Identification and characterization of a novel leaderless bacteriocin toyoncin T35 from Bacillus toyonensis

Antibiotics residues and antibiotics resistance have become a serious threat to human health. There is an urgent need for the development of antibiotic alternatives. Bacteriocins are considered one of the alternative to antibiotics because of their different antimicrobial mechanisms from antibiotics. Therefore, mining novel bacteriocins is of great significance for the development of antibiotic alternatives.

A novel aureocin A53-like leaderless bacteriocin, toyoncin T35, was identified in B. toyonensis T35. Toyoncin T35 was composed of 48 amino acid residues and its molecular weight was 5491.9950 Da. Toyoncin T35 exhibited strong antimicrobial activity against foodborne pathogens B. cereus (MIC, 0.71 µM), L. monocytogenes (MIC, 0.35 µM) as well as pathogenic bacteria S. suis (MIC, 2.84 µM). In addition, toyoncin T35 could inhibit B. cereus spore outgrowth, and possessed broad acid-base adaptability (pH 2-10) along with high heat tolerance (below 100 °C). Toyoncin T35 has no hemolysis activity and cytotoxicity even at a high concentration of 91.00 µM.

The novel leaderless bacteriocin toyoncin T35 has the potential to become an antibiotic alternative for treating diseases caused by foodborne pathogens B. cereus, L. monocytogenes, and pathogenic bacteria S. suis.