Biocontrol capabilities of three Bacillus isolates towards aflatoxin B1 producer A. flavus in vitro and on maize grains

In this study, we aimed to evaluate the biocontrol capabilities of Bacillus safensis RF69, Bacillus sp. RP103 and Bacillus sp. RP242 towards Aflatoxin B1 (AFB1) producer Aspergillus flavus. All Bacillus strains were able to reduce A. flavus mycelial growth rate, conidial germination, and viability in vitro. Ten days after the application of the bacteria on maize grains, A. flavus growth was reduced up to 47% and AFB1 was reduced up to 94%. Evaluations of the microbial interactions under a different set of environmental conditions showed that isolates Bacillus sp. RP103 and RP242 were able to maintain a dominant profile and antagonize A. flavus even in conditions of water and temperature stress. Bacillus safensis RF69 lost dominance when suboptimal environmental conditions were imposed. Our results indicate that isolates Bacillus sp. RP103 and RP242 are very promising biocontrol agent candidates, being capable to mitigate the A. flavus impact on the maize production chain. In addition, this study indicates that Bacillus safensis RF69 could be considered as a biocontrol agent if exploited at stable environmental conditions.