Rice-associated with Bacillus sp. DRL1 enhanced remediation of DEHP-contaminated soil and reduced the risk of secondary pollution through promotion of plant growth, degradation of DEHP in soil and modulation of rhizosphere bacterial community

Abstract

Di (2-ethylhexyl) phthalate (DEHP) attracted much attention since its excessive accumulation in soil and potential endocrine disrupting effects on human. In order to find an efficient approach for remedying DEHP-contaminated soil while reducing crop safety risk, a plant growth-promoting rhizobacteria (PGPR) with DEHP-degrading ability was isolated and identified as Bacillus sp. DRL1. The phytoremediation system that integrated the use of rice and DRL1 into remediation of DEHP-contaminated soil was evaluated. The results showed that DRL1-assisted rice effectively remove 83.9 % DEHP from soil within 30 d. Interestingly, the DEHP content in rice was significantly reduced by 7.7 % compared to non-inoculation treatment, which meant that due to its degradation ability, DRL1 could directly participate in the DEHP degradation in soil. Moreover, the inoculation of DRL1 could alleviate the negative effects of DEHP on rice and then improved its shoot height (31.4 %), root length (31.9 %) and dry weight (24.1 %), which might indirectly improve the phytoremediation efficiency of DEHP-contaminated soil. Above all, this study provided new perspective for the improvement of DEHP removal from soil by a phytoremediation approach while decreasing the secondary pollution risk. The important roles of soil enzyme and rhizosphere bacterial community in this phytoremediation process were also investigated and discussed.