Microbial and chemical contamination of inland and coastal waters in Southern Africa is a major challenge facing the water industry and regulatory authorities. Increased stresses on these surface water resources through human and environmental influences have resulted in deteriorating water quality that has severely encumbered the country’s capability to provide sufficient water to meet its needs and to ensure environmental sustainability. In addition, indiscriminate use of antibiotics has resulted in widespread contamination of surface waters, leading to accelerated development of antibiotic resistance and proliferation of resistant water-borne diarrhoeal-related pathogens, such as Escherichia coli and Vibrio cholerae. Despite the high level of contamination of South African surface waters, the microbiological quality of rivers and beaches in Durban, South Africa, have not been adequately investigated. Therefore, the current study assessed the seasonal fluctuations of the microbial and physicochemical quality of two rivers (Umgeni River and Umdloti River) and six beaches (Virginia Aerodome, Beachwood, Umgeni South, Battery, Sunkist, Addington) in Durban, using several bacterial indicator organisms and physico-chemical parameters as indices. The antibiotic resistance profiles (ARPs) of E. coli and V. cholerae strains, recovered from the water samples, were determined and changes in the microbial community of the water samples were monitored over a seasonal cycle, using denaturing gradient gel electrophoresis (DGGE). Spatial and seasonal fluctuations of the physico-chemical parameters differed significantly (p < 0.05) among the water samples with high heavy metal concentrations detected across the seasonal cycle. Temperature profiles ranged from 13°C to 26.5°C for the Umgeni River, 13°C to 27°C for the beaches and 12°C to 26°C for the Umdloti River while pH ranged from 6.30 to 8.45 (Umgeni River), 6.37 to 8.30 (beaches) and 5.96 to 7.94 (Umdloti River). Turbidity ranged from 0.53 NTU to 15.6 NTU (Umgeni River); 0.57 NTU to 2.37 NTU (beaches) and 2.23 NTU to 18.8 NTU (Umdloti River). During spring and summer, all river and beach water samples had < 500 μg/L phosphate concentrations; however, these concentrations increased significantly (p < 0.05) during autumn and winter in both rivers. Majority of the samples had low concentrations of ammonia and nitrates. Sulphate concentrations for the beach samples ranged from 2355 mg/L (B5 – summer) to 2899 mg/L (B2 – winter) as compared to the Umgeni and Umdloti Rivers which ranged from 3.90 mg/L (A4 – autumn) to 2762 mg/L (A1 – summer) and 4.47 mg/L (C4 – winter) to 168 mg/L (C1 – winter), respectively. According to the South African Target Quality Range guidelines for the heavy metals (in surface waters), all river and beach water samples exceeded the set limits for lead (Pb2+), mercury (Hg2+) and cadmium (Cd2+) across all seasons. During spring and summer all water samples complied with the aluminium guideline of 0 – 0.15 mg/L. Bacterial population profiles indicated that all sampling points failed to comply with the set guidelines (domestic use) for presumptive total coliform (TC), faecal coliform (FC) and total heterotrophic bacterial (THB) counts during all four seasons. Estimated TC, FC and THB populations as high as 8.6 x 101, 3.7 x 101 and 2.15 x 105 cfu/100ml, respectively, were obtained for some of the samples with peak indicator levels and generally a higher microbial load observed during the summer season. High prevalence of resistance to ampicillin [67.82% (Umgeni River)] was encountered among the E. coli isolates from the water samples followed by amikacin [53.33% (Umdloti River)], augmentin [49.6% (Umdloti River)], tetracycline [42% (Umgeni River)], streptomycin [37.1% (beaches)] and cotrimoxazole [33% (Umgeni River)]. The most frequently encountered form of resistance among the V. cholerae isolates was against cotrimoxazole [93.34% (Umgeni River)], streptomycin [84% (beaches)], erythromycin [78.7% (Umgeni River)], trimethoprim [77.7% (Umdloti River)], rifampicin [70% (Umgeni River)] and cefoxitin [45% (Umdloti River)]. Multidrug resistance among the E. coli isolates was indicated by twenty nine (Umgeni River), twenty six (beaches) and fourteen (Umdloti River) different resistance patterns, while the V. cholerae isolates produced eighteen (Umgeni River), thirty five (beaches) and twenty nine (Umdloti River) different resistance patterns. In addition, proportional resistances of the E. coli and V. cholerae strains to the different classes of antibiotics ranged from six to eleven and four to eleven different antibiotic classes, respectively. The present study suggests that the bacterial communities detected in the water samples collected from the rivers and beaches in Durban, followed seasonal dynamics and could possibly be the consequence of fluctuations