CLONING AND EXPRESSION OF GENES ENCODING VIOLACEIN BIOSYNTHESIS FOR INHIBITING PROTOZOAN PREDATION

Abstract

 Violacein is a natural violet pigment that is produced by several bacterial strains. It has an antiprotozoal property. Violacein-producing genes, vioABCDE, were obtained by PCR from two strains of Chromobacterium violaceum and two strains of Janthinobacterium lividum, respectively. A pBR322 derivative plasmid vector, pKNA94, was used for cloning of the genes, and they were expressed under the control of trp promoter in Escherichia coli JM109. Transformants of E. coli JM109 having each vioABCDE developed violet colonies. The colony of transformant having the genes from C. violaceum JCM1249 showed the strongest violet color. The transformant was used for grazing experiments with bacterivorous protozoa isolated. Protozoan grazing was remarkably inhibited, and it was found that the violacein producing recombinant had a strong antiprotozoal activity.