Solubilization of K and P nutrients from coal gangue by Bacillus velezensis

ABSTRACT Accumulation of coal gangue (CG) poses significant risks to both human health and ecological systems, underscoring the urgent need for sustainable methods to utilize this abundant waste material effectively. In this study, we successfully screened and isolated the Bacillus velezensis bacterial strain to enhance the solubilization of potassium (K) and phosphorus (P) nutrients from CG. The study employed XRD, FTIR, SEM, and HPLC techniques to investigate the underlying mechanisms of CG solubilization. Various parameters such as CG particle size, incubation time, initial inoculation ratio, concentration of CG, pH, and temperature were optimized to maximize solubilization efficiency. The Bacillus velezensis bacterium can dissolve minerals of CG by adhering to its surface and secreting various kinds of organic acids, particularly succinic acid. Pot experiments further demonstrated that Bacillus velezensis , in conjunction with CG, promotes alfalfa growth. These combined findings suggest that Bacillus velezensis and coal gangue hold promising potential as mineral soil conditioners, effectively enhancing plant growth. This approach presents a viable alternative for the environmentally responsible utilization of CG, addressing both ecological concerns and agricultural sustainability. IMPORTANCE Coal gangue piles not only occupy significant amounts of arable land but also cause serious environmental pollution. Therefore, finding sustainable methods for the clean utilization of CG is imperative. Although previous studies have shown that bacteria can promote the solubilization of available phosphorus and available potassium from CG, their impact on promoting plant growth remains understudied. To our knowledge, this study is the first to demonstrate the potential of Bacillus velezensis in enhancing the effectiveness of CG as a mineral fertilizer to support alfalfa growth. The evidence presented in this study provides an ecological strategy for the utilization of CG.