Isolation, identification and characterization of an antagonistic bacterium against Penicillium expansum

Abstract:

[Objective] In order to obtain an antagonistic strain which can effectively inhibit the growth of Penicillium expansum and to identify the antifungal substances produced by this strain. [Methods] The antagonistic strain BA-16 that could inhibit Penicillium expansum growth was isolated from apple surface and then identified through phenotypic, physiological, biochemical and phylogenetic (16S rRNA gene) analyses. Three primers were designed on the basis of the relevant genes and PCR was done. After the PCR product was purified and sequenced, the obtained sequences were analyzed by BLAST. The crude anti-fungal extracts were prepared by using acidic precipitation method and the active antagonistic substances were purified and identified by HPLC and MALDI-TOF-MS analysis. [Results] The strain BA-16 was identified as Bacillus amyloliquefaciens. PCR detection and BLAST analysis revealed that strain BA-16 expressed the sfp and fenB genes. The HPLC and MS analysis results demonstrated that the fermentation broth of the strain contained fengycin and surfactin. Moreover, fengycin played an important role in inhibiting Penicillium expansum. [Conclusion] The strain BA-16 will be a potential biological control agent against blue mold decay in apples.