Objective  Inhibitory effect of a strain of Brevibacillus brevis against Lasiodiplodia theobromae (Pat.) Griffon & Maubl on longan fruits was evaluated.

  Method  In vitro antagonistic activity of B. brevis FJAT-0809-GLX was observed by the inhibition zone and rate on the mycelial growth and morphology of L. theobromae. Efficacy of the strain for biocontrol on the pathogen was determined by in vivo experiments, as well as the activities of defense enzymes in longan peel.

  Result  Supernatant of the fermentation broth showed a pathogenic inhibition zone diameter of 15.77 mm and an inhibition rate that increased with increased fermentation time or treatment dosage. The inhibition rates reached 74.17% when 50 mL of the supernatant was applied. The supernatant inoculation on longan fruits significantly reduced the disease spreading rendering a healthy fruit rate of 68.33%. Meanwhile, the activities of superoxide dismutase and hydrogen peroxidase in the treated fruits became significantly higher than those of control.

  Conclusion   B. brevis FJAT-0809-GLX significantly inhibited the growth of L. theobromae as shown by in vitro plating as well as in the field challenge test. It demonstrated a potential venue for bio-controlling the disease on longan.