Functional Characterisation of Bacillus velezensis YB‐1652: A Dual Approach for Alleviating Soil‐Borne Diseases and Phenolic Toxicity in Peanut Cultivation

ABSTRACT The continuous accumulation of phenolic autotoxic compounds and soil‐borne pathogens significantly contributes to the challenges of continuous cropping in peanuts. To obtain microorganisms that can degrade phenolic compounds efficiently and antagonise peanut disease pathogens, sampling was conducted in continuously cropped peanut fields. Screening by assessments of phenolic acid degradation efficiency, plate confrontation assays and pot experiments identified a beneficial strain YB‐1652. Phylogenetic analysis based on 16S rDNA and gyrA gene sequences classified the strain as Bacillus velezensis . YB‐1652 demonstrated high degradation efficiency for several phenolic compounds, including benzoic acid (22.8%), vanillic acid (36.4%), 4‐coumaric acid (36.8%), ferulic acid (39.3%) and p ‐hydroxybenzoic acid (28.8%). Moreover, this strain exhibited strong inhibition of mycelial growth of Sclerotium rolfsii (responsible for peanut white mould) and Fusarium oxysporum (causing root rot), with inhibition rates of 85.3% and 75.5%, respectively. In greenhouse pot experiments using soil from a field with 20 years of continuous peanut cropping, YB‐1652 inoculation significantly promoted plant growth, resulting in a 68.7% (SD = 1.91) increase in seedling main stem height. Further analysis revealed that strain YB‐1652 produces several hydrolytic enzymes (cellulase, β‐glucanase, protease and amylase) as well as siderophores, which may contribute to its biocontrol and growth‐promoting functions. As a result, the strain exhibits substantial potential for mitigating the obstacles associated with continuous cropping systems.