[Investigation of algae pollution in Xiliu Lake and identification of toxic cyanobacteria by whole-cell PCR].

Objective: To investigate the contaminative condition of the floating algae (especially toxic cyanobacteria) in Xiliu Lake, and establish a whole-cell PCR method for identifying the toxic cyanobacteria.

Methods: The surface water of Xiliu Lake was sampled by plastic sampler from March, 2004, and the number of algae was counted by using blood cell counter. The phycocyanin intergenic spacer region (PC-IGS) and microcystin synthetase gene B (mcyB) were identified by whole-cell PCR in water samples, and the amplified product of mcyB was inserted into T vector and sequenced.

Results: Cyanobacteria, Chlorophyta, Bacillariophyta and Euglenophyta were main algae, and cyanobacteria was the dominant algae in summer and autumn. From July 7 to September 27,2 004, PC-IGS was detected positively in 11 samples, and from July 29 to September 27, mcyB was-detieted positively in 9 samples. Compared with the reported mcyB of Microcystis aeruginosa in Genbank, the homology of gene sequence was more than 97 t he homology of amino acid sequence was more than 94%.

Conclusion: In summer and autumn toxic cyanobacteria could be detected in Xiliu Lake. Toxic cyanobacteria could be identified successfully by whole-cell PCR.