Effect of NaCl Treatments on Tyramine Biosynthesis of Enterococcus faecalis

J Food Prot. 2015 May;78(5):940-5. doi: 10.4315/0362-028X.JFP-14-443.

Abstract

The effect of NaCl stress (0 to 8%, wt/vol) on the growth and tyramine production in two Enterococcus faecalis strains was examined during culture time. The growth of E. faecalis was inhibited by the increase in NaCl concentration, but tyramine production was unaffected. Tyramine accumulated rapidly during the logarithmic phase of the strains, and the final tyramine levels were approximately 800 μg/ml. Relative gene expression of four genes in the tyrosine decarboxylase locus, namely, tyrRS, tyrDC, tyrP, and nhaC, was evaluated at different incubation times. The results showed that NaCl stress could upregulate the expression of tyrDC and tyrP to improve the tyramine production of a single E. faecalis strain under certain conditions, and TyrS could act as a negative regulator on the genetic regulation of the tyramine cluster.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Enterococcus faecalis / enzymology
  • Enterococcus faecalis / genetics
  • Enterococcus faecalis / growth & development
  • Enterococcus faecalis / metabolism*
  • Sodium Chloride / metabolism*
  • Tyramine / biosynthesis*
  • Tyrosine Decarboxylase / genetics
  • Tyrosine Decarboxylase / metabolism

Substances

  • Bacterial Proteins
  • Sodium Chloride
  • Tyrosine Decarboxylase
  • Tyramine