Faculty of Applied Sciences
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Item Assessment of a biological nutrient removal process for the remediation of edible oil effluent(2002-05-10) Mkhize, Sandile Psychology; Bux, FaizalEutrophication is a natural process that is greatly aggravated by the action of man in the natural environment. Deterioration of South Africa's natural water resources results directly or indirectly from the discharge of industrial effluent rich in nutrient nitrogen and phosphorus. The South African edible oil refmeries generally discharge poor quality effluent which impacts negatively on the water resources and wastewater treatment installations. The main aim of this study was to assess the capacity of a laboratory scale effluent treatment process that will produce final effluent of acceptable quality with regards to organic load and phosphate concentration prior to its discharge into the municipal sewerage system. The study was conducted in three stages: wastewater characterization, treatability studies, and laboratory scale treatment investigations. After analysing various effluent parameters, treatability studies were conducted using an aerobic-anaerobic sequencing batch reactor with a total hydraulic retention time of 24 hours. The results showed an average of 75 % reduction of COD and more than 90 % removal of fats, oils and grease (FOG). Based on the results of effluent characterisation and treatability studies, a laboratory scale activated sludge effluent treatment process was designed and operated with two bioreactors (aerobic and anaerobic) in series. The system was operated for a period of one-month resulting in 70 % removal of COD and 4% reduction in phosphate (P04-P). After some structural and operational changes from the original design configuration, the system was the operated continuously for the duration of the study period. An optimum COD removal of 75 % and 107 mgll P04-P reduction was achieved during the last operational phase of the system. More than 95 % reduction in fats, oils and grease (FOG) had been achieved in both semi-continuously and continuously operated systems.b.7Item The co-localization of tissue kallikrein and transforming growth factor - beta 1 in the non-cancerous and cancerous kidney(2003) Moodley, Rumesha; Bhoola, K. D.Evidence suggests that the induction of tissue kallikrein, and the subsequently formed kinins, enhances proliferation of tumour cells because of their mitogenic property. Additionally, the kinin peptides are believed to promote the invasion of normal tissue by tumour cells. TGF-l is a potent inhibitor of the growth of renal epithelial cells, and is a classical anti-mitogen, which is central to many of its antiproliferative effects. No studies thus far have been performed, as to whether the proposed anti-mitogenesis ofTGF-1 has a regulatory effect on the cell proliferative action of kinins on renal epithelial and carcinoma cells.Item Directed evolution of B-xylanase from Thermomyces lanugtnosus(2000) Stephens, Dawn Elizabeth; Permaul, Kugen; Prior, A.; Singh, SurenMost natural enzymes may be unsuitable for biotechnological processes since they have evolved over millions of years to acquire their specific biological functions. Such enzymes are often genetically altered to suit the rigours of industrial processes. Directed evolution is one such strategy and makes use of iterative rounds of random mutagenesis, screening and recombination to enhance the existing properties of enzymes. Thermomyces lanuginosus is a thermophilic fungus that produces high levels of a thermostable xylanase. The xylanase gene from T lanuginosus DSM 5826 (xynA) was functionally expressed in E. coli as a LacZ-fusion protein (Schlacher et al., 1996) and later crystallized (Gruber et al., 1998). In this study, it was undertaken to improve the thermo stability and catalytic activity of xynA using error-prone PCR with different concentrations of MnCh. The first step prior to mutagenesis was to determine the levels of xylanase that could be attained by the wild type XynA, both in the presence and absence of an inducer. IPTG, a lactose analogue, was used since xynA was expressed with a lac promoter. High amounts of IPTG were found to adversely affect xylanase production, whilst a low amount (0.1 mM) enhanced xylanase production. This amount was used to later induce xylanase production by the variants obtained after mutagenesis. IPTG was found to increase the rate and production of xylanase. After random mutagenesis of xynA, transformed colonies were first selected for xylanase production on 0.4% Remazol Brilliant Blue xylan and then screened at different temperatures for improved stability and activity. After the first round of screening, four variants, viz., IB5, IB7, IBLl and ID2, showed slight improvement in both stability and activity and were subjected to further mutagenesis, using low concentrations of MnCh. Three