Bibliography: leaves 91-107. / Eragrostis curvula is a desiccation sensitive monocotyledonous plant and an economically important forage grass in southern Africa. This species has a potential to be improved for drought and salt resistance among other important agronomic traits. In this study, E. curvula was used as a model system to explore the feasibility of producing pasture grasses with increased tolerance to water deficit. To date, no reports have been published on transformation of this species. This study reports the transformation of E. curvula with Saccharomyces cerevisiae Hsp 12 gene using biolistic-mediated transformation. Firstly, a tissue culture protocol was established for E. curvula that was suitable for transformation studies. Although this species has been previously regenerated in vitro using inflorescence tissues, this study established new protocols that utilize leaf and seed as source of material. The aim of which was to find the best regenerable tissue that could be used for transformation studies. Plant regeneration was achieved from shoot explants cultured on MS medium supplemented with either 0.5 mg/I thidiazuron (TDZ) or 0.5 mg/I 6-benzylaminopurine (BAP) through the process of direct organogenesis. It was found that TDZ was the most effective cytokinin. Plant regeneration was also achieved from callus induced from immature leaves on MS medium supplemented with 2 mg/I 2,4- 0,0.01 mg/I BAP and 6 % (w/v) sucrose. Histological experiments performed gave clear evidence that plant regeneration from callus was through a process of indirect organogenesis. The regeneration protocol was combined with an optimized biolistic mediated transformation protocol using the PDS-I00/He apparatus of which both shoot explants and callus were used as target tissues. In the molecular aspect of the study, the Hsp 12 gene was ligated in the Sac I restriction site of pCAMBIAUbeeQ vector. The successful cloning of the Hsp 12 gene was confirmed by PCR and restriction endonuclease digestion. The resultant vector pCAMBIAUbeeQ Hsp 12 was purified and subsequently used for biolistic transformation of E. curvula. The regenerable shoot explants and callus tissue were bombarded with DNA (pCAMBIAUBeeQHsp12) coated on gold particles. As a comparative study, Agrobacterium tumefaciens was transformed with pCAMBIAUBeeQHsp12 vector for subsequent transformation of Nicotiana tabacum. Transient expression of GUS gene in transformed E. curvula shoot explants was visualized 72 h after bombardment. Optimized conditions for expression of GUS gene were gold micro projectiles, 7 cm travel distance and helium pressure of 9100 kPa. Transformed tissues were cultured on the regeneration medium without antibiotic selection. Putative transformants were generated and the presence of Hsp 12 gene was verified by PCR and its expression at RNA level was confirmed by RT-PCR. The presence of Hsp 12 protein in the transformed plants was analyzed using SDS-PAGE and MALDI-TOF peptide mass spectrometry.

The primary objectives of this research include an implementation of a 3-D algorithm in visualising the movement of solid suspended objects through image reconstruction and assessment of the quality of these images as well as validation of the application of the 3-D algorithm in visualising the movement of conductive solution.

Includes bibliographical references (leaves 98-103). / The increasing prevalence of diabetes worldwide has greatly increased the demand for insulin, a key type of treatment for many diabetics. For this purpose, the methylotrophic yeast Pichia pastoris has emerged as an additional microbial host for recombinant insulin production. A genetically modified Pichia pastoris MutS strain, engineered to produce the insulin precursor, was used as the experimental system in this study in order to optimise the insulin production process. The experimental system developed in this study employed a two-stage fed-batch feeding strategy in which growth was optimised by feeding glycerol to boost biomass followed by induction of the gene encoding insulin precursor by feeding methanol.

This thesis pertains to the extraction of copper via heap bioleaching, focussing specifically on the bioleaching of the mineral sulphide, chalcopyrite (CuFeS2). Industrial heap bioleaching offers an attractive alternative to conventional extraction methods, such as smelting, for processing low grade ores. There remain a number of operational challenges associated with bioleaching heaps, such as the lag time before efficient extraction is achieved and ineffective heap inoculation, as well as the difficulty in controlling the conditions within the heap.

This thesis contributes to the bioleaching knowledge base by improved understanding of the relationships between hydrodynamics and micro-organism-ore contacting and colonisation through an integrated study of microbiological and hydrological aspects of heap bioleaching within systems that mimic actual bio-heap environments.

Climate change, which is predominantly a result of anthropogenic global warming, is a major concern for humanity. The scientific consensus is that the rise of greenhouse gases, such as CO2, in the atmosphere has contributed to global warming. The increase in atmospheric CO2 is due to the burning of fossil fuels and deforestation. In South Africa, 77% of our primary energy needs are supplied by coal and our demand for energy is increasing. Cultivation of microalgae on flue gas from coal-fired plants and utilization of the algal biomass as an energy source has been proposed as a method for producing CO2-neutral fuels.

Modelling and simulation enhance our insight and understanding of chemical processes and aid in identifying bottlenecks and potential improvements. A simplified simulation package, providing a reasonable estimate of material and energy usage and process emissions is often valuable in very early stages of process development, when temporal and financial limitations do not allow for more detailed estimates. Environmental burdens are an increasing concern in industrial processes and various methodologies and tools have been developed for gathering and analysis of process information to enhance understanding of the process system and inform decision makers. The systems nature of these approaches is aimed at mitigation of environmental burdens through improved technologies, sustainable resource consumption and screening of process alternatives. Ideally, the process design team should bring together these tools in early stages of development when design flexibility is greatest. In the present study, such a simplified approach to bioprocess design is demonstrated using a case study for the large-scale production of citric acid.

The purpose of this research was to characterise the physical properties of microalgae, as a function of growth and suspension conditions, to enable exploitation of these characteristics for improved separation whilst allowing for water recycle.

Ammonium hexachlororuthenate (ACR) is a salt precipitated during a substitution reaction between ammonium and ruthenate dissolved in a strong hydrochloric acid medium. This precipitation reaction is used within the platinum industry as a means of recovering and purifying ruthenium. Application of this process at the Precious Metals Refinery of Anglo Platinum has brought to light certain inefficiencies. In recent years, volatility in the Ru market price occurred, indicating a potential to benefit financially from an improved Ru recovery. Consequently, this study was conducted to understand the effect of certain parameters on the process of precipitating ammonium hexachlororuthenate.

Includes bibliographical references (p.84-87). / The zinc oxide resource of Skorpion Zinc, an integrated zinc mine and refinery, near Rosh Pinah in southern Namibia, will be depleted by end of 2015 with a possible extension to 2017. Extensive exploration drilling was unsuccessful. With the abundant availability of zinc sulphide concentrates regionally the life of the operation may be extended by processing these concentrates. The leach kinetics of zinc sulphides is vastly slower than oxides, preventing the processing of zinc sulphides using the existing process, under current conditions. The challenge is to identify a suitable zinc sulphide treatment process that can be integrated with the existing plant. Information from the bench scale test work and an update of the economic models will provide sufficient accuracy for Skorpion to select either the pressure or the atmospheric leach process.