Screening endophyte with capability to improve phytoremediation efficiency from hyperaccumulators: A novel and efficient microfluidic method

Screening endophyte is the most important but also difficult to achieve a successful application in endophyte assisted phytoremediation process. Traditional screening procedure faced certain limitations including long time, difficulty in ascertaining the optimum strain and insignificant promotion efficiency of the selected strain in application. In this study, a novel endophyte screening method was established using microfluidic technology, realizing the real time observation of plant root phenotyping and allowing simultaneous incubation of different endophyte-plant systems. Using this method within two weeks, showed that endophyte Bacillus paramycoides (PE1), which possessed the best capability to improve phytoremediation efficiency from hyperaccumulator P. acinosa was successfully screened by evaluating root growth rate and effluent heavy metal (HM) concentration. PE1 increased root growth rate by 54.31 % and reduced the Cd concentration of chip effluent by 46.33 %. The results were verified by pot experiment, which showed that with PE1 inoculation, the biomass of P. acinosa promoted 42.50 % and Cd removal efficiency increased 55.49 %. Besides, significant and positive correlations were observed among the phytoremediation indicators obtained from microfluidic and traditional method, indicating the feasibility of microfluidic method. Our research provided a new and efficient method for endophyte screening, which could give a better understanding of endophyte assisted phytoremediation technology of HM contaminated soil.