Identification of two Bacillus amyloliquefaciens strains with high suppression to the key fruit pathogens of Chinese jujube

Abstract

Two bacterial strains (ZJ01 and ZJ02) isolated from the phyllosphere of Chinese jujube were tested for antifungal activities and morphological mechanisms against Phoma destructiva, Alternaria alternata and Fusicoccum spp., three key pathogens of jujube fruits. Based on their physiological characteristics and 16S rDNA gene sequences, both strains were identified as Bacillus amyloliquefaciens. The disease incidence of jujube fruits sprayed with the fermentation liquor of ZJ01 and ZJ02 on the puncture wounds before inoculation with the spores of those three key pathogenic fungi was 10% or 66.7%, significantly lower than that of Nutrient Broth medium treatment (100%). These results suggest that strains ZJ01 may be a potential biological control agent for Chinese jujube fruit diseases. The antagonistic bacteria could cause five kinds of hyphal alterations of the causal agents, the maximum number ever observed. Of them, hyphal swelling and excessive branching were the dominant phenomenon, the other three varied with the pathogens. The diverse morphological malformation might be helpful to understand the broad antifungal activity of Bacillus spp..

Keywords:

• Bacillus amyloliquefaciens
• biocontrol
• Chinese jujube
• Alternaria alternata
• Phoma destructiva
• Fusicoccum spp.

Acknowledgements

The authors wish to thank Nannan Xie, Haixu Yang, Yang Wang, Yanlin Zhao and Long Peng for technical assistance. We would like to thank Prof. J.S. Bal and Dr F.C. Shan for their kind assistances in manuscript revision.

Additional information

Funding

This study was supported by the Science and Technology Support Program of Hebei province, China (12220303D); the National Science and Technology Support Program of China (2013BAD14B03); and Science Fund for Distinguished Young Scholars of Hebei Province (C2010000679).