Isolation, molecular identification, and characterization of a unique toxic cyanobacterium Microcystis sp. found in Hunan Province, China.

Global proliferation of cyanobacterial blooms associated with climate change and eutrophication constitutes a serious environmental threat. In Hunan Province a freshwater pond located in Changsha City was found to contain high concentrations of cyanobacteria, however, the characteristics of these cyanobacteria at present are not known. This study thus aimed to isolate, identify the most common bloom-forming cyanobacteria in this region and determine the toxigenic characteristics of the predominant cyanobacteria. The cyanobacteria were isolated by serial dilution and identified using polymerase chain reaction (PCR). The cyanotoxins generated by the cyanobacterium were detected using high-performance liquid chromatography with an ultra-high resolution LTQ Orbitrap Velos Pro ETD mass spectrometry equipped with electrospray ionization interface (HPLC-ESI-MS). One  species of cyanobacterium was isolated and identified as Microcystis sp. YFM1 according to the sequence of the 16S ribosome deoxyribonucleic acid (16S rDNA). It was found that this cyanobacterium contained microcystin synthetase B gene (mcyB) and produced three types of cyanotoxins including microcystin-LR, RR and YR. Our findings indicate that the Microcystis sp. YFM1 isolated from the freshwater pond in Hunan Province exhibits unique characteristics distinguishable from other known cyanobacteria.