Cell-Free Fermentation Broth of Bacillus velezensis Strain S3-1 Improves Pak Choi Nutritional Quality and Changes the Bacterial Community Structure of the Rhizosphere Soil

Abstract

Bacillus velezensis is a plant growth-promoting rhizobacteria (PGPR) that has long been proven to improve the growth of plants, and it has been widely used in agriculture. However, in many reports, we observed that during the application of bacterial fluids, it appeared that the effect of the cell-free fermentation broth (CFB) was ignored. The purpose of this study is to compare the effect of the no inoculation treatment (CK), the B. velezensis strain S3-1 treatment (S), the CFB treatment in the Pak choi, soil bacterial community structure, soil enzyme activity, and field soil properties. The results have shown that, compared to the inoculation B. velezensis strain S3-1 treatment and the no-inoculation treatment; the inoculation of the CFB treatment can significantly enhance the soluble protein, soluble solids, ascorbic acid of Pak choi and increase the total phosphorus content and electrical conductivity (EC) in the soil. Based on high-throughput sequencing data, our analysis of soil microbial communities used R, NETWORK, and PICRUSt showed that the CFB treatment can enhance the relative abundance of Acidobacteria in the soil, decrease the abundance of native Bacillus in the soil, change the microbial community structure of the top 50 operational taxonomic units (OTUs), and improve soil microbial carbon metabolism and nitrogen metabolism. Overall, we observed that CFB treatment can also improve plant nutrition and change soil microbial communities. This study provides new insights for the application of microbial fertilizers in agricultural production.

Okra Growth, Yield and Rhizosphere Microbiome Responses to the Encapsulated Bioinoculant Application under Reduced Fertilization Regime

“…Increased soil P and K availability, according to published research, is directly linked to lower soil pH. Plant roots can absorb P and K to release OH − , which neutralizes H + in the soil and stabilizes the pH [ 46 , 47 ]. We believe that active microbial acid secretion and steady plant P and K uptake are responsible for the build-up of P and K in the inoculated soil.…”

A Review on the Biotechnological Applications of the Operational Group Bacillus amyloliquefaciens

“…It has been reported that the co-inoculation of B. velezensis S141 with Bradyrhizobium diazoefficiens USDA110 into soybean resulted in enhanced nodulation and nitrogen fixation efficiency by producing larger nodules [ 48 ]. In another related study, the members of OG Ba were able to solubilize phosphate, and produce IAA, ACC deaminase and siderophores [ 49 , 50 , 51 ].…”

A Holistic Approach for Enhancing the Efficacy of Soil Microbial Inoculants in Agriculture

“…Several waste products have been proven to be suitable for industrial inoculant production [99,90]; using waste products can lower production costs, which are a main limiting factor in the commercialization of bio-inocula, thus making their use attractive to manufacturers. Moreover, the production of cell-free fermentation liquids with strong phyto-stimulating and biocontrol properties [6,91] should increase manufacturers' interest due to the independence from interactions with the soil micro-and macro-biota. A specific production method is required for AMF-based products: the obligate biotrophic nature of AMF has, indeed, complicated the development of cost-efficient large-scale production methods to obtain high-quality AMF inoculum [92].…”