Abstract
Cyanobacteria are aquatic and photosynthetic prokaryotes which form harmful algal blooms under certain conditions. Water blooms of cyanobacteria from the genus Microcystis are of increasing concern due to their production of microcystin, a cyclic heptapeptide which is formed nonribosomally by peptide and polyketide synthetases. A number of studies have targeted the PCR amplification of microcystin synthetase gene cluster for the identification of toxic cyanobacteria, both in cultivated strains and environmental samples. In this study, water samples collected from seven sites and the cultures originated from the cyanobacterial bloom of the Lake Beira were analyzed by polymerase chain reaction (PCR) using the cyanobacterial specific oligonucleotide primers for the 16S rRNA gene and genus specific oligonucleotide primers for the mcy E gene. All DNA samples submitted to PCR reactions yielded the unique fragments of about 450 bp for the 16S rRNA gene and 250bp for the mcy E gene. The results of the BLAST EF051239 showed 98% of the nucleotide homology to the Microcystis aeruginosa gene of 16S ribosomal RNA and EF051238, 95% homology to the mcy E gene of M. aeruginosa (PCC 7941).These results confirm the presence of microcystin producing M. aeruginosa in the Beira Lake and the need for rapid identification of toxin producing cyanobacteria from environmental samples. Keywords : Cyanobacteria, mcy gene, microcystin, Microcystis aeruginosa doi:10.4038/jnsfsr.v36i3.159 Journal of the National Science Foundation of Sri Lanka 36 (3) 229-233
Highlights
Cyanobacteria are aquatic and photosynthetic prokaryotes which form harmful algal blooms (HAB) under optimal conditions such as high light and calm weather
A number of studies have targeted the polymerase chain reaction (PCR) amplification of microcystin synthetase gene cluster for the identification of toxic Microcystis strains[13] and this has enabled the development of specific oligonucleotide primers for genes common to production of all microcystins[14,15]
DNA amplification was performed for the mcyE gene using the modified protocol of Vaitomaa et al.[13] and general microcystin synthetase gene E forward primer mcyE-F2 (5’-GAAATTTGTGTAGAAGGTGC-3’) and the gene specific reverse primer for Microcystis MicmcyER8(5’-CAATGGGAGCATAACGAG-3’)[13].Reaction mixtures contained 0.4 μM of each primer, 0.1 mM of each deoxynucleoside triphosphate, 10 μL of 10xPCR Journal of the National Science Foundation of Sri Lanka 36 (3)
Summary
Cyanobacteria are aquatic and photosynthetic prokaryotes which form harmful algal blooms (HAB) under optimal conditions such as high light and calm weather. A number of studies have targeted the PCR amplification of microcystin synthetase (mcy) gene cluster for the identification of toxic Microcystis strains[13] and this has enabled the development of specific oligonucleotide primers for genes common to production of all microcystins[14,15].
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