Caseinolysis in cheese by Enterobacteriaceae strains of dairy origin

Morales, Pilar; Fernández-Garcı́a, Estrella; Núñez, Manuel

doi:10.1046/j.1472-765x.2003.01422.x

Cited by 53 publications

(37 citation statements)

References 17 publications

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“…Of the 47 tested cheese samples with pH <5.0, only 2 were positive for coliforms. This specific observation is consistent with previous studies; Manolopoulou and colleagues (2003) reported detecting die-off of E. coli and other coliforms in feta-style cheese with pH <5.0, and other studies demonstrated good growth of 10 different coliform strains (representing Hafnia, Serratia, Enterobacter, and Escherichia) in cheese with pH between 5.2 and 5.3 (Morales et al, 2003). One of the coliform-positive cheese samples with pH <5.0 was a soft bloomy rind cheese, and the other sample (pH 4.76) represented a fresh cheese, which may have been too young to allow for substantial coliform die-off.…”

Section: Milk Pasteurization Low Ph Low Water Activity and Other Csupporting

confidence: 92%

Coliform detection in cheese is associated with specific cheese characteristics, but no association was found with pathogen detection

Trmčić

Chauhan

Kent

et al. 2016

Journal of Dairy Science

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Coliform detection in finished products, including cheese, has traditionally been used to indicate whether a given product has been manufactured under unsanitary conditions. As our understanding of the diversity of coliforms has improved, it is necessary to assess whether coliforms are a good indicator organism and whether coliform detection in cheese is associated with the presence of pathogens. The objective of this study was (1) to evaluate cheese available on the market for presence of coliforms and key pathogens, and (2) to characterize the coliforms present to assess their likely sources and public health relevance. A total of 273 cheese samples were tested for presence of coliforms and for Salmonella, Staphylococcus aureus, Shiga toxin-producing Escherichia coli, Listeria monocytogenes, and other Listeria species. Among all tested cheese samples, 27% (75/273) tested positive for coliforms in concentrations >10cfu/g. Pasteurization, pH, water activity, milk type, and rind type were factors significantly associated with detection of coliforms in cheese; for example, a higher coliform prevalence was detected in raw milk cheeses (42% with >10cfu/g) compared with pasteurized milk cheese (21%). For cheese samples contaminated with coliforms, only water activity was significantly associated with coliform concentration. Coliforms isolated from cheese samples were classified into 13 different genera, including the environmental coliform genera Hafnia, Raoultella, and Serratia, which represent the 3 genera most frequently isolated across all cheeses. Escherichia, Hafnia, and Enterobacter were significantly more common among raw milk cheeses. Based on sequencing of the housekeeping gene clpX, most Escherichia isolates were confirmed as members of fecal commensal clades of E. coli. All cheese samples tested negative for Salmonella, Staph. aureus, and Shiga toxin-producing E. coli. Listeria spp. were found in 12 cheese samples, including 5 samples positive for L. monocytogenes. Although no association was found between coliform and Listeria spp. detection, Listeria spp. were significantly more likely to be detected in cheese with the washed type of rind. Our data provide information on specific risk factors for pathogen detection in cheese, which will facilitate development of risk-based strategies to control microbial food safety hazards in cheese, and suggest that generic coliform testing cannot be used to assess the safety of natural cheese.

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Section: Milk Pasteurization Low Ph Low Water Activity and Other Csupporting

confidence: 92%

Coliform detection in cheese is associated with specific cheese characteristics, but no association was found with pathogen detection

Trmčić

Chauhan

Kent

et al. 2016

Journal of Dairy Science

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“…Pseudomonas fragi was reported previously to be lipolytic and proteolytic, as were species belonging to the Enterobacteriaceae family, and they can contribute to spoilage through the production of volatile organic compounds and other undesirable metabolites, such as biogenic amines (47)(48)(49)(50)(51)(52). In contrast, B. thermosphacta and lactic acid bacteria were mainly correlated with carbohydrate metabolism.…”

Section: Discussionmentioning

confidence: 87%

Overlap of Spoilage-Associated Microbiota between Meat and the Meat Processing Environment in Small-Scale and Large-Scale Retail Distributions

