Two novel antimicrobial peptides against vegetative cells, spores and biofilm of Bacillus cereus

Abstract

Bacillus cereus is a ubiquitous bacterium that causes food-associated gastrointestinal diseases. The ability to form spores and biofilm makes this bacterium highly resistant to antimicrobial agents and food preservatives, posing persistent risks to consumers and the food industry. The excessive use of antibiotics and chemical preservatives has led to the emergence of resistant B. cereus strains, impacting the safety of food. Therefore, there is demand for new antimicrobial agents to combat B. cereus. The use of antimicrobial peptides (AMPs) for food preservation has attracted attention because they can preserve food quality with low possibility of bacteria acquiring resistance. In this research, a series of peptide derivatives based on the previously reported peptide D51 (sequence FLFRVASKVFPALIGKFKKK) was designed and synthesized. Two of the peptides, D51-P11G and D51-P11K, exhibited satisfactory antimicrobial (MICs: 8 μg/mL) activities toward B. cereus, including diarrheal and emetic reference strains. Peptides D51-P11G and D51-P11K showed good physiological stability, high safety and a low tendency to induce bacterial resistance. Meanwhile, at 16 μg/mL, D51-P11G and D51-P11K could inhibit spore germination and biofilm formation. Studies of the antibacterial mechanism suggested that D51-P11G and D51-P11K exert their antibacterial activities mainly via a membrane-lytic mechanism, but they also bound to genome DNA of the bacteria. Notably, D51-P11G and D51-P11K (32 μg/mL) could control the growth of B. cereus in boiled rice and minced meat, the antimicrobial activities were almost the same as or even better than nisin A (300 μg/mL). These findings suggest that D51-P11G and D51-P11K are ideal candidates for application against vegetative cells, spores, and biofilm of B. cereus.