Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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Please read the abstract in the front section of this document / Dissertation (M Inst Agrar ( Food Processing))--University of Pretoria, 2006. / Food Science / unrestricted

Salmonella is one of the leading foodborne pathogens causing illness today. Because of this, Salmonella rapid detection methods are under immense study for use in food. The traditional method, using the Food and Drug Administration- approved Bacterial Analytical Manual procedure, takes 4-6 days for Salmonella detection in food. Other rapid methods still take at least 16 h for detection due to their enrichment steps. The hypothesis of this study was that the use of immobilized antibodies coupled with polymerase chain reaction (PCR) can be used for the rapid capture and detection of Salmonella spp. in food without the need for pre-enrichment. The rapid detection system was developed using immobilized anti-Salmonella antibody beads to capture and separate Salmonella from food without using an enrichment step. Detection of the immunocaptured Salmonella was done through PCR or an enzyme-linked immunosorbent assay (ELISA)-based system entitled Rapid Immuno-Capture (RIC). The detection limit for buffer, chicken rinse, and shell eggs with static antibody capture PCR and RIC, was determined by inoculation of the Salmonella-free samples. The RIC assay detected Salmonella spp. in buffer at concentrations as low as 4 x 101 CFU/ml, and in chicken rinse and shell eggs, the assay detected Salmonella at 4 x 103 CFU/ml. The antibody capture with PCR detected Salmonella in buffer at concentrations as low as 4 x 102 CFU/ml, in chicken rinse at concentrations as low as 4 x 105 CFU/ml, and in shell egg at bacteria concentrations of 4 x 106 CFU/ml.

No description available.

Vibrio cholerae, a natural inhabitant of the marine environment, is capable of evolving from a strictly environmental to a pathogenic lifestyle. Upon this transition, the bacterium may cause the severe diarrheal disease cholera. To cause disease, ingested V. cholerae must survive a number of host defenses. Similarly, within the marine, V. cholerae is subject to various ecological pressures; these pressures may prompt the bacterium to develop adaptations that increase their survival in the environment as well as in response to host defenses. In the marine, V. cholerae can be found in different fractions: in sediment, in association with cyanobacteria, or in water. It is possible that different pressures found in each of these fractions may lead to specific host-associated phenotypes that increase the potential of V. cholerae to emerge as a pathogen. V. cholerae that do evolve into pathogens comprise a phylogenetically confined subset within the species that encode allelic variations of core genes, such as ompU, that confer virulence adaptations. In this study, we examined whether environmental V. cholerae isolated from different marine fractions exhibit distinct host-associated phenotypes and encode virulence associated alleles. We found that V. cholerae we isolated from different marine fractions did not show differences among the host-associated phenotypes tested, nor did fraction appear to select for and enrich a given virulence associated allele. Nevertheless, this study provides insight on the role of environmental conditions on the pathogenic potential of environmental V. cholerae.

published_or_final_version / Dentistry / Master / Master of Philosophy

The microbial composition of Pacific oysters (Crassostrea gigas) subjected to UV-treated seawater was determined by quantitative and qualitative means. A total of 2,779 microorganisms were identified from seawater and oysters during a 72 hour sampling period employing a computer assisted replica-plating technique. UV treatment effectively eliminated coliforms and Pseudomonas Type I from seawater but other gram-negative asporogenous rods were more resistant. The microogranisms commonly found in oysters, whether subjected to UV-treated seawater or not, were, in the order of predominance, Pseudomonas Type III or IV, Vibrio/Pseudomonas Type II, Flavobacterium/ Cytophaga and Acinetobacter /Moraxella. The composition of microbial flora in oysters remained relatively stable irrespective of the microorganisms present in the seawater. A total of 18 presumptive hemolytic vibrios were found in oysters but further confirmation revealed two isolates to be Vibrio parahaemolyticas and the remainder Aeromonas species. Approximately 10 percent of the microorganisms isolated from seawater and oysters were gram-positive cocci and 14 to 23 percent of these were coagulase positive, DNase positive, and (β-hemolytic on human blood agar. / Graduation date: 1971

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