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The main aim of this research was to utilise whey as a fermentation substrate for the production of microbial biopolymers.Of the three commercial biopolymer producers tested for biopolymer production in whey, only Pseudodomonas elodea produced significant apparent viscosities of up to 470cP at 2 s-1 on enriched whey broths. In these broths lactose utilisation was poor (14% w/v). A strain of P. elodea that had improved lactose utilising capacity was selected after six serial transfers on whey and lactose rich broths. After screening more than 60 bacterial isolates, a strain of Klebsiella oxytoca that initially produced a broth apparent viscosity of 36 cP at 12 s-1 in whey was isolated from raw milk. Biopolymer production was optimised in the K. oxytoca isolate.Concentrations of over 16 g/1 and broth apparent viscosities greater than 20,000 cP at 0.6 s-1 were obtained after optimisation. The biopolymer produced by the K. oxytoca isolate was shown to contain rhamnose, glucose and cellobiose, a composition not comparable to any reported polysaccharide. Polymer application studies indicated that it had potential to be used as a thickener, stabiliser, and binder. / Doctor of Philosophy (PhD)

Campylobacter jejuni (C. jejuni) is a food-borne bacterial pathogen that is the leading cause of Traveller’s Diaharea and Guillian-Barré Syndrome. Previous research determined that bacterial surface carbohydrates are virulence factors. Specifically, the study of the capsular polysaccharide (CPS) structures has widespread applications to understanding serotype cross-reactivity and biosynthetic pathways, the function of bacterial surface carbohydrates, and glycoconjugate vaccine development. This thesis characterized the CPS of C. jejuni HS:10 and subsequently used the CPS for developing a glycoconjugate vaccine. This was accomplished through extraction and purification of sugar from the bacteria, followed by characterization using chemical degradation, GC-MS, NMR and conjugation techniques. These analyses determined that the CPS was composed of a 3-linked GalNAc backbone and 6d-Galhepf attached at the 4th position with non-stoichiometrically attached O-methyl phosphoramidate attached to the 3 position of the heptose. Using this structure, a successful glycoconjugate vaccine was prepared using periodate oxidation and reductive amination.

Th.--Pharm.--Paris 5, 1984. N°: 106.

The rising demand for arable land, to meet the competing needs of food and energy for a growing population, will soon become unmanageable. There is therefore a pressing need to increase the efficiency with which these demands are met, or find alternative ways of meeting them. In this work, E. coli transformed with a copy of its own ADP-glucose pyrophosphorylase gene (glgC), under a lac promoter, was found to synthesise large inclusion bodies when grown in media supplemented with lactose and IPTG. Analysis of these inclusion bodies suggests that they are formed of polysaccharide, giving the cell a significantly higher total sugar content than a control grown under the same conditions. The inclusion bodies were found to react strongly with iodine, turning a blackish brown colour normally associated with iodine-starch reactions. Results also indicate that the bacteria are unable to digest these inclusion bodies once they have been formed. These findings suggest the presence of long α-helices, which would both bind with iodine and prohibit enzymatic digestion. It was therefore hypothesised that the extra GlgC enzymes were allowing glucan chains to extend at a faster rate during glycogen synthesis, leading to unbranched regions that were long enough to wind themselves into helices. The subsequent introduction of a copy of the E. coli branching enzyme gene (glgB), under the same lac promoter, was therefore expected to abolish the inclusion body phenotype, by allowing the branching of the polysaccharide to keep speed with the synthesis of its linear chains. This was indeed found to be the case. However, cells transformed with both additional gene copies were also found to accumulate a significantly higher total sugar content again: more than twice that of cells transformed with glgC alone and more than seven times that of a control, when grown under conditions designed to optimise polysaccharide synthesis. These transformants were also observed to grow to higher cell densities that a control, in various growth media. The results of both these transformations could be significant in meeting the demands of our growing society. In particular, the use of cyanobacterial glycogen as a carbon source for biofuels has recently been gaining interest, and the work presented here may well be applicable in this field, providing the possibility to significantly increase yields. Lastly, the effects of Isoamylases and Granule Bound Starch Synthase, taken from two starch producing organisms – Zea mays and Ostreococcus tauri – were investigated in an E. coli host. Results were inconclusive, but suggest many avenues for continuing the work.

