ANTIBACTERIAL EFFECT OF PIGMENTS OF THE GENUS JANTHINOBACTERIUM

Microbial pigments are known among natural sources, including melanin, pyocyanin, bacteriochlorophyll, violacein, prodigiosin and carotenoids, which exhibit a variety of biological activity as antioxidants and demonstrate anti-inflammatory, anti-cancer, antiparasitic and antimicrobial properties. Isolation, research and identification of pigment-producing strains are of interest for the development of biotechnological processes aimed at industrial biosynthesis of these compounds. The antibacterial properties of blue-violet (VIO) and red (RED) pigments of new strains of bacteria IB-ST-GO and IB-ST-GOR isolated from natural waters of the Shulgan-Tash cave's vaucluse spring (Southern Urals) have been studied. Sequence analysis of the 16S rRNA gene revealed that the producers of IB-ST-GO and IB-ST-GOR pigments belong to representatives of Janthinobacterium lividum with a similarity level of 99.72 and 99.86% respectively. The pigments were extracted with 96% ethanol from biomass obtained by cultivating strains on Wakimoto agar medium. According to the results of spectrophotometric analysis, it was found that the VIO pigment belongs to the violacein family, and the RED pigment belongs to the prodigiosin family. The isolated pigments were tested for antibacterial action against 8 types of gram-positive and gram-negative bacteria, inhibitory concentrations of both crude preparations were determined. VIO and RED pigments exhibit an inhibitory effect in the concentration range of 1.0-5.0 mg/ml for a sample of gram-positive bacteria, whereas for gram-negative bacteria, the level of inhibitory concentrations for RED is 10.0-20.0 mg/ml, and for VIO above 20.0 mg/ml. RED pigment exhibits a more dose-dependent effect and a higher selectivity towards gram-positive bacteria than VIO. Together, both pigments are strong inhibitors of the growth of grampositive bacteria, while the antimicrobial activity of both pigments against gram-negative bacteria is low.