Studies on Production and In Vitro Antibacterial Potentials of Violacein from Chromobacterium Violaceum Isolated from Otamiri River in Owerri, Imo State

Abstract

Chromobacterium violaceum was isolated from Otammiri River in Owerri, Imo State. The organism was isolated using nutrient agar and identified based on cultural and biochemical characteristics. The isolate produced violacein pigment on nutrient broth and the violacein produced was quantified and extracted with ethanol. The effects of different temperatures (4°C, 25°C, 30°C, 37°C, 40°C, 52°C), pH (4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0), incubation period (12hr, 24hr, 36hr, 48hr, 60hr, 72hr, 84hr, 96hr), carbon sources (dextrose, fructose, glucose, maltose, lactose, sucrose, starch), nitrogen sources (ammonium nitrate, ammonium chloride, yeast extract, beef extract, peptone) on violacein production by C violaceum isolated were examined. Antibacterial activity of gram negative and gram positive organisms was done and the MIC of violacein was determined. The amount of violacein produced by C violaceum was 34.98mg/l. The production of violacein was increased with increase in temperature reaching its maximum value at 37°C. The optimum pH and incubation time for the production of violacein from the isolate were pH 6.5 and 72hr. Glucose and yeast extracts were most efficient carbon and nitrogen sources for the violacein production from C violaceum isolated. The violacein was highly sensitive to S aureus and Escherichia coli with inhibition zone of 15mm resistant to Klebsiella aerogenes and Pseudomonas aeruginosa with no inhibition zone. This study revealed that violacein has antibacterial activity against Gram positive and Gram negative organisms and provides knowledge of factors influencing the production of violacein. It also revealed the MIC of violacein and the MBC against different bacteria. The findings from this work could be of interest and suggest the need for further investigations in terms of toxicological studies and purification of active components with a view to using violacein in novel drug development.