The isolation of benzo[a]pyrene-degrading strain and its cometabolic bioremediation with salicylic acid of long-term PAH-polluted soil

Polycyclic aromatic hydrocarbons (PAHs) are typical contaminants in soil, and the high-molecular-weight (HMW) PAHs are especially recalcitrant to remove. Microbial degradation as a promising approach has been used in PAH-polluted soil remediation; however, the removal of HMW PAHs still needs to be further explored. In order to isolate more HMW-PAH-degrading strains and improve the removal of HMW PAHs in long-term contaminated soil. Benzo[a]pyrene (BaP), as a representative HMW PAH was selected to explore the removal of HMW PAHs from soil. A BaP-degrading strain named Achromobacter xylosoxidans B-2 was isolated, and its degradation ability was explored in mineral salt medium (MSM) and PAH-contaminated soil. Cosubstrates were added to enhance the removal of PAHs in soil. The results showed that A. xylosoxidans B-2 could remove 87% of BaP at a concentration of 1 mg/L within 15 days in MSM. The average removal efficiency of HMW PAHs in soil was 19.92% after 30-day bioremediation by A. xylosoxidans B-2. Salicylic acid as cosubstrate increased the removal efficiency by 11.32%-14.66% for five-ring PAHs and 9.72%-13.02% for six-ring PAHs, respectively. The addition of cosubstrate not only improved the soil properties but also stimulated the soil microbial activity to enhance the removal of HMW PAHs. This study may provide new insights into bioremediation for HMW-PAH-contaminated soil.

Automated summary

In this study, a BaP-degrading strain named Achromobacter xylosoxidans B-2 was isolated and its degradation ability was explored in mineral salt medium (MSM) and PAH-contaminated soil. The results showed that A. xylosoxidans B-2 could remove 87% of BaP in 15 days in MSM and the average removal efficiency of HMW PAHs in soil was 19.92% after 30-day bioremediation. In addition, the addition of cosubstrates increased the removal efficiency of PAHs.