title: Assessment of virulence factors, antibiotic resistance and amino-decarboxylase activity in Enterococcus faecium MXVK29 isolated from Mexican chorizo.
abstract: Enterococcus faecium MXVK29 has the ability to produce an antimicrobial compound that belongs to Class IIa of the Klaenhammer classification, and could be used as part of a biopreservation technology through direct inoculation of the strain as a starter or protective culture. However, Enterococcus is considered as an opportunistic pathogen, hence, the purpose of this work was to study the food safety determinants of E. faecium MXVK29. The strain was sensitive to all of the antibiotics tested (penicillin, tetracycline, vancomycin, erythromycin, chloramphenicol, gentamicin, neomycin, kanamycin and netilmicin) and did not demonstrate histamine, cadaverine or putrescine formation. Furthermore, tyrosine-decarboxylase activity was detected by qualitative assays and PCR. Among the virulence factors analysed for the strain, only the genes encoding the sexual pheromone cCF10 precursor lipoprotein (ccf) and cell-wall adhesion (efaAfm) were amplified. The presence of these genes has low impact on pathogenesis, as there are no other genes encoding for virulence factors, such as aggregation proteins. Therefore, Enterococcus faecium could be employed as part of a bioconservation method, because it does not produce risk factors for consumer's health; in addition, it could be used as part of the hurdle technology in foods.
  
  
  CONCLUSIONS
  The use of molecular techniques has allowed, in recent years, to detect pathogenicity genes present in the genome of starter cultures used in food processing and preservation. The presence of these genes is undesirable, because horizontal transfer may occur with the natural biota of consumers. For this reason, it is important to analyse the presence of pathogenicity genes in such cultures. In this work, virulence factors and antibiotic resistance of Enterococcus faecium strain MXVK29, producing an antimicrobial compound with high antilisterial activity, were analysed. The results indicate that the strain is safe to be used in food processing as starter culture.
authors.affiliation: Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, Mexico.
authors.forename: Y M
authors.initials: YM
authors.lastname: Alvarez-Cisneros
authors.affiliation: Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, Mexico.
authors.forename: F J
authors.initials: FJ
authors.lastname: Fernández
authors.affiliation: Universidad Autónoma Metropolitana-Xochimilco, Mexico City, Mexico.
authors.forename: T
authors.initials: T
authors.lastname: Sainz-Espuñez
authors.affiliation: Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, Mexico.
authors.forename: E
authors.initials: E
authors.lastname: Ponce-Alquicira
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D016984:Enterococcus faecium / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification / Q000472:pathogenicity; D005519:Food Preservation; D059022:Food Safety; D006801:Humans; D008461:Meat Products / Q000382:microbiology*; D008800:Mexico; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D014439:Tyramine / Q000096:biosynthesis; D014445:Tyrosine Decarboxylase / Q000378:metabolism; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D014445:Tyrosine Decarboxylase; D014439:Tyramine
keywords: 
  Enterococcus
  ; Listeria sp.; bioconservation; enterocin operon; lactic acid bacteria; safety determinants