Screening and characteristics of antagonistic strains of Fusarium equiseti

Fusarium equiseti is one of the most harmful plant pathogens in North China. Isolating and screening the biocontrol bacteria resources for the control of Fusarium equiseti is of great significance. In this study, oat plants were used as materials to isolate and screen strains from the rhizosphere of oat using selective media. The antagonistic strains against Fusarium equiseti were screened using the plate confrontation method, and the growth-promoting properties of the strains were further investigated. The taxonomic status of the strains was confirmed using 16S rRNA molecular biology technology. The results showed that six antagonistic strains were obtained after screening, and the inhibition rates ranged from 41.84% to 91.16%. Among them, five strains had nitrogen fixation ability, and five strains had the ability to dissolve inorganic phosphorus with the activity of nitrogenase ranging from 51.82 to 210.81 nmol·(h·mL)⁻¹ (C₂H₄). Among the strains, only strains DRT-3, DRT-11, and DRT-17 had the ability to dissolve organophosphorus, and the dissolved phosphorus levels were 21.64, 31.65, and 28.64 µg·mL⁻¹, respectively. Six strains possessed the ability to secrete indole-3-acetic acid (IAA), with secretion levels between 41.74 and 157.28 µg·mL⁻¹. Identification based on 16S rRNA sequencing confirmed that DRT-2 and DRT-8 were Bacillus subtilis, DRT-11 was Acinetobacter sp., DRT-3 was Bacillus mycoides, and DRT-17 and DRT-18 were Pseudomonas fluorescens. In this study, the screening process identified strains that have biocontrol effects on the pathogens of oat root rot, laying the foundation for subsequent research on the prevention and control of oat root rot.