Assessment of PAH degradation potential of native species from a coking plant through identifying of the beneficial bacterial community within the rhizosphere soil

Abstract

Understanding the mechanisms underlying plant–rhizobacteria interactions in field-contaminated soils is crucial for designing effective rhizoremediation strategies. This study aimed to test the ability of four native herb species to remove polycyclic aromatic hydrocarbons (PAHs) and to analyze their associated bacterial community structures and functional genes within the rhizosphere from the abandoned site of a former Shenyang coking plant in China; the bulk soil was collected as control. All four species removed PAHs, of which the rhizosphere of Kochia scoparia had the highest PAH removal rate (almost 30.2%). Although the composition of the bacterial community within the rhizosphere varied among plant species, all plant species could promote the growth of Sphingomonas, Pedomicrobium, Rhodoplanes, Blastoccus, Mycobacterium, Devosia, and Pseudomonas, and their relative abundance positively correlated with the removal rates of PAHs, soil moisture, and total carbon/total nitrogen in the rhizosphere. Moreover, the activities of 1-aminocyclopropane-1 -carboxylic deaminase gene and Gram-negative ring-hydroxylating dioxygenase gene significantly (P < 0.05) increased compared with those in the control, and these activities had a strong positive correlation with the removal rates of PAHs [r = 0.759 (P < 0.01) and 0.87 (P < 0.01), respectively]. The findings of this study indicated that PAHs were the main factor driving the composition of beneficial bacteria in PAH rhizodegradation, and the PAH rhizoremediation of native plants grown in coking plant can be controlled though altering soil properties.