in certain environmental factors. A total of 87 different DGGE bands were detected among the Umgeni River water samples, 127 different DGGE bands among the six beach water samples and 107 bands in the Umdloti River samples, over the four seasons. Twenty one dominant bands were found among all sampling sites, indicating widespread phylotypes, whereas 14 bands were exclusively detected at only one sampling site (C1) potentially indicating unique phylotypes. Some bands appeared all year-round, whereas some other bands were specific to a particular season. Overall, the present study successfully demonstrated the poor microbiological quality of the investigated river and beach water resources which raise concerns over the management of these water resources and the subsequent deleterious effects these waters could have on the end users. This emphasizes the need for implementation of improved management strategies of these river catchments and beaches for continued sustainability. Furthermore, the high level of multi-antibiotic resistance demonstrated by the E. coli and V. cholerae strains, recovered from the water samples, reiterates the need to continuously monitor the changing trends in antimicrobial resistance patterns of these diarrhoeal-related bacterial pathogens. Therefore, continued surveillance of these surface waters used for recreational or domestic purposes and development of adequate prevention strategies are needed for public health reasons. Lastly, combining the use of conventional faecal indicators with molecular-based techniques, such as DGGE, can provide more information on the microbial load and diversity of surface waters. In addition, information regarding the effects of seasonal variations on microbial diversity as observed in this study is important for the sustainable management of surface water resources. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2010.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1975.

The age of Aspergillus parasiticus (1-11-105Wh1) mycelium was found to have an influence on the level of enzymes, responsible for the conversion of sterigmatocystin to aflatoxin B[1] and O-methylsterigmatocystin, present. These enzymes were active over a wide range of temperature and pH. Production of a cell free system by lyophiliization yielded the highest aflatoxin B[1] synthesising activity. Three other methods of preparing the cell free system capable of synthesising aflatoxin B[1] were also studied, ie,: french press, protoplast, and grinding, but with limited success. The lyophilized preparation had narrower temperature and pH optima for the conversion than whole mycelia. Initial purification of the aflatoxin B[1] synthesising enzyme was achieved by separating the crude cell free extract by gel filtration. The enzyme activity was located in a membrane fraction. The involvement of endoplasmic reticulum was indirectly concluded by the use of marker enzyme and chelating agents. This membrane fraction was ultracentrifuged and the released extrinsic proteins were separated by gel filtration. A fraction containing two proteins which were capable of converting sterigmatocystin to aflatoxin B[1] was isolated and characterised by isoelectric focusing and gel electrophoresis. The temperature and pH optima together with the cofactor requirements were studied. The Michaelis-Menten constant (Km) and the stoichiometry for the conversion of sterigmatocystin to aflatoxin B[1] was determined. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1984.

The principal objective of this study was to develop an alternative non-genetic rat model for type 2 diabetes (T2D). Six-week-old male Sprague-Dawley rats (190.56 ± 23.60g) were randomly divided into six groups namely: Normal Control (NC), Diabetic/Streptozotocin Control (STZ), Fructose-10 (FR10+STZ), Fructose-20 (FR20+STZ), Fructose-30 (FR30+STZ) and Fructose-40 (FR40+STZ) and were fed a normal rat pellet diet ad libitum for 2 weeks. During this period, the two control groups received normal drinking water whilst the fructose groups received 10, 20, 30 and 40% fructose in drinking water ad libitum respectively. After two weeks of dietary manipulation, all groups except the NC group received a single injection (i.p.) of streptozotocin (STZ) (40mg/kg BW) dissolved in citrate buffer (pH 4.4). The NC group received only a vehicle buffer injection (i.p.). One week after the STZ injection, animals with non-fasting blood glucose >300 mg/dl were considered as diabetic. Three weeks after the STZ injection, the animals in FR20+STZ, FR30+STZ and FR40+STZ were eliminated from the study due to the severity of diabetes and the FR10+STZ group was selected for the remainder of the 11 weeks experimental period. The significantly (p < 0.05) higher fluid intake, blood glucose, serum lipids, liver glycogen, liver function enzymes and insulin