Mosquito-related diseases are a major health concern worldwide, necessitating improved methods of prevention. In this study, we introduce two innovative tools to help deepen our understanding of mosquito behavior and enhance our control strategies. The first tool is a unique flight chamber designed to study spatial repellents – specific airborne chemicals that form an invisible barrier, deterring mosquitoes and mosquito-borne diseases away from humans. The amount of repellent needed to be effective, however, is unclear. Our flight chamber enables precise control and measurement of repellent levels in the air, facilitating study of mosquito responses. Initial findings show that mosquitoes are less active with repellents, but not entirely deterred. Continued work with our chamber could help pinpoint optimal repellent levels for effectiveness. Secondly, we developed a model system called BITES that mimics a mosquito biting a human. This system uses a capillary gelatin-alginate hydrogel (Capgel), which has vessels that can be populated with human cells and filled with blood. BITES attracts mosquitoes, which perform regular blood-feeding behaviors on the biomaterial. BITES can be used to study the mosquito-bite site more closely and potentially better understand disease transmission. These new tools can lead to improved strategies of mosquito control, and thereby reduce mosquito-borne diseases worldwide.

The enzymatic production of R-phenylacetylcarbinol (R-PAC), with either whole cells or partially purified pyruvate decarboxylase (PDC) as the biocatalyst, requires high PDC activity and an inexpensive source of pyruvate for an economical feasible biotransformation process. Microbial pyruvate produced by a vitamin auxotrophic strain of Candida glabrata was selected as a potential substrate for biotransformation. With an optimal thiamine concentration of 60 ??g/l, a pyruvic acid concentration of 43 g/l and yield of 0.42 g/g glucose consumed were obtained. Using microbially-produced unpurified pyruvate resulted in similar PAC concentrations to those with commercial pure substrate confirming its potential for enzymatic PAC production. To obtain high activity yeast PDC, Candida utilis was cultivated in a controlled bioreactor. Optimal conditions for PDC production were identified as: fermentative cell growth at initial pH at 6.0 followed by pH downshift to 3.0. Average specific PDC carboligase activity of 392 ?? 20 U/g DCW was achieved representing a 2.7-fold increase when compared to a constant pH process. A mechanism was proposed in which the cells adapted to the pH decrease by increasing PDC activity to convert the accumulated internal pyruvic acid via acetaldehyde to ethanol thereby reducing intracellular acidification. The effect of pH shift on specific PDC activity of Saccharomyces cerevisiae achieved a comparable increase of specific PDC carboligase activity to 335 U/g DCW. The effect of pyruvic acid at pH 3.0 on induction of PDC activity was confirmed by cultivation at pH 3 with added pyruvic acid. Using microarray techniques, genome-wide transcriptional analyses of the effect of pH shift on S. cerevisiae revealed a transient increased expression of PDC1 after pH shift, which corresponded to the increase in specific PDC activity (although the latter was sustained for a longer period). The results showed significant gene responses to the pH shift with approximately 39 % of the yeast genome involved. The induced transcriptional responses to the pH shift were distinctive and showed only limited resemblance to gene responses reported for other environmental stress conditions, namely increased temperature, oxidative conditions, reduced pH (succinic acid), alkaline pH and increased osmolarity.

