Polycyclic aromatic hydrocarbons degradation by free-air CO₂ enriched (FACE) bacteria into low molecular easy to degrade organic compounds

Among the 16 prioritized polycyclic aromatic hydrocarbons (PAHs), naphthalene, phenanthrene, fluoranthene, and pyrene have been used for bacterial degradation study. From the free-air CO₂ enriched (FACE) soil, five Bacillus strains were isolated and used to utilize the four model toxicants at different concentrations as the sole carbon source. Bacillus amyloliquefaciens has great resistance to different PAHs and better degradation capability. B. amyloliquefaciens can degrade naphthalene (0.5 mg mL^− 1), fluoranthene (0.1 mg mL^− 1), and pyrene (0.1 mg mL^− 1) up to 94%, 65%, and 56% respectively, while B. cereus mineralized phenanthrene (0.5 mg mL^− 1) up to 71% within seven days of incubation. B amyloliquefaciens and B. cereus have the capability of ring cleavage and they can convert PAH compounds into less toxic compounds. Based on the metabolites obtained through GC-MS, the biodegradation pathways for each PAH have been predicted to end up in the tricarboxylic acid cycle.