Incidence of laccase and biosurfactant producing bacteria from mesophilic to extreme environments to harness potential contribution in dye degradation and antimicrobial activity

Three separate bacterial populations were isolated and screened from diverse locations, classified as mesophiles, halophiles and thermophiles. Halophiles and thermophiles exhibited greater laccase activity than mesophiles and enhanced biosurfactant property noted in thermophiles. Based on phenotypic and biochemical characteristics, T17 was identified as Pseudomonas sp. and H27 as Bacillus sp. Bacillus sp. (laccase positive, best grown at 5% NaCl) was assessed for its ability to degrade Gentian violet, Safranine and Bromothymol blue at 24, 48 and 72 h of incubation across various dye concentrations (1 to 10%). The most effective dye degradation occurred with safranine (24.12%), followed by bromothymol blue (22.85%) and gentian violet, which exhibited over 20.16% degradation at 72 h. Thermophilic Pseudomonas sp. was utilized to assess the antimicrobial activity of its partially purified biosurfactant. It was particularly effective against Fusarium sp., Rhizoctonia sp. and Helminthosporium sp. at concentrations of 250 and 300 μg/ml, but it did not inhibit Alternaria sp. Similarly, the antibacterial activity of partially purified biosurfactant from Pseudomonas sp. was effective against all bacterial pathogens across a broad spectrum of concentrations ranging from 100 to 300 μg/ml. The findings underscore the extensive potential applications of laccase and biosurfactants sourced from halophiles and thermophiles.