Influence of optimised commercial medium on bacteriocin production by <i>Enterococcus faecium

Resumo

Enterocins carry out antimicrobial activity on several pathogenic and spoilage bacteria in food. The objective of this work was to evaluate the production of enterocins, using Enterococcus faecium, and their stability under different culture conditions. The isolate was incubated in ManRogosa Sharpe (MRS) medium with pHs 4.5, 5.0, 5.5, 6.0 and 6.5, and supplemented with lactose, mannose, mannitol, glycerol, tween 20, and tween 80. The optimum pH of production was between 6.0 and 6.5. The enterocin produced in mix (lactose 20, glycerol 20, tween20 5.0 g L^-1) was more efficient. None pH tested interfered with the reduction of the action of the enterocins. The thermal stability varied according to the isolate as well as the supplementation used. Tween 20 and 80 with regards to the stability to different chemical products of both isolates, presented reduction of the action. It was observed that the supplement mix had higher adsorption and that the bactericidal effect was observed within 2 hours of incubation. The results indicated that the different culture conditions did not affected the antagonistic action of enterocin.