Doctor of Philosophy / Department of Biological & Agricultural Engineering / Lisa R. Wilken / Microalgae are a potential feedstock for renewable and sustainable bioproducts and energy but there are significant scientific and engineering challenges to address before widespread acceptance of this platform. In particular, biorefining microalgae serves to maximize biomass valorization and minimize waste to improve process economics. The overall goal of this dissertation was the development of a biological-based microalgae biorefinery to enhance the economic feasibility of Chlamydomonas reinhardtii as a source of multiple products including native proteins and lipids. Specific objectives included accumulating biomass enriched in target biomolecules and determining processing strategies that eliminated the need to dry biomass, employed mild conditions to maintain extractability and quality, and minimized application of petroleum-derived and toxic solvents during extraction. The microalgae biorefinery developed included biomolecule accumulation, biomass harvesting, and targeted enzymatic degradation of the cell wall and organelles for release of native proteins and lipids. Biomass was cultivated, and kinetic studies indicated that 48 h nitrogen deprivation was adequate for protein and lipid accumulation. Four lytic enzymes were screened for their ability to permeate the C. reinhardtii cell wall and the C. reinhardtii-produced enzyme, autolysin, led to >85% cell disruption. TEM imaging confirmed cell disruption and retention of lipid droplets in organelle remnants indicating that protein, lipids, and starch could be distinctly partitioned and recovered. A design of experiments optimization study determined that incubation of disrupted biomass at pH 12 for 4 h at 45°C resulted in up to 65% of total protein released from disrupted biomass followed by 40-50% protein recovery with isoelectric precipitation. The cell disruption and protein extraction steps were subsequently integrated to minimize unit operations, processing time, and energy inputs. Secondary application of trypsin led to release of ~73% of total lipids (enriched in triacylglycerols) from the disrupted biomass. Characterization by thin layer chromatography and GC-FID of released lipids revealed similar profiles of enzymatically released lipids as compared to those released by conventional extraction procedures. Finally, the composition of released lipids indicated favorable combustion behavior, high oxidation stability, and suitability as biodiesel. The developed biological-based biorefinery is a promising step towards adoption of microalgae as a source of bioproducts to provide energy and food to meet the needs of a growing population. The second focus of the work was mitigation strategies for isolation of critical impurities (or potential co-products) while processing microalgae and plant hosts. Specific emphasis was placed on evaluating the impact of proteases, polysaccharides, phenolic compounds and pigments, phytic acid, and host cell proteins on the processing of microalgae and other plant hosts for extraction, recovery, and purification of therapeutic proteins. This review served as evaluation of the broader implications of application of the biorefinery to transgenic microalgae and other plants.

Agentes com propriedades antimicrobianas e antifúngicas são nanoencapsuladas em nanopartículas tendo em vista aumentar os efeitos contra as infecções microbiológicas causadas por Aspergillus ssp. e Staphylococcus aureus. Dentre os sistemas veiculares para entrega de fármacos as nanocápsulas de núcleo lipídico se destacam e tem sido largamente estudadas devido aos seus potenciais terapêuticos. Neste estudo desenvolvemos e caracterizamos as nanocápsulas de núcleo lipídico revestidas com quitosana para assim associar efeitos antimicrobianos, do fármaco e de material de revestimento das nanocápsulas. Para tanto, encapsulamos a dapsona nas nanocápsulas com o propósito obter sua dupla atividade antimicrobiana, associada à da quitosana, material de revestimento. Posteriormente, as nanocápsulas contendo dapsona e revestidas com quitosana foram secas pela técnica de spray-drying a fim de desenvolver uma plataforma tecnológica para a obtenção de produtos intermediários e finais, para futuras aplicações pulmonares ou tópicas dos pós de nanocápsulas. As formulações de nanocápsulas de núcleo lipídico e as com dapsona revestidas com fosfatidilcolina e polissorbato 80 e fosfatidilcolina, polissorbato 80 e quitosana apresentaram distribuição unimodal. Por meio da microscopia eletrônica de transmissão foi possível observar a coroa hidrofilica das nanocápsulas constituida de estruturas micelas. Os resultados demonstraram uma redução de até dez vezes na concentração de dapsona quando nanoencapsulada em sistema nanoestruturado revestidos com fosfatidilcolina, polissorbato 80 e quitosana em comparação com a administração da dapsona em solução para efeitos antibacterianos. As formulações de nanocápsulas de núcleo lipídico sem o fármaco revestidas com fosfatidilcolina, polissorbato 80 e quitosana também inibiram