Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1989. / Includes bibliographical references (leaves 159-172) / Microfiche. / xvii, 172 leaves, bound ill. 29 cm

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 66-68). / viii, 68 leaves, bound ill. 29 cm

Submitted in fulfilment of the requirements of the degree of Master of Technology: Biotechnology, Durban University of Technology, 2014. / Cyanobacteria contain phycocyanin a light harvesting pigment found to have numerous biotechnological applications, such as: a natural colorant in food and cosmetics, fluorescent tags employed in clinical and immunological research and also in therapeutic processes. Successful phycocyanin production depends on growth characteristics, ability to accumulate high quantities of the pigment, and an effective downstream process. Therefore, the aim of this research was to optimize the extraction method and production by determining the optimal cultivation conditions for phycocyanin producing cyanobacterium. This cyanobacterium was isolated from a hypersaline water body in Kwa-Zulu Natal, and subsequently purified using traditional streak and spread plate techniques. Different cell disruption techniques and a range of buffers were evaluated for the extraction of phycocyanin. The buffer concentrations and pH was subsequently optimized. Results showed that maximum phycocyanin was extracted when cells were suspended in 50mM sodium phosphate buffer (pH-7.5) supplemented with 10 % lysozyme and then disrupted using the freeze–thaw method at -20 & 4°C. The UV-Vis absorption spectral scan of the crude extracted pigments showed a peak at 620 nm. This corresponds to phycocyanin production. Unwanted proteins were removed using a 25and 50% saturated ammonium sulphate precipitation, followed by dialysis. SDS-PAGE showed two subunits with molecular masses of 19 and 20 kDa. These masses corresponded to phycocyanin α and β subunits. Furthermore, a food grade purity ratio (A615/A280) of 1.20 was achieved. The effects of various abiotic factors (temperature, light and pH) on growth and phycocyanin production of the Cyanothece sp. was investigated. Temperature ranging from 20-45°C and pH (5-10) was evaluated for 2 weeks. Cultures were then subjected to four photoperiods (24:0, 18:06 12:12 and 8:16 h light: dark) three light intensities (25, 75 and 125 µmol photons per m2 per –s) at varying wavelengths i.e. blue, red and green and Grolux light. Ideal conditions were observed at 35°C, 125 µmol photons.m2.s-1 of Grolux light for a 16:8 light and dark photoperiod. It was observed that the highest biomass and phycocyanin production was found to be at 35°C, temperatures below or above resulted in a decrease in both growth and pigment synthesis. Phycocyanin concentration changed in response to light quality and intensity. A significantly higher (p<0.05) phycocyanin yield was found when the culture was exposed to 125 µmol photons.m2.s-1 of Grolux light compared with the other three light conditions. Using Design of experiments, a series of fractional factorial experiments were carried out to optimize media components for pigment production. The final optimized growth medium was determined from a central composite design using response surface plots together with a mathematical point-prediction tool and consisted of 2g/L NaNO3, 0.06g/L K2HPO4, 0.12 g/L MgSO4.7H2O, 0.033 g/L CaCl2.2H2O, 100g/L NaCl, 12mL minor nutrients and 0.5 trace metal. A 72 % increase in phycocyanin was observed. This research revealed that this particular Cyanothece sp. shows great potential as a reliable source of phycocyanin.

Graduation date: 2001

Coibamide A is a methyl-stabilized cyclic depsipeptide with a lariat side chain that was isolated from a marine cyanobacterium as part of an International Cooperative Biodiversity Groups program based in Panama. Previous testing of this potent and selective growth-inhibitory agent in the National Cancer Institute (NCI) in vitro 60 human cell line panel revealed a "COMPARE-negative" profile indicative of a unique mechanism of action. Presented herein is a collection of studies characterizing the mechanism of action of coibamide A and cataloguing the cytotoxicities of putative coibamide A and related structures from efforts at its total synthesis. We report that coibamide A induces apoptotic and non-apoptotic cell death in human U87-MG and NCI-SF-295 glioblastoma cells, respectively, which can occur independently of a rapid and sustained mTOR-independent autophagic response. Loss of cell viability from coibamide A exposure was concentration-dependent and time-sensitive, characterized by extensive cytoplasmic vacuolization and an absence of apoptotic morphology and DNA fragmentation prior to cell rounding and detachment from the substratum. Coibamide A also induces a cytostatic effect mediated by a G1 phase specific cell cycle arrest and inhibits glioma cell invasion but not migration. Lastly, structure activity relationships suggest that linearization, loss of N-methylation and disjoining of the cyclic and side chain structures of coibamide A are not well-tolerated modifications to retain activity. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Jan. 8, 2013 - Jan. 8, 2014