The enzymatic production of R-phenylacetylcarbinol (R-PAC), with either whole cells or partially purified pyruvate decarboxylase (PDC) as the biocatalyst, requires high PDC activity and an inexpensive source of pyruvate for an economical feasible biotransformation process. Microbial pyruvate produced by a vitamin auxotrophic strain of Candida glabrata was selected as a potential substrate for biotransformation. With an optimal thiamine concentration of 60 ??g/l, a pyruvic acid concentration of 43 g/l and yield of 0.42 g/g glucose consumed were obtained. Using microbially-produced unpurified pyruvate resulted in similar PAC concentrations to those with commercial pure substrate confirming its potential for enzymatic PAC production. To obtain high activity yeast PDC, Candida utilis was cultivated in a controlled bioreactor. Optimal conditions for PDC production were identified as: fermentative cell growth at initial pH at 6.0 followed by pH downshift to 3.0. Average specific PDC carboligase activity of 392 ?? 20 U/g DCW was achieved representing a 2.7-fold increase when compared to a constant pH process. A mechanism was proposed in which the cells adapted to the pH decrease by increasing PDC activity to convert the accumulated internal pyruvic acid via acetaldehyde to ethanol thereby reducing intracellular acidification. The effect of pH shift on specific PDC activity of Saccharomyces cerevisiae achieved a comparable increase of specific PDC carboligase activity to 335 U/g DCW. The effect of pyruvic acid at pH 3.0 on induction of PDC activity was confirmed by cultivation at pH 3 with added pyruvic acid. Using microarray techniques, genome-wide transcriptional analyses of the effect of pH shift on S. cerevisiae revealed a transient increased expression of PDC1 after pH shift, which corresponded to the increase in specific PDC activity (although the latter was sustained for a longer period). The results showed significant gene responses to the pH shift with approximately 39 % of the yeast genome involved. The induced transcriptional responses to the pH shift were distinctive and showed only limited resemblance to gene responses reported for other environmental stress conditions, namely increased temperature, oxidative conditions, reduced pH (succinic acid), alkaline pH and increased osmolarity.

Thesis (DBA) -- Macquarie University, Macquarie Graduate School of Management, 2007. / Bibliography: p. 209-223. / Introduction -- The biotechnology industry -- Literature review -- Methodology -- Case studies -- Discussion -- Conclusion. / Australia has a strong record of medical science research. Of the country's seven Nobel Prize winners, six have been within the bioscience sector. But Australia has been struggling to produce an FDA-approved blockbuster drug. The high level of research output in biotechnology is inconsistent with the low level of commercialisation of products resulting from the research.-- What distinguishes the successful companies in the Australian biotechnology industry? In particular, what obstacles are encountered by Australian scientists attempting to commercialise their inventions and are these obstacles spicific to the Australian context? Biotechnology impacts on an extraordinary range of industries, particularly in the health care sector, and is one of the major drivers of sustainable economic growth in the 21st century. The contrast between the Australian biotechnology industry's potential and achievements inhibits its ability to contribute to national wealth. This study investigates the difficulties encountered by Australian biotechnology firms in their attempts to commercialise their research.-- Garnsey's (1998) small firm growth model, based on engineering firms with in-house production, has been used to identify obstacles to biotechnology innovation and problems encountered in commercialising the research before the firm has been established. The research question asks to what extent the model can assist in understanding the obstacles that impede the growth of Australian biotechnology firms.-- Taking a qualitative approach and using an integrated and coherent case study methodology, the research identifies major obstacles to the growth of five firms through three clearly identifiable phases. Findings from the comparative case study analysis show that the firms' growth patterns generally conform to the model, but with major deviations due to specific differences between the engineering and biotechnology industries, Although biotechnology firms worldwide face similar obstacles to their growth, Australian firms encounter additional problems that seriously impede potential commercialisation of their biotechnology research. / Mode of access: World Wide Web. / xiv, 378 p

Thesis (M.S.)--University of Nevada, Reno, 2006. / "December, 2006." Includes bibliographical references (leaf 33). Online version available on the World Wide Web.

