Enhanced degradation of polycyclic aromatic hydrocarbons (PAHs) in the rhizosphere of sudangrass (Sorghum × drummondii).

Grasses are advantageous in the removal of polycyclic aromatic hydrocarbons (PAHs) in soil because of their fibrous root, high tolerance to environmental stress, and low nutritional requirements. In this study, a pot experiment was conducted to test the ability of four grasses to remove PAHs in the soil, and to investigate the corresponding bacterial community shift in the rhizosphere of each. Sudangrass achieved the maximum removal of PAHs at 98% dissipation rate after 20 days. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and next-generation sequencing revealed that sudangrass specially enriched the growth of a known PAHs degrader, Sphingomonadales, regardless of the presence or absence of PAHs in the soil. Moreover, the gene copy numbers of PAHs catabolic genes, PAH-RHDα and nidA, as measured by real time-PCR (RT-PCR) were highest in the soil planted with sudangrass. Overall, this study suggested that sudangrass further enhanced the dissipation of PAHs by enriching Sphingomonadales in its rhizosphere.
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