Bioflocculant exopolysaccharide (EPS) production by ten (10) cyanobacterial strains comprising of five (05) heterocystous and five (05) non-heterocystous strains during their photoautotrophic growth was investigated. Highest level of EPS was produced by Anabaena sp. BTA992 among the investigated strains with high flocculation capacity. The cyanobacterial EPS consisted of soluble protein and polysaccharide that included substantial amounts of neutral sugars and uronic acid. The flocculant bound a cationic dye, alcian blue, indicating it to be polyanionic. EPS production was maximum during stationary growth phase and late phase of growth at pH 8.5. The strain was identified by 16S rRNA typing and GenBank accession number was obtained as KJ830950. The investigation revealed that this Anabaena sp. could be a potential candidate for the commercial EPS production and might be utilized in applications as an alternative to synthetic flocculants.
Key words: cyanobacteria, exopolysaccharide, flocculants, 16S rRNA typing, pH
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