Production of bacteriocin using Bacillus licheniformis ATCC 9789 and determination of its structural and antimicrobial properties

Bacteriocins are a group of unique molecules that are produced by some microorganisms and are considered as part of the host's innate immunity. Nowadays, the use of biological preservatives in the food industry is increasing widely. In the present study, Bacillus laciniformis ATCC 9789 was used to produce bacteriocin. The antimicrobial activity of produced bacteriocin was investigated against foodborne pathogens. Further, after purification, the characteristics of produced bacteriocin, including stability against heat, pH, enzyme and ultraviolet (UV) rays, as well as minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined. Also, molecular weight, functional groups and temperature characteristics of bacteriocin were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-Page), Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) tests. This bacteriocin had very good stability in different temperatures, pHs and against trypsin and pepsin enzymes and under UV rays. The SDS-Page test showed that the produced bacteriocin consists of two parts with a molecular weight of 17 and 20 kDa. The results of FTIR analysis showed peptide characteristics and DSC results had two exothermic peaks at 190 and 325 ⸰C, respectively. In general, in this research, after extracting and ensuring the existence of bacteriocin, its antimicrobial effect was evaluated by determining MIC and MBC on foodborne pathogens. The results showed that the bacteriocin produced by B. licheniformis had a significant antimicrobial effect on foodborne pathogens.