Efficient benzo[a]pyrene bioremediation by a novel halotolerant Rhodococcus ruber TN-1 in salinity environment: Mechanical insight from whole-genome, degradation efficiency and microbial properties

Benzo[ a ]pyrene (BaP) contamination in highly saline environments has received increasing attention; however, efficient degradation of BaP by halotolerant BaP-degrading bacteria from contaminated water and soils remains poorly understood. In this study, a novel BaP-degrading bacterium, designated Rhodococcus ruber TN-1, was isolated, and its BaP degradation performance was evaluated. Whole-genome sequencing revealed genes and gene clusters associated with benzoate and xylene transport and degradation, naphthalene degradation, and the catabolism of other aromatic compounds. Strain TN-1 exhibited high BaP degradation efficiency in water, with a degradation efficiency exceeding 95% after 3 d of cultivation. Inoculation with strain TN-1 significantly improved the BaP degradation efficiency in three types of saline soil. After 14 d of reaction, the BaP degradation rate increased from 12.08% to 26.94% in the control to 44.03–59.12%. Correlation analysis revealed that the degradation rate of soil BaP was positively correlated with soil catalase (CAT) activity and negatively correlated with salinity. Metagenomic and quantitative real-time PCR (qPCR) analyses demonstrated that the addition of strain TN-1 significantly increased microbial abundance in three saline soils, with strain TN-1 becoming the dominant microorganism and accelerating the microbial degradation of BaP. These findings highlight strain TN-1 as a promising bioaugmentation agent for the remediation of BaP-contaminated saline soils.