Plastics have changed the world of materials due to their high durability, low price, low density, and ease of processing. Unfortunately, the majority of plastic goods produced are discarded instead of recycled, leading to a massive accumulation of plastic waste in landfills and natural habitats. To decrease the impact of plastic waste, sustainable materials and synthetic methods are needed. This dissertation focuses on new strategies for developing renewable and degradable polymers with minimal energy input as well as new methods to blend legacy polyolefins with renewable polymers. The first half of the dissertation focuses on synthesizing polymers using light while the second section focuses on combining traditional polyolefins with renewable polymers. Photo-mediated polymerizations are an attractive alternative to traditional thermal polymerizations due to their ease of setup and the spatiotemporal control afforded by light. Using LED lights also affords a synthetic technique that requires little energy input, thus decreasing the overall environmental impact of the material. In this work, coupling LEDs with a trithiocarbonate allowed for the synthesis of many different polymers and topologies. Bottlebrush polymers synthesized with light afforded molar masses in excess of 11 million Da without the oligomerization of the bottlebrush polymers. These bottlebrush polymers were then used to make reversibly crosslinkable adhesives, allowing for a new example of recyclable adhesives. The second half of the dissertation focuses on developing sustainable polymers using ring-opening metathesis polymerization (ROMP) to combine the properties of polyolefins with renewable polymers. First, polyketones synthesized by ROMP were developed for their potential use as photodegradable polymers. This initial study probed the synthesis of different polyketone monomers and the properties of their respective polymers. Next, a photodegradable and biodegradable thermoplastic elastomer (TPE) was synthesized that incorporated a ketone containing polybutadiene (PB) flanked by polylactide (PLA). The thermomechanical properties were controlled based on the relative length of each block while the rate of photodegradation was controlled by the mol% of ketone incorporated into the PB block. Finally, ABA triblock copolymers of cellulose derivatives and polyolefins were developed for their uses as compatibilizers for blends. With the addition of as little as 1 wt% of the ABA triblock copolymer, the respective blends showed large imp / PHD

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Food Technology in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / The aim of this study was to evaluate bambara groundnut [BGN] non-starch polysaccharides [NSP] subject to the incorporation into model and food systems with a view to establish their functional and physicochemical properties. BGN insoluble dietary fibre [BGNIF] and soluble dietary fibre [BGNSF] were successfully extracted from four varieties (black-eye: BLE, red: RED, brown: BRN and brown-eye: BRE). Physicochemical properties evaluated revealed the high bulk density of all BGNIF and BGNSF varieties, which could contribute to cost-effective packaging. The microstructures of BGNIFs were irregular in shape with different sizes. The colour parameters (lightness, redness, yellowness, chroma and hue angle) differed significantly [p ≤ 0.05] across all BGNIF and BGNSF varieties; and indicated a yellowish-red colour for BGNIFs and a light yellow colour for BGNSFs. Negligible amounts of condensed tannins [CT] were found in BGNIFs (0.014 – 0.160 mg.g-1). Higher amounts polyphenols [PP] were present in BGNSFs (45.42 – 55.90 mg.g-1 gallic acid equivalents [GAE]) compared to the amount PP in BGNIFs (6.14 – 15.56 mg.g-1 GAE). Major sugars identified were arabinose/galactose, xylose and mannose in BGNIFs, and xylose and mannose in BGNSFs. The functional properties evaluated revealed high swelling capacity of BGNIFs (6.37 – 7.72 ml.g-1) and no significant [p > 0.05] difference in water retention capacity. Fat absorption capacity ranged from 1.38 – 1.52 g oil.g-1 dry weight for BGNIFs and 4.04 – 4.55 g oil.g-1 dry weight for BGNSFs. Variability in BGNIF (91.2%) and BGNSF (79.4%) physicochemical and functional properties could both be explained by two principal components (BGNIF component 1: PP, redness, yield; and component 2: xylose, yellowness and chroma; BGNSF component 1: yellowness, chroma, mannose content; and component 2: redness, fat absorption and fructose content). Following an IV optimal mixture design, an optimum white bread formulation was obtained using 59.5% water, 4.3% yeast and 8.5% BGNIF. Bread enriched with the four BGNIF varieties (BLE, RED, BRN and BRE) were tested for several physicochemical properties. Significant [p ≤ 0.05] differences existed between the control and BGNIF enriched loaves for crumb grain characteristics (including pore area distribution, feret angle, circularity, roundness and aspect ratio). Specific loaf volume of BGNIF enriched loaves ranged from 3.33 – 3.85 ml.g-1 and were significantly [p ≤ 0.05] lower compared to the control bread (4.16 ml.g-1). Favourable texture characteristics obtained with the BGNIF enriched breads were lower hardness, chewiness and gumminess compared to the control loaf. Crust and crumb colour parameters (lightness, redness, yellowness, chroma and hue angle) were significantly [p ≤ 0.05] different across all loaves. BRE BGNIF bread (3.43 ± 0.20) had the significantly [p ≤ 0.05] lowest crumb colour difference compared to the control bread; whilst BRN (1.72 ± 0.42) and BRE (2.44 ± 0.78) loaves had the lowest significant [p ≤ 0.05] crust colour difference compared to the control. Favourable chemical properties were the high total dietary fibre [TDF] (7.14 – 8.33%) content of all BGNIF enriched loaves compared to the control loaf (4.96%). Significant [p ≤ 0.05] differences were also observed for some loaves for moisture content, condensed tannins and polyphenol content. Variability in bread physicochemical properties was differentiated by three components (component 1: bread textural properties; component 2: specific loaf volume and bread lightness; component 3: crumb colour parameters) which accounted for a cumulative variation of 92.8%. All bread loaves were also sensorially acceptable as rated moderately like to like very much (>3 rating on a 5-point hedonic scale) by consumers for all parameters (appearance, crust and crumb colour, aroma, taste, texture and overall acceptability) evaluated. Furthermore, brown BGNSF was tested for stabilising effects in an orange beverage emulsion. BGNSF and orange oil were varied at two levels each based on a 22 augmented factorial design and the effects determined on the equilibrium backscattering [BS] flux as emulsion stability indicator. The BS profiles which resulted from the Turbiscan stability analysis revealed flocculation at low rates as the major destabilisation mechanism. The optimal formulation producing a stable emulsion was identified as low oil (6%) and high BGNSF (30%) concentrations. The objective of this study was therefore achieved and showed that positive physicochemical and functional properties are associated with BGNIF and BGNSF from black-eye, red, brown and brown-eye varieties. Furthermore, the incorporation of BGN fibres in white bread and a beverage emulsion was shown to contribute positive technological properties in these systems.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A incorporaÃÃo de compostos nutracÃuticos como vitaminas, probiÃticos, peptÃdeos bioativos e antioxidantes em sistemas alimentÃcios proporciona uma maneira simples de desenvolver novos alimentos funcionais que podem ter benefÃcios fisiolÃgicos ou reduzir os riscos de doenÃas. Pectinas tÃm sido investigadas por sua capacidade de produzir esferas de gÃis de pectinato de cÃlcio contendo bioativos. Quitosana tambÃm tem sido muito utilizada na preparaÃÃo de esferas por suas propriedades mucoadesivas. Neste estudo, trÃs tipos de esferas de pectina/cÃlcio/quitosana com diferentes graus de reacetilaÃÃo foram produzidas no intuito de encapsular um potente antioxidante natural extraÃdo da manga, a mangiferina. Inicialmente, duas amostras de pectina cÃtrica foram caracterizadas por FTIR, 1H RMN, Reologia e GPC. A pectina cÃtrica com menor grau de metoxilaÃÃo foi escolhida para a preparaÃÃo das esferas por apresentar melhores propriedades geleificantes. As esferas produzidas foram caracterizadas por FTIR, MEV e intumescimento. A formaÃÃo do complexo pectina/cÃlcio/quitosana reacetilada foi observada por FTIR e MEV. Foi realizado um estudo de liberaÃÃo controlada de mangiferina a partir de trÃs tipos de esferas obtidas por duas metodologias diferentes. Os valores de percentual de liberaÃÃo foram bastante significativos, chegando atà 75%. O comportamento dos mecanismos de liberaÃÃo de mangiferina das esferas de pectina/cÃlcio/quitosana mostrou que o bioativo foi liberado a partir da matriz principalmente por meio de relaxaÃÃo das cadeias polimÃricas. / Incorporation of nutraceuticals compounds such as vitamins, probiotics, bioactive peptides and antioxidants in food systems provides a simple way to develop new functional foods that can have physiological benefits or reduce risks of disease. Pectins have been investigated for their ability to produce spheres of calcium pectinate gels containing bioactive. Chitosan has also been widely used in the preparation of beads due to its mucoadhesive properties. In this study, three types of spheres of pectin/calcium/chitosan with different degrees of reacetylation were produced in order to encapsulate a powerful natural antioxidant extracted from mango, mangiferin. Initially, two samples of citrus pectin were characterized by FTIR, 1H NMR, Rheology and GPC. The citrus pectin with the lowest degree of methoxylation was chosen for the preparation of beads due to its better gelling properties. The beads produced were characterized by FTIR, SEM and swelling. The formation of the reacetylated complex pectin/calcium/chitosan was observed by FTIR and SEM. A study of controlled release of mangiferin was conducted from three types of beads obtained by two different methodologies. The values of percentage of release were quite significant, reaching up to 75%. The mechanisms behaviour for the release of mangiferin from spheres of pectin/calcium/chitosan showed that the bioactive was released from the matrix mainly through relaxation of the polymer chains.

