Response of Soil Microbiome Structure to Biological Control Agents (BCAs) in Strawberry Greenhouse

Continuous cropping always leads to severe abiotic and biotic problems, especially the high-intensity land utilization in greenhouses, which causes widespread concern. Effective Microorganisms (EM) and Bacillus subtilis (BS) have been widely used to promote plant growth and increase yields as biological control agents (BCAs). However, their effects on soil microbes are obscure. To regulate the microbial community in continuous cropping strawberry soils, we developed four soil amendments by combining EM and BS with compost. The amplicon sequencing of bacterial and fungal ribosomal markers was applied to study the response of the soil microbiome structure. We noticed a sharp increase in bacterial diversity after the addition of EM-treated high compost and BS-treated low compost, while there was no significant change in fungal diversity among treatments. Interestingly, both the relative abundance and FUNGuild predictions was consistent in revealing that BCAs may inhibit fungal pathogens in soils. Correlation analysis indicated that soil microbial community was indirectly driven by soil properties. Co-occurrence networks demonstrated that BCAs could be microecologically homogeneous through enhancing bacterial network complexity and modularity. Collectively, EM-treated high compost and BS-treated low compost can well regulate the microbial community structure and thus maintain soil health.