Detection of antibacterial peptides in artisanal rennet and evaluation of their antibacterial activity

This study assessed the antimicrobial effectiveness of artisanal lamb and goat rennet compared to industrial calf rennet against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Results showed all three rennets were more effective against E. coli than S. aureus. Only lamb rennet achieved complete inhibition of both bacteria at a minimum inhibitory concentration of 7000 ppm. An extensive peptidomics analysis was conducted to characterize these rennet samples and correlate their antimicrobial activity with the data on endogenous peptides. Moreover, a prediction of the potential antimicrobial activity of the peptides was carried out with specific bioinformatic tools available online, proving that the isolated peptides did have the tested biological activity. Lamb rennet was found to contain 73 antimicrobial peptides with bioactivity scores between 1 and 0.52, including casocidin-I, known for its broad-spectrum antibacterial activity. Further research is ongoing to explore the applications of artisanal rennet in cheese production.