title: Pseudomonas spp. and Serratia liquefaciens as Predominant Spoilers in Cold Raw Milk.
abstract: The storage of fresh raw milk at low temperature does not prevent proliferation of psychrotrophic bacteria that can produce heat-resistant proteolytic enzymes contributing to the reduced shelf life of dairy products. This study aimed to identify the dominant psychrotrophic proteolytic enzyme-producing population of raw milk from Brazil. Raw milk samples collected in 3 different cooling tanks in Brazil were stored at optimal (45 h at 4 °C followed by 3 h at 7 °C) and suboptimal (45 h at 7 °C followed by 3 h at 10 °C) conditions to simulate farm storage and transportation allowed by Brazilian laws. The highly proteolytic enzyme-producing strains isolated from stored cold raw milk were characterized by repetitive sequence-based Polymerase Chain Reaction (PCR) analysis. This clustering resulted in 8 different clusters and 4 solitary fingerprints. The most proteolytic isolates from each rep-cluster were selected for identification using miniaturized kit, 16S rDNA and rpoB gene sequencing. Serratia liquefaciens (73.9%) and Pseudomonas spp. (26.1%) were identified as the dominant psychrotrophic microorganisms with high spoilage potential. The knowledge of milk spoilage microbiota will contribute to improved quality of milk and dairy products.
authors.affiliation: Dept. of Microbiology, Univ. Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, Minas Gerais, Brazil.|Inst. for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, B-9090, Melle, Belgium.
authors.forename: Solimar G
authors.initials: SG
authors.lastname: Machado
authors.affiliation: Dept. of Microbiology, Univ. Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, Minas Gerais, Brazil.
authors.forename: Fernanda L
authors.initials: FL
authors.lastname: da Silva
authors.affiliation: Dept. of Microbiology, Univ. Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, Minas Gerais, Brazil.
authors.forename: Denise M S
authors.initials: DM
authors.lastname: Bazzolli
authors.affiliation: Inst. for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, B-9090, Melle, Belgium.|Dept. of Pathology, Bacteriology and Poultry Diseases, Ghent Univ. (UGent), Salisburylaan 133, B-9820, Merelbeke, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
authors.affiliation: Dept. of Statistics, Univ. Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, Minas Gerais, Brazil.
authors.forename: Paulo M de A
authors.initials: PM
authors.lastname: Costa
authors.affiliation: Dept. of Microbiology, Univ. Federal de Viçosa (UFV), Av. Peter Henry Rolfs, S/N, Viçosa, Minas Gerais, Brazil.
authors.forename: Maria Cristina D
authors.initials: MC
authors.lastname: Vanetti
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001938:Brazil; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005506:Food Contamination; D005516:Food Microbiology; D063427:Food Quality; D008892:Milk / Q000382:microbiology*; D010447:Peptide Hydrolases / Q000378:metabolism; D011549:Pseudomonas / Q000302:isolation & purification*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D044090:Serratia liquefaciens / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D012336:RNA, Ribosomal, 16S; D010447:Peptide Hydrolases
keywords: Rep-PCR; heat-resistant proteolytic enzyme; proteolytic; psychrotrophic; spoilage