Preliminary study on the effects of Bacillus subtilis GYH20240327-1 on the microbiome and metabolomics of Platycodon grandiflorus and Scutellaria baicalensis during growth

Objective To investigate the effects of Bacillus subtilis GYH20240327-1, isolated from traditional fermented yogurt, on the rhizosphere microbiomics and metabolomics of Platycodon grandiflorus and Scutellaria baicalensis Georgi. Methods The Bacillus subtilis strain was isolated from yogurt, applied to fertilizer, and used in the planting field. By measuring four apparent plant growth indicators, high-throughput sequencing (16S rRNA and ITS), and LC-MS-based metabolomics analysis of related rhizosphere soil samples, we preliminarily explored and compared the effects of Bacillus subtilis -containing fertilizer on the growth and development, microbial communities, and metabolite profiles of two medicinal plants. Results The results show that fertilization treatment has a certain growth-promoting effect on Platycodon grandiflorus and Scutellaria baicalensis during the critical three-month period from flowering to harvest, and it also reshapes their rhizosphere microbial communities. In Platycodon grandiflorus soil, the abundances of Acidobacteriota and Gemmatimonadota increased, while Proteobacteria decreased. In Scutellaria baicalensis soil, Basidiomycota increased, whereas Ascomycota and Mortierellomycota decreased. Metabolomics revealed significant enrichment in pathways for plant hormone biosynthesis, linoleic acid metabolism, biosynthesis of plant secondary metabolites, and vitamin B6 metabolism. Conclusion Bacillus subtilis GYH20240327-1 can effectively promote the growth and development of the rhizosphere of medicinal plants, alter the soil microbial community structure, and affect the composition of plant metabolites, showing its potential as a biofertilizer to improve cultivation efficiency.