1,3-β-glucans are a class of natural polysaccharides with unique pharmacological properties and the ability to form triple helical structures and resilient gels. Curdlan and other 1,3-β-glucans have found application pharmacologically in the treatment of cancers and acceleration of wound healing in humans and in the impartation of infection resistance in animal husbandry. Structurally, these polysaccharides have found application in food science as thermal gels, in nanostructure formation as helical scaffolds, and in drug delivery as nanocarriers for drugs and as inclusion complexes with polynucleotides. A literature review of the important work on Curdlan research reveals two streams of research: investigation of the pharmacological significance of these polymers and their application in increasing host immunocompetency and investigation of the nature of the triple helix and its application in a variety of fields from food gels to drug delivery. Two significant contributions to the field of Curdlan research have been completed including 1) The development of a Curdlan nanoparticle drug delivery platform and 2) A new multi-component liquid crystalline hydrogel providing a new route to form polynucleotide inclusion complexes with Curdlan for gene delivery. The developed nanoparticle platform exhibited high encapsulation of chemotherapeutic drugs and a 24-hour controlled release with a particle size of 109.9 nm. The liquid crystalline hydrogel exhibited homogeneous inclusion of DNA into amorphous and crystalline phases of Curdlan and delayed and triggered release of polynucleotide content. This work has been a significant demonstration of the potential of Curdlan as a new polymer for multi-functional drug delivery.

Univ., Diss.--Regensburg, 1985.