title: Analysis of factors affecting the ratio of microcystin to chlorophyll-a in cyanobacterial blooms using real-time polymerase chain reaction.
abstract: Chlorophyll-a concentration has been used as an indicator to estimate microcystin levels in water bodies. This study examined the microcystin to chlorophyll-a ratio in a fishpond in Japan. The ratio varied spatially and temporally during the six-month field survey, which is consistent with reports by other researchers. We investigated the causes of the variability of the ratio by quantifying microcystin synthetase (mcy) A gene with real-time PCR, so as to observe the growth of microcystin-producing cyanobacteria and Microcystis strains in natural cyanobacterial blooms. The application of real-time PCR enabled corroboration of the relationship between the toxigenicity and the toxicity of the blooms. The microcystin to chlorophyll-a ratio was influenced by the combined effects of the durability of the toxic bloom, and the quantity of microcystin-producing cyanobacteria carrying the mcy A gene, especially toxic Microcystis strains. Cyanobacterial blooms produced more microcystin when high concentrations of microcystin-producing Microcystis aggregated in a stationary state with low growth rates. The variable toxicity of blooms needs to be reflected in accurate and efficient alert systems for toxic cyanobacteria and cyanotoxins.
authors: Environmental Appraisal Center, Korea Environment Institute (KEI), 290 Jinheungno, Eunpyeong-gu, Seoul, 122-706, Korea. jhha@kei.re.kr
authors: Joo H
authors: JH
authors: Ha
authors: Taira
authors: T
authors: Hidaka
authors: Hiroshi
authors: H
authors: Tsuno
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000032:analysis*; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods; D005068:Eutrophication; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology; D007564:Japan; D052998:Microcystins / Q000032:analysis* / Q000633:toxicity; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D001426:Bacterial Proteins; D052998:Microcystins; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; C078588:microcystin; D010453:Peptide Synthases; C432283:microcystin synthetase A; D000077194:Chlorophyll A