Isolation and Characterization of Vibrio Spp. By Sequencing of 16s rDNA From Coelomic Fluid of Sea Urchin (Stomopneustes variolaris)

Author(s): Ravitheja. S and *Chandra. M

Abstract: Aim of the present study was to molecular characterization of bacterial species isolated from coelomic fluid of sea urchin (Stomopneustes variolaris) collected from St. Mary’s Island, Malpe beach, West Coast of India. Two morphologically different species of bacteria viz., Vibrio parahaemolyticus3KCL and Vibrio sp. SOVt012 were isolated and identified by biochemical tests and confirmed through molecular characterization approach. Bacterial 16S rDNA gene was amplified using suitable primers. The amplified 16S rDNA gene sequence was compared with the sequence in NCBI sequence database. The average number of bacterial colonies was recorded with a count of 98 for 1x107cfu/mL. Halophilic nature was determined by streaking the isolates on nutrient agar plate containing 0.5% NaCl. Only Vibrio parahaemolyticus3KCL showed the growth but Vibrio sp. SOVt012 didn’t show the growth and it is confirmed as a true halophile. Limit of halotolerance was analysed for both the isolates on nutrient broth with higher NaCl concentrations and found to be growing well and as a result they are highly halotolerant. The antibacterial activities of cell free isolates were performed by well diffusion method against human bacterial pathogens viz., S. typhi, S. pyogenes, E. coli and E. faecalis. However, a zone of inhibition was not observed against any pathogens. The results indicated that even though coelomic fluid of sea urchin associated with bacteria they didn’t show any antibacterial activity, but it is the reservoir of few halotolerant and halophilic Vibrio spp. This data will be used to provide information on the magnitude of such pathogens in sea urchin.

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