Detailed analyses of the lipid class and fatty acid composition were carried out for the marine microalgal species Nannoch/oropsis oculata (Droop) (CCAP strain no. 849/1) of the division Eustigmatophyceae (Hibberd). The alga was grown in batch and continuous culture using a novel culturing apparatus, the cage culture turbidostat, the construction of which is detailed in full. The total lipid extract yielded by the alga varied in a growth-phase dependent manner within the range 25 % to 80 % of the lyophilised cell mass. Of this between 40 % and 70 % was recovered as fatty acid methyl esters (FAME) upon transesterification. The total fatty acid composition of N. oculata consisted mainly of 16:0, 16:1 and 20:5(n-3), these three fatty acids often accounting for greater than 80 % of the total fatty acid mass. Between 9 % and 50 % of the mass of total FAME was accounted for by 20:5(n-3), the balance being accounted for by variations in the relative proportions of 16:0, 16:1, 18:1, 18:2 and 20:4. During periods of low cellular division rate, such as the lag- and stationary-phases, the proportion of polyunsaturated fatty acids (PUFA) (mainly 20:5(n-3» decreased. The total fatty acids became increasingly saturated as higher proportions of shorter chain length fatty acids accumulated, mainly in triacylglycerols (TAO). Increased cellular proportions of total lipid resulted from TAO accumulation which occurred on account of preferential partitioning of carbon into TAO biosynthesis whilst cellular division was suspended. The fatty acid composition of the TAO was more saturated at high synthesis rate and vice-versa at lower rates. The galactolipids, monogalactosyldiacylglycerol (MODO) and digalactosyldiacyl glycerol (DODO) were rich in 20:5(n-3) during exponential cell division containing up to 77 % and 53 % 20:5(n-3) respectively. Phosphatidylcholine (PC) was the only cl~s to contain significant proportions of CIS fatty acids during exponential growth, thus implicating its involvement in the acyl chain elongation reactions between the Cl6 and C20 fatty acids. Culture incubation temperature in the range 5 °C to 25°C did not influence the fatty acid composition of N. oculata. The effect of temperature upon culture dynamics at the lower culture incubation temperatures gave an apparent decrease in the PUFA content of the total fatty acid at a given point on the cultures growth curves. By expressing the data in tenns of culture doubling periods during the exponential-phases of growth it was found that temperature had no real effect upon fatty acid unsaturation or chain length. at either the total or the individual lipid class FAME level after the cells had passed through five doubling periods. Increasing the culture medium salinity from one quarter to one and a half times that of normal seawater decreased the un saturation and chain length of the fatty acids at both total and individual lipid class levels. The change resulted from the progressive accumulation of 18:1 and 18:2"at the expense of 20:5. Variation of salinity did not affect the dynamics of the cultures in the same respect as temperature in that a lag-phase was not observed on the cultures growth curves. However. such a phase was evident in the fatty acid profile of the cells in the period following inoculation. The 'effects of culture illumination intensity in the range 45 Jill m-2 sec-I to 170 Jill m 2 sec-! were examined under continuous culture conditions using the cage culture turbidostat Accumulation of saturated TAG by the cells at the higher illumination intensities gave an apparent decrease in the rate of PUFA biosynthesis. The polar lipid classes were found to be more highly unsaturated at higher illumination intensities. At lower illumination intensity TAG accumulation was reduced and the total fatty acid composition was accordingly more unsaturated. The fatty acid composition of the TAG component was more unsaturated but those of the polar lipid classes were less unsaturated than at higher illumination intensity. Increased illumination increased the degree of un saturation of the polar lipid cl~sses. Excess fixed carbon was partitioned into TAG biosynthesis. primarily as 16:0 and 16:1. The net accumulation of this lipid class even at high cell division rates resulted in a low overall unsaturation level. The effects of decreasing nitrate concentration in the range 1.0 mM N03 - to 0.001 mM N03 - had a similar basis to those of illumination in that the changes in the total fatty acid composition were largely governed by the rate of TAO accumulation. At high nitrate concentrations the cellular division rate was relatively high and the proportion of TAO in the total lipid extract was low. Consequently, both total and individual lipid classes contained high proportions of unsaturates, particularly 20:5(n-3). However, when the nitrate concentration was decreased, such that it began to limit the rate of cellular division, TAG accumulated Cursory analyses of the molecular species of the galactolipid classes, MODO and DODO, and phospholipid class PC are presented. The effects of environmental variables are discussed in tenns of the changes which may occur in the growth phase distribution of the cells in asynchronous culture, along with the concommitant changes in the lipid composition of the cells. The potential linkage of the elongation and desaturation reactions with both MODO and PC is also discussed briefly with reference to future research.

