(191af) Production Improvement and a Novel Separation Method of Bacteriocin Y31 Produced By Enterococcus Faecium Y31

Class IIa bacteriocins have strong antibacterial activity against Listeria monocytogenes and contain a conserved YGNGVXCXXXXCXV sequence motif at their N-terminus. This class has attracted particular attention because of their unique characteristics and potential superiority for use as biopreservatives due to its antibacterial activity against L. monocytogenes, which is a common food pathogen. However, one of bottlenecks to industrialize class IIa bacteriocin are that separation and purification steps of this class are cumbersome and its output is low. If the separation and purification steps can be simplied, and its output can be improved, industrialization of the class bacteriocin would be expected soon.

A novel method of improving Enterocin Y31 production was proposed. Culture of strain Enterococcus faecium Y31 producing class IIa bacteriocin without any protein and peptide, Enterocin Y31 prodution was improved only by adjusting pure amino acid, vitamins and mineral substance. The results showed that the growth of E. faecium Y31 is not related to the production of Enterocin Y31, a chemical defined medium SDM was determined by single omission experiment, Enterocin Y31 production in SDM was 1.6 times higher than that in MRS.

Comparation between general separation and purification method (extraction of crude protein, chromatography and dialysis) and chemical defined medium-ultrafiltration method were researched. The results showed that chemical defined medium-ultrafiltration separation and purification method was more rapid and simple, the purity was the same. The recovery rate of chemical defined medium-ultrafiltration was 80%, while that of general separation and purification was 6.4%, meaning that the recovery rate was improved 12.5 times. The chemical defined medium-ultrafiltration separation and purification method avoided a complete loss of antibacterial activity in the separation process of Enterocin Y31. Its molecular weight was 6.7kDa, Enterocin Y31 contained abundant amino acid and the content of Met was highest, and partial amino acid sequence was N-T-A-H-S-D-F-N-R.