Abstract

This study aimed to screen and isolate a purple-violet pigment-producing bacterium from soil samples collected from Talley Valley Wildlife Sanctuary, India, and develop an optimized procedure for enhanced pigment production for potential industrial, agricultural, and medicinal applications. A preliminary study was also conducted to evaluate textile-dyeing properties of the pigment produced by the bacterium. The purple–violet-colored bacterium was isolated on a nutrient agar plate, and a pure culture was prepared and maintained for further studies. The bacterium’s identity was established using both morphological and molecular (16S rRNA gene sequence analysis) approaches. An optimum culture medium was developed for enhanced pigment production by adjusting various growth factors, such as pH, temperature, incubation period, and concentration of media components, for maximum pigment production. The isolated bacterium strain NFML 5214 (PV613353.1) was identified as Chromobacterium vaccinii based on 16S rRNA gene sequence analysis, which showed 99.07% similarity to C. vaccinii strain 21-1 (CP017707.1). The bacterium produced the maximum amount of pigment on the 6th day of incubation at pH 6 and 30°C with optimized concentrations of peptone (7 g/L), beef extract (4 g/L), and NaCl (2 g/L). The total yield of pigments in the optimized medium (192 mg/L) showed a 69.42% increase compared with the yield of the basal medium (113 mg/L). A hot water extract dyeing process of white muslin cloth revealed dark purple fastness. Since C. vaccinii is reported to produce violacein and deoxy-violacein, further studies are needed to characterize the pigments and evaluate their potential medicinal properties, such as antimicrobial, antidiabetic, and antioxidant properties, and industrial value, such as pharmaceutical and textile dyes as an alternative to synthetic dyes.

Key words: 16S rRNA gene, Chromobacterium vaccinii, purple-violet pigment, Soil bacterium.