| Co-Investigator(Kenkyū-buntansha) |
金 凡徹 韓国江原大学校, 自然科学大学, 教授
安 泰夾 韓国江原大学校, 自然科学大学, 教授
WATANABE Yoshito SHINSHU UNIV., FAC.TEXTILE & TECHNO., ASSIST.PROFESSOR, 繊維学部, 講師 (10021172)
PARK Ho-dong SHINSHU UNIV., FAC.SCIENCES,LECTURER, 理学部, 助手 (20262686)
HAYASHI Hidetake SHINSHU UNIV., FAC.SCIENCES,PROFESSOR, 理学部, 教授 (60087129)
AHN Tae-sok KWANDONG UNIV., FAC.SCIENCE,PROFESSOR
KIM Bom-chul KWANDONG UNIV., FAC.SCIENCE,PROFESSOR
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| Research Abstract |
Cyanobacterial bloom samples were collected in the warm season during 1995-1997 from the twelve lakes and artificial dams in Korea. Six species of Microcystis and Anabaena respectively, and two species of Oscillatoria were identified in lakes studied. The cyanotoxins of 47 samples collected from the lakes were identified as microcystins-RR,-YR,-LR ; desmethyl-7-microcystin-LR (7-DMLR), plus anatoxin-a. Microcystins were the main components of cyanotoxin in the blooms in Korean lakes, and anatoxin-a was detected in a few lakes. In 34 of the 47 cyanobacteria bloom samples, the samples included microcystins and the total amounts of microcystin varied between 20-1,500 mu g per & freeze-dried bloom material. In 4 of the 26 cyanobacteria samples analyzed, the samples contained anatoxin-a and the amounts varied. The total microcystin concentations of 30samples in the lakes were equal to their intracellular microcystin because the extra cellular microcystin was not detected in all samples.
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the lakes studied, except Lake Younglang and Mijae, provide for the drinking water sources, the presence of cyanotoxin can be a potential threat and requires more attention to water treatment.
Possible pathways of microcystins in a lake ecosystem were studied from three viewpoints, production, accumulation and decomposition. Compared to production, the other two processes have not been fully clarified to date. Two strains of bacteria were isolated as participating in the decomposition of microcystins ; the strains were identified as Sphignomonas. When Sphignomonas was added to microcystins, the peptied was decomposed to 100 % of the control in 6 days. The highest degradation rate of microcystins-RR and -LR were 13 and 5.4 mug/mg/day, respectively.
Accumulation of microcystins mainly produced by cyanobacteria Microcystis was investigated for freshwater mussels and fishes collected from Lake Suwa, where the heavy blooms of Microcystis occurred every summer. Microsystins-RR and -LR were detected in the mussels Unio douglasiae, Anodonta woodiana, Cristaria plicata, and fish Cyprinus carpio, whereas no microcystin was identified by the present method in fishes, such as Carassius carassius and Hypomethus transpacificus. Less
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