Microbial inoculant-induced modifications of rhizospheric metabolites and microbial communities enhance plant growth

Microbial inoculants play important roles in the remediation of abandoned mine sites by stimulating plant growth. However, further investigations are required to elucidate their impacts on soil microbial communities and metabolites in this process.

For this study, we employed amplicon sequencing and Liquid Chromatography-Tandem Mass Spectrometry (LC–MS/MS) techniques to examine the responses of soil microbial communities and metabolic functions to microbial inoculants using a pot experiment.

Our findings indicated that microbial inoculants significantly influenced the structures of both bacterial and fungal communities. Network analyses revealed that microbial inoculants enhanced the stability and complexity of bacterial co-occurrence networks while reducing those of their fungal counterparts. Moreover, microbial inoculants increased the importance of stochastic processes in community assembly, particularly within fungal communities. Metabolomic analyses showed that microbial inoculants significantly modified the metabolic profiles of rhizospheric soil and upregulated metabolic pathways of phenylpropanoids and isoflavonoids. Correlation analyses and structural equation modeling (SEM) analysis further showed that microbial inoculants promote plant growth by influencing keystone microbial genera and the metabolism of phenylpropanoids and isoflavonoids.

Overall, this study demonstrated that microbial inoculants promote plant growth through the modification of rhizospheric keystone microbial taxa and the metabolism of phenylpropanoids and isoflavonoids. These results offer valuable insights into the complex biological processes influenced by microbial inoculants in the rhizosphere.