Caracterização parcial de termoresistência e estabilidade a compostos químicos de bacteriocinas produzidas por Enterococcus sp

Abstract

Bacteriocins has a broad spectrum of antimicrobial activity on various pathogenic and deteriorating bacterium in food. Several bacterial genera produce enterocins, between them, the genus Enterococcus sp. The objective of this study was to study the production of enterocins produced by Enterococcus faecium in the pH 4.5, 5.0, 5.5, 6.0 and 6.5 where the culture medium was supplemented with lactose, mannose, mannitol, glycerol, tween® 20 and tween 80 with different concentrations. The antagonistic tests used bacterium Listeria innocua CLIP 12612. About the best parameters for the production of enterocin, these were tested for stability against the action of the chemicals SDS, EDTA, Tween® 20, Tween® 80 and NaCl, Temperatures of 40, 50, 60, 70, 80, 90, 100°C for 30 minutes and 121°C for 15 minutes, various pHs 3, 5, 7 and 9, adsorption and on their bactericidal and/or bacteriostatic action. The results showed that the pH great of production was between 6.0 and 6.5, and the supplements with larger inhibition activity were lactose 20 g/L, glycerol 20 g/L and tween®20 5.0 g/L. These supplements also were added in the medium MRS, referred to as MIX. The enterocins remained stable at the analyzed pHs and maintained their inhibitory activity after heat treatment at 100°C for 30 minutes. However, had reduction in the activity of the enterocins when submitted to 121°C for 15 minutes. Among the chemicals evaluated, the SDS and EDTA were the ones that presented the highest activity, and the enterocins produced with the Mix showed the highest inhibition halo. It was also evidenced effect bactericidal and/or bacteriostatic, and the highest percentage adsorption occurred between 60-65% between enterocins produced. The results indicate that the enterocins produced by Enterococcus faecium strains have potential applicability in foods as bioconservatives.