Date of Award:

5-1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Bacteriology and Public Health

Committee Chair(s)

G. H. Richardson

Committee

G. H. Richardson

Committee

R. S. Spendlove

Committee

C. A. Ernstrom

Abstract

Attempts were made to adapt the microtiter hemagglutination inhibition assay technique for the assay of enterotoxin A. The presence of a potent hemagglutinin in crude and partially purified preparations and the instability of sensitized erythrocytes prevented its use for routine analysis of enterotoxin from culture media and foods.

A capillary tube immunological assay was developed in which 1 μ g of enterotoxin/ml was detected in less than 1 hr . Interfacial reaction of antisera and enterotoxin solutions in a 1 mm internal diameter capillary tube allowed rapid detection and serological typing of enterotoxins.

Staphylococcus aureus growth and enterotoxin A development in Cheddar cheese slurry was evaluated. S. aureus growth and enterotoxin production occurred at 32 C. in 45 and 60% moisture cheese slurries following inoculation with 10 3 to 10 5 bacteria/gram.

Hydrogen peroxide (0. 5%) treatment of slurry at 37 C did not inhibit S. aureus and enterotoxin A development. Heating slurry at 72 C for 30 min eliminated staphylococci but reinoculation with ripening organisms was essential. Addition of sorbic acid (0. 2 to 0. 3%) to a slurry adjusted to pH 5. 0 with lactic acid, inhibited staphylococci. in milk and slurry. Cheese flavor development was retarded due to inhibition of micrococci and lipolysis. Non-protein nitrogen increases paralleled that of sorbate-free controls. Sorbate treatment was preferred over other treatments .

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