Identification of Bacillus megaterium as a Probiotic and Its Action to Control Biofilms of Foodborne Pathogens
Bacillus megaterium isolated from coffee fermentation demonstrated potential probiotic properties against Bacillus cereus ATCC 11778, Escherichia coli ATCC 8739, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311 through the production of active compounds, including δ-valerolactam and ε-caprolactam. This is the first report on its potential utility in producing active compounds, forming protective biofilms, or blocking cell adhesion and aggregation of foodborne pathogenic bacteria on material mimicking the intestinal mucosa. The quorum-sensing signal molecule N-butanoyl-L-homoserine lactone, an auto-inducer for biofilm formation, was detected in the crude culture supernatant, supporting its capability for biofilm formation. Characterization assays showed B. megaterium to tolerate up to 6% bile salt and to survive at pH 1.5. In addition, it demonstrated negative hemolytic activity and sensitivity to antibiotics at the level. It also produced various bioactive compounds that function with therapeutic properties. Therefore, B. megaterium has potential to be used as a human and animal probiotic in the future.