ANTIBACTERIAL, ANTIOXIDANT AND CYTOTOXIC ACTIVITY OF BACTERIAL CAROTENOIDS ISOLATED FROM RHODOPSEUDOMONAS PALUSTRIS KRPR01 AND KRPR02

The microbial pigments have more applications than synthetic pigments and are easily biodegradable and safe to use. Among all bacteria, the anoxygenic phototrophic purple non-sulfur bacteria have more applications and can synthesize different pigments. In this present study, bacterial carotenoids were isolated from the two novel strains of Rhodopseudomonas palustris and evaluated its applications. The antibacterial activity was studied by zone inhibition method. The pigment A1 and A2 showed more antibacterial activity against gram-negative and gram-positive bacteria. In-vitro antioxidant activity of bacterial pigments and bacterial extracts were evaluated by DPPH assay. The pigment A2 and Rp. KRPR02 showed more radical scavenging activity. The percentage inhibition of DPPH radical for pigment A2 (82.74 ± 4.49) and bacterial extract of Rp. KRPR02 bacteria (83.33 ± 5.46) is almost nearer to the percentage inhibition of DPPH radical for standard (ascorbic acid) which is 96.41 ± 1.81. In-vitro cytotoxic activity was studied by MTT assay and found that the pigments showed cytotoxic activity against the HeLa cell line, DU145 cell line, MCF7 cell line and Miapaca -2 cell line. The pigments were found to have significant antibacterial, antioxidant and cytotoxic activity, thus can be used as potential biological agents in medicine.