Bioproduction, optimisation, and spectral characterisation of red pigment from Deinococcus proteolyticus as a sustainable natural pigment for industrial applications

Deinococcus has received substantial acceptance for its bioremediation activity. Howbeit, one of its red-pigmented species (Deinococcus proteolyticus) is yet to be explored as a potential natural dye for fabrics. In this study, Deinococcus proteolyticus was isolated from abattoir wastewater. The optimum conditions for intense pigment production were investigated with different parameters (agitation, inoculum size, temperature, pH, and incubation time). The ethanolic extract of the red pigment derived from Deinococcus proteolyticus was characterized using UV–visible spectrophotometer, Fourier Transform Infra-Red (FTIR) Analysis, and Gas-Chromatography-Mass Spectrometry (GC–MS). The red pigment was explored as an antibacterial and natural dye for fabrics. This study identified Deinococcus proteolyticus optimum conditions for intense red pigment production as 1% standardized inoculum in pH medium 7, placed in an incubating shaker (120 rpm) at 25 °C for 60 h. The UV–visible spectrum of the ethanol-extracted red pigment showed surface plasmon resonance peaks at 261 and 481 nm. The FTIR spectral peaks of the red pigment indicate the presence of several functional groups among which are alkyne C–H bend (618.7 cm−1), skeletal C–C vibrations (950.5 cm−1), H-bonded OH stretch (3347.1 cm−1). The GC–MS analysis detected 15 compounds among them are n-Hexadecanoic-acid, 9,12,15-Octadecatrien-1-ol, (Z, Z, Z)-, Phytol and 9,12-Octadecadienoic-acid, ethyl-ester which are relatively abundant. The red pigment showed no antibacterial activity but was retained on fabrics when used as a natural dye. This study concluded that the bio-produced red pigment from Deinococcus proteolyticus has great potential as a simple, cost-effective, eco-friendly and sustainable natural dye for fabrics and other industrial uses.