o crescimento bacteriano e fúngicos quando a quitosana foi administrada nas concentrações relativas. O efeito da quitosana demostrou elevado potencial para inibir o crescimento bacteriano e fúngico. Os pós das nanocápsulas contendo dapsona revestidas com quitosana e secas com leucina apresentaram produtos intermediários para futuras aplicações biológicas, tanto para via respiratória quanto para via tópica a fim coibir as infecções causadas pelos microorganismos. / Agents with antimicrobial and antifungal properties were encapsulated into nanoparticles in order to improve the effects against microbial infections caused by Aspergillus spp. and Staphylococcus aureus. Among the carriers for drug delivery systems of the lipid core nanocapsules have been widely studied because of their therapeutic potential. In this study we have developed and characterized the lipid core nanocapsules coated with chitosan thus to associate antimicrobial effects of the drug to nanocapsules of the coating material. To this end, dapsone was encapsulated into the nanocapsules in order to obtain a double antimicrobial activity, associated to the chitosan coating material. Subsequently, the nanocapsules containing dapsone and coated with chitosan were dried by spray-drying technique in order to develop a technological platform to obtain intermediates and final products for future pulmonary or topical application of nanocapsules powders. The lipid core nanocapsules with and without dapsone coat with phosphatidylcholine and phosphatidyl choline and polysorbate 80, polysorbate 80, and chitosan showed unimodal distribution. By transmission electron microscopy it was possible to observe the crown of hydrophilic nanocapsules consisting of micellar structures. The results showed a reduction of up to ten times the concentration of dapsone when nanocoated in nanostructured system coated with phosphatidylcholine, polysorbate 80 and chitosan compared to administration of dapsone in solution for antibacterial effects.The lipid core nanocapsule formulations without drug coated with phosphatidylcholine, polysorbate 80, chitosan also inhibit bacterial and fungal growth when chitosan was administered in relative concentrations. The effect of chitosan demonstrated high potential to inhibit bacterial and fungal growth.The powder of nanocapsules containing dapsone coated with chitosan and dried with leucine showed intermediate products for future biological applications, for both the airway and topically to prevent infections caused by microorganisms.

Orientador: Maria Palmira Daflon Gremião / Banca: Beatriz Stringhetti Ferreira Cury / Banca: Silmara Marques Alegretti / Resumo: A esquistossomose é uma doença que atinge cerca de 200 milhões de pessoas no mundo todo. A alta incidência desta doença está ligada à falta de condições sanitárias, ao diagnóstico tardio e, principalmente, à falta de tratamento medicamentoso eficiente. O praziquantel é o fármaco de primeira escolha para o tratamento da esquistossomose. No entanto, falhas no tratamento com este fármaco e relatos de isolamento de S. mansoni tolerantes podem comprometer a eficiência do PZQ. Assim, o PZQ representa um fármaco em que pesquisas para melhorar as suas propriedades biofarmacêuticas são necessárias, pois apresenta baixa solubilidade em meio aquoso e biodisponibilidade baixa ou errática. O presente trabalho vê como finalidade desenvolver carreadores lipídicos nanoestruturados (NLC) contendo praziquantel empregando como sistema lipídico o monoestearato de glicerila (GMS) e o ácido oléico (AO) e como sistema tensoativo a associações de monoestearato de polioxietileno sorbitano 60 (TWEEN60), fosfatidilcolina, Poloxamer (Pluronic F-127 PLU). Os NLCs foram preparados através de dois diferentes métodos, de sonicação e alta velocidade de cisalhamento a quente. Os sistemas foram caracterizados através da avaliação dos parâmetros de distribuição de tamanho, potencial zeta, índice de polidispersidade e eficiência de encapsulação. O transporte intestinal do fármaco foi avaliado através do modelo do saco intestinal invertido. Ambos os métodos de obtenção empregados mostraram-se eficazes para o preparo dos NLCs em escala nanometrica, com índice de polidispersidade homogeneo e um... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Schistosomiasis is a debilitating disease with high misfit in the quality of people life reached about 200 million people worldwide. The high incidence of this disease is linked to poor sanitary conditions, late diagnosis, and especially the lack of effective drug treatment. Praziquantel is the drug of first choice for treatment of schistosomiasis. However, treatment failures with this drug and reports of isolation of S. mansoni tolerance may compromise the efficiency of PZQ. Thus, the PZQ represents an example in which surveys to improve the biopharmaceutical properties are needed, since it has low solubility in aqueous and low or erratic bioavailability. This work aims to develop nanostructured lipid carriers (NLC) containing praziquantel employing as lipid system the glycerin monostearate (GMS) and oleic acid (OA) as a surfactant system and some combination of polyoxyethylene sorbitan monostearate 60 (TWEEN60), phosphatidylcholine and Poloxamer (Pluronic F-127 PLU) as a surfactant system. NLCs were prepared by two different methodologies, the sonication and high shear rates to warm. The systems were characterized by determination of size distribution, zeta potential, polydispersity index and encapsulation efficiency. The intestinal transport of the drug was evaluate by using the model of inverted intestinal sac. Both methods were effective for the preparation of NLCs with an average diameter in the nanometer range, the polydispersity index indicating homogeneity of particle size and a zeta... (Complete abstract click electronic access below) / Mestre

