Rav Nidhi H., Mistry Rakesh N. and Panchal Hetal K.
Abstract
Cyanobacteria are Gram-negative microbes which are also known as blue-green algae, play significant roles ecologically. In this study, 35 different aquatic and terrestrial samples were collected from different regions of India. All the samples were inoculated in liquid BG-11 medium for enrichment. These enriched samples were used to isolate cyanobacteria on a BG-11 agar medium. 20 cyanobacterial species were isolated and identified based on their morphological characteristics. Different parameters like growth rate, chlorophyll estimation, and protein estimation were performed. 10 species were tested for the production of antimicrobial compounds from algal pellets and supernatants against 3 Gram-negative and 1 Gram Positive bacteria. Oscillatoria sp. (C2) pellet showed the highest inhibitory activity against Escherichia coli with a zone size of 22 mm. An Oscillatoria sp. (C4) pellet and supernatant were found most effective against Pseudomonas aeruginosa and Staphylococcus aureus giving 14mm and 15mm size inhibition zones respectively. The Phormidium sp. (C29) supernatant showed inhibitory activity against Salmonella typhimurium with a 15mm zone size. The same 10 isolates were used to check Zinc (Zn) and Copper (Cu) biosorption efficacy with both immobilized and free biomass for 50ppm and 100 ppm concentrations. Biosorption of Zn and Cu metals with immobilized cells showed good results compared to free biomass for both concentrations. All the parameters were performed in triplicates. This study demonstrates the efficacy of isolated cyanobacterial species in antimicrobial compound production and metal biosorption.