Application of biochar with functional microorganisms for enhanced atrazine removal and phosphorus utilization

At present, the soil is facing serious problems of reduced nutrient utilization and organic pollution. In this study, a straw-based biochar BC550 with four phosphate-solubilizing bacteria and Acinetobacter lwoffii DNS32, a degrading bacteria of herbicide atrazine were co-cultured as a combined application to improve soil available phosphorus while repairing the atrazine contaminated soil. The porous structure and surface characteristics of BC550 ensures its ability to adsorb atrazine and is beneficial to the phosphorus solubilization of phosphate-solubilizing bacteria. Phosphate-solubilizing bacteria could use the intermediate metabolites produced during the degradation of atrazine by strain DNS32 to grow and secrete low molecular weight organic acids to promote the expression of atrazine-degrading genes trzN, atzB, and atzC in strain DNS32. The addition of BC550 directly increases the total and available phosphorus content in the soil, and may further stimulate degradation by concentrating of atrazine in proximity of the degrading bacteria on the biochar surface. The combined application showed 49% higher ability to degrade 100 mg L−1 atrazine within 24 h and 27% higher ability to degrade 20 mg kg−1 atrazine within 3 days than pure degrading bacteria DNS32, in liquid and soil experiments, respectively. This research will help provide a promising in situ remediation technique to improve the quality of the soil environment. •Biochar BC550 could increase the activity of phosphate-solubilizing bacteria.•Phosphate-solubilizing bacteria use atrazine metabolites to growth.•Low molecular weight organic acids increased the degradation ability of strain DNS32.