Reclamation of waste coal gangue activated by Stenotrophomonas maltophilia for mine soil improvement: Solubilizing behavior of bacteria on nutrient elements

The coal gangue has occupied the farmland and caused severe pollution to the surrounding environment, which was discharged with vast amount as a by-product of coal mining and washing. A sustainable and ecological microorganism activation method was proposed to disposal coal gangue as mineral fertilizer. A Stenotrophomonas maltophilia YZ1 bacteria was separated and found to be useful in solubilizing nutrient elements in coal gangue. The contents of available P, available K and available Si in the treated coal gangue reached 278.4 mg/kg, 1305.3 mg/kg and 522.7 mg/kg, respectively. The YZ1 bacteria dissolved the minerals of monetite (CaHPO4), muscovite and annite by the organic acids, which were the metabolism product of YZ1 bacteria. The solubilizing mechanisms of phosphate minerals included the release of protic and the chelation of organic acid with calcium. The microbial activation method can provide nutrient elements for soil, which may realize the reclamation of coal gangue in a harmless way. [Display omitted] •Activation of P, K and Si by microorganism as agriculture fertilizer is approach to the reclamation of waste coal gangue.•A Stenotrophomonas maltophilia YZ1 strain was found to have obviously solubilization function for available P, K and Si.•P is mainly loaded in monetite (CaHPO4), while K occurs in the muscovite and Si mainly exists in quartz and kaolinite.•The solubilization of P is caused by acetic acid, formic acid and tartaric acid produced by YZ1 bacteria metabolism.•The dissolution mechanism of CaHPO4 is mainly included protonation of organic acid and chelation of organic ligand.