Technological potential of Bacillus megaterium in Cacao bean fermentation

During the fermentation of cacao beans, a succession of microorganisms, including yeasts, lactic acid bacteria, acetic acid bacteria, and Bacillus, are involved in the generation of aroma and flavor precursors. These microbial consortia have been extensively studied, except for the genus Bacillus. Accordingly, this work aimed to isolate and select Bacillus isolates and evaluate their effect on the fermentation process of CCN51 genotype cacao beans. The isolates were obtained from a fermentation process using native cacao material. The isolates were selected based on growth performance and biological activity assays, including the production of pectinases, proteases, citrate lyases, and antifungal activity. Subsequently, their effect as a starter culture on the CCN51 genotype beans was evaluated. The isolates were individually evaluated at a concentration of 7 × 106 CFU/mL in a proportion of 1% starter culture (v/w) relative to the cacao mass. Temperature, pH, acidity, fermentation index, and cut test were monitored, showing higher fermentation index values (up to 1.5) and a reduction of insufficiently fermented beans (from 36% in the control to 13–20%) in inoculated treatments. The evaluation of the effect of Bacillus isolate on cacao fermentation indicated that the B. megaterium isolate improved the sensorial quality of cacao beans, decreased their bitterness and astringency, and highlighted flavors such as floral, fruity, nutty, and cane sugar-malt. It also registered antifungal activity against mycotoxin-producing fungi. It can be concluded that Bacillus has biotechnological potential as a producer of enzymes of interest for cacao processing and the food industry.