A study of the effect of nisin and pediocin on cultures of Staphylococcus aureus isolated from chicken carcasses

Abstract

Staphylococcus aureus is an important pathogen associated with foodborne illnesses. Antibiotic-resistant strains have been discovered, and therefore finding alternative substances to control this pathogen has become important to prevent its proliferation. Bacteriocins are metabolites produced by several bacterial genera, including lactic acid bacteria. These substances have been revealed to have bioactive properties, including antimicrobial ones. We aimed to analyze the effect of the bacteriocins nisin (1.25% and 2.5%) and pediocin (1%, 5% and 10%) on different isolates of Staphylococcus aureus obtained from poultry carcasses. Seven strong biofilm-forming isolates of S. aureus were used. We evaluated the antimicrobial activity of these bacteriocins on the isolates and also determined the decrease in bacterial count in whole UHT milk upon nisin addition. Thermal stability of the bacteriocins in skimmed and whole UHT milk was also evaluated. In the antimicrobial activity test, only nisin showed an opposing effect on S. aureus isolates, except for the F3-3 isolate, which was not sensitive to this substance. In assessing arbitrary units, nisin showed higher activity than 100 AU mL-1 for two S. aureus isolates (F4-1 and F5-1). In evaluating the effect of bacteriocins, nisin (1.25%) showed a bacteriostatic effect on the growth of S. aureus F4-1. Regarding the thermal stability of nisin and pediocin, there was a reduction in the residual activity of both substances when heat-treated, which demonstrated the influence of a higher fat content (approximately 3%). The results revealed that the higher antimicrobial effect of nisin may be worth exploring for use in growth control of S. aureus in meat products.