Rehabilitation and revegetation of mined coastal sand dunes on the east coast of South Africa makes sense. It recovers ecosystem services such as carbon sequestration. The outcome of rehabilitation, which covers a third of the mined area, is a secondary coastal dune forest similar to the forests in the region. The aim of revegetation, on the other hand, is to establish Casuarina equisetifolia J.R.Forst.&G.Forst. plantations on the remaining two thirds of the mined area, for the small-scale production of charcoal. The ratio of these two post-mining land use options has consequences for the carbon sequestration potential of the mined area. As growth rate could be a reflection of carbon sequestration rate, this study compared the growth rate of Acacia kosiensis P.P.Swartz, the species that dominates rehabilitated stands, to that of C. equisetifolia in response to rainfall. The carbon sequestration potential of the two post-mining land use options was subsequently evaluated by measuring carbon storage in wood, the herb layer, litter and soil in different-aged stands. I also compared the financial potential of the two land use options. Tree ring analysis could not be applied to the two species. No correlation between growth and rainfall could be found either. On average, A. kosiensis grew twice as fast as C. equisetifolia. Carbon storage in the wood, herb layer, litter and soil in rehabilitated stands of known age (7, 11, 17 and 21 years old) differed from the revegetated stands (8, 12, 16 and 19 years old). More carbon was stored in the revegetated stands than the rehabilitated stands. I attribute this primarily to the relatively larger wood and litter components of the former. C. equisetifolia, however, is harvested for charcoal production after about sixteen years of age, thus releasing most of the carbon stored in wood. The present ratio of rehabilitation to revegetation (1:2) is not optimal for long-term carbon sequestration. Rehabilitation costs more, but the income potential thereof, as determined in this study, is less than that of revegetation. This, however, does not reflect the true financial potential of the two land use options. The financial analysis performed in this study only considered income from the sale of timber, charcoal and carbon credits. It excluded other potential benefits of the rehabilitation of coastal dune forests. These may include the contribution to biological conservation and ecological services such as dune stabilisation and water purification. Coastal dune forests also provide habitat for a variety of organisms adapted to live in them. All these have a value. Their inclusion in a detailed cost-benefit analysis could render rehabilitation as the more financially efficient option. / Dissertation (MSc (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

The aim of this dissertation was to explore the cultural dimensions of relocating to another country. This included identifying the main differences and difficulties that expatriates faced in an ‘expatriate episode’, i.e. in adapting to a new work and socio-cultural environment abroad as well as re-adapting when repatriating to their home countries. More than 180 expatriates were interviewed, from 30 countries of origin, and relocating to 60 different countries. Where possible, face-to-face interviews were conducted. E-mail interviews were used to converse with interviewees located far from the researcher, and this method proved helpful and reliable. Findings of earlier researchers were tested for relevance. The main findings of cultural differences identified in the workplace showed that although Hofstede’s dimensions of power distance, uncertainty avoidance, individualism versus collectivism, and masculinity and femininity are still relevant, new models are needed. Other business differences were discussed, including the importance of building relationships before doing business, conducting meetings appropriately, understanding the role of women, obtaining status, and motivating employees. The practical implications of these differences were identified. In many situations, knowing about these differences allowed the expatriates to adjust their behaviour successfully. Expatriates who were not in managerial positions often either had to accept the new ways or find a new job. Expatriates had to learn to communicate effectively, adjusting to differences in verbal and non-verbal communication. Speaking a new language was the most obvious difference, while other aspects, such as language pace, degrees of formality, directness, showing emotions when communicating, and showing disagreement varied between cultural domains. Non-verbal aspects of communication, such as touch, personal space, eye contact, gestures and posture also differed. If the expatriates understood the cultural norms in their new domain, they could choose if they wanted to adapt or not. It also helped them avoid misinterpreting and making wrong judgments about other people’s behaviour. Most expatriates went through a 3-stage adjustment process. Knowing that they would likely experience difficulties did not prevent these from happening, but it did help them to cope. Difficulties included inner turmoil, anger towards their new environment and loneliness. Non-working spouses were lonelier as they usually did not have a job and the support network that accompanies it. Support from family and friends, both other expatriates and locals, helped expatriates the most to adjust, especially the spouses. Other helpful things