Screening, Identification, and Antifungal Properties of a Bacterial Strain F1 with Antagonistic Activities Against Aspergillus flavus
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Abstract:
To obtain a biocontrol bacteria that can effectively suppress the growth of Aspergillus flavus in raw food materials, products fermented by lactic acid bacteria and spices were used as the starting materials. One strain, F1, was screened from black pepper through strain isolation, preliminary screening, and re-screening, and showed a strong inhibitory effect towards Aspergillus flavus. This strain was identified based on morphological, cultural, physiological, and biochemical characteristics, and the 16s rDNA analysis followed by phylogenetic tree construction, to be Bacillus amyloliquefaciens (Preservation number: CGMCC No. 1094). The strain had a close genetic relationship with the commercialized biocontrol strain Bacillus amyloliquefaciens FZB42. The culture supernatant of strain F1 was subjected to ultrafiltration treatment, enzymatic hydrolysis test, and stability test. The results implied that the antifungal component of strain F1 was protein substances with molecular weights of 30 ku~100 ku. About 87.43% of the antifungal activity remained after the treatment at 100 ℃ for 30 min, and over 70% of antifungal activity remained when the pH was in the range of 3.0~10.0. This study suggests that the strain Bacillus amyloliquefaciens F1, isolated from black pepper, can produce relatively stable antifungal proteins through metabolism, and, thus, present an antagonistic effect on Aspergillus flavus. Therefore, this strain has the potential for application in food products.
