Abstract: To develop biocontrol strains with preventive and therapeutic effects against wheat sheath blight,this study screening HB-10 strain.HB-10 strain exhibited significant control effects against the Rhizoct.onia cerealis.The strain was identified,optimized for fermentation,and evaluated through pot experiments to assess its efficacy.Results showed that HB-10 strain achieved an inhibition rate of 89.72% against Rhizoctonia cerealis.Morphological and molecular identification confirmed HB-10 strain as Pseudomonas aeruginosa.Antimicrobial spectrum analysis demonstrated the strong antagonistic effects of HB-10 strain against various pathogens,including Magnaporthe oryzae,Fusarium moniliforme,Alternaria alternata and Sclerotinia Sclerotiorum.In pot experiments,HB-10 strain exhibited a relative preventive efficacy of 69.42% against wheat sheath blight.Orthogonal tests and response surface analysis revealed the optimal growth medium for HB-10 strain consisted of 10 g/L glucose,20 g/L yeast extract,and 10 g/L KCl.The optimal fermentation conditions included a rotational speed of 215 r/min,temperature of 37℃,inoculum size of 4%,initial pH of 7.3,and a culture time of 84 h.After optimization,the average OD⁶⁰⁰ value of HB-10 strain at 24 h increased by 181.8%(5.92) compared to the non-optimized condition,resulting in improved inhibition rate against the pathogenic bacteria.These research findings provide a theoretical basis for the development and application of a biocontrol agent using Pseudomonas aeruginosa HB-10,in the prevention and control of wheat sheath blight.

Key words: wheat sheath blight, biocontrol bacterium, fermentation optimization, Pseudomonas aeruginosa