were making choices, understanding the new cultural domain, and joining in local activities. Helpful resources for expatriates were identified, which included cultural training and information about the new country, new friends and local literature. In retrospect, expatriates wished they had obtained more information about the country, learnt the local language, made better choices, planned differently, and known themselves better. More than half of those expatriates who had repatriated to their home countries said that this process was more difficult than moving to a new country, which came as a big surprise to many. Their main difficulties included being judgmental towards their home country and its people, and feeling alone and misunderstood. / Dissertation (MSocSci (Anthropology))--University of Pretoria, 2007. / Anthropology and Archaeology / unrestricted

Farm profitability and the measurement of such profitability are usually calculated by traditional profitability measures such as return on equity (ROE), return on assets (ROA), net farm income (NFI) and the operating profit margin (OPM). The emergence of economic value added (EVA) during the 1990’s has changed the field of performance measurement. The question arises whether the new value measurement can give a better answer about value creation than traditional measures in specific areas such as farm profitability. This study examines the applicability of EVA as a measurement tool to measure the profitability and value creation by a sample South African milk producers. Milk production is one of the most important agricultural products in the economy. Fresh milk is ranked ninth among the top 20 gross production value contributors in agriculture in South Africa. The study reviewed EVA and few traditional measures (ROA, ROE, NFI and OPM). The literature review formed the basis for the application. The main objective of this study was to calculate and evaluate EVA as a financial performance measure that can be used by milk producers. Further objectives were to evaluate the financial performance of six milk producers, to determine whether these milk producers created value, and to compare EVA with traditional measures to see whether EVA is a better measure of wealth creation than other profitability measures. Based on the calculations using the traditional measures, it can be conclude that only four farms were profitable and that the other two were unprofitable. Although three farms of the four profitable ones had low returns, the results suggested that they were still profitable and that value has been created. Based on the EVA calculation, only one farm created value while the rest destroyed it. A comparison achieved using these measures shows that EVA gives the clearest results, while the traditional measures were misleading in three of the farms. A comparison of EVA and the four traditional measures showed that EVA was the best measure and gave more reliable results than the traditional measures in some cases. From the results it could be concluded that the EVA and the traditional measures can fruitfully be used together. EVA should take the commanding role, while the traditional measures can provide additional information. / Dissertation (MSc (Agric))--University of Pretoria, 2006. / Agricultural Economics, Extension and Rural Development / unrestricted

The contamination of environmental media by total petroleum hydrocarbons (TPH) is a concern in many parts of the world; particularly as most petroleum components like polycyclic aromatic hydrocarbons (PAHs) are either toxic or carcinogens. In South Africa, the sale of major petroleum products by the South African Petroleum Industry Association (SAPIA) reveals that about 21 billion litres of petroleum products are sold per year. These products include bitumen, diesel, fuel oil, illum paraffin, jet fuel and petrol. In addition, 19.5 million tonnes of crude oil are brought into South Africa annually to feed the country’s four refineries. The production of oily sludges at refineries, transportation, storage, and handling of petroleum products by end users, results in environmental contamination. The soil environment is particularly vulnerable to hydrocarbon contamination as most of the accidental spillages by trucks, rail locomotives and pipelines have a direct impact on the soil medium. As most of the petroleum compounds are either toxic or carcinogenic, their removal from the soil is necessary. The literature reveals that biological treatment of hydrocarbons is cost effective compared to other treatment options. However, in order to improve the efficiency of biological treatments, there is a need to understand the microbial diversity of TPH stressed environments and how simple biomonitoring ‘instruments’ can be used to evaluate the removal of hydrocarbons from the soil. The message from the literature indicates some potential solutions to the existing problems associated with soil microbial diversity and biotreatment of hydrocarbon contaminated soil, which must be investigated. The main aim of this work was to evaluate the microbial diversity of the different soil environments disturbed by Total Petroleum Hydrocarbons (TPHs) and the potential use of plants and microorganisms in monitoring and removing hydrocarbons from the soil. In addition, the potential of the culture-independent methods in complementing, the culture-dependent methods when evaluating soil microbial diversity were also evaluated. The polyphasic approach was successfully used in