Bioprospecting for genes involved in the production of chitosanases and microcystin-like compounds in Anabaena strains

Bioinformatic tools guided PCR amplification assays were employed for analyzing two Anabaena strains A. laxa and A. iyengarii which exhibited chitosanase activity, allelopathic and fungicidal activity. Sequencing of a 297 bp fragment obtained by amplification with primers directed towards mcy A gene (involved in the production of microcystins), revealed significant similarity with the condensation domain, while amplification with specific primers towards N-methyltransferase (NMT) domain showed 59% similarity with a homologous domain in a toxic strain of Microcystis aeruginosa. An amplified product of 172 bp obtained using specific primers derived from the coding region of chitinase (chi IS) gene in Streptomyces sp., showed 100% similarity with hydrogenbyrinic acid a, c-diamide cobaltochelatase gene in Anabaena, and significant similarity with chi IS gene of Streptomyces sp. under less stringent conditions. The 663 bp sequence obtained by employing specific primers for chitosanase (choA) derived from Mitsuaria chitosanitabida 3001 strain, showed 100% similarity with glycoside hydrolase family three domain like protein(s). This study is a first time report on the presence of homologues of chitosanase in cyanobacteria which can play a role in allelopathic activity exhibited by these oxygenic photosynthetic prokaryotes.