for inhibition of A. cylindrica NIES-19 and that algal Iysis largely attributed to direct interaction between S. herbicidovorans HY0210-AK1 and A. cylindrica NIES-19. The alga-lytic bacterium HY0210-AK1 caused cell lysis and death of three strain of Micro-cystis aeruginosa, but revealed no alga-Iytic effects on the Stephanodiscus hantzschii.