This thesis examines droplets striking water repelling surfaces as well as the movement of a soil based bacteria under various light and heat conditions. Droplet impact studies have shown that introducing a macroscopic feature to a water repelling surface can reduce the amount of time that droplet is in contact with the surface. By manipulating water droplets to impact different sized needles at varying speeds, we present how a needle can induce a similar reduction in the residence time of the droplet to more widely studied features. Results show the spreading and lift-off characteristics of the droplet are dependent on the impact speed as well as the size of macroscopic feature. A separate topic examines environmental motivators for mobility in a terrestrial cyanobacteria species called Microcoleus vaginatus. This cyanobacteria is indigenous to cold deserts, such as the Colorado Plateau or Mojave Desert in North America, and is essential to the health and preservation of the biological soil crust. These bacteria are the first organisms to grow in new soil, secreting a carbohydrate that acts as soil glue, thereby increasing soil adhesion. It has been shown that these bacteria will rise to the surface of the soil from their subsurface homes after rainfall, but it is unclear how they are able to make this journey. It is also unclear if other factors, such as nutrient levels or heat and light, affect their movement. Here we present an investigation of M. vaginatus’ response to light and heat in order to determine if these basic stimuli affect movement, thereby informing future restorative models.

A research Report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science, 2018 / Cyanobacteria cells enter water treatment plants from the raw water abstracted from surface water destined to supply the water treatment plants. The presence of cells might interfere with purification processes such as coagulation and flocculation and may subsequently result in the release of taste and odourous compounds. This study is aimed at determining the efficiency of a Recovered Wash Water Plant (RWWP), in removing cyanobacteria cells and associated organic compounds at three stages of treatment, namely raw water, after sedimentation and after filtration. Concentration outcomes were statistically analysed to determine removal ability of the RWWP. The cyanobacteria genera Microcystis, Anabaena and Oscillatoria were detected in the three sampling points (raw water, after sedimentation and after filtration) selected. The organic compounds detected included geosmin, 2-methylisoborneol (2-MIB), and a cyanotoxin, microcystin. It is recommended that the effectiveness of the RWWP should be investigated seasonally during further research / MT 2020

No description available.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 200-219).

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.

Master of Science / Department of Biological & Agricultural Engineering / Philip L. Barnes / Bloom-forming cyanobacteria are harmful to both environment and public health because of the release of water soluble toxins. This report provides a broad overview of cyanobacteria and cyanotoxins and the current state of knowledge about the bloom control management. Cyanobacteria blooms usually flourish in warm, lentic, and eutrophic waters. Several environmental factors such as temperature, nutrients, light intensity, and turbulence can affect cyanobacterial growth and the formation of bloom. Cyanobacteria can synthesize multiple types of toxins, which cause human and animal toxications worldwide. Cyanobacterial blooms also cause detrimental effects on aquatic ecosystems, and the taste and odor problems in drinking water supplies. Due to the adverse effects, treatments that are used for removing both cyanobacterial cells and aqueous cyanotoxins should be carried out once cyanobacterial blooms occur in freshwaters. Strategies based on physical, chemical, and biological methods are carried out to remove the cyanobacteria and cyanotoxins. All of these strategies have both advantages and disadvantages: some physical treatment methods can remove cyanotoxins within the intact molecules, but the cost is usually high and further processing is needed; some chemical methods are cheap and can degrade the cyanotoxins, however, the toxicological characterization of the chemical and the by-products needs to be investigated; some biological treatments are more environmentally friendly, but the long reaction time and some other external factors also pose some problems that affect the efficiency of the treatments. The paper concludes that the key to success is to find a reasonable balance between those advantages and disadvantages, and the specific conditions of each unique aquatic ecosystem should be taken into consideration. As well, some suggestions are also proposed for the further development of more robust monitoring and management strategies.

The filamentous cyanobacteria Nostoc punctiforme ATCC 29133 is a model species fordevelopment of sustainable production methods of numerous compounds. One of its uniquefeatures is the anaerobic environment of the strains nitrogen fixing heterocyst cells. To be ableto properly utilize this environment, more knowledge regarding what regulates cell specificexpression is required. In this study, three motifs of the NsiR I promoter of Anabaena sp.PCC 7120 was studied in this system utilizing YFP-fluorescence as a reporter to determinetheir impact on spatial expression pattern. Investigations were performed on immobilizedcells with the use of confocal microscopy and results point towards sigma factor regulation.

published_or_final_version / abstract / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

No description available.

In the Paris Agreement from 2015, nations agreed to limit the effects of global warming to well below 2°C. To be able to reach those goals, cheap, abundant and carbon neutral energy alternatives needs to be developed. The microorganisms that several billion years ago oxygenated the atmosphere; cyanobacteria, might hold the key for creating those energy technologies. Due to their capacity for photosynthesis, metabolic engineering of cyanobacteria can reroute the carbon dioxide they fix from the atmosphere into valuable products, thereby converting them into solar powered cell factories. Of the many products bacteria can be engineered to make, the production of terpenoids has gained increasing attention for their attractive properties as fuels, pharmaceuticals, fragrances and food additives. In this thesis, I detail the work I have done on engineering the unicellular cyanobacterium Synechocystis sp. PCC 6803 for terpenoid production. By deleting an enzyme that converts squalene into hopanoids, we could create a strain that accumulates squalene, a molecule with uses as a fuel or chemical feedstock. In another study, we integrated two terpene synthases from the traditional medical plant Coleus forskohlii, into the genome of Synechocystis. Expression of those genes led to the formation of manoyl oxide, a precursor to the pharmaceutically active compound forskolin. Production of manoyl oxide in Synechocystis was further enhanced by engineering in two additional genes from C. forskohlii that boosted the flux to the product. To learn how to increase the production of squalene, manoyl oxide or any other terpenoid, we conducted a detailed investigation of each step in the MEP biosynthesis pathway, which creates the two common building blocks for all terpenoids. Each enzymatic step in the pathway was overexpressed, and increased flux was assayed by using isoprene as a reporter and several potential targets for overexpression were identified. The final part of this thesis details the characterization of native, inducible promoters and ribosomal binding sites in Synechocystis.