Some cyanobacteria strains have biofertilization and bioconditioning effects in soils. The objective of this study was to identify cyanobacteria with potential to improve the N fertility and structural stability of degraded soils and evaluate their effectiveness in soils of the Eastern Cape, South Africa. Isolation and characterization of the indigenous cyanobacteria strains with desirable properties was first to be undertaken because their effects are known to differ from strain to strain. Cyanobacteria strains 3g, 3v, and 7e were identified from 97 strains isolated from selected soils. Nostoc strains 3g and 3v had greater ability to produce exocellular polysaccharides (EPS) but low potential to fix atmospheric N2 (4.7 and 1.3 nmol C2H4 μg chl-1 h-1, respectively). On the other hand, strain 7e had the highest capability to fix atmospheric N2 (16.1 nmol C2H4 μg chl-1 h-1) but had the least ability to produce EPS. Evaluation of the strains was done in glasshouse studies starting with Nostoc strain 9v isolated from a Tanzanian soil, followed by the indigenous strains isolated from soils in Hertzog and Qunu, South Africa. Inoculation was done by uniformly applying cyanobacteria on the surface of potted soils at a rate of 6 g m-2. First harvest and soil sampling took place after six weeks, and the top 25 mm of the soil was mixed, replanted, and sampled again after a further six weeks (second harvest). Inoculation with Nostoc strain 9v increased soil N by 40 percent and 17 percent in Guquka and Hertzog soils, respectively, and consequently increased maize dry matter yields by 40 and 49 percent. Soil C increased by 27 percent and 8 percent in Guquka and Hertzog soils, respectively, and this increase was significantly associated with that of soil N (R2 = 0.838). Higher contents of soil C, soil N and mineral N, however, were found in non-cropped soils. Scanning Electron Microscopy (SEM) revealed coatings of EPS on soil particles and fragments of non-cropped inoculated soils, with iii other particles enmeshed in networks of filaments, in contrast to cropped and/or non-inoculated soils. The proportion of very stable aggregates was increased by inoculation but cropping with maize reduced the aggregate stability. Inoculating Hertzog soil with indigenous strains 3g and 7e increased the nitrate N in the first cropping by 49 percent and 69 percent respectively, in cropped soils. In the second cropping increases in mineral N were 41 percent and 43 percent in 3g and 7e inoculated soils, respectively. Maize dry matter yields were higher on inoculated soils both in the first and second harvest in response to the improved N status of the soil. Increases in aggregate MWD in cropped soil as determined by fast wetting, mechanical breakdown and slow wetting were 85 percent, 33 percent, 33 percent, respectively, for 3g inoculation, 64 percent, 41 percent, and 41 percent, respectively, for 7e inoculation and 60 percent, 24 percent, 50 percent for inoculation with 9v. In non-cropped soil, increases in MWD as determined by fast wetting, mechanical breakdown and slow wetting were 11 percent, 0 percent, 7 percent, respectively for 3g inoculation, 21 percent, 11 percent, and 7 percent, respectively for 7e inoculation, and 25 percent, 36 percent, and 19 percent for strain 9v inoculation. Scanning electron microscopy observations, which were confirmed by chemical results, revealed that inoculated soils had high EPS and filaments that encouraged soil aggregation and improved aggregate stability. Results of this study show that cyanobacteria strains isolated and selected for their ability to fix atmospheric N2 and produce EPS improved the fertility status and aggregate stability of degraded soils from South Africa.