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Isolation and identification of a Bacillus megaterium strain with ochratoxin A removal ability and antifungal activity

Shang, Linlin, Bai, Xuexia, Chen, Chi, Liu, Lijun, Li, Mingyan, Xia, Xiaoshuang, Wang, Yun
Food control 2019 v.106 pp. 106743
Aspergillus ochraceus, Bacillus megaterium, Penicillium, adsorption, antifungal properties, bacteria, biological control, cell viability, corn, culture media, food safety, fungal growth, fungi, heat treatment, liquid chromatography, liquids, mycelium, ochratoxin A, ribosomal RNA, soil sampling
Ochratoxin A (OTA) is a type of mycotoxin mainly produced by fungus belonging to the genus Aspergillus and Penicillium and plays a critical role in food safety since it causes serious health problem. Biological control by using microorganisms is considered a promising approach for detoxification of this mycotoxin. In order to find bacteria with efficient OTA elimination capability, one bacteria strain JSW-B1 with OTA removal ability was isolated from soil samples and was identified as Bacillus megaterium based on morphological and 16S rRNA analysis. After incubation of isolate JSW-B1 in liquid culture medium containing 2.5 μg/mL OTA for 72 h, the OTA removal percentage was 80.3%. No degradation products of OTA could be detected by liquid chromatography. About 62.6% OTA could be removed by the viable cell fraction after incubation for 72 h compared to 13.7% by cell-free supernatant. Meanwhile, heat treatment significantly enhanced OTA removing capability of the cells, suggesting that the OTA removal activity of the isolate JSW-B1 was mainly attributed to the adsorption by bacterial cells. In addition, the antifungal experiments revealed that isolate JSW-B1 was able to suppress the mycelial growth of Aspergillus ochraceus on solid medium with an inhibition ratio of 41.9% and reduce the fungal incidence on maize corns with a reduction ratio of 15%. Taken together, our results indicated that B. megaterium JSW-B1 could be considered as potential biological agent to control toxigenic fungal growth and mycotoxin contamination in agricultural products.