Taxonomic identification, phenol biodegradation and soil remediation of the strain Rhodococcus sacchari sp. nov. Z13^T

Phenols are highly toxic chemicals that are extensively used in industry and produce large amounts of emissions. Notably, phenols released into the soil are highly persistent, causing long-term harm to human health and the environment. In this study, a gram-positive, aerobic, and rod-shaped bacterial strain, Z13^T, with efficient phenol degradation ability, was isolated from the soil of sugarcane fields. Based on the physiological properties and genomic features, strain Z13^T is considered as a novel species of the genus Rhodococcus, for which the name Rhodococcus sacchari sp. nov. is proposed. The type strain is Z13^T (= CCTCC AB 2022327^T = JCM 35797^T). This strain can use phenol as its sole carbon source. Z13^T was able to completely degrade 1200 mg/L phenol within 20 h; the maximum specific growth rate was μ_max = 0.93174 h^-1, and the maximum specific degradation rate was q_max = 0.47405 h^-1. Based on whole-genome sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, strain Z13^T contains a series of phenol degradation genes, including dmpP, CatA, dmpB, pcaG, and pcaH, and can metabolize aromatic compounds. Moreover, the potential of strain Z13^T for soil remediation was investigated by introducing Z13^T into simulated phenol-contaminated soil, and the soil microbial diversity was analyzed. The results showed that 100% of the phenol in the soil was removed within 7.5 d. Furthermore, microbial diversity analysis revealed an increase in the relative species richness of Oceanobacillus, Chungangia, and Bacillus.