Evaluation of Growth Kinetics of Chromobacterium violaceum and Antimicrobial Activity of Violacein

The study was carried in order to estimate the growth rate of the Chromobacterium violaceum and antibacterial and antifungal activities of the violacein a violet color dye that is produced by this bacterium. The results revealed that C. violaceum showed a typical growth curve with all the four phases. There is a maximum growth in the time period of 6 to 18 h after the inoculation that represents the exponential phase. The doubling time during this phase was found to be 1.246 h. Production in a 5 L bubble column reactor was done and the antibacterial and antifungal activities of violacein extracted from the bacterium was tested against three Gram-positive bacteria: Staphylococcus aureus, Bacillus subtilis, Bacillus cereus; two Gram-negative bacteria: Escherichia coli, Proteus vulgaris; and one fungal strain Aspergillus niger. It clearly showed that violacein is able to inhibit the strains of Staphylococcus aureus, Bacillus subtilis, and Bacillus cereus. The maximum inhibition is seen in Staphylococcus aureus with an inhibition zone of 5 mm.