No description available.

Driven by the increase in industrialization and population, the global demand of energy and material products is steadily growing. Microalgae have come into prominence in the past several decades due to their ability to utilize solar energy to fix atmospheric carbon dioxide, and produce biomass and lipids at productivities much higher than those possible with terrestrial biomass. The main objective of this research is to maximize the biomass and lipid production of Chlorella vulgaris by varying different external conditions so as to achieve the ideal feedstock for the production of commodity chemicals and implement wastewater treatment. The effects of various culture medium compositions on Chlorella vulgaris growth and lipid production were investigated using batch culture. Thirteen culture media: Modified Chu’s No. 10, Bold basal, BG-11, Modified BG-11, N-8, M-8, RM, Modified Spirulina, F-si, Fogg’s Nitrogen free, Fog, F/2, and Johnson medium were compared in terms of optical density, biomass production, specific growth rate and lipid production. Following a 10-day culture in a temperature controlled environment, Bold basal medium was found to have the highest average biomass productivity of 48.056 ± 2.097 mg L -1 day -1 , with overall specific growth rate of (d -1 ): 0.211 ± 0.003 and lipid productivity of 9.295 mg L -1 day -1 among the selected media. This is a basis for the optimization of different cultivating medium to enhance algal lipid production. In order to maximize the quality and quantity of the algal biomass and lipid content in Chlorella vulgaris, different strategies were used using different ratios of nitrogen and phosphorus source in the modified Bold basal medium (BBM). In the 12-day batch culture period, the highest biomass productivity obtained was 72.083 mg L -1 day -1 under Bold basal medium with Nitrogem control Phosphorus limited conditions. The highest lipid content, lipid concentration and lipid productivity obtained were 53.202%, 287.291 mg/L and 23.449 mg L -1 day -1 respectively, under Bold basal medium with Nitrogen Control Phosphorus Deprivation conditions. Nitrogen starvation was found to be the critical factor affecting the biomass production and lipid accumulation while the starvation of phosphorus induced a higher total lipid content and affected the lipid composition of Chlorella vulgaris cultures. Recently, as the demand for pure microalgae strains for the production of algal lipid as a feedstock of renewable energy has been increasing, the designation of an effective photobioreactor (PBR) for mass cultivation is essential to assure stability in the amount of feedstock. Various PBRs design such as bubbling, air-lift, porous air-lift was compared. In general, the bubbling design is a better PBR designs than the others, having the highest biomass concentration of 0.78 g/L during the culture time. Besides, it was observed that the 35 cm draft tube of the porous air-lift PBR had shorter mixing time (24.5 seconds) and higher biomass concentration (0.518 g/L) than the 50 cm air- lift design. The bubbling PBR with the highest gas flowrate of 2.7 L/min produced the highest biomass production of 0.74 g/L within the cultivation time. The information is shown to be a useful guide for determining the optimal condition of the PBRs. Light wavelengths and intensities were determinant factors in affecting the growth and lipid content of autotrophic organisms such as C. vulgaris. The experiment investigated the effect of algal lipid production by using LEDs (Light Emitting Diodes) with different wavelengths. C. vulgaris was grown in the effluent for 10 days under the photoperiod of 18:6 h Light/Dark cycles with different visible light sources (cool white, blue and red) and intensities (50 μmol m -2 s -1 ) at 25°C. The overall maximum dry biomass of 1353.33 mg/L was observed at 50 μmol m -2 s -1 cool white light during 10th culture day, with the highest overall productivity of dry biomass production (117.23 mg/L d -1 ) within cultivation time. The highest lipid content (34.06 %) was obtained with the blue color due to light efficiency and deep penetration to the photosynthetic pigments (chlorophyll) in C. vulgaris. However, the highest lipid productivity was observed in cool white light of 318.63 mg/L during the 10th culture day. The effect of light intensity toward the lipid productivity was further investigated by increasing the light intensity of cool white light. The highest lipid productivity was observed at 110 μmol m -2 s -1 in a light intensity of 658.99 mg/L during the 10th culture day. In high irradiance (110 μmol m -2 s -1 ), the proportion of poly unsaturated fatty acid (C18:1 and C18:2) contributed most of the fatty acid methyl ester (FAME) content in the collected sample, irrespective of all treatments. The next study optimized the harvesting rate of algae by using an electro- coagulation-flotation (ECF) harvester, which combines the electrochemical reaction in the electrodes and the dispersion of hydrogen gas to allow floatation of microalgae cell for surface harvesting. The response surface methodology model (RSM) was employed to optimize different ECF parameters: electrode plate material, electrode plate number, charge of electrode, electrolyte concentration and pH of the solution. The model revealed that aluminum was the best electrode material for the ECF process. It was also found that a three electrode plates setup with one anode and two cathodes had the best performance