Agentes com propriedades antimicrobianas e antifúngicas são nanoencapsuladas em nanopartículas tendo em vista aumentar os efeitos contra as infecções microbiológicas causadas por Aspergillus ssp. e Staphylococcus aureus. Dentre os sistemas veiculares para entrega de fármacos as nanocápsulas de núcleo lipídico se destacam e tem sido largamente estudadas devido aos seus potenciais terapêuticos. Neste estudo desenvolvemos e caracterizamos as nanocápsulas de núcleo lipídico revestidas com quitosana para assim associar efeitos antimicrobianos, do fármaco e de material de revestimento das nanocápsulas. Para tanto, encapsulamos a dapsona nas nanocápsulas com o propósito obter sua dupla atividade antimicrobiana, associada à da quitosana, material de revestimento. Posteriormente, as nanocápsulas contendo dapsona e revestidas com quitosana foram secas pela técnica de spray-drying a fim de desenvolver uma plataforma tecnológica para a obtenção de produtos intermediários e finais, para futuras aplicações pulmonares ou tópicas dos pós de nanocápsulas. As formulações de nanocápsulas de núcleo lipídico e as com dapsona revestidas com fosfatidilcolina e polissorbato 80 e fosfatidilcolina, polissorbato 80 e quitosana apresentaram distribuição unimodal. Por meio da microscopia eletrônica de transmissão foi possível observar a coroa hidrofilica das nanocápsulas constituida de estruturas micelas. Os resultados demonstraram uma redução de até dez vezes na concentração de dapsona quando nanoencapsulada em sistema nanoestruturado revestidos com fosfatidilcolina, polissorbato 80 e quitosana em comparação com a administração da dapsona em solução para efeitos antibacterianos. As formulações de nanocápsulas de núcleo lipídico sem o fármaco revestidas com fosfatidilcolina, polissorbato 80 e quitosana também inibiram o crescimento bacteriano e fúngicos quando a quitosana foi administrada nas concentrações relativas. O efeito da quitosana demostrou elevado potencial para inibir o crescimento bacteriano e fúngico. Os pós das nanocápsulas contendo dapsona revestidas com quitosana e secas com leucina apresentaram produtos intermediários para futuras aplicações biológicas, tanto para via respiratória quanto para via tópica a fim coibir as infecções causadas pelos microorganismos. / Agents with antimicrobial and antifungal properties were encapsulated into nanoparticles in order to improve the effects against microbial infections caused by Aspergillus spp. and Staphylococcus aureus. Among the carriers for drug delivery systems of the lipid core nanocapsules have been widely studied because of their therapeutic potential. In this study we have developed and characterized the lipid core nanocapsules coated with chitosan thus to associate antimicrobial effects of the drug to nanocapsules of the coating material. To this end, dapsone was encapsulated into the nanocapsules in order to obtain a double antimicrobial activity, associated to the chitosan coating material. Subsequently, the nanocapsules containing dapsone and coated with chitosan were dried by spray-drying technique in order to develop a technological platform to obtain intermediates and final products for future pulmonary or topical application of nanocapsules powders. The lipid core nanocapsules with and without dapsone coat with phosphatidylcholine and phosphatidyl choline and polysorbate 80, polysorbate 80, and chitosan showed unimodal distribution. By transmission electron microscopy it was possible to observe the crown of hydrophilic nanocapsules consisting of micellar structures. The results showed a reduction of up to ten times the concentration of dapsone when nanocoated in nanostructured system coated with phosphatidylcholine, polysorbate 80 and chitosan compared to administration of dapsone in solution for antibacterial effects.The lipid core nanocapsule formulations without drug coated with phosphatidylcholine, polysorbate 80, chitosan also inhibit bacterial and fungal growth when chitosan was administered in relative concentrations. The effect of chitosan demonstrated high potential to inhibit bacterial and fungal growth.The powder of nanocapsules containing dapsone coated with chitosan and dried with leucine showed intermediate products for future biological applications, for both the airway and topically to prevent infections caused by microorganisms.