variants, viz., 2B7-1O, 2B7-6 and 2BIl-16, with markedly enhanced stability, were obtained. Variant 2B7-10 exhibited a five fold higher activity (3430 nkat/ug total protein) than the wild type XynA (657 nkatl ug total protein). It retained 71% of its activity after treatment at 80°C for 60 min and had a t1/2of 215 min at 70°C, which is higher than that attained by XynA. Long-term thermo stability screening at 70, 80, 90 and 100°C revealed that variants 2B7-6 and 2B11-16 were, however, the most stable enzymes generated in this study, although their activities were lower or almost comparable with their parents. Sequence analysis of variant ID2 revealed 4 amino acid substitutions within the a-helix of the protein. This region was strongly conserved with the more stable variant xylanases generated in this study. The most profound mutation seen with variant 2B7-10 was the disruption of the disulphide bridge. Most of the mutants obtained in this study displayed a trade-off between stability and activity, the exception being mutant 2B7-10. Currently, DNA shuffling techniques are being used to recombine these traits in a single xylanase.Item Physiological and biochemical evaluation of pure cultures of problematic filamentous bacteria isolated from activated sludge(2004) Ramothokang, Tshireletso R.; Bux, FaizalSince the development of the activated sludge process, bulking and foaming have been a major problem affecting treatment efficiency. Filamentous bacteria have long been known to be the primary cause of bulking and foaming problems in activated sludge wastewater treatment systems. Attempts to cure filamentous bulking and foaming have thus far not shown great success in effective long-term control measures due to a lack of understanding of these organisms. Chemical methods such as chlorination and the use of hydrogen peroxide are still used to cure bulking but are only effective as interim measures. This could be due to the main factors stimulating filamentous bacterial growth not being changed by these methods for curing bulking and also, a lack of in-depth understanding of filamentous bacteria by scientists. It is therefore important to gain a proper understanding of these bacteria on the basis of their physiological, biochemical and growth characteristics. For all this to be successfully attained, filamentous bacteria need to be studied in pure culture so as to facilitate a better understanding of bulking and foaming and the control thereof during wastewater treatment. The aim of this study was therefore, to isolate and cultivate problematic filamentous bacteria and determine the physiological, biochemical and morphological traits of these organisms in pure culture, with the purpose of being able to integrate these findings to in situ analysis. Using four different isolation techniques, a total of 14 isolates from 7 different wastewater systems were obtained and evaluated for a range of physical, chemical, redox and substrate conditions. Results of the study indicate that filamentous survival and proliferation in BNR systems is largely due to varied phosphate uptake capacities and widespread ability to denitrify both nitrate and nitrite. Lipid hydrolysis is also a major component of filamentous bacterial metabolism with hydrolysis of other large compounds, as revealed by Biolog, such as starch, dextrin, proteins/peptides, Tween 40, Tween 80 and nucleosides indicating an affinity for larger slowly biodegradable substrates. They also strive on a variety of amino acids and sugars. The results obtained in this study revealed that filamentous bacteria are more diverse and complex in their biochemistry and physiology hence the difficulty in achieving long- term optimal control of filamentous bulking in activated sludge. It was concluded that filamentous bacteria have the ability to survive during times of starvation where growth factors are limiting and, this may be attributed to their ability to store storage compounds such as PHB, glycogen and polyP. The filaments' ability to store storage compounds and denitrify, suggests that they may in fact play significant roles in denitrification and EBPR. It is also concluded from this study that the filamentous bacteria under study are sensitive to aromatic compounds and that they have an affinity for slowly biodegradable polymers such as lipids, nucleosides, proteins/ peptides, dextrin and starch. Also concluded is that, the use of Biolog for biochemical profiling! fingerprinting of filamentous bacteria is useful, however, due to the possibility that some organisms may in fact, not grow and! or may give negative results on some and! or all substrates, other strategies. for biochemical profiling be established and used in this regard. Identification and evaluation of filamentous bacteria based on morphological traits is limiting and requires development and optimization of in situ techniques, such as DNAIRNA based probes