Potential antifungal activity of acetic acid bacteria isolated from Vietnamese fermented cocoa beans

Aspergillus sp. and Fusarium sp. are known for the mycotoxigenic potential fungi, and are found in agricultural products, animal feed, etc. Therefore, prevention of mycotoxin hazard needs to be considered and thoroughly handled. Current food preservation methods are mainly based on chemical way, which are not environmentally friendly, persist in food and humans for a long time, and cause adverse effects on health. The biological method aligned with current trends, in which organic acid-producing bacteria are considered a potential solution because of their ability to extend the preservation time, safety level, maintain the food structure and other health benefits. In Vietnam, there was no study investigating the antifungal activity of acetic acid bacteria. Therefore, this study focused on evaluating the potentiality of antifungal activities against Aspergillus flavus UBOCC-A-10866 and Fusarium foetens M79 of 13 AAB strains isolated from Vietnamese fermented cocoa beans from Dak Lak, Ba Ria-Vung Tau and Dong Nai provinces. The results showed that acetic acid bacteria strains were all capable of inhibiting fungal growth (from 23-58% of mycelium diameter after 7 days), in which 03 AAB strains (G60T96, M61N96 and G62N24) were selected due to their great fungi inhibition activities. The minimum inhibitory concentrations of cell-free supernatant of these strains were determined from 0.32 to 0.64 mg/mL.