No description available.

In recent years, advances in computer architecture and lipid force field parameters have made Molecular Dynamics (MD) a powerful tool for gaining atomistic resolution of biological membranes on timescales that other tools simply cannot explore. With many key biological processes involving membranes occurring on the nanosecond timescale, MD allows us to probe the dynamics and energetics of these interactions in molecular detail. Specifically, we can observe the interactions taking place as a peptide or protein comes into contact with a lipid bilayer, and how this may shape or alter the bilayer either locally (changes in headgroup orientation, lipid fluidity) or in bulk (lipid demixing, membrane curvature). The resolution achieved through atomistic MD can be directly compared with other tools such as NMR and EPR to gain a full perspective of how these biological systems behave over different timescales. As my background is in computational physics, this thesis not only looks into broadening our understanding of various interactions with biological membranes, but also into the development of construction and analytical software to assist in my research and benefit others in the field. One aspect of biological membranes that could vastly benefit from MD simulations is that of antimicrobial peptides (AMPs). These peptides primarily target and destroy microbes by permeabilising the cell membrane through a variety of proposed mechanisms, where each mechanism relies on the AMP to adopt specific conformations upon contact with bacterial membranes. In this thesis, I present an investigation into the interactions between a synthetic AMP and an inhibitor peptide designed to regulate antimicrobial activity through the formation of a coiled coil structure, which restricts the AMP from adopting new conformations. Simulations captured the spontaneous formation of coiled coils between these peptides, and specific residues in their sequences were identified that promote unfolding. This knowledge may lead to better design of coiled coil forming peptides. Another aspect of biological membranes that can be explored with MD is the interactions between model bacterial membranes and amphipathic helices, such as the MinD membrane targeting sequence (MinD-MTS). This 11-residue helix is responsible for anchoring the MinD protein to the inner membrane of Bacillus subtilis and plays a crucial role in bacterial cell division. MinD is known to exhibit sensitivity to transmembrane potentials (TMVs), whereby its localisation and binding affinity to bacterial membranes are disrupted upon removal of the TMV. Simulations revealed rapid insertions of MinD-MTS peptides into the headgroup region of a model bacterial membrane. Analytical software was constructed to measure the membrane properties of the lipids surrounding inserted MinDMTS peptides, which revealed splayed lipid tails and suggests the MinD-MTS may be capable of inducing membrane curvature. Additional simulations were conducted to investigate the influence of a TMV on model bacterial membranes, where software was constructed to measure changes in membrane properties. An analysis of these simulations suggests that a TMV is capable of lowering the transition temperature of a model bacterial membrane by a few degrees, yielding increased fluidity in the lipids and increased perturbations on the membrane surface. Finally, another aspect of biological membranes that can be explored through MD is that of electroporation. This induction of transient water pores in cell membrane provides an exciting aspect for drug delivery applications into cells, whereby electric fields are applied to cells to increase the uptake of therapeutic drugs. Simulations of membranes with high voltage TMVs were conducted that sought to investigate the implications of electroporation across a variety of bilayer compositions at different temperatures. Software was constructed to measure changes in membrane and system properties, which revealed that pore formation occurred at the same threshold voltage for different bilayer compositions in the fluid phase (~1.9 V) and a higher voltage for DPPC bilayers in the gel phase (~2.4 V). The TMV was found to be highly dependent on the area per lipid (APL), implying that bilayers with bulkier lipids or those transitioning from gel to fluid will experience smaller TMVs and fewer pore formations. These simulations also revealed lipid flip-flopping through pores, where charged lipids tended to translocate in the direction of the electric field to produce an asymmetrically charged bilayer. Finally, simulations utilising charged peptides with membranes yielded electroporation effects, whereby the charged peptides generate an identical TMV to those produced by an ion imbalance of equal magnitude. This suggests that charged peptides, such as AMPs, may be capable of permeabilising cell membranes through electroporation mechanisms.

