Comparison of bacteriocins production from Enterococcus faecium strains in cheese whey and optimised commercial MRS medium

The production of bacteriocins from cheap substrates
could be useful for many food industrial applications.
This study aimed at determining the conditions needed for
optimal production of enterocins SD1, SD2, SD3 and SD4
secreted by Enterococcus faecium strains SD1, SD2, SD3
and SD4, respectively. To our knowledge, this is the first use
of cheese whey—a low-cost milk by-product—as a substrate
for bacteriocin production by E. faecium; skimmed
milk and MRS broths were used as reference media. This
cheese manufacturing residue proved to be a promising
substrate for the production of bacteriocins. However, the
levels of secreted antimicrobial compounds were lower than
those achieved by E. faecium strains in MRS broth.
Bacteriocin production was affected strongly by physical
and chemical factors such as growth temperature, time of
incubation, pH, and the chemical composition of the culture
medium. The optimal temperature and time of incubation
supporting the highest bacteriocin production was determined
for each strain. Different types, sources and amounts
of organic nitrogen, sugar, and inorganic salts played an
essential role in bacteriocin secretion. E. faecium strains
SD1 and SD2—producing high bacteriocin levels both in
cheese whey and skimmed milk—could be of great interest
for potential applications in cheese-making.