# Novel antifungal metabolites from Bacillus velezensis XYDY-1 effectively control peanut Cylindrocladium black rot caused by Calonectria ilicicola

## TL;DR

A new strain of Bacillus velezensis was found to produce antifungal compounds that effectively control a peanut disease caused by Calonectria ilicicola.

## Contribution

The discovery of novel antifungal metabolites from Bacillus velezensis XYDY-1 for controlling peanut black rot is presented.

## Key findings

- Bacillus velezensis XYDY-1 inhibited the growth of eight pathogenic fungi, including Calonectria ilicicola.
- 8-hydroxyquinoline at 10 mg/mL showed 98.31% inhibition of fungal growth.
- The culture filtrate of XYDY-1 enhanced peanut plant growth and biocontrol efficacy against the pathogen.

## Abstract

Cylindrocladium black rot of peanut is caused by the fungus Calonectria ilicicola (anamorph: Cylindrocladium parasiticum). This quarantined plants pathogen, causes this diseasethat threatens the healthy production of peanuts. The objective of this study was to screen andexplore the extracts of biocontrol bacteria against C. ilicicola.

A bacterial strain XYDY-1 was isolated from saline-alkali soil samples collected near peanut plants and identified as Bacillus velezensis based on morphological characteristics, 16S rDNA, and gyrB sequence analyses. The bacterial suspension of XYDY-1 exhibited significant inhibitory effects on the growth of eight pathogenic fungi, including C. ilicicola, Aspergillus niger, Fusarium pseudograminearum, F. oxysporum, F. neocosmosporiellum, Sclerotium rolfsii, Rhizoctonia solanikühn, and Sclerotinia sclerotiorum. Extracellular enzyme assays revealed that XYDY-1 possessed protease, cellulase, amylase, chitinase, and β-1,3-glucanase activities. Furthermore, genomic analysis confirmed the presence of genes srfAD, fenB, ituA, and bmyA, which encode surfactin, fengycin, iturin, and bacillomycin D, respectively, all of which contribute to the inhibition of hyphal growth. Ultra-high-performance liquid chromatography coupled with quadrupole-electrostatic field orbitrap high-resolution tandem mass spectrometry (UPLC-QE Orbitrap MS/MS) analysis detected antifungal compounds in B. velezensis metabolites, including 8-hydroxyquinoline, tunicamycin, Validamycin A, chloramphenicol palmitate, pyocyanin, and Surfactin C. 8-Hydroxyquinoline, tunicamycin, Surfactin C and Validamycin A exhibited significant antifungal activity in assays conducted with pure compounds. Of these, 8-hydroxyquinoline at a concentration of 10 mg/mL displayed the highest efficacy, yielding an inhibition rate of 98.31%. Additionally, greenhouse pot experiments demonstrated that the culture filtrate of XYDY-1 significantly promoted peanut plant growth, increasing fresh and dry biomass by 39.02% and 39.09%, respectively, compared to control treatments with culture medium alone. Moreover, the culture filtrate enhanced peanut resistance to C. ilicicola, achieving a biocontrol efficacy exceeding 56.41%.

B. velezensis XYDY-1, a plant-growth-promoting rhizobacterium, was able to protect peanuts from C. ilicicola infection and is a promising biocontrol agent.It can provide scientific basis for the development of new biological control pesticides, reduce the use of chemical pesticides, and promote the sustainable development of agriculture.

The online version contains supplementary material available at 10.1186/s12866-025-04687-w.