Crude glycerol is the major byproduct of the biodiesel industry. In general, for every 100 pounds of biodiesel produced, approximately 10 pounds of crude glycerol are created. Because this glycerol is expensive to purify for use in food, pharmaceutical, or cosmetics industries, biodiesel producers must seek alternative methods for its disposal. Using crude glycerol as a carbon source for fermentation is a promising alternative use for this waste material. In this project, we propose to use crude glycerol in the fermentation of the microalga Schizochytrium limacinum, which is a prolific producer of docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid with proven beneficial effects on treating human diseases such as cardiovascular diseases, cancers, and Alzheimer's. The first part of this study provided "proof-of-concept" that Schizochytrium limacinum was capable of utilizing crude glycerol while producing DHA. The results show that pretreated crude glycerol was a viable carbon source for algal growth and DHA production, with 75 g/L to 100 g/L of glycerol being the optimum concentration range. In addition to glycerol concentration, temperature, trace metal levels, ammonium acetate concentration, and NH4Cl concentration also had significant effects (P < 0.1) on algal DHA production. Optimizing these factors using response surface methodology led to a DHA yield of 4.91 g/L and a DHA productivity of 0.82 g/L-day. The second part of this study investigated the effects of impurities within the glycerol on DHA production and algal biomass composition, with a goal of ensuring that the algal biomass produced from crude glycerol can be safely utilized as an ingredient in omega-3 fortified foods or animal feed additives. Crude glycerol samples obtained from different biodiesel producers were tested. All the samples contained methanol, soaps, and various elements including calcium, phosphorus, potassium, silicon, sodium, and zinc. Both methanol and soaps in the glycerol negatively influence algal DHA production. The two impurities can be removed from the culture medium by evaporation through autoclaving (for methanol) or by precipitation through pH adjustment (for soap). The results showed that the crude glycerol-derived algal biomass contained 45-50% lipid, 14-20% protein, and 25% carbohydrate, with 8-13% ash content. Palmitic acid (C16:0) and DHA (C22:6) were the two major fatty acids in the algal lipid. ICP analysis showed that that boron, calcium, copper, iron, magnesium, phosphorus, potassium, silicon, sodium, and sulfur were present in the algal biomass, but no heavy metals (such as mercury) were detected. The crude glycerol-derived algal biomass had a high level of DHA and a nutritional profile similar to glucose-derived commercial algal biomass, suggesting a great potential for using crude-glycerol derived algae in omega-3 fortified food or feed. Overall, this study shows that crude glycerol can be used as a safe and effective substrate for algal culture to produce high levels of omega-3 fatty acids. With the rapid expansion of the biodiesel industry, there is an urgent need to develop new markets for large quantities of crude glycerol. This research provides an exciting opportunity to utilize a large quantity of this low grade glycerol. / Master of Science

