title: Production of tyramine by Enterococcus faecalis strains in water-boiled salted duck.
abstract: The potential to produce biogenic amines was investigated with 15 Lactococcus lactis and 15 Enterococcus faecalis strains isolated from water-boiled salted duck. The production of biogenic amines from the isolated strains grown in de Man Rogosa Sharpe broth containing precursor amino acids was determined by thin-layer chromatography and high-performance liquid chromatography. None of the L. lactis strains produced any biogenic amines, whereas 12 strains of E. faecalis produced tyramine and b -phenylethylamine. PCR assays were used to detect the presence of tyrosine decarboxylase genes in all of the isolated strains. Only the 12 biogenic amine-producing Enterococcus strains had a 924-bp fragment characteristic for the tyrosine decarboxylase gene. The comparison of the amplified partial tyrDC gene sequences of the 12 positive Enterococcus strains revealed 99% similarity within the same species. The tyramine production of the sterilized water-boiled salted duck inoculated with E. faecalis R612Z1 increased significantly during storage. This study reveals that the isolated E. faecalis strains can produce tyramine and β-phenylethylamine in the medium; however, they can only produce tyramine in water-boiled salted duck.
authors: Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
authors: Fang
authors: F
authors: Liu
authors: Lihui
authors: L
authors: Du
authors: Weiyan
authors: W
authors: Xu
authors: Daoying
authors: D
authors: Wang
authors: Muhan
authors: M
authors: Zhang
authors: Yongzhi
authors: Y
authors: Zhu
authors: Weimin
authors: W
authors: Xu
mesh_terms: D000818:Animals; D001679:Biogenic Amines / Q000096:biosynthesis; D002855:Chromatography, Thin Layer; D004372:Ducks / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000378:metabolism*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005784:Gene Amplification; D006801:Humans; D010627:Phenethylamines / Q000378:metabolism; D014439:Tyramine / Q000096:biosynthesis*; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D001679:Biogenic Amines; D010627:Phenethylamines; D014445:Tyrosine Decarboxylase; D014439:Tyramine