title: Detection, identification, and typing of Listeria species from baled silages fed to dairy cows.
abstract: Anaerobiosis, critical for successful ensilage, constitutes a challenge in baled silages. The loss of complete anaerobiosis causes aerobic deterioration and silages undergo dry matter and nutrient losses, pathogen growth, and mycotoxin production. Silage may represent an ideal substrate for Listeria monocytogenes, a pathogen of primary concern in several cheeses. The aim of this research was to investigate the occurrence of Listeria in baled silage fed to cows producing milk for a protected designation of origin cheese, and to characterize isolates by repetitive sequence-based PCR. Listeria spp. were detected in 21 silages and L. monocytogenes in 6 out of 80 of the analyzed silages; 67% of positives were found in molded zones. Results of the PCR typing showed genotypic homogeneity: 72.9 and 78.8% similarity between strains of Listeria spp. (n=56) and L. monocytogenes (n=24), respectively. Identical profiles were recovered in molded and nonmolded areas, indicating that contamination may have occurred during production. The application of PCR allowed the unambiguous identification of Listeria isolated from baled silages, and repetitive sequence-based PCR allowed a rapid and effective typing of isolates. Results disclose the potential of the systematic typing of Listeria in primary production, which is needed for the understanding of its transmission pathways.
authors.affiliation: Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, 10095 Grugliasco (TO), Italy.
authors.forename: D M
authors.initials: DM
authors.lastname: Nucera
authors.affiliation: Department of Veterinary Sciences, University of Turin, 10095 Grugliasco (TO), Italy.
authors.forename: M A
authors.initials: MA
authors.lastname: Grassi
authors.affiliation: Department of Veterinary Sciences, University of Turin, 10095 Grugliasco (TO), Italy.
authors.forename: P
authors.initials: P
authors.lastname: Morra
authors.affiliation: Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, 10095 Grugliasco (TO), Italy.
authors.forename: S
authors.initials: S
authors.lastname: Piano
authors.affiliation: Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, 10095 Grugliasco (TO), Italy.
authors.forename: E
authors.initials: E
authors.lastname: Tabacco
authors.affiliation: Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, 10095 Grugliasco (TO), Italy. Electronic address: giorgio.borreani@unito.it.
authors.forename: G
authors.initials: G
authors.lastname: Borreani
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D002417:Cattle; D002611:Cheese / Q000382:microbiology; D005260:Female; D005838:Genotype; D008087:Listeria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development; D008892:Milk / Q000382:microbiology; D012820:Silage / Q000382:microbiology*
keywords: Listeria contamination; aerobic deterioration; baled silage; mold count; plastic film damage