Exploring the PAHs dissipation and indigenous bacteria response in soil amended with two different microbial inoculants

This study investigated the bioremediation of PAHs in soil by two different microbial inoculants prepared with Paracoccus aminovorans HPD-2 and the carrier humic acid (HA) or montmorillonite (Mont). After incubation for 42 d, the greatest removal of PAHs, 42.8 % or 41.6 %, was observed in microcosms with 0.2 % HA inoculant or 2 % Mont inoculant. The PAH removal efficiency in these treatments was significantly greater than that in soil amended only with planktonic HPD-2. Bacterial community analysis showed that the survival of Paracoccus aminovorans was enhanced in the treatments with Mont inoculant compared with the treatments with HA inoculant or with HPD-2 alone. Moreover, the diversity of PAH-degrading bacterial genera was greater in the treatments containing Mont inoculant than in the treatments containing HA inoculant. These results indicate that the organic material HA and inorganic material Mont promote PAH removal in different ways. Specifically, HA promotes PAHs bioavailability to accelerate the degradation of PAHs in soil, whereas Mont protects PAH-degrading microorganisms to promote pollutant removal. Overall, the findings suggest that HA and Mont are promising materials for microbial immobilization for the bioremediation of PAH-contaminated soil.

Automated summary

This study investigated the bioremediation of PAHs in soil using different microbial inoculants prepared with Paracoccus aminovorans HPD-2 and the carrier humic acid (HA) or montmorillonite (Mont). The results showed that the greatest removal of PAHs was observed in microcosms with 0.2% HA inoculant or 2% Mont inoculant. Bacterial community analysis revealed that the survival of Paracoccus aminovorans was enhanced in the Mont inoculant treatments compared to the HA inoculant treatments. Furthermore, the treatments containing Mont inoculant had a greater diversity of PAH-degrading bacterial genera compared to the treatments containing HA inoculant.