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  4. BACILLALES INFLUENCE QUALITY AND SAFETY OF DAIRY PRODUCTS

BACILLALES INFLUENCE QUALITY AND SAFETY OF DAIRY PRODUCTS

File(s)
Beno_cornellgrad_0058F_10677.pdf (2.5 MB)
Permanent Link(s)
https://doi.org/10.7298/X4S46Q50
https://hdl.handle.net/1813/59049
Collections
Cornell Theses and Dissertations
Author
Beno, Sarah Marie
Abstract

Bacillales, an order of Gram-positive bacteria, are commonly isolated from dairy foods and at various points along the dairy value chain. Three families of Bacillales are analyzed in this work: (i) Listeriaceae (represented by Listeria monocytogenes), (ii) Paenibacillaceae (represented by Paenibacillus), and (iii) Bacillaceae (represented by the Bacillus cereus group). These families impact both food safety and food quality. Most Listeriaceae are non-pathogenic, but L. monocytogenes has one of the highest mortality rates of foodborne pathogens. Listeria spp. are often reported in food processing environments. Here, 4,430 environmental samples were collected from 9 small cheese-processing facilities and tested for Listeria and L. monocytogenes. Prevalence varied by processing facility, but across all facilities, 6.03 and 1.35% of samples were positive for L. monocytogenes and other Listeria spp., respectively. Each of these families contains strains capable of growth at refrigeration temperatures. To more broadly understand milk spoilage bacteria, genetic analyses were performed on 28 Paenibacillus and 23 B. cereus group isolates. While no specific genes were significantly associated with cold-growing Paenibacillus, the growth variation and vast genetic data introduced in this study provide a strong foundation for the development of detection strategies. Some species within the B. cereus group have previously been shown to grow at refrigeration temperatures, but the genetic analyses provided here will be of importance for the development of screening tools and to more successfully assess spoilage risk. Overall, the work presented here covers groups of bacteria that are common challenges for the dairy industry and provides large data sets to encourage additional research surrounding these topics.

Date Issued
2017-12-30
Keywords
Microbiology
•
Food science
Committee Chair
Wiedmann, Martin
Committee Member
Worobo, Randy W.
Christy, Ralph Dean
Degree Discipline
Food Science and Technology
Degree Name
Ph. D., Food Science and Technology
Degree Level
Doctor of Philosophy
Type
dissertation or thesis

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