Submitted in fulfilment for the requirements for the degree of Doctor of Technology: Biotechnology, Durban University of Technology, 2010. / South African edible oil processing plants produce approximately 3 x 105 tonnes of oil annually with up to 3 tonnes of water for every tonne of oil produced. Wastewater that contains oil extracts varies in organic loading from 30,000 to 60,000 mg.l-1 COD. This wastewater can be used to grow oleophilic fungi to produce valuable industrial products. The global vitamin B market is approximately R25.5 billion with 4500 metric tonnes being produced. A large proportion of this is produced using the fungus Eremothecium gossypii using oil substrates. The aim of this study was to to develop a novel method to produce riboflavin with the aid of fungi, using edible oil effluent (EOE) as substrate, and to optimize the production thereof by statistical experimental design. Four fungi were surveyed for their growth potential on EOE and two, E. gossypii (CBS109.51) and C. famata (ATCC 208.50) were found to produce sufficient riboflavin for further study. Mutation of these organisms using ethylmethane sulphonate (EMS) increased riboflavin production from 3.52 mg.l-1 to 38.98 mg.l-1, an 11-fold increase. An enzyme pathway responsible for this was found to involve isocitrate lyase and comparison of this enzyme’s activity in the mutant against the wild-type using Michaelis-Menten kinetics showed a higher reaction velocity (Vmax) with a reduced substrate affinity (Km) indicating that the mutation was associated with this enzyme. Biomass comparisons were fitted to the sigmoid Gompertz model which was used to compare the wild-type to the mutant and increased specific growth rates and doubling times were observed in mutated cultures of E. gossypi. A strategy of statistical experimental design was pursued to optimize media components and iterative fractional factorial experiments culminating in a central composite optimization experiment were conducted. Statistically verified mathematical models were developed at each stage to identify important media components, predict media interactions, show directions for improvement and finally, predict maximum riboflavin production. An eight-factor resolution IV fractional factorial increased riboflavin production to 112 mg.l-1 followed by a four-factor resolution V experimental design which increased riboflavin production to 123 mg.l-1. A two-factor (yeast extract and NaCl) central composite experimental design predicted a maximum riboflavin production of 136 mg.l-1 which was a 3.5-fold increase from the mutant, and 38.6-fold higher than the E. gossypii wild-type. The optimized value was achieved within predicted confidence intervals in confirmatory experiments. Cost implications for production of riboflavin on EOE were calculated and a 10% technology uptake by the edible oil industry could yield a riboflavin industry with a 63.65 million rand turnover and a potential 24.96 million rand gross profit margin. / National Research Fund.