evaluating microbial diversity in both hydrocarbon-contaminated and uncontaminated soils. The approach involved the use of community level physiological profiles (CLPP) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to evaluate the effects of hydrocarbons on the soil microbial communities of both the contaminated and non-contaminated soil layers at a diesel contaminated site. Because of the ability of the molecular methods (PCR-DGGE) to complement the CLPP, the polyphasic approach is recommended when evaluating soil microbial diversity and the effect of pollutants on microbial community structure as the approach appears to compensate for the limitations of each of the methods of evaluating microbial diversity. However, further work is needed to improve the recovery of bacteria from the soil, particularly where the interest is to evaluate the availability of the indigenous microbial populations for bioremediation. The substrate utilisation pattern and 16S DNA fragments of the soil microbial communites in different soil layers at a diesel contaminated site were different. The substrate utilisation pattern of the topsoil was different from the substrate utilisation pattern of the soil layers below 1m. In addition, the substrate utilisation pattern of the contaminated and uncontaminated soil layers were different. 16S DNA fragments of the different soil layers were also different. While the metabolic activities of different samples as reflected by CLPP does not necessarily imply the difference in community structure of the samples, PCR-DGGE revealed differences in 16S DNA fragments and this complemented the results of the culture based methods. The results suggest that the use of functional and genetic approaches (in combination) have a better chance of revealing a ‘clearer’ picture of soil microbial diversity. The distribution of hydrocarbon-utilising bacteria and the efficiency of biodegradation of hydrocarbons vary with soil depth. The biodegradation rate of hydrocarbon was highest in the topsoil compared to other soil layers and this was supported by the high number of hydrocarbon-degrading bacteria in the topsoil compared to soil layers at and below 1m. The results suggest that the biological removal of hydrocarbons varies in different soil layers and that microbial diversity as measured by CLPP and PCR-DGGE varies with depth in hydrocarbon-contaminated soil. The information about metabolic activities of different soil layers is important when assessing the footprints of degradation processes during monitored natural attenuation (MNA). However, further studies are required to understand the effect of (not only) other pollutants, but the influence of soil components (pore volume, level of adsorbents and other environmental factors) on the microbial diversity of different soil layers in both ‘shallow’ and deep aquifers. The microbial diversity of different environments contaminated by hydrocarbons has different community level physiological profiles. At diesel depots where similar hydrocarbons are used for maintenance of locomotives, the number of bacteria (both total culturable heterotrophic bacteria and hydrocarbon-degrading bacteria) was proportional to the level of hydrocarbon contamination. However, there was no significant difference in the level of total culturable heterotrophs (TCHs) and the hydrocarbon degrading bacteria. In addition, the biological activities as evaluated by CO2 production were higher in nutrient amended treatments in which high numbers of TCHs were present. Microbial diversity of polluted surfaces needs to be studied further to investigate the concentration or the thickness of the hydrocarbons layer on the rock surfaces that encourages the attachment or colonization of the TCHs and the hydrocarbon-degrading bacteria. The hydrocarbons rather than the geographical origin of the soil sample appear to be more important in determining functional or species diversity within the bacterial communities. The samples from different locations were as different as samples from the same location but from contaminated versus uncontaminated soil. The results of the soils from different locations artificially contaminated by different hydrocarbons also reached the same conclusion. However, further work is required to investigate the importance of soil heterogeneity in community studies of soil environments contaminated by similar hydrocarbons. The removal of Polycyclic Aromatic Hydrocarbons (PAHs) in multi-planted soil microcosm was higher compared to PAHs removal in monoculture soil microcosms. In addition, the PAH removal was higher in the vegetated soil microcosms compared to the non-vegetated microcosms. There was however, no significant difference in the PAH removal in the soil microcosms planted with Branchiaria serrata and the microcosm with Eulisine corocana. The Principle Component Analysis (PCA) and Cluster analysis used to analyse the functional diversity of the different treatments revealed differences in the metabolic fingerprints of the PAH contaminated and non-contaminated soils. However the differences in metabolic diversity between the multi-planted and mono-planted treatments were not clearly revealed. The results suggest that multi-plant rhizoremediation using tolerant plant species rather than monoculture rhizoremediation have the potential to enhance pollutant removal in moderately contaminated soils. Lepidium sativum, a plant with short germination period, was successfully used to monitor, the removal of Polycyclic Aromatic