Correlations between soil metabolomics and bacterial community structures in the pepper rhizosphere under plastic greenhouse cultivation

Microbial communities in the plant rhizosphere are critical drivers of soil organic matter conversion and thus affect plant growth, especially under plastic greenhouse vegetable cultivation (PGVC). By high-throughput sequencing and soil metabolomics, we investigated the differential structures and functions of the soil bacterial community in pepper rhizosphere and bulk soils under PGVC. It was found that the soil properties, including the total dissolved organic carbon content, did not show significant differences between the rhizosphere and bulk soil. However, the soil metabolite profiles and the soil bacterial community structures changed in pepper rhizosphere. Eleven differential metabolites were detected between rhizosphere and bulk soils, including organic acids and sugars, which were positively or negatively correlated with the relative abundances of the differential bacteria. Pathway enrichment analysis indicated that the most differentially expressed metabolic pathway was starch and sucrose metabolism, and the main functional genes participating in this pathway were predicted to be downregulated in rhizosphere soil. This study linked the differential soil microbe and soil metabolite profiles in the pepper rhizosphere under PGVC and provided new insights into plant-microbe interactions in soil.