Comparison of cyanobacterial microcystin synthetase (mcy) E gene transcript levels, mcy E gene copies, and biomass as indicators of microcystin risk under laboratory and field conditions

摘要: Increased incidences of mixed assemblages microcystin-producing and nonproducing cyanobacterial strains in freshwater bodies necessitate development reliable proxies for cyanotoxin risk assessment. Detection microcystin biosynthetic genes water blooms cyanobacteria is generally indicative the presence potentially toxic strains. Although much effort has been devoted toward elucidating biosynthesis mechanisms many genera, little known about impacts co-occurring on cellular growth, mcy gene expression, or copy distribution. The present study utilized conventional microscopy, qPCR assays, enzyme-linked immunosorbent assay to how competition between Microcystis aeruginosa CPCC 299 Planktothrix agardhii NIVA-CYA 126 mcyE copies, concentration under controlled laboratory conditions. Furthermore, analyses environmental samples from Missisquoi Bay, Quebec, enabled us determine various potential toxigenic biomass correlated with concentrations a lake. Results our indicated significant downregulation expression cultures M. plus P. most sampling days agreement depressed growth recorded cultures, suggesting that interaction two species probably resulted suppressed cultures. although copies McyE transcripts were detected all field measureable levels, only showed positive correlations (R2 > 0.7) concentrations, while transcript levels did not. These results suggest are better indicators risks microcystins than proxies, especially comprising nontoxic cyanobacteria.