Characterization and antibacterial activity of violacein producing deep purple pigmented bacterium Pseudoalteromonas luteoviolacea (Gauthier, 1982) isolated from coral reef ecosystems

Abstract

The present study describes the isolation, characterization and antibacterial activity of two strains of the deep purple pigmented bacterium Pseudoalteromonas luteoviolacea designated P42 (Accession no. MN647538) and M64 (Accession no. MN647537), isolated from two coral reef regions viz. Minicoy Lagoon in the Lakshadweep Sea and Palk Bay, off Olaikuda village in Tamil Nadu, India. Ultrastructural examinations were done using scanning and transmission electron microscopy. Presence of violacein pigment was qualitatively analysed by chemical methods; UV-VIS spectrophotometry and FTIR spectroscopy. The strains, P42 and M64 were found to have antibacterial activity against 13 out of the 36 marine bacterial species tested. Antibiogram analysis revealed the sensitivity of both the strains to all the antibiotics tested, except for the resistance of P42 to Penicillin G and Trimethoprim. This study reports the isolation and characterization of P. luteoviolacea for the first time from India. Since both the isolated strains have shown clear evidence for the presence of violacein as well as antibacterial activity against selected marine bacteria, both P42 and M64 can be suggested as potent antibacterial agents.