一株拮抗钟器疫腐霉的类芽孢杆菌SEC-488的筛选、鉴定与全基因组分析OA

Root brown rot caused by Phytopythium vexans is a major constraint on ramie yield and quality.To identify biocontrol microorganisms with antagonistic activity against P.vexans,we isolated an antagonistic bacterial strain,SEC-488,from ramie rhizosphere soil samples.Its antifungal activity was e-valuated using a dual-culture assay.Microscopic and scanning electron microscopy observations,biocon-trol-related functional assays,whole-genome sequencing,and bioinformatic analyses were conducted to assess its biocontrol potential.The results showed that SEC-488 significantly inhibited the mycelial growth of P.vexans in vitro,with an inhibition rate of(76.10±0.65)%.Microscopic observations revealed pronounced alterations in hyphal morphology and ultrastructure of the pathogen after exposure to SEC-488.Functional characterization indicated that SEC-488 exhibits protease and amylase activities and pos-sesses multiple biocontrol-related traits,including phosphate solubilization,potassium solubilization,ni-trogen fixation,and siderophore production.Based on morphological characteristics,physiological and bi-ochemical properties,16S rDNA gene phylogenetic analysis,and whole-genome average nucleotide iden-tity(ANI)and in silico DNA-DNA hybridization(isDDH)comparisons,SEC-488 was identified as a member of the genus Paenibacillus.Genome annotation revealed the presence of 310 carbohydrate-active enzyme-related genes and 17 biosynthetic gene clusters for secondary metabolite.These findings provide experimental evidence and a theoretical basis for the biocontrol of ramie root brown rot.