Master of Science / Department of Animal Sciences and Industry / Teresa L. Douthit / Supplementation of lipids in the form of triglycerides is a safe method for increasing energy density in equine diets; however the effects of calcium salts of fatty acids (CSFA) on nutrient digestibilities in the horse are unknown. Eight cecally cannulated Quarter Horses were utilized in a crossover design in which horses consumed 1.5% BW smooth bromegrass hay and 0.5% BW concentrate supplemented with 4.1% soybean oil (SB) or 4.9% Enertia s/f® (E), a proprietary CSFA, for 28 d. Feces were collected for determination of apparent total tract digestibility of nutrients, and cecal digesta was evaluated for pH and concentrations of VFA and LCFA. Serum was collected following a 16-h fast and analyzed for triglycerides and cholesterol. Apparent total tract digestibilities of DM, NDF, ADF, CP, ether extract, and GE were unaffected by lipid source (P > 0.10). Serum triglycerides tended to be greater in horses consuming E compared to SB (P = 0.10); but, serum cholesterol concentrations were not different (P = 0.45). Cecal pH was unaffected by lipid source. Cecal concentration of total VFA tended to be greater in horses consuming SB compared to E at 2-h post feeding (P = 0.07). Cecal propionate concentrations were greater at 2-h post feeding for horses fed SB compared to horses fed E (P = 0.03). A treatment × time interaction was detected for total cecal LCFA concentration in which total cecal LCFA were greater in horses consuming E compared to SB at 2-h following consumption of a meal but became more similar as time progressed (P < 0.01). Secondly, an in vitro study was conducted to determine the effect of Co chloride on fermentation parameters using an equine cecal fluid inoculum in a 2 × 5 factorial arrangement of treatments. Alfalfa or smooth bromegrass hay (5 g DM) were utilized as substrates and were supplemented with 0.0, 0.5, 5.0, 25.0, or 50.0 mg Co/kg substrate DM. Cultures containing alfalfa had greater IVDMD compared to those with smooth bromegrass hay (P < 0.01). There was a forage × Co interaction in which gas production increased with time and was greater in cultures containing alfalfa (P < 0.01). Production of acetate, propionate, butyrate, isobutyrate, isovalerate, and total VFA, as well as acetate:propionate, were increased in cultures containing alfalfa compared to those containing brome hay (P < 0.05).

Master of Science / Department of Biological & Agricultural Engineering / Lisa R. Wilken / Microalgae has potential as a biofuel feedstock and as a source of valuable bioproducts for a variety of food, feed, nutraceutical, and pharmaceutical industries. However, several challenges are associated with bioproduct extraction from microalgae. The complexity of microalgae cell necessitates use of energy intensive disruption methods but current chemical or mechanical techniques can degrade economically valuable bioproducts. Aqueous enzymatic extraction (AEE), is a non-solvent and environmentally friendly bio-product recovery method that provides an opportunity to design an integrated process for protein and oil fractionation while reducing industrial costs. Based on the mechanistic understanding of biomolecule distribution and compartmentation, an aqueous enzymatic treatment for the release of internally stored proteins and lipid bodies in wild type Chlamydomonas reinhardtii was developed. In this study, we optimized harvesting times that maximized lipid and protein yields in nitrogen depleted cultures of the microalgae Chlamydomonas reinhardtii. Furthermore, an aqueous enzymatic extraction (AEE) treatment was developed. First, four lytic enzymes were tested for their ability to permeate C. reinhardtii cell walls. After cells were permeable, another set of enzymes were tested for their ability to release internally stored bioproducts. Protein recovery and lipid characterization after enzymatic treatment indicated a 54% release of total soluble protein and a localization of lipids to the chloroplast. Additionally, the development of secondary enzyme treatment for chloroplast disruption achieved about 70% total lipids released into the supernatant. Taken together, results indicate the application of an enzymatic treatment scheme for protein and oil recovery as a promising alternative to traditional extraction processes.