resistance (HOMA-IR) and significantly (p < 0.05) lower body weight, oral glucose tolerance, number of pancreatic β-cells and pancreatic β-cell functions (HOMA-beta) of FR10 group demonstrate that the 10% fructose-fed followed by 40 mg/kg of BW STZ injected rat can be an excellent alternative model for T2D. To validate this newly-developed model, an acute intervention trial study was conducted to investigate the anti-diabetic effects of L-Carnitine and white mulberry leaf tea extracts in the newly developed animal model of type 2 diabetes (T2D). Male Sprague-Dawley rats (mean BW 191.88g±16.40g) were randomly divided into 5 groups namely: Normal Control (NC), Diabetic/Streptozotocin control (FR10+STZ), Mulberry Tea Low (FR10+STZ+MTL, 0.25%), Mulberry Tea High (FR10+STZ+MTH, 0.5%), and L-Carnitine (FR10+STZ+CARN). In first three weeks, T2D was induced in all other groups except NC group by using above-mentioned procedure. Mulberry tea was supplied ad libitum and L-carnitine was administered to the FR10+STZ+CARN group at a concentration of 500mg/kg BW once daily during week 4-8 of the intervention trial. The FR10+STZ+CARN group had significantly (p < 0.05) lower total cholesterol, triglycerides, total proteins and fluid intake compared to the diabetic control (FR10+STZ). The NFBG non-significantly reduced in FR10+STZ+CARN group compared to the FR10+STZ group, whereas MT did not. FR10+STZ+MTL had significantly higher serum triglycerides level compared to the NC group, and significantly higher HDL-cholesterol and fluid intake compared to the FR10+STZ group. FR10+STZ+CARN and FR10+STZ+MT groups had significantly lower total proteins compared to NC and FR10+STZ groups, but significantly lower albumin compared to NC group only. The data of the this section of the study suggest that CARN may be effective in normalizing lipid profiles rather than blood glucose in diabetic rats which may aid in the reversal of insulin resistance. On the other hand, MT used in this study did not display any significantly beneficial anti-diabetic effects at least in this experimental condition. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.

The fluorodinitrobenzene (FONB), succinic anhydride (SA), dansyl chloride (DAN), dye-binding lysine (OBL), total lysine (TL), ninhydrin (NIN) and Tetrahymena lysine (TET) methods were compared for their ability to assess available lysine in soyaprotein heated in the absence or presence of glucose, lactose or xylose and in formaldehyde-treated lactalbumin. The reactive lysine methods showed comparable sensitivity to lysine damage in soyaprotein heated in the absence of sugar, the results indicating the presence of acid labile isopeptides and unidentified acid stable derivatives. Results for soyaprotein heated with glucose, lactose or xylose showed that the type of sugar and the extent of heat treatment has a strong influence on the progress of the Maillard reaction. Furthermore since fructoselysine (F-L) and lactulosyl-lysine (L-L) are colourless up to 30% loss of available lysine can occur without any change in product colour. The FONB method is the most sensitive for mildly damaged glucose-soya samples followed by DAN or OBL, SA and TL whereas for mildly damaged lactose-soya samples the order is OBL, FONB, SA, TL and DAN. For severely damaged samples the DAN or SA methods were the most sensitive followed by OBL, FONB and TL. Formylation of lactalbumin occurred more readily at higher formaldehyde concentrations. Exposure time had less effect while pH (5 and 9) had no effect. Methylene derivatives reached maximum levels sooner than the methylol compounds. Lysine and tyrosine but not histidine formed methylene bridges while tyrosine was found to condense with free formaldehyde during acid hydrolysis raising questions as to the interpretation of similar studies reported in the literature. The FONB, OBL and DAN methods were all very sensitive to this type of damage with the NIN and TL methods being less sensitive and the SA method being completely unsuitable. The TET assay is unsuitable for 'early' Maillard damage since at low sample-N levels growth is stimulated by its ability to utilise unavailable F-L and L-L while at higher N-levels growth is inhibited. No single method is most suitable for all types of damage. Furthermore, all except DAN and DBL are either too long, rather complicated, require expensive equipment or involve the use of dangerous chemicals. The DAN method appears promising but the problem of converting arbitrary fluorescence units to lysine values needs to be overcome. The DBL is recommended for routine analysis since it is simple, economical and highly sensitive to all lysine damage provided care is taken to optimise dye-binding for each type of material analysed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1985.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg.

