Microbial Diversity and Antifungal Potential of Lactic Acid and Acetic Acid Bacteria from Vietnamese Fermented Cocoa Beans

This study explored the microbial diversity of Vietnamese cocoa fermentation and the antifungal potential of indigenous bacteria. Cocoa beans were collected from three Vietnamese regions at different fermentation stages. Bacteria were isolated and identified using 16S rRNA gene sequencing. A total of 22 lactic acid bacteria (LAB) and 9 acetic acid bacteria (AAB) strains were identified, belonging to the genera Lactiplantibacillus, Limosilactobacillus, Levilactobacillus, Lacticaseibacillus, Pediococcus, Acetobacter, Gluconobacter, and Komagataeibacter. Four strains, including three LAB strains (L. plantarum L11E48, L. plantarum L15E48, L. brevis L8DN24) and one AAB strain (A. ghanensis G63E48), were evaluated for their ability to inhibit Aspergillus flavus and Fusarium foetens on agar media and bread. All strains demonstrated strong antifungal activity, inhibiting 51–100% mycelial growth of both fungi after 7 days of incubation. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of cell-free supernatant were 640 μL/mL against A. flavus and varied from 160 to 320 μL/mL against F. foetens. When applied in breadmaking, L. plantarum L15E48, L. brevis L8DN24, and A. ghanensis G63E48 delayed fungal growth for 1–2 days. These findings provide valuable baseline data on Vietnamese cocoa fermentation microbiota and highlight the potential of indigenous LAB and AAB strains for biocontrol, food preservation applications, and starter culture development.