Date of Award:
5-1975
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Biology
Department name when degree awarded
Bacteriology and Public Health
Committee Chair(s)
Gary H. Richardson
Committee
Gary H. Richardson
Committee
C. Anthon Ernstrom
Committee
Paul B. Carter
Abstract
The metachromatic agar-diffusion test of Lachica, Hoeprich, and Genigeorgis (1971) was modified by adding 17 ml of the agar medium to a 100 by 15 mm plastic petri dish, using 5 µl samples and 3 mm wells. The test detected 0.5 ng/ml of thermonuclease in 3 hr at 37 C. This was equivalent to 106 to 107 cells/ml of Staphylococcus aureus strains 196 E, 14458, and 19095 grown in Brain Heart Infusion (BHI) broth. The test sensitivity was decreased ten fold in raw and pasteurized milk.
One-half gram of cheese was dissolved in 4.5 ml of 0.1 M sodium citrate for quantitative studies. When staphylococcal (>8 x 108 /ml) contaminated raw milk was pasteurized and made into cheese, more thermonuclease activity/ml was noted in the curd than whey. During prolonged storage at 4 C, thermonuclease activity decreased in raw and pasteurized milk and laboratory made cheese.
Bacillus subtilus, Streptococcus faecalis var liquefaciens, Streptococcus thermophilus, and Streptococcus cremoris strain ML8 reduced thermonuclease activity during growth incubation in BHI broth.
Thermonuclease was detected directly in staphylococcal contaminated laboratory aged cheese (>107 /gm) without prior purification, concentration, or extraction procedures.
Checksum
7ee75d5451883d4c8d13147604c14a66
Recommended Citation
Hong, Gene Leong, "Evaluation, Assay, Distribution, and Survey of Staphylococcus aureus Thermonuclease in Milk and Cheese Products" (1975). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 5162.
https://digitalcommons.usu.edu/etd/5162
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