Background/Objectives:
Bacillus probiotic mixtures have been used as a novel source of antimicrobial production. However, there is a need to emphasize the potential of co-cultured
Bacillus strains and to understand the underlying mechanisms involved in their combination formulation.
Methods:
Bacillus strains
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Background/Objectives:
Bacillus probiotic mixtures have been used as a novel source of antimicrobial production. However, there is a need to emphasize the potential of co-cultured
Bacillus strains and to understand the underlying mechanisms involved in their combination formulation.
Methods:
Bacillus strains BPR-11, BPR-16, and BPR-17, were cultured either as mono or multi-cultures. The bacterial growth and density were evaluated by measuring their optical density. The chemical profiles of their bioactive extracts were analysed by LC-MS, and their antimicrobial activity were tested against selected pathogens.
Results: Our results reveal that co-cultured strains significantly increased bacterial growth, with an optical density level of, 2.67 which was significantly higher than the monocultures of BPR-11 (2.24), BPR-16 (2.32), and BPR-17 (2.22). Furthermore, the ethyl acetate extracts from these bacterial cultures showed that the combined co-culture (F1) exhibited the highest antimicrobial activity, with MICs of 25 µg/mL against
C. perfringens,
E. coli, and
S. aureus, and 50 µg/mL against
P. aeruginosa and
S. enterica. In contrast, the monocultures BPR-16 and BPR-17 showed moderate activity with MICs of 50 µg/mL against
C. perfringens,
E. coli, and
S. aureus, and 100 µg/mL against
P. aeruginosa and
S. enterica. BPR-11 had the lowest antimicrobial activity, with MICs of 100 µg/mL against
C. perfringens,
E. coli, and
S. aureus, and no activity against
P. aeruginosa and
S. enterica. Metabolite profiling showed that the extract from the co-culture had a marked increase in the production of antimicrobial metabolites, including C
13-C
16 surfactin C. Lastly, the metabolism study of surfactin C analogues suggested that they were highly stable (99%) when incubated with cytochromes P450 over 120 min.
Conclusions: Together, these findings highlight the potential for multi-strain co-culturing to develop new antimicrobials and provide valuable insights into the synergistic effects for antimicrobial production.
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