Phytomicrobial remediation technology of PAH-contaminated soils has drawn great attention due to its low-cost, eco-friendly, and effective characteristics, but the mechanism underlying the removal of PAHs by rhizosphere in wastewater-irrigated soil is so far not clear. To evaluate the dissipation of PAHs and the shifts of bacterial community structure under plant-microorganism symbiotic system in an agricultural soil, a rhizo-box experiment with Fire Phoenix (a genotype mixture of Fesctuca arundinecea L.) or/and inoculated Mycobacterium sp. was conducted for 60 days. The changes of bacterial community structure and the contents of PAHs were analyzed by denaturing gradient gel electrophoresis (DGGE) and high-performance liquid chromatography (HPLC), respectively. The results showed that the removal rate of PAHs in phytomicrobial combined treatment was 53.7% after 60 days. The PAH-degraders were dominated by Microbacterium sp., Sphingomonas sp., Mycobacterium sp., and Flavobacterium sp. The plant of Fire Phoenix induced the appearance of Pseudomonas sp. and TM7 phylum sp. oral clone. The highest of bacterial diversity index was observed in unrhizosphere soils (MR-), rather than that in rhizosphere soils (MR+). In combination, phytomicrobial combined treatment of Fire Phoenix and Mycobacterium strain enhanced the removal rate of PAHs and changed the structure of bacterial community and bacterial diversity. Bacterial community has great effect on PAH degradation in PAH-contaminated soil from the wastewater-irrigated site. Our study can provide support information for PAH degradation enhancement by the synergetic effect of Fire Phoenix and Mycobacterium sp.
Keywords: Bacterial community; Phytomicrobial remediate; Polycyclic aromatic hydrocarbons; Rhizoremediation.