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No description available.

The biology of the sub-aquatic lichen, Dermatocarpon luridum, was investigated. This lichen is sparsely distributed within the temperate climatic zones around the world, colonizing rock along watercourses that regularly experience water level fluctuations. Specimens collected from Canada and Austria were cultured using standard growth media. Brightfield microscopy was used for algal species identification, while fungal ITS, algal ITS and algal actin gene sequences were used for phylogenetic and population genetic evaluation. Results were: 1) axenic cultures of the photobiont were successful, while those of the mycobiont were not successful; 2) Diplosphaera chodatii is the photobiont associated with D. luridum var. luridum and allies, suggesting algal sharing between mycobiont species; 3) genetic diversity is high, and gene flow was high within local populations, but low between continental populations. Diplosphaera chodatii may be a keystone species contributing to the survival of D. luridum var. luridum along with other sub-aquatic, aquatic and terrestrial lichens.

The biology of the sub-aquatic lichen, Dermatocarpon luridum, was investigated. This lichen is sparsely distributed within the temperate climatic zones around the world, colonizing rock along watercourses that regularly experience water level fluctuations. Specimens collected from Canada and Austria were cultured using standard growth media. Brightfield microscopy was used for algal species identification, while fungal ITS, algal ITS and algal actin gene sequences were used for phylogenetic and population genetic evaluation. Results were: 1) axenic cultures of the photobiont were successful, while those of the mycobiont were not successful; 2) Diplosphaera chodatii is the photobiont associated with D. luridum var. luridum and allies, suggesting algal sharing between mycobiont species; 3) genetic diversity is high, and gene flow was high within local populations, but low between continental populations. Diplosphaera chodatii may be a keystone species contributing to the survival of D. luridum var. luridum along with other sub-aquatic, aquatic and terrestrial lichens.

The study of organisms from extreme environments is an emerging field of research with applications to multiple scientific areas. One of these extreme environments is Great Salt Lake (GSL), whose microbiology has yet to be extensively studied. This dynamic and unique environment offers an excellent opportunity to increase understanding of hypersaline ecology. Cultivation of microorganisms remains an important part of ecology research, as it is essential for understanding microbial physiology. We report here the culturing and characterization of isolates from Rozel Point, located on the northeastern shore of Great Salt Lake. This site was chosen because of the presence of petroleum seeps at Rozel Point and the extreme salinity of the North Arm of GSL. We hypothesize that culturing at GSL will reveal a diverse prokaryotic population, with both commonly isolated and novel organisms. We would predict that prokaryotes at GSL will share many features in common with other hypersaline microbial communities, but that given the distinctive properties of the site, there will be unique characteristics as well. Samples were taken from Rozel Point and cultured using direct plating, enrichment cultures, and dilution cultures with a variety of minimal and complex halophilic media. Fluorescence in situ hybridization (FISH) was used to examine abundance of cultured organisms in the environment. Culturing and characterization has revealed both isolates novel and previously uncultured, with many unique characteristics. FISH demonstrated that, unlike most environments, in GSL the dominant species are culturable. These results show the value of culturing in discovering new organisms and demonstrating diversity at the microbial level. Culturing of these organisms will allow for further research to be done on microbial processes that occur in this system and the unique properties of halophilic microbes.

