Inhibition of Bacillus subtilis and Listeria innocua by nisin in combination with some naturally occurring organic compounds

The application of combined preservative factors (hurdle technology) is very effective in controlling the growth of food spoilage and foodborne pathogenic bacteria. Antimicrobial activity of nisin alone and in combination with some natural organic compounds (carvacrol, cinnamic acid, eugenol, diacetyl, and thymol) on the growth of gram-positive bacteria Bacillus subtilis and Listeria innocua was investigated. All the organic compounds tested exhibited antimicrobial activity against the microorganisms used; however, the MICs varied between 0.8 and 15.0 mM depending on the potency of the compound or the sensitivity of the target strain. Investigation of the interaction between the organic compounds and nisin against the test organisms revealed different patterns, varying from synergistic to antagonistic. Combinations of nisin with carvacrol, eugenol, or thymol resulted in synergistic action against both test organisms. Activity of nisin and cinnamic acid together was synergistic against L. innocua, but only additive against B. subtilis. In contrast, the combination of diacetyl and nisin resulted in an antagonistic effect against both test organisms. This study highlights the potential of the combination of these compounds with nisin to inhibit pathogen growth in food.