Call number: LD2668 .T4 1950 P67 / Master of Science

In 2004, a field sampling study was initiated along the southern shoreline area of Lake Pontchartrain in Jefferson Parish, specifically, around Bonnabel Canal (Pumping Station No.1) to identify the effect of urban stormwater discharges on Lake Pontchartrain and to simulate the plume patterns from the Bonnabel Canal. Sixteen sampling stations were selected along the south shore of Lake Pontchartrain. Under dry weather conditions Fecal Coliform values exceeded the limit of 200 MPN/100mL at 3 of 16 stations. Fecal Coliform counts were found to be "wet" weather-dependent and unsuitable for primary contact recreation for at least three to four days following a pumping/rain event. A 3-D Hydrodynamic Model (COHERENS) and the TECPLOT™ equation feature were used for the prediction of contaminant plumes from the Bonnabel Canal into the Lake Pontchartrain. The model verified the three day wet weather effect of stormwater discharges along the shoreline of the study area.

Introduction: Chronic peridontitis is an inflammatory disease that is caused by the accumulation of bacteria in the form of a biofilm in the periodontal pocket. It can be treated with oral hygiene in conjunction with β-lactam antibiotics. Many oral anaerobic bacteria associated with chronic periodontal diseases have developed resistance to β-lactam antibiotics by virtue of their production of β-lactamase enzymes. This study investigated the prevalence of β-lactamase-producing anaerobic bacteria in the oral cavities of South African patients with periodontitis and the genes responsible for these enzymes production. Methods: Periodontal pocket debri was collected from 48 patients with chronic periodontitis and cultured anaerobically on blood agar plates with and without β-lactam antibiotics. Presumptive β-lactamase-producing isolates were evaluated for definite β-lactamase production using the nitrocefin slide method and identified using the API Rapid 32A system. Antimicrobial sensitivity was performed using a disc diffusion test. Isolates were screened for the presence of the BlaTEM and BlacfxA genes using Polymerase Chain Reaction (PCR). Amplified PCR products were sequenced and the BlacfxA gene was further characterized using Genbank databases. Seventeen isolates containing BlacfxA gene were subjected to broth microdilution technique to determine minimum inhibitory concentrations of Amoxycillin, Augmentin, and Penicillin. Results: Seventy five percent (36 of 48) of patients carried, on average 2 strains of β-lactamase-producing oral anaerobic bacteria, which constituted 10% of the total cultivable oral flora. A total of 85 oral anaerobes were isolated from patients. The predominant isolates were gram negative species such as Prevotella spp (58%), Bacteroides spp (18%) and Porphyromonas spp (7%). The disc diffusion antimicrobial sensitivity test showed that 40% of the strains were resistant to β-lactam antibiotics. PCR results revealed that none of the anaerobes carried BlaTEM. The BlacfxA gene was identified in 51% of the β-lactamase-producing bacteria. Variants of the BlacfxA gene included cfxA2 (77%), cfxA3 (14%) and cfxA6 (9%). Minimum inhibitory concenration antimicrobial susceptibility test results showed that more than 53% of the strains were resistant to β-lactam antibiotics when the BlacfxA gene was present. Conclusions: A high prevalence of β-lactamase-producing oral anaerobic bacteria was found in South African patients with chronic periodontitis. Although, it comprised 10% of their oral flora these anaerobes can protect non-β-lactamase-producers by releasing these enzymes into the environment. The most prevalent β-lactamase gene in this population was BlacfxA subcategory cfxA2 which has epidemiological implications and genetic transfer can occur among these bacteria. On average fifty percent of the isolates that carried this gene were resistant to β-lactam antibiotics therefore alternative antimicrobial agents should be considered in patients that are non-responsive to β-lactam antibiotics. This study indicates that there is a need for education in the dental community regarding antibiotic resistance and regular surveillance with diagnostic testing is needed.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2014. / During the last few decades, Streptomycetes have shown to be an important and adaptable group of bacteria for the production of various beneficial secondary metabolites. One such secondary metabolite, epsilon polylysine (ε-PL), produced by Streptomyces albulus is of particular interest due to its antimicrobial activity. This work aimed to study different facets surrounding ε-PL and its production. Firstly, to grow S. albulus CCRC 11814, using economically viable crude glycerol as a carbon source and subsequently measure ε-PL production using an anionic dye, trypan blue. Secondly, to evaluate the antimicrobial activity of ε-PL against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger and Penicillium simplissium. Thirdly, to determine whether there is economic feasibility of ε-PL as a food preservative in South Africa. Lastly, to develop and optimise tools for metabolic engineering such as recombineering and group II introns to improve ε-PL production. The results obtained in this study fall into three different areas: In terms of growth studies, S. albulus grew in the presence of crude glycerol, although the growth was suboptimal, 0.48 g/L as compared to 1.04 g/L produced using pure glycerol or glucose. This is due to the pressures on the bacteria from the impurities of crude glycerol such as methanol and salts. ε-PL antimicrobial activity was effective at a concentration of 100 μg/ml against S. aureus, E. coli and A. niger. It was however, ineffective against P. aeruginosa owing to the low outer membrane permeability of the bacteria. Due to the ability of S. albulus to grow in crude glycerol, it could be used as a financially viable option to produce ε-PL as a natural food preservative in South Africa. The economic feasibility of ε-PL as a food preservative in South Africa showed potential in terms of market research as well as the financial evaluations. However; the production volumes are low due to the use of the crude glycerol and may not cater for the large food industry in the country. For these reasons, metabolic engineering could be employed to improve these production volumes. The first step to metabolic engineering was to develop novel tools which can be used for genetic modifications in S. albulus. The group II intron tools for gene knockouts were developed by the construction of a vector which subsequently requires sequencing and testing to perform gene knockouts. Based on current knowledge, this is the first experiment of its kind. In terms of introduction of genetic material post gene knockouts, iii transformation was shown to be a more effective gene transfer technique as opposed to electroporation, producing 7.75 transformants/μg and 0.038 transformants/μg of DNA, respectively. Future work would involve the use of biocatalysis for metabolic engineering of S. albulus by either removing genes inhibiting ε-PL or overexpressing the enzyme responsible for its production. This research has developed the groundwork for future ε-PL production improvement using biocatalysis and economically viable crude glycerol as a carbon source for applications of the secondary metabolite as a food preservative.