<p>Rapid growth of energy consumption and greenhouse gas emissions from fossil fuels have promoted extensive research on biofuels. <a>Algal biofuels have been considered as a promising and environmentally friendly renewable energy source</a>. However, several limitations have inhibited the development of cost-effective biofuel production, which includes unstable cultivation caused by invading organisms and high cost of lipid extraction. This dissertation aims to investigate photochemical approaches to prevent culture collapse caused by invading organisms and biological approaches for the development of cost-effective lipid extraction methods.</p><p> </p><p>As a chemical-free water treatment technology, ultraviolet (UV) irradiation has been widely applied to inactivate pathogens but has not been used in algal cultivation to control invading organisms. To evaluate the potential of using UV irradiation to control invading algal species and minimize virus predation, <i>Tetraselmis sp. </i>and <i>Paramecium bursaria Chlorella virus 1</i> (PBCV-1) were examined as challenge organisms to evaluate effectiveness of UV disinfection. The concentration of viable (reproductively/infectively active) cells and viruses were quantified by a most probable number (MPN) assay and a plaque assay. A low-pressure collimated-beam reactor was used to investigate UV₂₅₄ dose-response behavior of both challenge organisms. A medium-pressure collimated-beam reactor equipped with a series of narrow bandpass optical filters was used to investigate the action spectra of both challenge organisms. Both challenge organisms showed roughly five log₁₀ units of inactivation for UV₂₅₄ doses over 120 mJ/cm². the most effective wavelengths for inactivation of <i>Tetraselmis</i> were from 254 nm to 280 nm, in which the inactivation was mainly attributed to UV-induced DNA damage. On the contrary, the most effective wavelength for inactivation of PBCV-1 was observed at 214 nm, where the loss of infectivity was mainly attributed to protein damage. These results provide important information for design of UV reactors to minimize the impact of invading organisms in algal cultivation systems.</p><p> </p><p>Additionally, a virus-assisted cell disruption method was developed for cost-effective lipid extraction from algal biomass. Detailed mechanistic studies were conducted to evaluate infection behavior of <i>Chlorovirus </i>PBCV-1 on <i>Chlorella sp.</i>, impact of infection on mechanical strength of algal cell wall, lipid yield, and lipid distribution. Viral disruption with multiplicity of infection (MOI) of 10^-8 completely disrupted concentrated algal biomass in six days. Viral disruption significantly reduced the mechanical strength of algal cells for lipid extraction. Lipid yield with viral disruption increased more than three times compared with no disruption control and was similar to that of ultrasonic disruption. Moreover, lipid composition analysis showed that the quality of extracted lipids was not affected by viral infection. The results showed that viral infection is a cost-effective process for lipid extraction from algal cells as extensive energy input and chemicals required by existing disruption methods are no longer needed.</p><p> </p><p>Overall, this dissertation provides innovative approaches for the development of cost-efficient algal biofuels. Application of UV disinfection and viral disruption significantly reduces chemical consumption and improves sustainability of algal biofuel production.<br></p>

A utilização descontrolada de pesticidas tem provocado no decorrer dos anos a intoxicação de milhares de pessoas no mundo, uma vez que, seus resíduos têm sido depositados em alimentos, em solos e em ambientes aquáticos. Assim, a construção de duas novas plataformas sensoras para a detecção de pesticidas é o objetivo desse trabalho. Na primeira plataforma foi utilizado o polieletrólito catiônico polietilenoimina (PEI) em conjunto com o polissacarídeo extracelular algal (PSE) produzido pela microalga criptofícea Cryptomonas tetrapirenoidosa preparados através da técnica de deposição \"spin-coating\". E a segunda plataforma foi produzida por eletrodeposição pulsada, entre um potencial de redução e um de oxidação, utilizando nanoestruturas de óxido de zinco (ZnO). Para caracterizar as plataformas, foram utilizadas as técnicas de microscopia eletrônica de varredura com fonte de emissão de campo (FEG-SEM), difração de raios X (XRD), espectroscopia de absorção ultravioleta-visível (UV-Vis), microscopia de força atômica (AFM) e espectroscopia de reflexão-absorção no Infravermelho com modulação da polarização (PM-IRRAS). Através da imobilização da enzima polifenol oxidase na forma de extrato bruto em sua fonte natural (fruto abacate), as plataformas de PEI/PSE e ZnO, foram avaliadas como biossensores de catecol e do inseticida carbaril. De modo comparativo, as plataformas de PEI/PSE sem a presença imobilizada da enzima também foram estudadas para a detecção do catecol e do carbaril. A simplicidade na formação e na construção dessas plataformas vem qualificá-las como viáveis a serem produzidas em escala industrial e com baixo custo de processamento. E diante dos resultados obtidos no desenvolvimento desses biossensores destaca-se a eficiência e a rapidez de detecção, o que os tornam economicamente promissores e competitivos em termos de aplicações ambientais. / The uncontrolled use of pesticides has resulted over the years the intoxication of thousands of people in the world, since their waste has been deposited in food, in soil and aquatic environments. Thus, the construction of two new sensors platforms for pesticide detection is the objective of this work. At first platform was used cationic polyelectrolyte polyethyleneimine (PEI) along with the extracellular algal polysaccharide (EPS) produced by microalgae criptofícea Cryptomonas tetrapirenoidosa prepared by deposition technique \"spin-coating\". The second platform was produced by pulsed electrodeposition between a reduction and an oxidation potential using nanostructures zinc oxide (ZnO). To characterize the platforms, we used the techniques of field emission gun scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), ultraviolet visible absorption spectroscopy (UV-Vis), atomic force microscopy (AFM), and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). By immobilization of the polyphenol oxidase enzyme as a crude extract in their natural source (avocado fruit), platforms PEI/PSE and ZnO, they were evaluated as catechol and carbaryl insecticide biosensors. In a comparative way, the platforms PEI/PSE without the presence of immobilized enzyme were also studied for detection of catechol and carbaryl. The simplicity in the formation and construction of these platforms comes qualify them as viable to be produced on an industrial scale and low cost processing. And on the results obtained in the development of such biosensors stand out the efficiency and speed of detection, which make them economically promising and competitive in terms of environmental applications.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 201-227).