Hydrocarbons (PAHs) from the soil. The sensitivity of L. sativum eased with increasing concentration of the polycyclic aromatic hydrocarbons in the artificially contaminated soil while no germination occurred in the historically polluted soil. When used during phytoremediation of PAH, the germination level of L. sativum was inhibited during the first weeks, after which germination increased, possibly due to PAH dissipation from the soil. The methodology based on the sensitivity of L. sativum to PAH can be used as a monitoring tool in bioremediation of soil contaminated with PAH. However, the methodology should be developed further to gain more knowledge on aspects of bioavailability of PAH in both the aged as well as the freshly spiked soil. Also critical is the sensitivity of the seeds to other pollutants (e.g. heavy metals), which are most likely to occur in the presence of the PAHs. Although the biological activities have the potential to monitor the removal of hydrocarbons from the soil, the methodologies have not been developed sufficiently to cater for the heterogeneity of the soil and to differentiate toxicity by the parent compound and the metabolites. At present, it is best that they be used to complement existing conventional monitoring instruments. Finally, the biological removal of hydrocarbons is cost-effective compared to other treatments. However, inherent physical, chemical and biological limitation hampers the efficient utilisation of the bioremediation technologies. Biostimulation approaches involving the stimulation of indigenous pollutant-degrading bacteria should be preferred ahead of bioaugumentation. The latter approach should be considered when the contaminated site does not have the indigenous pollutant-degrading bacteria. Even in this case, the aim should be to ‘seed’ the biodegradation knowledge to the indigenous microbial populations due to poor survival of the added strains. / Thesis (PhD (Biotechnology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

This study has been carried out in one irrigation scheme of the Eastern Cape Province, South Africa. The study assessed the economic performance of a smallholder irrigation scheme (Zanyokwe Irrigation Scheme). The study took place in a former homeland area (Ciskei). This region is submitted to a semi-arid and relatively mild climate. The infrastructures were built during the apartheid era, in order to provide employment and food to the local black population. Currently, the farmers crop from 1 to 10 hectares, producing vegetables and maize with low productivity. The government has engaged in a revitalization process, aimed at upgrading infrastructures and establishing new local organisations. Its objectives are to curtail the financial burden of operation and maintenance costs and withdraw from any direct farming activities and management of the schemes. The process includes the rehabilitation of infrastructure and establishment of Water User’s Associations, which are to take over ownership and collective management of the scheme. In such context the aims of the research were: (i) To evaluate the diversity of livelihoods and the contribution of farming; (ii) To estimate productivity of land and water; (iii) To identify factors influencing production at farm level; (iv) To examine the role of land tenure onto productivity. The conceptual framework for operation of an irrigation scheme, the Smile (sustainable management of irrigated land and environment) approach, the sustainable livelihood framework and descriptive statistics were used for analysis of the data. Primary data were obtained from 55 randomly selected households from the Zanyokwe Irrigation Scheme. Verbal description, interpretation and appreciation of facts were used for the qualitative data analysis. Descriptive statistics and typologies were employed to analyse the quantitative data. Findings indicate that irrigation households pursue heterogeneous livelihood strategies due to different access to livelihood assets and heterogeneous constraints and incentives. A socioeconomic comparison on the land size indicates that land size in the scheme is not uniform, it varies from one person to another. Land tenure in Zanyokwe is very diverse. It is highlighted that land tenure does not seem to have impact onto the farming style adopted by farmers, with the exception of leasing which is not practised by non-farming holders and dry-land farmers. It is demonstrated that there is no direct or clear relationship between land tenure system and farming styles, farmer’s types, or cropping systems adopted. It is indicated that farmers under leasing arrangement are having small size, few years of settlement and youngest household head. Leasing arrangement is relatively new tenure in the scheme. The level of education in the scheme is very low. It is observed that more educated farmers have larger size of land in the scheme. The diversity of the farmer’s situation has been highlighted through the use of typological techniques. Five household types have been identified within the scheme, and thorough economic analyses have been carried out. Particularly, some vulnerable types of farmers have been identified. The results on irrigation performance indicate that productivity of water varies among crop management styles. For example, potato and butternut (high-yield) showed R2.55 and R1.75 as gross margin per cubic meter used respectively, and potato and butternut (low yield) showed R0.09 and R0.14 as gross margin per cubic meter used