The purpose of this study was to evaluate the effect of pyridoxine deficiency on lipogenesis in the rat. It is important in studies of this type to standardize not only the food intake but also the feeding pattern of the experimental and control animals. Pair-feeding of the control rats with the deficient ones imposes on the former animals a feeding pattern similar to meal-feeding. The latter pattern elicits several adaptive changes related to energy utilization by the rat. Therefore, an attempt was made to minimize the difference in the feeding frequency between the deprived and control groups by meal-feeding of the former group. The data were compared with those obtained when only food intake was controlled. Male weanling Wistar rats were used in the present studies. The deprived rats were allowed food either ad libitum (nibbling) or for 2 hours each day (meal-feeding). The appropriate controls were given a complete diet in quantities isocaloric with the consumption of the deprived groups. Decreased fat storage as well as feed efficiency in pyridoxine deficient rats were obvious at that time, regardless of the mode of feeding employed. The fatty acid content of the epididymal adipose tissue was affected in the same manner as body fat. Pyridoxine deprivation also suppressed total body fatty acid synthesis in vivo from glucose-U-¹⁴ C, whether the animals were meal-fed or nibbling. However, the rates of fatty acid synthesis in the epididymal adipose tissue of the meal-fed deprived rats tended to exceed those observed in the control. The lipogenic capacity of liver slices from fed nibbling deprived rats exceeded that of the controls, as evidenced by increased fatty acid labelling in the presence of glucose-U-¹⁴C or acetate-1-¹⁴ C. However, when the nibbling deprived rats were fasted and refed prior to sacrifice, the incorporation of acetate-1-¹⁴ C into fatty acids was lower than in the controls. No differences in the labelling of liver fatty acids and glyceride glycerol were observed when the meal-fed deprived rats were compared with their controls. However, pyridoxine deficiency in meal-fed rats was associated with a decrease in the capacity of the liver to oxidize glucose, as comparison with the controls revealed. Epididymal adipose tissue segments from nibbling deprived rats showed less incorporation of ¹⁴C from labelled glucose into CO₂, fatty acids and glyceride glycerol than those from the corresponding controls (expressed on the basis of the deoxyribonucleic acid content of the tissue). In contrast, increased lipogenic potential of adipose tissue preparation from the deprived meal-fed rats in the presence of insulin was observed. In these rats, a decrease in adipocyte size was suggested by lipid/DNA ratio lower than that of the controls. Thus, the increased lipogenic capacity observed was possibly due to a decrease in adipocyte size, itself associated with increased sensitivity to insulin. The activities of glucose-6-phosphate dehydrogenase and malic enzyme were depressed in both the liver and the adipose tissue of the pyridoxine-deprived rats. Since these enzymes are concerned with the production of the NADPH needed for reductive fatty acid synthesis, the results were consistent with the in vivo finding. However, the activities of these enzymes did not appear to limit the in vitro lipogenic potential of the tissues investigated, since NADPH produced from glucose-6-phosphate dehydrogenase and malic enzyme alone seemed to be sufficient to support the rates of lipogenesis seen. The alterations in lipogenesis in pyridoxine deprivation observed in the present and other investigation could not be explained on the basis of the known functions of the pyridoxine-dependent enzymes. / Land and Food Systems, Faculty of / Graduate

An assay based on Nile red fluorescence was developed for quantitative analysis of triglycerides, a common cellular component with important biological functions and is routinely analyzed for diagnosis of metabolic disorders and as an important feedstock of food industry and biodiesel production. Based on studies on the Nile red fluorescence of pure, binary, and ternary systems of triglycerides, ethanol, and water, 20% ethanol aqueous solution was determined to be the most suitable solvent for lipid fluorescence measurement. Excellent linearity was established for lipid samples in the range of 0.1- 0.5 mg/ml with several different lipid standards and vegetable oils. Results also suggest that the fluorescence of triglycerides was not sensitive to the fatty acid composition of lipids. This finding is important since it implies that the assay could potentially be used for the measurement of triglyceride content of different oil crops without causing significant variations. The results of this method were then verified by comparing with the results of the conventional gravimetric methods. The results of the fluorescence assay were consistently lower than that of the gravimetric method by approximately 10%. This phenomenon was tentatively attributed to the fact that the gravimetric method measures the total amount of lipophilic materials in samples while the fluorescence assay is selective to glycerides. Attempts were also made to apply this assay to estimate the lipid content of green alga Neochloris oleoabundans. However, the results were less than ideal due to the existence of interfering components in the extract of microalga samples that could significantly repress the fluorescence of lipids.