Establishing Heterologous Production of Microcins J25 and Y in Bacillus subtilis

Microcin J25 (MccJ25) and microcin Y (MccY) are lasso peptides and considered potential alternatives to antibiotics and harmful preservatives. The combination of these two microcins can provide a wide antimicrobial spectrum against food-borne Salmonella. Currently, MccJ25 and MccY are produced using Escherichia coli expression systems; however, the entire production process is accompanied by negative effects from endotoxins. In this study, we identified Bacillus subtilis as a suitable host for MccJ25 and MccY production. High-level production of microcins was achieved by promoter optimization, host strain selection, and recombinant expression. The engineered strains produced maximum yields of 2.827 μM MccJ25 and 1.481 μM MccY. This is the first study to demonstrate the expression of MccJ25 and MccY in B. subtilis, and it offers a few engineered strains that are without antibiotic resistance markers, inducer-free, sporulation-deficient, and free of the negative effects of endotoxins for antibacterial therapy and food preservation.