respectively, is measured in terms of gross margin per volume of irrigation water consumed as an estimate for return to irrigation water. Contingent analysis of willingness to pay indicated that farmers with limited demand, hence limited income from irrigation farming are not willing to pay, and it also suggests that farmers with high consumption of water are willing to pay for water related activities. Findings indicate that land productivity (yield/ha) is higher for specialised subsistence farmers than others types, per unit of land used The following recommendation arises on the basis of the findings of this study and evidence from other studies on smallholder irrigation in South Africa. Agriculture is likely to be a necessary feature of rural development in the Eastern Cape Province for years to come. It is highly recommended that intensification should be promoted along with training, and improved access to inputs at reasonable cost since high yielding crops are more profitable and more conducive to water valuation, and high yields come with intensification, since one given crop can perform very differently depending on the way it is grown. / Dissertation (M Inst Agrar (Agricultural Economics))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

The genus Pantoea has seven species and two sub-species, isolated from diverse geographical and ecological sources. The majority of Pantoea species are plant-associated and cause a wide variety of diseases on a range of hosts. P. ananatis causes disease on many agricultural crops including onion, maize, sudangrass, honeydew melon and pineapple. P. ananatis has been identified as the causal agent of a serious bacterial blight and dieback of Eucalyptus in South Africa. Bacterial isolates have also been recovered from Eucalypts in South America and Uganda exhibiting Pantoea ananatis-like symptoms. These isolates have not been identified. Identification of P. ananatis, based on phenotypic analysis, is difficult due to similarities in phenotypic characteristics between Pantoea species and related Enterobacteriaceae. Regular isolations of P. ananatis have highlighted the need for a rapid, molecular-based identification technique for the pathogen. A PCR assay, based on amplification of a partial region of the 16S-23S ITS gene with species-specific primers, was evaluated for the rapid identification of P. ananatis. Authentic strains of P. ananatis were included in the study, along with the unidentified isolates from South America and Uganda, and authentic strains of all species of the genus Pantoea. All authentic strains of P. ananatis produced a single PCR product of 398 bp following amplification. Only one unidentified isolate from South America produced the 398 bp PCR product. The only other species to be detected by the primers was P. stewartii subsp. indologenes. For the 16S-23S ITS-PCR assay to successfully detect only P. ananatis, the species-specific primers will have to be modified to increase their specificity. Little is known concerning the genetic relatedness between species and strains of Pantoea, and no standardised molecular typing system exists for the genus. The entire 16S-23S ITS gene was evaluated for a genetic relatedness study for the genus Pantoea. Universal primers were used to amplify the entire spacer region. Multiple amplification products were visible for all Pantoea strains and the unidentified isolates. This indicated that the Pantoea genome contains multiple copies of the rRNA operon and a high degree of similarity exists among the rRNA operons of species of the genus Pantoea. Therefore it is not possible to determine the genetic relatedness of Pantoea species based on a typing technique targeting the 16S-23S ITS region. The entire genome was then screened by AFLP analysis to examine the genetic relatedness of the genus Pantoea. The AFLP technique was found to be successful and distinct clusters were visible for each Pantoea species in the dendrogram. The majority of the South American and Ugandan isolates formed three separate clusters from P. ananatis. Representative strains were chosen from among the unidentified isolates for 16S rRNA sequencing. Based on the resulting phylogram, it is clear that at least two new Pantoea species or subspecies exist among the South American and Ugandan isolates, and more than one Pantoea species may be associated with bacterial blight and dieback of Eucalyptus. DNA-DNA hybridisations will be performed on these isolates to determine their correct taxonomic position within the genus Pantoea. / Dissertation (MSc (Microbiology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

The junior and small-scale mining sectors in South Africa play an important role in the livelihoods of numerous communities. Mining is an opportunity, in the post-1994 democratic era, for many individuals to obtain access to much required empowerment and socio-economic development. These sectors are, however, not without numerous characteristics that pose problems for operators, legislators, and other role-players. Mining is inherently risky, with operators experiencing numerous difficulties throughout the life of mine. This critical analysis provides understanding relating to the junior and small-scale mining sectors of South Africa, as well as how mineral resource management issues impact these sectors. The different phases within the risk management cycle are described together with key techniques available to reduce the associated risks. The applicability of these techniques