Antagonistic effect of Bacillus atrophaeus ZY1825 on five forage diseases and optimization of fermentation conditions

Bacillus atrophaeus ZY1825 is a bacterial strain isolated from desert sandy soil with biocontrol potential. In this paper, through the plate confrontation method, the antagonistic effect of common vetch anthracnose, ryegrass leaf spot, alfalfa spring black stem, barley fusarium root rot, and alfalfa root rot was determined. The physiological and biochemical characteristics were determined, and the fermentation conditions were optimized. The inhibition rates of the bacteria against the five pathogens were 49.29%, 47.21%, 50.78%, 44.28%, and 45.99%, respectively. The strain is Gram-positive bacteria. The optimal fermentation medium was potato 200 g, sucrose 15 g, yeast extract 12 g, magnesium sulfate 5 g, and distilled water 1000 mL. The number of viable bacteria reached the maximum of 9.28 × 10⁹ cfu·mL⁻¹ at 32 ℃ and 210 r·min⁻¹ liquid culture for 24 h, which was 5.91 times higher than that before optimization, and the inhibition rate of Fusarium oxysporum was increased by 33.45%. This study can provide technical parameters and a theoretical basis for the further use of Bacillus atrophaeus ZY1825 to prepare biocontrol agents to control forage diseases.