Thesis (M. Tech.(Environmental Health)) - Central University of Technology, Free State, 2005 / As the concentration of dust has been shown to be proportional to seasonal change in the Free State Province of South Africa, one might expect the prevalence of associated microorganisms to follow the same pattern. The presence of dust is also associated with an aerosolised microbial population that gets blown into almost any unsealed environment including food storage facilities at schools. In addition, facility design and storage practices at these schools are under-developed and could subsequently lead to the contamination of stored food by dust, insects and rainwater. The foods in question include fortified biscuits that are intended for malnourished, and in several cases immunocompromised, children who are susceptible to opportunistic pathogens. Therefore this study aimed to determine the impact of facility design on the level and distribution of viable airborne microorganisms (fungi and bacteria) in the storage rooms and the outdoor environment at both rural (higher dust exposure) and urban schools. Besides the pathogenicity of these organisms, their ability to degrade the sugars (major fortifying agent) in the mentioned biscuits was also established. The results showed the presence of Escherichia coli, which signifies faecal contamination and could be attributed to the lack of toilet facilities in the schools, especially in rural areas. Although Staphylococcus sp. is normally related to poor personal hygiene practices, these organisms were also isolated from the air of the storerooms and school premises. The presence of moulds and airborne microorganisms was attributed to unfavourable environmental conditions as well as crowding in the classrooms. The microbial contamination originally present on the fortified biscuits or originating from the air further caused deterioration in the quality of the food. The fungi present in the air (identified species) cause respiratory problems when inhaled by children as they are opportunistic pathogens. It is further evident that a change of season corresponded to a general change in bioaerosol composition, such as the increased presence of dust during the winter months. It was further concluded that schools situated in different environments (urban/rural) should have storerooms that address the various environmental factors influencing bioaerosols. This would impact not only directly on the health of children in terms of their exposure to possible allergens, but also indirectly through the food that they consume as part of the feeding programme.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2018. / Trihalomethanes (THMs) are a group of four compounds that are formed, along with other disinfected by-products. This happens when chloride or other disinfectants are used to control microbial contamination in drinking water, which then reacts with natural organic or inorganic substances in water. Trihalomethanes are better known by their common names such as chloroform, bromodichloromethane, chlorodibromomethane and bromoform. These four compounds are known to be classified as cancer group B carcinogens (shown to cause cancer in laboratory animals). Trihalomethane levels tend to increase with pH, temperature, time and the level of “precursors" present. Precursors are known to be organic substances which react with chloride to form THMs. One significant way of reducing the amount of THMs in water is to eliminate or reduce chlorination before filtrations and reduce precursors. There are guideline limits for THMs in the SANS 241:2015 document, but they are not continuously monitored and their levels in natural water are not known. The aim of this study is to develop a rapid, fast and reliable liquid-liquid microextraction technique, to determine the presence of THMs in natural water sources. This study particularly focuses on different water sources e.g. river, underground, borehole and chlorinated water. Chlorinated water is the water that has been presumably treated for bacteria and fungus growth. The results that were obtained for chlorinated water are as follow, 10.120 μg/L − 11.654 μg/L for chloroform, 2.214 μg/L - 2.666 μg/L for bromodichloromethane, 0.819 μg/L − 0.895 μg/L chlorodibromomethane and 0.103 μg/L - 0.135 μg/L for bromoform from validation data. All these THMs concentrations have been found to be below the SANS 241:2015 limits. Natural water shows a very high affinity for chloroform. This is what is expected under normal conditions as chloroform is the most abundant THM of all THMs present in natural water. The liquid-liquid microextraction technique that was optimized and used for the determination of THMs in this study is a rapid, simple and inexpensive technique that provides low limits of detection (LOD) e.g. 0.1999 μg/L chlorodibromomethane and 0.2056 μg/L bromoform and wide dynamic range (LOQ) of 0.6664 μg/L chlorodibromomethane and 0.6854 μg/L bromoform for the determination of THMs.

