Growth of <i>Enterococcus durans</i> E204 producing bacteriocin-like substance in MRS Broth: Description of the growth and quantification of the bacteriocin-like substance

Abstract

Bacteriocin-like substance E204 is an antimicrobial compound produced by Enterococcus durans E204 isolated from camel milk of Morocco that shows a broad spectrum of inhibitory activity against taxonomically related microorganisms. It is sensitive to digestive proteases. In the first study, de Man, Regosa and Sharpe (MRS) broth was inoculated by E204 strain, incubated for 30°C at 200 rpm and monitored by checking dry cell weight, nutrients consumption, lactic acid and bacteriocin-like productions. The maximum biomass (2.3 g/l) and antimicrobial activity (32 AUml^-1) were obtained at 12 h of incubation. No increase in the production of bacteriocin-like was recorded after the exponential phase. In the other hand, the quantification of the antimicrobial activity was carried out by a photometric assay on culture tubes based on the determination of the ID50 dose causing 50% growth inhibition of Enterococcus faecium 410 CECT in 6 h of incubation. The highest bacteriocin-like titre (279.71 BUml^-1) was obtained at acidic pH (3.5) and at 70°C after 10 min of incubation.

Key words: Enterococcus durans, bacteriocin-like, MRS broth, nutrients consumption, quantification.