## 4 Discussion  
We screened and optimized the submerged fermentation medium nutrients to synthesize secondary metabolites from the _B. velezensis_ BP-1 strain. These secondary metabolites were evaluated against _P. arachidola_ to control web blotch disease in peanut plants. It is stated that _B. velezensis_ has a strong ability to control fungal phytopathogens [38; 39; 40; 41]. As previously described by [PERSON] et al. and [PERSON] et al. [42; 43], fungus pathogens acquire resistance to a number of antagonists. In order to accomplish this task, new strains of antagonistic bacteria and new formulations are urgently needed. In the current study, a novel nutrient media for the fermentation process was introduced. According to our results, the _B. velezensis_ BP-1 strain grown in semolina and peanut root extract-containing medium had more significant antifungal effects than the other fermentation nutrients. The results proved that semolina flour and peanut root extract were the most significant optimal carbon and nitrogen resources in the fermentation medium, respectively. [PERSON] et al., 2008, and [PERSON] et al., 2018 [44; 45], discovered that the ratio of the substrate medium, which is made up of diverse carbon, nitrogen, and inorganic micro-element sources, has a substantial influence on microbial production and bioactivity. Semolina flour had a significant influence on the antifungal activity of _B. velezensis_ BP-1 when used as a carbon source in a submerged fermentation medium. Semolina flour in a fermentation broth may boost the antifungal activities and biomass production of the _B. velezensis_ BP-1 strain. A recent study indicates that semolina has more protein and gluten than other grains [46]. The findings indicated that the composition of peanut root extract has the potential to replace tryptone extract as a nitrogen source in the fermentation of the BP-1 strain, hence sustaining and enhancing the strain's biological control activity. [PERSON] et al. [47] said that the root metabolites of certain plant species could be changed to support a certain microbial strain with the desired abilities. Similarly, MgSO\({}_{4}\), an inorganic salt that has been optimized, may effectively replace NaCl as the base medium. It has been shown that Mg\({}^{2+}\) plays a significant role in the manufacturing of proteins by activating a variety of enzymes and taking part in the synthesis of amino acids, the transcription and translation of genes, the generation of proteins that serve as the structural components of ribosomes, and other processes [48; 49]. The outcomes demonstrated that the experimental layout considerably influences the synthesis of secondary metabolites that conceal _B. velezensis_ BP-1's antagonistic action against _P. arachidola_. The studies confirmed the effectiveness of the response surface methodology's central composite design. In order to identify the ideal parameters for improvement, the response surface approach is an appropriate mathematical and statistical methodology. Designing an experimental design could be helpful for demonstrating the interactions between different parameters. Applications of response surface methodology to enhance fermentation parameters have recently become very common [50; 51]. The results were analyzed to figure out the optimal medium content level and its interaction with the other three significant parameters, which were later optimized using the central composite design via RSM. Because of its efficacy and longevity, the central composites design is the most appropriate design for fermentation [31; 52]. The fermentation batch's metabolism indicated that as the number of bacteria rose, the total sugar levels declined but any decreasing sugar levels climbed, showing that _B. velezensis_ BP-1 was consuming both total sugar and amino nitrogen to promote its own development. Eventually, the rate of development of the _B.