>Magister Scientiae - MSc / Extreme weather events in combination with geographical changes in groundwater utilization, groundwater availability, aquifer recharge, and ultimately changes in the quality of water resources, are expected in the future. As a consequence of changing weather patterns and urbanization the demand for groundwater is likely to increase in certain areas. We know that most waterborne pathogenic health epidemics are associated with contamination of farm water and wastewater. There is however limited understanding of the nature and extent of chemical, physical and biological processes that control the fate and transport of the microorganisms in primary and secondary aquifers. In this thesis, transport results are reported, where E. coli and PDR1 were selected as the biological tracers transported through a primary aquifer at the University of the Western Cape. In conjunction with the microbes salt and Rhodamine (chemical tracers) were injected to compare their fate and transport mechanism in the primary aquifer medium. A series of controlled Darcy experiments under laboratory and field conditions were conducted. Each provided a different data and information. The results from laboratory studies were used to improve design of the field studies. In both cases, the data collected provided information on fate and transport of microbes in groundwater. The field design phase of the experiment was an up-scaling of the laboratory phase of this project. The amount of chemical tracers injected into the aquifer was increased in proportion to the size of the research site. Tracer tests using chemical and microbial tracers were conducted simultaneously. Results of laboratory tests demonstrate a 5 times slower transport of microbes, compared to tests with salts during the laboratory phase. The salts at field scale show a breakthrough occurring after 2 days whereas the microbes –did not break through during the 28 days of the observation period. A new borehole was drilled closer to the pumping borehole to eliminate distance or travel time, but this had no effect on field results for the microbes. / National Research Foundation

M. Tech. Pharmaceutical Sciences Tshwane University of Technology 2013. / Aims of the present study was to evaluate the inhibitory activities of essential oils against Fusarium isolates and their corresponding biofilms. In this study, the chemical compositions of the oils were established using gas chromatography with both mass spectrometric and flame ionization detection, for identification and quantification, respectively.

Ingestion of contaminated chicken meat is a major cause of Campylobacteriosis in Europe and the USA. The environment, including wild birds, is considered to be an important reservoir for chicken colonization. The aims of this study were to determine the population structure of Campylobacter amongst chicken and wild bird sources on a single farm, and to establish the extent to which genotypes flow between them and ultimately infect humans, using MLST and antigen sequence typing. A pilot study amongst farm animals and wild birds in Lancashire demonstrated that Campylobacter genotypes from human disease were common on the farm and could be isolated from more than one animal source. Between 30-50% of wild geese and Starlings were shedding Campylobacter, with a seasonal peak in shedding rate in Spring. Genotypes were divergent from those previously isolated from human disease, retail meat and farm animal sources, with the majority being restricted to the host source. The carriage rate of Campylobacter was between 70- 100% amongst 78 free-range poultry flocks tested at 56 days of age. Up to seven genotypes were found to co-exist within a flock, and genotypes varied throughout the year on a random basis. Some Campylobacter strains were isolated from one farm site only, but a small percentage of them had spread nationally and were stable over a period of a decade. A total of 23% of Campylobacter isolates from free-range chickens were indistinguishable to those from human disease, and 5% were indistinguishable from wild birds. A total of 6% of genotypes isolated from wild birds were indistinguishable from those isolated from human disease. Wild birds could not be completely disregarded as a potential reservoir of Campylobacter for both humans and poultry, but their role is likely to be limited.

Thesis (PhD.(Medical Virology)--Faculty of Health Sciences)-University of Pretoria, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--Michigan State University. Dept. of Microbiology, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Michigan State University. Dept. of Microbiology, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis PlanA (M.S.)--University of Wisconsin--Stout, 2006. / Includes bibliographical references.

Thesis (Ph. D.)(Microbiology)--University of Pretoria, 2007. / Includes bibliographical references. Available on the Internet via the World Wide Web.