Stellato

Storia

Filippis

et al. 2016

Appl Environ Microbiol

151

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Microbial contamination in food processing plants can play a fundamental role in food quality and safety. The aims of this study were to learn more about the possible influence of the meat processing environment on initial fresh meat contamination and to investigate the differences between small-scale retail distribution (SD) and large-scale retail distribution (LD) facilities. Samples were collected from butcheries (n ‫؍‬ 20), including LD (n ‫؍‬ 10) and SD (n ‫؍‬ 10) facilities, over two sampling campaigns. Samples included fresh beef and pork cuts and swab samples from the knife, the chopping board, and the butcher's hand. The microbiota of both meat samples and environmental swabs were very complex, including more than 800 operational taxonomic units (OTUs) collapsed at the species level. The 16S rRNA sequencing analysis showed that core microbiota were shared by 80% of the samples and included Pseudomonas spp., Streptococcus spp., Brochothrix spp., Psychrobacter spp., and Acinetobacter spp. Hierarchical clustering of the samples based on the microbiota showed a certain separation between meat and environmental samples, with higher levels of Proteobacteria in meat. In particular, levels of Pseudomonas and several Enterobacteriaceae members were significantly higher in meat samples, while Brochothrix, Staphylococcus, lactic acid bacteria, and Psychrobacter prevailed in environmental swab samples. Consistent clustering was also observed when metabolic activities were considered by predictive metagenomic analysis of the samples. An increase in carbohydrate metabolism was predicted for the environmental swabs and was consistently linked to Firmicutes, while increases in pathways related to amino acid and lipid metabolism were predicted for the meat samples and were positively correlated with Proteobacteria. Our results highlighted the importance of the processing environment in contributing to the initial microbial levels of meat and clearly showed that the type of retail facility (LD or SD) did not apparently affect the contamination. IMPORTANCEThe study provides an in-depth description of the microbiota of meat and meat processing environments. It highlights the importance of the environment as a contamination source of spoilage bacteria, and it shows that the size of the retail facility does not affect the level and type of contamination. Meat is a complex niche with chemical and physical properties that allow the colonization and development of a variety of microorganisms, especially bacteria (1, 2). Several factors can influence the occurrence of microbes in meat. After slaughtering, meat can be contaminated by microorganisms from water, air, and soil, as well as from the workers and equipment involved in the processing. In the later processing steps of the fresh meat chain (i.e., handling, cutting, and storage), abiotic factors such as temperature, gaseous atmosphere, pH, and NaCl levels select for certain bacteria, allowing colonization of the meat surface by different spoilage-related species and...

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“…The following species, less frequently detected on the surface of cow teats, were (13). Gram-negative bacteria may have a positive or negative effect on the flavor of cheeses, depending on their ratio in the microbial community (41,42). The species of Clostridium predominantly detected using the direct molecular method were not the most common species found in milk (i.e., Clostridium lituseburense and Clostridium perfringens) (15,45).…”

Section: Discussionmentioning

confidence: 99%

Cow Teat Skin, a Potential Source of Diverse Microbial Populations for Cheese Production

Verdier‐Metz¹,

Gagné

Bornes

et al. 2012

Appl Environ Microbiol

132

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The diversity of the microbial community on cow teat skin was evaluated using a culture-dependent method based on the use of different dairy-specific media, followed by the identification of isolates by 16S rRNA gene sequencing. This was combined with a direct molecular approach by cloning and 16S rRNA gene sequencing. This study highlighted the large diversity of the bacterial community that may be found on teat skin, where 79.8% of clones corresponded to various unidentified species as well as 66 identified species, mainly belonging to those commonly found in raw milk (Enterococcus, Pediococcus, Enterobacter, Pantoea, Aerococcus, and Staphylococcus). Several of them, such as nonstarter lactic acid bacteria (NSLAB), Staphylococcus, and Actinobacteria, may contribute to the development of the sensory characteristics of cheese during ripening. Therefore, teat skin could be an interesting source or vector of biodiversity for milk. Variations of microbial counts and diversity between the farms studied have been observed. Moreover, Staphylococcus auricularis, Staphylococcus devriesei, Staphylococcus arlettae, Streptococcus bovis, Streptococcus equinus, Clavibacter michiganensis, Coprococcus catus, or Arthrobacter gandavensis commensal bacteria of teat skin and teat canal, as well as human skin, are not common in milk, suggesting that there is a breakdown of microbial flow from animal to milk. It would then be interesting to thoroughly study this microbial flow from teat to milk.

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Caseinolysis in cheese by Enterobacteriaceae strains of dairy origin

Cited by 53 publications

References 17 publications

Coliform detection in cheese is associated with specific cheese characteristics, but no association was found with pathogen detection

Coliform detection in cheese is associated with specific cheese characteristics, but no association was found with pathogen detection

Overlap of Spoilage-Associated Microbiota between Meat and the Meat Processing Environment in Small-Scale and Large-Scale Retail Distributions

Cow Teat Skin, a Potential Source of Diverse Microbial Populations for Cheese Production

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