Isolation and characterisation of<i>Bacillus amyloliquefaciens</i>S13-3 as a biological control agent for anthracnose caused by<i>Colletotrichum gloeosporioides</i>

Abstract

Abstract Bacillus amyloliquefaciens S13-3 was isolated from soil as a biological control agent for anthracnose caused by Colletotrichum gloeosporioides. In vitro bioassay demonstrated that S13-3 suppressed C. gloeosporioides mycelial growth. The biocontrol activity of S13-3 toward grape ripe rot caused by C. gloeosporioides was confirmed in a vineyard. S13-3 also reduced the severity of strawberry anthracnose caused by C. gloeosporioides on detached strawberry leaves. The finding that S13-3 showed tolerance to some chemical pesticides and copper suggested that S13-3 could be applied before and/or after chemical pesticide or Bordeaux mixture treatment in the field. S13-3 possesses ituD and lpa-14 genes, both of which play a role in iturin A production, in its genome and expressed their transcripts during culture. Iturin A production by S13-3 was detected in the culture medium and its concentration was 0.064 mg/mL in the medium after culture for 6 days, suggesting that the antagonistic activity of S13-3 toward C. gloeosporioides may depend on iturin A production. Due to the inhibitory effects of S13-3 on anthracnose caused by C. gloeosporioides, S13-3 is expected to contribute to the further improvement of integrated pest management systems against C. gloeosporioides, and to potentially reduce the amounts of chemical fungicides used in the field.