This project examined the role of functional diversity of bacterial prey organisms on a mixotrophic flagellate’s function. The concept of functional diversity and its role for ecosystem functioning is a subject of ongoing research and controversially discussed. Mixotrophy is the combination of different modes of nutrition in one organism. In the case of this project’s organism, Ochromonas tuberculata, the combination of phototrophy and heterotrophy or phagotrophy. Mixotrophs can have a severe impact on nutrient cycling or carbon fixation in aquatic ecosystems, therefore it is important to investigate what drives their ecological functioning. For this project, two sets of bacterial prey traits were investigated and their effect on the flagellate’s growth rate. The first experiments involved the addition of heat-killed bacterial prey with heterotrophic mode of nutrition (Escherichia coli) and phototrophic mode of nutrition (Synechocystis sp.) on their own and in conjunction to generate a functional diversity. The last experiment investigated heat-killed Gram-negative (Escherichia coli) and Gram-positive bacterial prey (Staphylococcus aureus and Bacillus subtilis) each on their own and in conjunction. The acclimated O. tuberculata cultures in this project were non-axenic and flagellate cell densities were recorded daily over five days after the addition of the prey in each experiment. The results showed that prey with a phototrophic mode of nutrition resulted in a significantly higher growth rate over the course of the experiments than heterotrophic prey or a mix of both under the experimental conditions. For the second set of bacterial functions tested, the results showed no clear effect of the different bacterial functions on the flagellate’s growth rate. This was attributed to the heat-killing method used. The heat-killing method is assumed to have harmed the bacteria structurally and therefore negate the effect of the differences in cell wall properties. Therefore, this question could not be fully investigated. Overall, the experimental setup was not ideal to tackle the research question, nevertheless the results can provide ideas for possible improvements of the experimental setup.

Doctor of Philosophy / Department of Chemistry / Christopher T. Culbertson / Microfluidic devices have a wide variety of biological applications. My Ph.D. dissertation focuses on three major projects. A) culturing a non-adherent immortal cell line within a microfluidic device under static and dynamic media flow conditions; B) designing and fabricating novel microfluidic devices for electrokinetic injecting analytes from a hydrodynamic fluid; and C) using this novel injection method to lyse single non-adherent cells by applying a high electric field across the cell at a microfluidic channel intersection. There are several potential advantages to the use of microfluidic devices for the analysis of single cells: First, cells can be handled with care and precision while being transported in the microfluidic channels. Second, cell culturing, handling, and analysis can be integrated together in a single, compact microfluidic device. Third, cell culturing and analysis in microfluidic devices uses only extremely small volumes of culturing media and analysis buffer. In this dissertation a non-adherent immortal cell line was studied under static media flow conditions inside a CO[subscript]2 incubator and under dynamic media flow conditions in a novel portable cell culture chamber. To culture cells they must first be trapped on a microfluidic device. To attempt to successfully trap cells, three different types of cellular traps were designed, fabricated and tested in polydimethylsiloxane (PDMS)-based microfluidic devices. In the first generation device, cubic-shaped traps were used. After 48 h of culturing in these devices the cell viability of 79 [plus or minus] 6 % (n = 3). In the second generation device, circular wells with narrow connecting channels were employed. However, after 12 h of culturing, no viable cells were found. While the second generation device was not capable of successfully culturing cells, it did demonstrate the importance of culturing under dynamic conditions which lead to next design. The third generation microfluidic device consisted of hydrodynamic shaped traps that were used to culture the cells in a less confined environment. The cell viability after 12 h in this design was 29 [plus or minus] 41% (n = 3). In addition to cell trapping, a novel electrokinetic injection method was developed for injecting analytes from a hydrodynamic flow into a separation channel that was followed by an electrokinetic separation. As the hydrodynamic flow could introduce some excess band broadening in the separation, the actual band broadening of an analyte was measured for different channel depths and hydrodynamic fluid flow rates. The results consistently showed that the separations performed on these devices were diffusion limited. Finally, using this novel injection method, single cell lysis was performed by applying a high voltage at the microfluidic channel intersection. The results of these studies may eventually be applied to help answer some fundamental questions in the areas of biochemistry and pharmaceutical science.

Robust Vallisneria americana was cultured for restoration purposes. Preliminary studies, with various iron treatments, were conducted to ascertain the amount of phosphorous release into the water column from sediments. There was a significant difference in the amount of phosphorous released if commercial sediment was used with a low iron amendment or without an iron amendment. The second study consisted of planting V. americana on two different sediment types while supplying half of the plants with additional CO2. Plants grown on pond sediment with additional CO2 had significantly more biomass. In the third study all plants were grown on pond sediment, and half were treated with CO2. All plants that were treated with additional CO2 had significantly more biomass than those that were aerated.