The potential role of electric field in enhancement of microbial-assisted phytoremediation of dibutyl phthalate contaminated soil

Abstract

Dibutyl phthalate (DBP) continues being one of the most frequently detected plasticizers in agricultural soils. Electrokinetic-assisted bioremediation was considered as one of the eco-friendly and sustainable treatment systems for contaminated soils. Moreover, as an auxiliary factor, plant growth promoting rhizobacteria (PGPR) received increasing attention recently in improving phytoremediation efficiency, and the PGP traits might be enhanced by electric fields application. Therefore, the feasibility of the combined application of electricity and PGPR in assisting phytoremediation was innovatively verified in this research. The results showed that the DBP removal efficiency of maize inoculated with PGPR strain DCZL-2 increased from 58 % to 62 % compared to only phytoremediation process. and the electric field further enhanced the contaminated soil remediation (11 %). Interestingly, PGPR promoted the maize absorption of Na+ from DBP-contaminated soil, while the electric field could strengthen the excretion of Na+ from plant cells (19 %). Additionally, DCZL-2 was observed to increase the plants photosynthesis (10 %), and the microcurrent could further improve the photosynthetic efficiency (40 %). Furthermore, compared to the single PGPR-plant group, the increased relative abundance of DBP-degrading bacteria and denitrifying bacteria could enhance DBP biodegradation and soil nutrient cycling. Therefore, in addition to the growth-promoting properties of PGPR on maize growth, the electric fields could further alleviate the DBP stress on plants, thereby achieving higher remediation efficiency. Overall, this study confirmed that the combined use of electricity and PGPR-assisted phytoremediation could ecologically and efficiently remediate DBP-contaminated soil.