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, for the degree of Master of Science in Medicine. / Analysis of organisms involved in hospital infections has shown that Gram-positive bacteria have assumed an increasingly important role. Examples that have been recognised as important pathogens are staphylococci , enterococci, streptococci, Corynebacterium jeikeium and Leuconostoc species. Methicillin resistance in staphylococci has become a major problem in certain hospitals. Viridans streptococci continue to be the most frequent cause of native valve endocarditis. Leuconostoc species are being increasingly isolated from blood cuIture specimens. strains of Gram-positive bacteria have become resistant to specific antibiotics; e.g. staphylococci to methicillin, enterococci to ampicillin, and viridans streptococci to penicillin. JK corynebacteria are sensitive only to vancomycin and resistant to other antimicrobials normally used for treating infection caused by Gram-positive bacteria. In this study various combinations of antimicrobials against 35 clinical isolates of Gram-positive bacteria obtained from three hospitals in the Johannesburg area (Johannesburg, Hillbrow, and Baragwanath) from 1987- 1988 were investigated. The MIC / MBC results conformed to others described in worldwide studies. Results when different methodologies for determining synergy were used, varied. This emphasizes the need for standardization, especially with regard to the time-kill studies. Most antimicrobial combinations demonstrated tested against Leuconostoc species synergy using the checkerboard method, but these results were not confirmed by time-kill procedures, which showed mainly indifference. Synergy was also obtained when gentamicin plus ciprofloxacin was combined Corynebacterium jeikeium. Because of increasing resistance and the fact that Gram- positive bacteria cause serious infections, various and new combinations of antimicrobials need to be tested before treating these infections. Parts of this dissertation have been presented at the following congresses: 10th Annual Congress of the Society of Medical. Laboratory Technologists of South Africal Sun city 1989 75th Anniversary Congress of Pathology Johannesburg 1990 11th Annual Congress of the Society of Medical Laboratory Technologists of South Africa, Durban 1991 / Andrew Chakane 2019

by Kit Sing Au. / Bibliography: leaves 283-326 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1984

by Tat-ming Lau. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1981. / Bibliography: leaves 288-329.

by Kam-hing So. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 152-162.

Miu-kuen Kong. / Thesis (M. Ph.)--Chinese University of Hong Kong. / Bibliography: leaves 164-186.

