Evaluation of Cyanobacterial toxicity against corresponding field-soil Bacteria

Abstract

Toxic property of locally isolated Cyanobacterial strains were evaluated against soil bacteria, isolated from respective rice fields. Cyanobacterial samples, locating visually either conspicuous growth on soil surface or floated /submerged inlogged water, were collected, identified and isolated as an axenic culture. In the meantime soil samples from concerned fields were also collected for isolation of bacteria. Using recommended media, bacterial strains were isolated and characterized biochemically. Crude extracts of three Cyanobacterial strains (Oscillatoria curviceps, Lyngbya shackletoni. and Anabaena unispora) were taken for assessment of its antibacterial activity against Gram +ve and Gram –ve bacterial isolates i.e. Staphylococcus sp. Xanthomonas sp. Bacillus sp., proteus sp. and Klebsiella sp. respectively.  Maximum growth-inhibition of bacterial isolates was found by crude extract of Oscillatoria curviceps rather Lyngbya shackletoni and Anabaena unispora correspondingly. Observation of present investigation reveals that exotoxins released by Cyanobacterial strains exhibit antibacterial property that may affect to microbial community of agriculture fields and ultimately to the nature/ quality of soil.