Degradation of cationic dyes and alkali lignin using DyP-producing Bacillus cereus SDP6 isolated from similipal biosphere reserve soil.

Unlabelled: Dye-contaminated industrial effluents pose a serious environmental impact and need immediate attention. Due to the significant role of Dye-decolorizing peroxidases (DyPs) producing ligninolytic bacteria in the degradation of various industrial dyes, ligninolytic bacteria were isolated from Similipal Biosphere Reserve, Odisha, and screened for their DyP activities. Six out of 12 isolated bacteria (SDP1-12) showed DyP activity. SDP6 having highest DyPase activity of 2.67 U/mL/min, was identified as through biochemical and 16 S rRNA sequence analyses. SDP6 was able to degrade alkali lignin (55.74%) and decolorize76.49% of methylene blue (MB) compared to crystal violet, brilliant green, malachite green, and azure B with decolorization percentages of 60.85%, 56.79%, 32.69%, and 55.13% respectively. Optimization by Response Surface Methodology enhanced decolourization of MB upto 83.15% with an increase of 1.08 times from unoptimized conditions. Decolourization of MB by SDP6 best fitted with the pseudo-second-order kinetic model and Langmuir isotherm model, exhibited decolourization of 285.71 mg/L MB. Bacterium-treated MB showed spectral shifts in spectral analyses, indicating degradation of MB, which was evident from the phytotoxicity studies. The present study revealed that SDP6 is a non-pathogenic and non-antibiotic-resistant bacteria offering efficient degradation of dye-contaminated industrial effluents.

Supplementary Information: The online version contains supplementary material available at 10.1038/s41598-025-16278-w.