The diesel-degrading capabilities of Acinetobacter calcoaceticus isolates LT1, LT1A and V2 were established in previous studies. LT1 and LT1A were isolated from diesel-contaminated soil and V2 was from soil contaminated with used engine oil. Isolates were grown in Bushnell-Haas medium supplemented with 1% sterile diesel. Determination of diesel-degradation patterns by gravimetric analysis and harvesting of cells for RNA extraction were performed at regular time intervals over a 60 day period. The involvement of genes alkM, alkR, rubA, rubB, estB, lipA, lipB, and xcpR in hydrocarbon degradation has been reported in previous studies. LT1, LT1A, and V2 were compared in terms of gene expression levels by real-time quantitative PCR. Expression levels were assessed by relative quantification and normalized against the 16S rRNA reference gene using the Relative Expression Software Tool - XL (REST-XL). Amplification of all genes, except rubB, was achieved with a high degree of efficiency. The expression of rubA, alkM, alkR, xcpR, and lipB based on pair-wise randomization, was all down-regulated in LT1A in relation to LT1. Highest expression levels of the aforementioned genes were documented during the initial stages of incubation for LT1 while LT1A showed highest expression levels midway through the study period. LT1, LT1A, and V2 achieved 58.6%, 51.7%, and 48.3% diesel degradation after 5 days of incubation, respectively. The higher percentage of diesel degradation achieved by LT1 can be attributed to higher levels of overall gene expression in the initial stages of degradation. Amplification of alkane hydroxylase alkM of V2 revealed a possible second hydroxylase gene that was expressed after 20 days of incubation. Amplification of alkR and xcpR in V2 isolates also resulted in multiple product formation. Very low lipB and lipA expression was detected in LT1 and LT1A and the absence of lipA expression in V2 suggests that lipases were not involved in diesel degradation. In contrast, estB was predominantly expressed in V2, and suspected to be involved in the release of a bioemulsifier that was only observed in V2 samples. Although all three isolates were comparably efficient in degrading diesel, the results of this study suggest that different mechanisms may be employed in the degradation process. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Bacteria of the genus Acinetobacter are known to be involved in the degradation, leaching and removal of various hazardous compounds from the environment. Several studies of Acinetobacter spp. have reported on the genes involved in alkane degradation; but less is known about the proteins that are expressed at certain points within the degradation period. Acinetobacter sp. LT1A and Acinetobacter sp. V2 were isolated from diesel- and used engine oil-contaminated soils respectively. In a previous investigation (Toolsi, 2008), these isolates have been shown to demonstrate different gene expression patterns during diesel degradation using real time PCR. The real time PCR data showed that isolate V2 made use of multiple alkane hydroxylases whereas LT1A made use of only one, and the expression of the alkane hydroxylase regulator alkR and secretory protein xcpR also revealed multiple product formations in isolate V2 as compared to LT1A. Thus the objectives for the current investigation were to monitor the hydrocarbon degradation ability of Acinetobacter sp. isolates V2 and LT1A using medium chain (C14) and long chain (C28) hydrocarbon substrates and to compare the hydrocarbon degradation abilities and protein expression patterns of both isolates. To achieve this, the isolates were grown for 20 days in Bushnell Haas liquid medium supplemented with tetradecane (C14) or octocosane (C28) as a sole carbon source. Gravimetric analysis was used to monitor degradation and whole cell protein was extracted from the culture medium throughout the 20-day study period. The protein expression patterns were visualized using 1D and 2D PAGE. The 2D PAGE images were analyzed using the PDQuest Advanced 2D image analysis software (BIORAD). By day 20, approximately 90% of C14 was degraded by both isolates, whereas only 36% of C28 had been broken down. In both the C14 and C28 degradation assays, the isolates achieved significant amounts of hydrocarbon degradation as compared to the abiotic controls. One-dimensional and 2D SDS-PAGE gels indicated that there are observable differences in protein expression patterns between the isolates during C14 and C28 degradation. Both isolates achieved similar rates of hydrocarbon usage, but appear to do so using different, unidentified, protein systems. Analysis of the 2D-SDS PAGE gel images revealed that more proteins were required for the utilization of the long chain alkane (C28) as compared to the medium chain alkane (C14) for both isolates. Potential spots of interest were identified from the 2D SDS-PAGE images and sequenced. The identities of these proteins were found to be: a conserved hypothetical protein, TonB-dependent receptor protein, Peptidyl-prolyl-cis-trans isomerase and a Protein containing DUF1559. No alkane hydroxylase components were detected in this study. This investigation demonstrated the need for more studies at the proteomic level. Future investigations should focus on the insoluble subproteome of the isolates and make use of larger sample sizes (replicates) to reduce variation in spot detection and quantification. Genomic sequencing of the isolates will also shed light on the genetics and biochemistry of alkane metabolism in these Acinetobacter sp. isolates. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.

Abstract available in PDF file. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.