我們研究趨磁螺菌 AMB-1局限在 100微米厚的空間內的運動，細菌濃度約為每立方厘米 10⁹個。整個過程以一台安裝在顯微鏡上的攝像機，以暗場摸式觀察及拍攝。在地球磁場下，我們可以觀察到細菌聚集成環紋，並開始擴大。擴大的初始速度與細菌的游泳速度接近。半小時後，環紋擴大至離液滴邊緣毫米左右，然後停止擴大。環寬約 130微米，比大腸桿菌的趨化環結構小 100倍。我們對這個現象作出了一系列的實驗，研究其特性。 / 我們測試了不同化學成份的實驗緩衝液對環紋的影響。發現當緩衝液缺少琥珀酸時，環紋不會出現；另一方面，當使用琥珀酸作為緩衝液的唯一化學成份時，環紋能清楚地被觀測。這表明琥珀酸是環紋形成的關鍵成份。 / 實驗環境的氧氣含量能按不同比例混合氮和氧來控制。當環境改變為純氮時，環紋進一步擴大；當環境氧氣含量提高時，環紋縮小。實驗結果與微好氧細菌的特性相同。 / 在施加外加的磁場後，環紋被拉成長橢球形，證明細菌的擴散在環紋的形中有重要的作用。在更大的外加磁場下（ 0.3mT，十倍地球磁場），細胞聚集在液滴的兩端，隨後在這些位置長出環紋。該現象證明了環紋會在高細菌濃度的條件下形成， AMB-1有可能存在群體感應機制。 / We study the motion of Magnetospirillum magneticum strain AMB-1 in solution of concentration around 10⁹ cells cm⁻³, which was conned between two glasses with separation 100 μm. The motion was imaged with a EMCCD camera attached to a microscope in darkeld mode and growing ring pattern was observed. Under the earth magnetic eld, the ring migrated under the velocity close to the bacteria swimming velocity. After about half an hour, the ring had expanded to around 1 mm from the edge of droplet. The ring width is about 130 μm, which is 2 orders of magnitude smaller than that of similar ring structure found in E. Coli. A series of experiments were conducted to study the properties of such ring. / In studying the chemical composition of the buffer uid, different compositions were tested. No ring was obseved when succinic acid was absent; on the other hand, ring pattern was observed when using succinic acid alone as a buffer, which suggests that succinic acid is one of the key components of ring formation. / Oxygen level was controlled by mixing nitrogen and oxygen in dierent ratios. Ring further expanded to the edge of droplet when pure nitrogen was pumped in; and shrank when oxygen level was high. The results are consistent with the property of micro-aerophilic band in all micro-aerophilic bacteria. / With an applied magnetic eld, the swarm ring elongated to ellip¬soidal shape, which suggests that the diusion of bacteria plays an important role in the formation of ring. Under even larger magnetic eld (10 times earth magnetic eld), cells aggregated at opposite ends of the droplet, and rings formed at these positions afterwards, which suggests that ring grows at high cell concentrations. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Siu Kit = 趨磁螺菌AMB-1的環紋觀測 / 陳兆傑. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 48-50). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Chan, Siu Kit = Qu ci luo jun AMB-1 de huan wen guan ce / Chen Zhaojie. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- History --- p.1 / Chapter 1.2 --- General Properties of MTB --- p.1 / Chapter 1.2.1 --- Microaerophilic --- p.2 / Chapter 1.2.2 --- Magnetotaxis and Magnetosome --- p.2 / Chapter 1.3 --- Motivation --- p.6 / Chapter 1.3.1 --- Observation of Ring Pattern --- p.6 / Chapter 2 --- Experimental Setup --- p.8 / Chapter 2.1 --- Cell Culturing --- p.8 / Chapter 2.1.1 --- Incubation --- p.9 / Chapter 2.1.2 --- Culture Characterization --- p.11 / Chapter 2.1.3 --- Storage --- p.11 / Chapter 2.1.4 --- Strain Maintenance --- p.11 / Chapter 2.2 --- Bacteria Tracking --- p.14 / Chapter 2.2.1 --- Darkfield microscopy --- p.14 / Chapter 2.2.2 --- Concentration Measurement --- p.17 / Chapter 2.2.3 --- Darkfield image and cell density --- p.18 / Chapter 2.3 --- Design of Experiment --- p.19 / Chapter 2.3.1 --- Magnetic Field --- p.19 / Chapter 2.3.2 --- Chemicals --- p.20 / Chapter 2.3.3 --- Air Chamber --- p.20 / Chapter 3 --- Experimental Result and Analysis --- p.22 / Chapter 3.1 --- Ring properties --- p.22 / Chapter 3.2 --- Chemotactic Property --- p.24 / Chapter 3.3 --- Oxygen Concentration Control --- p.27 / Chapter 3.3.1 --- Micro-aerophilic property --- p.27 / Chapter 3.4 --- Response to Magnetic Field --- p.28 / Chapter 3.4.1 --- Ring under constant magnetic field --- p.32 / Chapter 3.4.2 --- Analysis on the change of shape --- p.35 / Chapter 4 --- Conclusion and Discussion --- p.41 / Chapter 4.1 --- Discussion --- p.41 / Chapter 4.1.1 --- Formation of ring --- p.41 / Chapter 4.1.2 --- Band Property --- p.43 / Chapter 4.2 --- Suggested Focus --- p.44 / Chapter A --- MSGM Content --- p.45 / Chapter B --- Shrinking of Ring --- p.47 / Bibliography --- p.48