Bacillus subtilis bioorganic fertilizer regulates Brassica chinensis L. growth and soil microflora changes

As a functional probiotic, Bacillus subtilis can be used as a bio-organic fertilizer to replace the use of chemical fertilizers while maintaining soil fertility. However, the effects of bacillus subtilis bioorganic fertilizer application on yield and quality of Brassica chinensis L. commercial crop, soil physical and chemical properties and microflora have not been clarified. Using high-throughput sequencing, we conducted pot experiments using Brassica chinensis L. plants subjected to four fertilization treatments: control without fertilization (CK), chemical fertilizer application (CF), organic fertilizer application (OF), and bioorganic fertilizer application (BF). Compared with CK, BF had significant higher soil available potassium and pH values, increased plant height and biomass, significantly improved quality parameters, and decreased the diversity of bacterial and fungal communities. PCoA analysis showed a clear separation of bacterial and fungal communities from BF and CK, with significant enrichment of Bacillus, Ammoniphilus (bacteria) and Trichoderma, Mortierella (fungi) treated with BF. Network analysis indicated bacteria dominate among soil microbes and that Bacillus subtilis was able to stimulate the development of beneficial microbial communities. In addition, predictive functional profiling also demonstrated that the application of bioorganic fertilizer promoted the alteration of microbial functional pathways. Overall, the application of Bacillus subtilis bioorganic fertilizer effectively improved soil fertility, yield and quality of Brassica chinensis L. and improved soil microflora. These conclusions have valuable implications for promoting the safe planting of facility vegetables and the sustainable development of the environment.