Submitted in fulfillment of the requirements of the Degree of Master of Technology: Biotechnology, Durban University of Technology, 2011. / Riboflavin (vitamin B2), an essential water-soluble vitamin is commercially produced because it cannot be synthesized by vertebrates. Although this vitamin is produced chemically, bioproduction is a better option since it is more economical, requires less energy, produces less waste and can use renewable sources. In this study we investigated spent oil from the food and motor industries as alternative cheap carbon sources for the bioproduction of this vitamin. Commercial fungal strains namely; Eremothecium gossypii ATCC 10895, Eremothecium gossypii CBS 109.51, Eremothecium ashbyi CBS 206.58 and the yeast, Candida famata ATCC 20850, as well as a laboratory mutated Eremothecium gossypii EMS 30/1 strain were used. Statistical experimental design using a series of fractional factorial experimental designs was used to optimize the effect of yeast extract, peptone, malt extract, K2HPO4 and MgSO4.7H2O to supplement the used oils for optimum riboflavin production. Response surface methodology based on central composite experimental designs was then applied and together with the point predictions made, production media for both substrates were further optimized. The optimized conditions were then tested with laboratory experiments. Results showed that mutant E. gossypii EMS 30/1 produced the most riboflavin in spent motor oil (20.45 mg.l-1) while Candida famata ATCC 20850 produced the highest concentration (16.99 mg.l-1) in spent vegetable oil. With these strains and using the experimental designs from the fractional factorial experiments, supplemented spent motor and spent vegetable oils produced 66.27 mg.l-1 and 72.50 mg.l-1 riboflavin, respectively. The central composite optimization results showed that 0.18 g.l-1 and 0.45 g.l-1 K2HPO4 and 12.5 g.l-1 malt extract increased the production to 91.88 mg.l-1 and 78.68 mg.l-1 in spent vegetable oil and motor oil respectively. A point prediction from the response surface methodology was used to validate these and it was found that 103.59 mg.l-1 riboflavin was produced by mutant E. gossypii EMS 30/1 using 2.5 g.l-1 yeast extract, 0.5 g.l-1 peptone, 12.5 g.l-1 malt extract, 0.18 g.l-1 K2HPO4 and 0.3 g.l-1 MgSO4.7H2O. After optimizing K2HPO4 in a one-factor-at-a-time experiment, 82.75 mg.l-1 riboflavin was produced by C. famataon v SVO using 6.5 g.l-1 peptone, 12.5 g.l-1 malt extract 0.15 g.l-1 K2HPO4 and 1.75 g.l-1 MgSO4.7H2O. This is a 5.08 and 4.87 fold increase respectively when compared to spent oil prior to optimization. This shows that spent motor oil and mutant E. gossypii produces 103.59 mg.l-1 riboflavin while spent vegetable oil and C. famata produces 82.75 mg.l-1 riboflavin. Hence, E. gossypii can be used to generate riboflavin using spent motor oil and C. famata, using spent vegetable oil.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2013 / Biotechnology as a science has become increasingly more important because of what it has to offer in various fields. These include the development of medicines for human and animal health; improved crop agriculture for enhancing food security; and environmental sustainability, all of which are of the utmost importance, not only globally, but also in southern Africa. Through a participatory and collaborative process of biotechnology capacity development at the Universities of Namibia (UNAM) and the Witwatersrand (WITS) in the Southern African Development Community (SADC) region, it was identified that science curricula need to take cognizance of ‘worldview’ and the impact this may have in the context of teaching and learning. The purpose of this study was to investigate the potential barriers, or factors contributing, to learning in the two southern African universities in the context of the biotechnology curriculum. The study focused on how African epistemologies should be taken into consideration to facilitate capacity development in biotechnology at the tertiary education level, and in so doing, facilitate the development of a culturally sensitive, generic biotechnology curriculum which reaches across both literal and cultural borders and is relevant to these countries. The methodology of phenomenography was used in this case study and it resulted in two categories of description that formed the outcome space of the experience of biotechnology. These categories of description included a theoretical and practical perspective and a worldview perspective. This study has confirmed that worldview differences can lead to barriers to learning in biotechnology. Furthermore, theoretical and practical concepts included in the curriculum need to be carefully considered to make the curriculum responsive to African needs in order to provide for epistemological access, and so that the inherent cross-cultural experience between the learners’ life-world and biotechnology is recognized. The value of this study is affirmation that formulation, development, teaching and learning of a biotechnology curriculum should be regarded as an ‘African product’, where worldview and the theoretical and practical perspectives are carefully considered to provide a qualification to make a difference for capacity development in southern Africa. (339 words)

Thesis (MTech (Food Technology)--Cape Peninsula University of Technology, 2009 / The primary aim of this study was to establish the effects of both cavitation, (20 KHZ), and heat (55°C or 60•C) on Saccharomyces cerevisiae GC210 (MATa lys2) suspended in physiological saline. Fluorescent flow cytometry was used to determine the effects of moist heat and acoustic cavitation on S. cerevisiae cells. Results from this study could be used as a guide for use by the food industry for the combined use of heat and sonication to disinfect various solutions contaminated with S. cerevisiae.

Benzoylformate decarboxylase (BFD) from Pseudomonas putida catalyzed the formation of 2-hydroxy-1-phenylpropanone (2-HPP), a 2-hydroxy ketone, from the kinetic resolution of rac-benzoin in the presence of acetaldehyde. The formation rate of 2-HPP via kinetic resolution of benzoin was 700-fold lower compared to the formation via direct carboligation of benzaldehyde and acetaldehyde. Further investigations revealed that BFD not only accepts (R)-benzoin but also 2-HPP as the substrate. A typical Michaelis–Menten type kinetics was observed starting from enantiopure (S)- or (R)-2-HPP. The formation of racemic 2-HPP while using benzoin as the donor in the presence of acetaldehyde and the racemization of (R/S)-2-HPP were detected. The equilibrium constant determined, showed favoured conditions towards the product side i.e. (R)-benzoin and 2-HPP. In the end, an extended reaction mechanism was proposed by supplementing the already known mechanism with the C–C bond cleavage activity of BFD towards 2-hydroxy ketones. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.