Cheese whey as substrate for bacteriocins production by Enterococcus faecium strains.

The production of bacteriocins from cheap substrates could be very attractive for many food industrial applications. This study aimed at determining the conditions needed for the optimal secretion of enterocins by the E. faecium strains SD1, SD2, SD3 and SD4, isolated from Sardinian goat´s milk (Schirru et al., 2012). Cheese whey, inexpensive milk by-product, was used as substrate while skimmed milk and MRS broth were studied as reference media. Growth temperature played an important role in the bacteriocins secretion and highest levels were recorded at 37oC. Interestingly, the E. faecium strains were able to grow in cheese whey at levels similar to those detected in skimmed milk and MRS broth. However, the bacteriocins production was lower. Optimal enterocins production was detected once the strains were grown in MRS medium where organic nitrogen sources were found to be essential for high bacteriocin productions while different sugar sources resulted in variable bacteriocin levels. This study showed that cheese whey, world-wide disposal and pollution problem for the dairy industry, could be a good substrate for the production of bacteriocins. However, the optimisation of MRS medium seems to be more crucial towards the cost-effective production of high bacteriocins levels to be used in the food processing industry. As alternative, supplementing cheese whey with some of the MRS components may be an interesting approach for the optimisation of bacteriocins productions by the studied E. faecium strains.