Aspectos de seguridad de Enterococcus faecium MXVK29 y Enterococcus faecalis MXVK22 aislados de productos cárnicos y caracterización molecular de sus bacteriocinas

Bioconservation is the controlled use of microorganisms or their metabolites to control the microflora in decomposition and also pathogens increasing the shelf life and improving the sanitary quality of food. Enterococci are lactic acid bacteria (LAB) that contribute to the organoleptic properties o...

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Detalles Bibliográficos
Autor: YENIZEY MERIT ALVAREZ CISNEROS
Tipo de recurso: tesis doctoral
Estado:Versión publicada
Fecha de publicación:2011
País:México
Institución:Universidad Autónoma Metropolitana
Repositorio:Repositorio Institucional de la UAM Iztapalapa
Idioma:español
OAI Identifier:oai:bindani.izt.uam.mx:zk51vg973
Acceso en línea:https://doi.org/10.24275/uami.zk51vg973
Access Level:acceso abierto
Palabra clave:info:eu-repo/classification/LEM/Industria y comercio de la carne -- Medidas de seguridad
info:eu-repo/classification/LEM/Bacteriocinas
info:eu-repo/classification/LEM/Conservación de alimentos
info:eu-repo/classification/LEM/Food conservation
info:eu-repo/classification/LEM/Meat industry and trade Security systems
info:eu-repo/classification/LEM/Carne Conservación
info:eu-repo/classification/LEM/Carne -- Conservación
info:eu-repo/classification/LEM/Meat Conservation
info:eu-repo/classification/LEM/Bacteriocins
info:eu-repo/classification/LEM/Biotecnología
info:eu-repo/classification/LEM/Biotechnology
info:eu-repo/classification/cti/6
Descripción
Sumario:Bioconservation is the controlled use of microorganisms or their metabolites to control the microflora in decomposition and also pathogens increasing the shelf life and improving the sanitary quality of food. Enterococci are lactic acid bacteria (LAB) that contribute to the organoleptic properties of fermented foods, as well as having the ability to produce bacteriocins (enterocin), which can be degraded by proteolytic enzymes present in the gastrointestinal tract; in addition they could be used as natural preservatives. However, some studies have demonstrated that the genus Enterococcus may act as reservoirs for antibiotic resistance genes, in addition, they may carry some virulence determinants, thus rising concerns about the safety of strains found in foods. The purpose of this study was to identify if the strain of Enterococcus faecium MXVK29 and Enterococcus faecalis MXVK22 can be used as potential fermentation starters. The methodology was divided in different seccions: production kinetics, minimum inhibitory concentration determination, capacity to generate resistant strains, determination of safety aspects of enterococci strains, purification and partial molecular characterization of enterocins. The profile for both bacteriocins is a primary metabolite and they showed an antimicrobial activity of 2133.33 AU/mL and 4266.66 AU/mL (enterocin produced by E. faecalis MXVK22 and E. faecium MXVK29, respectively). Bacteriocin concentrations (2133, 1066, 533, 267 and 134AU/mL) tested in this study have a bacteriostatic effect on Listeria strains, with the exception of Listeria monocytogenes 911204/47LMB, who did not show an inhibitory effect on any concentration. The minimum inhibitory concentration of bacteriocin was 2535, 6040, 3969, and 11021 UA/mL for bacteriocin produced by E. faecium MXVK29 and 4263, 2425, 1209 and 3810 AU/mL for bacteriocina produced by E. faecalis MXVK22 (Listeria innocua, Listeria monocytogenes LM82, LMB911204/47 and ScottA, respectively). Resistant strains of Listeria showed changes in genomic profiles where compared to sensitive strains. The virulence factors (cylA, cylB y cylM, agg, gelE, esp, efaAfs, efaAfm, cpd, cob, ccf y ace) were amplified by PCR in all strains tested (Enterococcus faecalis MXVK22 and Enterococcus faecium MXVK29), the ccf gene encoding a sex pheromone was positive for all strains tested. Enterococcus faecium MXVK29 was sensitive to all antibiotics tested, unlike Enterococcus faecalis MXVK22 that showed resistance to vancomycin and tetracycline. Enterococcus faecalis MXVK22 did not form any biogenic amines, in contrast to Enterococcus faecium MXVK29 that had positive activity decarboxylase for tyramine. The yield obtained with the purification protocol was 32.7% for the bacteriocin extract (EB) Enterococcus faecium MXVK29 and 32.1% for EB Enterococcus faecalis MXVK22. Amino terminal sequence of the bacteriocina produced by Enterococcus faecium MXVK29, presented a hydrophilic and cationic consensus sequence YGNGV(X)C(X)4C with two cysteine residues at positions 9 and 14. The PCR amplified fragment had 100% similarity to the mature peptide of enterocin A and enterocin B produced by Enterococcus faecium MTCC5153. The consensus sequence of the obtained sequences was aligned with100% similarity with the partial sequence of the enterocin operón (entAIF) reported in NCBI database. Enterococcus faecium MXVK29 could be used as part of a bioconservation method either as a starter culture, bioprotector culture or additive, additionally the enterocin A has a great potential for use as natural preservative in food.

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