for use in the junior and small-scale mining sectors is highlighted. Opportunity does exist for junior and small-scale prospects and operations to include such techniques in either the search for funding or monthly planning and functioning. It is, therefore, the risk management cycle and how it currently applies to a mineral resource suitable for exploitation by the junior and small-scale mining sectors that are the core focus. No management process can create additional value in the ground, but various available mechanisms can go a long way to quantifying the inherent risk that exists, highlighting the need to manage the risks and hopefully allowing the entrepreneur access to the intrinsic opportunities of the emerging mining sector in South Africa. / Dissertation (MSc (Earth Science Management and Practice))--University of Pretoria, 2007. / Geology / unrestricted

In Africa, as everywhere else in the world, the interpretation of the gospel message takes place in a particular and unique context. This means that in doing theology one should take into account the spirit and the gospel message, but also the culture of the people the message is communicated. During the Graeco-Roman period (First century Mediterranean world) the proclamation of the gospel message could not ignore the culture of the Romans, Greek and Jews. It is therefore argued in this study that the reading and interpretation of the gospel message in Africa should seriously take into consideration the African religio-cultural cues. Therefore, the current researcher calls this hermeneutical paradigm, inculturation hermeneutic. In the first chapter of this thesis, the problem posed is that while many Africans today are exposed to modern education, traditional thought is still the source of the basic world-view. Even though a greater majority of Africans are Christianized, they still adhere to their traditional religious customs and practices such as the veneration of ancestors and visiting traditional doctors. These questions are investigated using the inculturation hermeneutic approach. The gospel features embedded in the traditional African culture are examined. Some of the features are the aspect of birth, marriage, attributes of God, the role of traditional healers and sacrifice. These features show that African traditional culture respected the birth of a child. This was considered to be a gift from God. Therefore all necessary rituals were performed to ensure that the child learns all what is expected of it. The child becomes a member of society and is able to live harmoniously with other people and with God. Marriage became an institution respected as basis of procreation, another gift from God. The attributes of God in African culture show that African traditional people knew God as Creator and sustainer of life. The researcher manages to demonstrate that these aspects of African traditional life have embedded or enshrined features that are in the gospel message and which could be made explicit and highlighted in proclaiming the Gospel in an African context. The cult of ancestor veneration has been investigated. Evidence from a variety of scholars indicates that Africans never worship ancestors. The cultural practices that Africans perform aim at demonstrating their faith in God. They are symbolic in nature. However, uninformed readers may interpret these rituals as secular and of no religious value. The different rituals are therefore explained and discussed in detail. The attempt in discussing the cult of ancestor veneration is not to validate this practice. The researcher endevours to show that the cult embodies an important element of the Gospel mediatorship. Salvation is another concept that has also been investigated. When analyzed and interpreted within the African cultural context, this aspect also demonstrates the embodiment of gospel features. Salvation is approached holistically, that is, the health of the human body as well as the spirit are taken as a whole. Some case studies of African communities are examined to establish how these communities understand salvation. Some biblical texts are cited to illustrate points of contact or similar lines of thinking, where both biblical and African communities express their faith in God. These texts are in no way intended to compare the two religions or put them on equal footing. This would result in one being used as a yardstick for the other. I think scholars should interpret each religion in its own context and evaluate its embodiment of gospel features. This means that each religion has its own unique way whereby it embodies the gospel message. And in this thesis, the submission is that African traditional culture and religion embodies gospel features. / Thesis (DPhil (Biblical and Religious Studies))--University of Pretoria, 2006. / Biblical and Religious Studies / unrestricted

