title: Dynamics of microcystin production and quantification of potentially toxigenic Microcystis sp. using real-time PCR.
abstract: Cyanobacterial blooms in eutrophied water body are generally composed of various genotypes with or without microcystin-producing genes (mcy gene cluster). Thus there is a need for quantification of potent toxin producing strains. The present study aimed at identifying microcystin variants and its producer strains in Durgakund pond, Varanasi, India, based on quantification of cpcBA-IGS and mcyA (condensation domain) genes using real-time PCR and LC-MS. Increase in microcystin concentrations was correlated with increase in mcyA copy number and the level of pigments (chlorophyll a, phycocyanin and carotenoids). Also, selected environmental factors (water temperature, light irradiance, rainfall, pH, N and P) and the concentration of microcystin variants (MC-LR, -RR and -YR) were also assessed in samples during May 2010 to April 2011 to establish the possible correlation among these parameters. Nutrients favored cyanobacterial bloom but it could not be correlated with the levels of microcystin variants and seemed to be geographically specific. Microcystis sp. dominant in the pond comprised potentially toxigenic cells. The ratio of potentially toxigenic Microcystis sp. to that of total Microcystis sp. ranged from 0% to 14%. Such studies paved the way to identify and quantify the most potent microcystin producer in the tropical aquatic body.
authors.affiliation: Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221 005, India.
authors.forename: Ankita
authors.initials: A
authors.lastname: Srivastava
authors.forename: Gang-Guk
authors.initials: GG
authors.lastname: Choi
authors.forename: Chi-Yong
authors.initials: CY
authors.lastname: Ahn
authors.forename: Hee-Mock
authors.initials: HM
authors.lastname: Oh
authors.forename: Alok Kumar
authors.initials: AK
authors.lastname: Ravi
authors.forename: Ravi Kumar
authors.initials: RK
authors.lastname: Asthana
mesh_terms: D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002853:Chromatography, Liquid; D004587:Electrophoresis, Agar Gel; D005068:Eutrophication / Q000187:drug effects; D018628:Gene Dosage / Q000235:genetics; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007194:India; D008027:Light; D057230:Limit of Detection; D013058:Mass Spectrometry; D052998:Microcystins / Q000096:biosynthesis* / Q000633:toxicity*; D046931:Microcystis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010798:Phycocyanin / Q000378:metabolism; D061005:Ponds / Q000382:microbiology; D011891:Rain; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012015:Reference Standards; D015203:Reproducibility of Results; D012621:Seasons; D013696:Temperature; D018675:Toxicity Tests
chemical_list: D052998:Microcystins; D010798:Phycocyanin; D002734:Chlorophyll; D010758:Phosphorus; D002338:Carotenoids; C078588:microcystin; D009584:Nitrogen; D000077194:Chlorophyll A