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 19, 2010) Includes bibliographical references (p. 32-33)

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references.

Thesis (Ph. D.)--University of California, Los Angeles, 2003. / Vita. Includes bibliographical references.

A utilização descontrolada de pesticidas tem provocado no decorrer dos anos a intoxicação de milhares de pessoas no mundo, uma vez que, seus resíduos têm sido depositados em alimentos, em solos e em ambientes aquáticos. Assim, a construção de duas novas plataformas sensoras para a detecção de pesticidas é o objetivo desse trabalho. Na primeira plataforma foi utilizado o polieletrólito catiônico polietilenoimina (PEI) em conjunto com o polissacarídeo extracelular algal (PSE) produzido pela microalga criptofícea Cryptomonas tetrapirenoidosa preparados através da técnica de deposição \"spin-coating\". E a segunda plataforma foi produzida por eletrodeposição pulsada, entre um potencial de redução e um de oxidação, utilizando nanoestruturas de óxido de zinco (ZnO). Para caracterizar as plataformas, foram utilizadas as técnicas de microscopia eletrônica de varredura com fonte de emissão de campo (FEG-SEM), difração de raios X (XRD), espectroscopia de absorção ultravioleta-visível (UV-Vis), microscopia de força atômica (AFM) e espectroscopia de reflexão-absorção no Infravermelho com modulação da polarização (PM-IRRAS). Através da imobilização da enzima polifenol oxidase na forma de extrato bruto em sua fonte natural (fruto abacate), as plataformas de PEI/PSE e ZnO, foram avaliadas como biossensores de catecol e do inseticida carbaril. De modo comparativo, as plataformas de PEI/PSE sem a presença imobilizada da enzima também foram estudadas para a detecção do catecol e do carbaril. A simplicidade na formação e na construção dessas plataformas vem qualificá-las como viáveis a serem produzidas em escala industrial e com baixo custo de processamento. E diante dos resultados obtidos no desenvolvimento desses biossensores destaca-se a eficiência e a rapidez de detecção, o que os tornam economicamente promissores e competitivos em termos de aplicações ambientais. / The uncontrolled use of pesticides has resulted over the years the intoxication of thousands of people in the world, since their waste has been deposited in food, in soil and aquatic environments. Thus, the construction of two new sensors platforms for pesticide detection is the objective of this work. At first platform was used cationic polyelectrolyte polyethyleneimine (PEI) along with the extracellular algal polysaccharide (EPS) produced by microalgae criptofícea Cryptomonas tetrapirenoidosa prepared by deposition technique \"spin-coating\". The second platform was produced by pulsed electrodeposition between a reduction and an oxidation potential using nanostructures zinc oxide (ZnO). To characterize the platforms, we used the techniques of field emission gun scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), ultraviolet visible absorption spectroscopy (UV-Vis), atomic force microscopy (AFM), and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). By immobilization of the polyphenol oxidase enzyme as a crude extract in their natural source (avocado fruit), platforms PEI/PSE and ZnO, they were evaluated as catechol and carbaryl insecticide biosensors. In a comparative way, the platforms PEI/PSE without the presence of immobilized enzyme were also studied for detection of catechol and carbaryl. The simplicity in the formation and construction of these platforms comes qualify them as viable to be produced on an industrial scale and low cost processing. And on the results obtained in the development of such biosensors stand out the efficiency and speed of detection, which make them economically promising and competitive in terms of environmental applications.

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