The commercial significance of the dairy fermentation industry which incorporates the production of cheeses, is well recognised and ranks second only to the production of alcoholic beverages. Consumers today demand greater choice and variety with improved quality standards. Lactic acid bacteria, in particular the genera Lactococcus, Leuconostoc, Lactobacillus, Streptococcus and Pediococcus play a central role in the production of new and exotic flavoured cheeses. Gurira&Buys (2005) found that the Pediococcus species crude pediocin extract that were isolated from South African Gouda cheeses was inhibitory against food pathogens, Listeria monocytogenes and Bacillus cereus. Selected Pediococcus species were evaluated in this study for their activity against available mixed strain mesophilic lactic acid Gouda cheese starter cultures. The commercially available starter cultures, Nizostar 500MT, LL 50C and DairysafeTM were evaluated. The starter cultures were evaluated for their sensitivity to the Pediococcus species crude pediocin extract on the basis of their lactic acid production, pH and growth levels. The mesophilic mixed strain lactic acid Gouda cheese starter culture, DairysafeTM was identified as the starter culture that was the least sensitive to the Pediococcus species crude pediocin extract as the lactic acid production and pH level of DairysafeTM was the least affected. Thus, starter culture, DairysafeTM was used in conjunction with live cultures of Pediococcus acidilactici ST 79 and Pediococcus pentosaceus ST 13 as an adjunct culture in the manufacture of Gouda cheese. Gouda cheese made using DairysafeTM as the starter culture and live cultures of P. acidilactici ST 79 and P. pentosaceus ST 13 as an adjunct culture was found to have a chemical composition comparable to that of the cheese, to which no adjunct culture had been added. The addition of the Pediococcus species as an adjunct culture in Gouda cheese manufacture had no significant effect on the levels of lipolysis or proteolysis of the cheese during the 45 day ripening period. However, there were significant differences noted in the sensory attributes of the cheese manufactured using Pediococcus species as an adjunct culture and the cheese manufactured without an adjunct culture. The results of this study indicate that P. acidilactici ST 79 and P. pentosaceus ST 13 can be used as an adjunct culture in conjunction with a pediocin resistant starter culture, such as DairysafeTM to produce a cheese that is physico-chemically comparable to Gouda cheese currently on the market but is clearly differentiable from the homogenous products currently available. / Dissertation (MSc (Food Science))--University of Pretoria, 2007. / Food Science / unrestricted

Numerous classes and types of chemicals, which contaminate soil, complicate the removal of many toxic compounds from the environment. For example, many soils are contaminated with one or more metals, radioactive and inorganic compounds. Large areas are polluted with recalcitrant organic substances that pose environmental problems due to their toxicity and tendency to disperse through wind and water errosion. Polycyclic aromatic Hydrocarbons (PAHs) are ubiquitous pollutants found in soil at wood preservation plants and gasworks. PAHs are chemical compounds that persist in the environment and thus cause pollution worldwide. Their persistence in the environment is due to their low water solubility. The major source of PAHs is from the combustion of organic material such as coal, tar, wood and rubber. PAHs have been detected in a wide variety of environmental samples including air, soil, sediments, water, oils, tars and foodstuff. Most people are exposed to PAHs when they breathe smoke, autoemissions or industrial fumes. Because PAHs are toxic, mutagenic and carcinogenic to humans and animals, their elimination from the environment is of paramount importance. The estimated costs for the clean up of PAHs contaminated sites with conventional techniques such as incineration and landfilling are enormous. The search for alternative methods to restore polluted sites in a less expensive, less labour intensive, safe and environmentally friendly way is required. Such an alternative method is rhizoremediation, which is defined as the use of plants in association with microorganisms to degrade environmental pollutants such as PAHs. Microbial communities exposed to hydrocarbons become adapted, exhibiting selective enrichment and genetic changes resulting in an increased proportion of hydrocarbon degrading bacteria and bacteria plasmid encoding hydrocarbon catabolic genes. Adapted microbial communities have higher proportions of hydrocarbon degraders that can respond to the presence of hydrocarbon pollutants. The aim of this study was to identify bacteria isolated from the rhizosphere of Elusine coracana, Biddens pilosa, Brantha serratia and Cyperus esculentus grown in polluted and unpolluted soil and to evaluate the potential of bacteria isolated from the rhizosphere of these plants grown in polluted soil for their ability to bioremediate Polycyclic aromatic Hydrocarbons (PAHs). Different concentrations (1%, 3% and 5%) of naphthalene and acenaphthene (PAHs) were made and added to 500ml Bacteriological agar.1000µl of bacterial suspensions were spread onto the surface of naphthalene and acenaphthene-based agar plates and incubated for 48h at 37OC. Results showed that Brevibacillus brevis, Brevindimonas versicularis, Vibrio vulnificus, Chryseo indologenes, Micrococcus spp, Bacillus stearothermophilus, Pseudomonas putida and Pseudomonas spinosa showed excellent growth in all concentrations in naphthalene based agar medium. However, Micrococcus spp and Pseudomonas spinosa showed limited growth in acenaphthene based agar medium. Amongst all these bacteria tested for their potential in utilizing PAHs, B. brevis, V. vulnificus, C. indologenes, B. stearothermophilus, and P. putida were the most promising for biodegradation of PAHs, since none of them were affected by any change in concentration either in naphthalene or acenaphthene. / Dissertation (MSc (Microbiology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted