Mineral-solubilizing microbial inoculants facilitate the rejuvenation of soil multifunctionality and plant growth at abandoned mine sites

The mining industry continues to have considerable adverse effects on ecosystems, which necessitates the development of robust and effective strategies for the remediation of abandoned mine sites. One such approach involves the integration of mineral-solubilizing microorganisms into existing external soil spray seeding technologies. These microorganisms have the capacity to reduce mineral particle sizes, stimulate plant growth, and facilitate the release of essential soil nutrients. Despite the potential benefits of mineral-solubilizing microbial inoculants, their impacts on overall soil multifunctionality and microbial communities, associations with microbial diversity, soil multifunctionality, and plant growth remain largely unknown. To bridge these knowledge gaps, we conducted a 1-year greenhouse experiment, which involved a comprehensive assessment of various parameters including soil nutrients, enzyme activities, functional gene copies, and microbial communities. Our findings unveiled that the application of mineral-solubilizing microbial inoculants led to a significant augmentation of soil multifunctionality. Additionally, the application of microbial inoculants increased the relative abundances of Bacilli (class), Bacillales (order), Bacillaceae (family), and Bacillus (genus). While no significant relationship emerged between microbial alpha diversity and soil multifunctionality, our investigation found positive correlations between the Bacillus groups, keystone ecological cluster, and soil multifunctionality. Furthermore, our results suggested that the indirect impact of microbial inoculants on plant growth was primarily channeled indirectly through their influence on Bacilli, keystone ecological cluster, and soil multifunctionality, as opposed to changes in the overall bacterial or fungal diversity. Overall, our study underscores the significance of mineral-solubilizing microbial inoculants for the rejuvenation of abandoned mine sites, while providing valuable insights for future research aimed at optimizing the efficacy of external soil spray seeding techniques.