Isolation, purification, and identification of antifungal protein produced by Bacillus subtilis SL-44 and anti-fungal resistance in apple

Apple anthracnose is a fruit fungal disease that is currently recognized as one of the most severe threats to apples worldwide. In this study, antifungal protein from Bacillus subtilis SL-44 was isolated, purified, identified, and applied for Colletotrichum gloeosporioides control. The antagonistic experiment showed that SL-44 had an excellent broad spectrum against plant pathogenic fungi. The optimal fermentation conditions were as follows: initial pH was 7, inoculum volume was 2%, and rotational speed was 180 r/min. The optimized yield of antifungal protein increased by 45.83% compared with that before. The crude protein was isolated and purified by -(NH4)(2)SO4 precipitation, DEAE-Sepharose Fast Flow, and Sephadex G-100 column chromatography. LC-MS analyzed that antifungal protein was likely to be a novel protein with a molecular weight of 42 kDa. The mechanism revealed that the antifungal protein may disrupt the cell wall structure of C. gloeosporioides and function as its antifungal action. Additionally, antifungal protein significantly alleviated the size of the lesion to more than 70% in the apple infection protection test. In conclusion, antifungal protein has remarkable potential in developing fungicides for the biological control of apple anthracnose.

Automated summary

Apple anthracnose is a severe global fungal disease, and this study isolated, purified, identified, and applied an antifungal protein from Bacillus subtilis SL-44 for controlling Colletotrichum gloeosporioides. The antifungal protein showed excellent broad-spectrum activity against plant pathogenic fungi. The optimal fermentation conditions were determined, and the antifungal protein's production was improved by 45.83%. The protein was identified as a novel protein with a molecular weight of 42 kDa and was found to disrupt the cell wall structure of C. gloeosporioides, leading to its antifungal action. In apple infection protection tests, the antifungal protein significantly reduced lesion size by more than 70%. This study highlights the remarkable potential of antifungal protein in developing fungicides for the biological control of apple anthracnose.