# Metabolomic profiling of Bacillus amyloliquefaciens MU-10 and its antagonistic effects on Cercospora arachidicola

## TL;DR

A new strain of Bacillus amyloliquefaciens is shown to effectively control peanut leaf spot disease through its bioactive metabolites, with optimized fermentation enhancing its antifungal properties.

## Contribution

The study identifies key metabolites from Bacillus amyloliquefaciens MU-10 that contribute to its antifungal activity against Cercospora arachidicola.

## Key findings

- Strain MU-10 showed 76 mm inhibition zone against C. arachidicola in vitro.
- Optimized fermentation increased production of bioactive metabolites like 3-O-acetylisopimaric acid and vanillylamine.
- Greenhouse tests showed 93.33% disease control efficiency of MU-10 against peanut leaf spot.

## Abstract

Early leaf spot disease in peanut severely impacts crop yield and quality. In response, biological control by Bacillus strains offers an alternative approach to replace harmful chemical fungicides, as these bacteria produce bioactive secondary metabolites. The effectiveness of these metabolites greatly relies on the submerged fermentation process, which in turn depends on optimizing the nutrient media—especially since there is a significant difference between nutrient-optimized fermentation medium (OP) and nonoptimized fermentation medium (NOP).

In the present study, we isolated an antagonistic strain, Bacillus amyloliquefaciens MU-10, from soil and identified it. According to in vitro experiments, strain MU-10 exhibited potent antifungal activity against C. arachidicola, with an inhibition zone of 76 mm. Similarly, under greenhouse conditions, the disease control efficiency of the MU-10 strain against peanut leaf spot disease was 93.33%. SEM analysis revealed that the hyphae of the pathogen were destroyed and that the effect of MU-10 reduced the abundance of spores. UHPLC-MS/MS was used to elucidate the bioactive secondary metabolites produced by strain MU-10 in OP and NOP submerged fermentation. A total of 831 metabolites were detected in OP, 32% of which were classified as organic acids. Among these were 83 differentially expressed metabolites (DEMs). According to the VIP scores, 12 metabolites were identified as key contributors to group separation, including the upregulated 3-O-acetylisopimaric acid and vanillylamine. Conversely, pyrrole-2-carboxylic acid was identified as a downregulated VIP metabolite in OP. The receiver operating characteristic (ROC) curves confirmed all the metabolic results. Pure compound validation was confirmed by the use of commercially synthesized vanillylamine, pyrrole-2-carboxylic acid, and syringic acid as key antifungal agents.

Nutrient-optimized fermentation significantly increased the production of Bacillus-based biocontrol products. This improvement represents a significant advancement in sustainable, environmentally friendly crop disease management, providing an effective solution for controlling early leaf spot in peanuts.

The online version contains supplementary material available at 10.1186/s12866-025-04695-w.