Bacteriocinogenic activity of Leuconostoc lactis RK18 isolated from fermented food

Safety of fermented foods is mostly ensured by the presence of lactic acid bacteria, which besides having an important role in the enhancement of food shelf-life, also enhance the organoleptic characteristics of the products. One of the major attributes of lactic acid bacteria is their bactericidal activity against spoilage and pathogenic bacteria by the production of proteinaceous substances that are commonly known as bacteriocins. The present study aimed to characterize a proteinaceous compound produced by Leuconostoc lactis RK18, isolated from a fermented Cambodian food product. It was found that Ln. lactis RK18 produced a Class IIa bacteriocin, capable of inhibiting important foodborne pathogens such as Listeria monocytogenes. Bacteriocin RK18 remained stable in the temperature range between 30°C to 80°C) and at pH values ranging from 4 to 6. Although susceptible to some detergents, it showed great resistance to several enzymes. RK18 was produced in the early stage of Ln. lactis RK18 growth cycle, which brings an advantage when competitive growth is desired or for pathogen inhibition purposes, since it can inhibit pathogenic bacteria before its exponential growth. Even though more studies must be performed, Ln. lactis RK18 appears to have the potential to play an important role in the safety of food products and could be a good candidate to be used as a starter culture in the production of other fermented products.