and micro autoradiography. Bulking and BNR are elaborate and still not fully understood. The filaments' ability to take up phosphates and denitrify means that an advanced understanding of the roles they play in BNR systems and AA- bulking (Anoxic- Aerobic) is still required. Physiological and biochemical fingerprinting of pure cultures of filamentous bacteria is an important basis to understanding these organisms, and establishing potential bulking and foaming criteria for in situ evaluation and verification. It is from a study such as this that the main goal of curing bulking and gaining an enhanced understanding of BNR may be achieved.Item Invertase production by Saccharomyces cerevisiae Y07 and Y09 strains grown on sugarcane blackstrap molasses(2001) Maharaj, Anesh Dawnarian; Odhav, BhartiYeast invertase is used in the sugar industry to produce high-test molasses in South Africa. Invertase also has important applications in the sweet and confectionery industry. Currently, NCP Yeast (PTY) Ltd. (Durban) is producing high invertase activity yeast by fermentation of S. cerevisiae Y07, using sugar cane blackstrap molasses as a substrate. There are two problems with this fermentationItem Incidence and characterization of Fusarium species in crown rot of bananas(2002) Ramsunder, Kumindra Devrajh; Odhav, Bharti; Okole, Blessed N.Fusarium species produce toxic mycotoxins that are known to exert adverse health effects in humans and animals. No attempts have been made to establish mycotoxin-producing capabilities of isolates of Fusarium species from bananas exhibiting symptoms of crown rot. Crown rot is one of the most serious post harvest problems in banana and the disease is caused by different fungal species, principally Fusarium species. Banana, which is of great economic significance in growing countries (i.e. Costa Rica, Cameroon, Ecuador) is seriously affected by crown rot and is a major cause of fruit lossItem Development and microbial community analysis of a biological treatment process for edible oil effluent(2003) Bux, Faizal; Tivchev, G. N.Globally, wastewaters emanating from edible oil manufacturers contain high organic (BOD & COD) and phosphate loads and known for creating shock-loading problems for the receiving wastewater treatment installations. Discharge of poor quality final effluents also negatively impact on and cause eutrophication of natural water sources such as rivers and dams. In South Africa, a large concentration ofthe edible industries are localized in the Pietermaritzburg region of Kwa-Zulu Natal and have been regularly associated with discharge of poor quality final effluent that did not subscribe to municipal regulation standards. Current treatment of choice for wastewater's in the edible oil industry have been limited primarily to dissolved air flotation combined with the use of chemical coagulants or physical separation of oil and grease via a gravity fat trap and subsequent pH correction. These physico-chemical methods have achieved limited success and the emulsified grease tends to clog sewer pipes and pumps producing poor quality effluents. Therefore, the aim of the current research was to develop suitable treatment technology focussing on adapting activated sludge process to remediate edible oil effluents and determine the microbial community of the process using novel molecular techniques.Item Evaluation of the bleach-enhancing effects of xylanases on bagasse-soda pupil(2002) Bissoon, Sadhvir; Singh, SurenThe extent of diffusion and surface modification of a purified 23.6 kDa xylanase isolated from Thermomyces lanuginosus on bagasse pulp was evaluated. Polyclonal anti-xylanase antibodies were raised in two rabbits and in conjunction with immunogold labeling and microscopic studies enzyme diffusion and degradation studies were performed. The purity of the xylanase was confirmed by SDS-PAGE and western blots confirmed the antigen-antibody hybrid on the nitrocellulose membrane.Item The isolation and characterization of phytoalexin and constitutive agents from plants for mycotoxin control(2000) Mohanlall, Viresh; Odhav, BhartiPlant medicine is an important area of commercial activity in South Africa. This is a rapidly expanding market, thus we are evaluating natural and stressinduced compounds (phytoalexins) from plants as agents that may be able to control mycotoxins. Natural compounds from Bridelia micrantha, Warburgia salutaris, Lippia javanica and Scenecio serratuloides and stress-induced compounds (phytoalexins) from Citrus sinensis cv Valencia were screened for antitunqal and antimycotoxic activity by bioautography against a test organism (Cladosporium cladosporoides) and mycotoxin producing fungi (Fusarium moniliforme and Aspergillus flavus).Item Development of a recognition of prior learning assessment model for the hospitality industry to be used by tertiary education institutions(2003) Dixon, Sharmaine; Anderson, Diana Jane