Thesis (M.S.)--University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references (leaves 39-43)

Submitted in fulfillment of the requirements for the Degree of Master of Technology: Biological Sciences at Technikon Natal, 2000. / Spice oils are known to exhibit antifungal activity and therefore have the potential to control mycotoxin production. There is a need in the food industry to find measures to control mycotoxins that are frequently associated with grains that form the staple diet of the majority of the population in South Africa. Clove, cinnamon, oregano, tumeric, eucalyptus, neem, aniseed, mace and nutmeg oils were tested to determine their inhibitory potential against growth of Aspergillus parasiticus and Fusarium moniliforme using the agar overlay technique. Varying concentrations of the spice oils, ranging from 0.1 ppm to 2.0 ppm, were incorporated into broth cultures of A. parasiticus and maize patty cultures ofF. moniliforme. Levels of production of aflatoxins and fumonisin were determined using standard thin layer chromatography and highpressure liquid chromatography methods. In addition, the active component of the spice oils were isolated, characterised and tested. The inhibitory potential of these compounds for field use was tested by incorporating clove oil, whole cloves and ground cloves in samp / M

Call number: LD2668 .T4 1985 C348 / Master of Science

Vibrio bacteria are emerging pathogens responsible for 80,000 illnesses and 100 deaths in the United States each year. Infections are directly linked to the marine environment and are acquired by consuming contaminated seafood or exposing wounds during aquatic activities. Florida has the highest national incidence of vibriosis, with 20% of its cases reported from the Indian River Lagoon region, a popular recreation destination. This study utilized a combination of cultivation and molecular techniques to investigate the local distribution of V. vulnificus, V. parahaemolyticus and V. cholerae in this local waterway. The targeted species were found in an array of samples which may facilitate their transmission to humans. Overall, these bacteria were abundant in estuarine sediments (Vp: 2,439 CFU/g, Vv: 303 CFU/g, Vc: 176 CFU/g), on the sharp edges of oyster shells (Vp: 82 CFU/cm, Vv: 102 CFU/cm, Vc: 41 CFU/cm), and in the water column (Vp: 3.78 CFU/ml, Vv: 5.51 CFU/ml, Vc: 2.46 CFU/ml). Vibrio also pose a hazard to recreational anglers as they were recovered from fish (Vp: 61%, Vv: 55%, Vc: 30%), live bait shrimp (Vp: 80%, Vv: 37%, Vc: 0%) and hooks (Vp: 32%, Vv: 18%, Vc: 0%). Additionally, a molecular analysis of the V. vulnificus virulence revealed that the local population was dominated by disease-causing (vcgC) strains, which may explain why wound-related infections are common in this region. Vibrio occurrence varied both spatially and temporally due to their relationship with salinity and temperature. These bacteria exhibited a strong negative correlation with salinity, being particularly abundant near freshwater discharge locations. Due to Florida’s year-round warm climate, these species were found to be permanent members of the local microbial community. Seasonal peaks in abundance occurred between August and October, a period which corresponds with the warmest water temperatures as well as frequent rainfall. Predictive models were constructed based on these parameters to provide a better understanding of how, when and where Vibrio spp. may be encountered by humans. This information is important for both water management and healthcare initiatives, with an overall goal of improving local recreational safety. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Diseases in natural ecosystems are often assumed to be less severe than those observed in domestic cropping systems due to the extensive biodiversity exhibited in wild vegetation communities. In Australia, it is this natural biodiversity that is now under threat from Phytophthora cinnamomi. The soilborne Oomycete causes severe decline of native vegetation communities in south-western Victoria, Australia, disrupting the ecological balance of native forest and heathland communities. While the effect of disease caused by P. cinnamomi on native vegetation communities in Victoria has been extensively investigated, little work has focused on the Anglesea healthlands in south-western Victoria. Nothing is known about the population structure of P. cinnamomi at Anglesea. This project was divided into two main components to investigate fundamental issues affecting the management of P. cinnamomi in the Anglesea heathlands. The first component examined the phenotypic characteristics of P. cinnamomi isolates sampled from the population at Anglesea, and compared these with isolates from other regions in Victoria, and also from Western Australia. The second component of the project investigated the effect of the fungicide phosphonate on the host response following infection by P. cinnamomi. Following soil sampling in the Anglesea heathlands, a collection of P, cinnamomi isolates was established. Morphological and physiological traits of each isolate were examined. All isolates were found to be of the A2 mating type. Variation was demonstrated among isolates in the following characteristics: radial growth rate on various nutrient media, sporangial production, and sporangial dimensions. Oogonial dimensions did not differ significantly between isolates. Morphological and physiological variation was rarely dependant on isolate origin. To examine the genetic diversity among isolates and to determine whether phenotypic variation observed was genetically based, Random Amplified Polymorphic DNA (RAPD) analyses were conducted. No significant variation was observed among isolates based on an analysis of molecular variance (AMQVA). The results are discussed in relation to population biology, and the effect of genetic variation on population structure and population dynamics. X australis, an arborescent monocotyledon indigenous to Australia, is highly susceptible to infection by P. cinnamomi. It forms an important component of the heathland vegetation community, providing habitat for native flora and fauna, A cell suspension culture system was developed to investigate the effect of the fungicide phosphonate on the host-pathogen interaction between X. australis and P. cinnamomi. This allowed the interaction between the host and the pathogen to be examined at a cellular level. Subsequently, histological studies using X. australis seedlings were undertaken to support the cellular study. Observations in the cell culture system correlated well with those in the plant. The anatomical structure of X australis roots was examined to assist in the interpretation of results of histopathological studies. The infection of single cells and roots of X. australis, and the effect of phosphonate on the interaction are described. Phosphonate application prior to inoculation with P. cinnamomi reduced the infection of cells in culture and of cells in planta. In particular, phosphonate was found to stimulate the production of phenolic material in roots of X australis seedlings and in cells in suspension cultures. In phosphonate-treated roots of X australis seedlings, the deposition of electron dense material, possibly lignin or cellulose, was observed following infection with P. cinnamomi. It is proposed that this is a significant consequence of the stimulation of plant defence pathways by the fungicide. Results of the study are discussed in terms of the implications of the findings on management of the Anglesea heathlands in Victoria, taking into account variation in pathogen morphology, pathogenicity and genotype. The mode of action of phosphonate in the plant is discussed in relation to plant physiology and biochemistry.

In some areas the effect of pathogenicity of microorganisms upon the European corn borer have been explored. The microorganisms studied were: Nosema, pyraustae, Nosema necatrix, and Bacillus thuringlensis var, thuringiensie. Most studies have been limited to either laboratory or field work. In this thesis, a comparative study of mortality, percent infection, and tune intervals in which infection occurs have been explored, in the field and the laboratory studies.It is concluded: (1) field recovered borers at different day intervals showed interaction between the experimental microorganisms and time intervals (2) that the microorganisms used in the field, especially N. necatrix, may be used as effective microbial control agents against Ostrinia nubilalis.Ball State UniversityMuncie, IN 47306

published_or_final_version / abstract / toc / Medicine / Master / Doctor of Medicine

Thesis (Ph. D.)--University of Hawaii at Manoa, 1982. / Bibliography: leaves 242-245. / Microfiche. / xiii, 245 leaves, bound ill. 29 cm

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Bibliography: leaf 141-157.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.