Purification, characterization and production optimization of a vibriocin produced by mangrove associated Vibrio parahaemolyticus

Objective: To identify a potential bacterium which produces antimicrobial peptide (vibriocin), and its purification, characterization and production optimization. The bacteria subjected in the study were isolated from a highly competitive ecological niche of mangrove ecosystem. Methods: The bacterium was characterized by phenotype besides 16S rRNA gene sequence analysis. The antibacterial activity was recognised by using agar well diffusion method. The vibriocin was purified using ammonium sulphate precipitation, butanol extraction, gel filtration chromatography, ion-exchange chromatography and subsequently, by HPLC. Molecular weight of the substance identified in SDS-PAGE. Production optimization performed according to Taguchi's mathematical model using 6 different nutritional parameters as variables. Results: The objective bacterium was identified as Vibrio parahaemolyticus. The vibriocin showed 18 KDa of molecular mass with mono peptide in nature and highest activity against pathogenic Vibrio harveyi. The peptide act stable in a wide range of pH, temperature, UV radiation, solvents and chemicals utilized. An overall ~20% of vibriocin production was improved, and was noticed that NaCl and agitation speed played a vital role in secretion of vibriocin. Conclusions: The vibriocin identified here would be an effective alternative for chemically synthesized drugs for the management of Vibrio infections in mariculture industry.