for harvesting. Additionally, sodium chloride (NaCl) at 8 g/L in harvesting medium could increase the flocculant concentration and reduce electric power consumption. Also, having the culture medium at pH 4 also had a significant effect on improving the flocculant production. Combining these optimal conditions, the highest flocculant concentration reached 2966 mg/L in 60 mins; a 79.8% increase in flocculant concentration, based on the tested conditions. The results of this study show the significance of different parameters affecting the coagulation and flocculation of C. vulgaris and provide a reference for the design of a large-scaled harvester for microalgae harvesting in the further study. To conclude, this research comprises a study on the use of indigenous algae for the production of algal lipid, which is used to produce commodity chemicals. Details on the use of nutrient sources, the techniques of cultivation and the optimization of cell harvesting were included so as to remove nutrients from effluents to minimize the occurrence of eutrophication in harbor, thereby providing economic advantages. Thus, the optimization of these processes is very adequate and offers significant advantages for the wastewater treatment. The developing of algal cell biotechnology is necessary to further enhance algal lipid production in an attempt to apply it commercially.

Saline deterioration in the South African public water system has been documented and disposal of brine wastes has been identified as part of the problem. The broad aim of this research programme was to undertake an initial technical study to evaluate the feasibility of integrating algal biotechnology into a disposal function for these wastes. A demonstration of utility in the form of products and waste treatment could produce a beneficiation of saline effluents and provide incentives necessary to deal with the disposal issue. The study attempted to demonstrate a synthesis between the two main thrusts in algal biotechnology that have produced large-scale practical applications - stable, predictable algal production in saline media and the cost effective High Rate Oxidation Ponding (HROP) process for incorporating algal production into a waste treatment function. Tannery organic saline effluents and the biotechnology of Dunaliella salina culture producing β- carotene were chosen as paradigms for the study. 1. The alga was shown to grow in certain tannery effluents producing enhanced biomass yields compared to defined inorganic medium cultivation. The potential for amino acid or protein supplementation of defmed culture media was noted. 2. A reduction in organic load simultaneous with the growth of D.salina was recorded in laboratory-scale simulations of the HROP process. Rates similar to the fresh water HROP equivalent were demonstrated. 3. These results suggested the uptake and storage of organic nitrogen by D.salina. The consequent inhibition of β-carotene accumulation by the organism presented a potentially insurmountable obstacle to the feasibility of β-carotene production in this medium. Uptake and release of organic compounds, previously demonstrated in phytoplankton and other micro-algae, was confirmed in this study for D.salina. The evidence acquired indicated the internalization of both glycine and bovine serum albumin. An ultrastructural study demonstrated mechanisms by which this process might occur. 4. The release of substantial quantities of glycerol was shown. A mechanism whereby D. salina may use this to regulate ammonia availability via control of its associated bacterial population was observed. Glycerol release was identified as presenting an application in treating refractory organic wastes, such as secondary sewage sludges, by elevating C:N ratios. This could demonstrate a significant utility for brine waste impoundments. 5. A multistage production process was proposed to deal with the problem of β-carotene inhibition by separation of the growth and metabolite accumulation functions into separate unit operations. It was shown in this study that the stress of nitrogen deficiency combined with high salinity provides for effectiveβ-carotene accumulation under the conditions of low illumination that pertain in dense cultures. Subjected to these conditions effluent-grown cells show delayed but unimpaired {j-carotene accumulation. 6. A role for the plant hormone abscisic acid in mediating the stress response was demonstrated in D.salina. Fluorescence induction studies suggested the presence of a signalling process forming part of a sensitivity control mechanism. Stress induction of β-carotene accumulation could occur through four clearly defined stages. Potential was identified for using this response as a physiological probe for monitoring and regulating the stress induction process. 7. The multistage processing concept requires effective algal cell separation technology. The use of cross-flow ultrafiltration and diafiltration with a polyethersulfone tubular membrane system was demonstrated as an effective process for the recovery and washing of D. salina. Cell concentrates were produced in a viable form. 8. Process designs incorporating the findings of the research programme are presented demonstrating how effluent and organic waste treatment functions may be combined with the production of D.salina and its products. Application of the multi-stage processing concept to β-carotene production in a defined medium process was identified as offering a potential four-fold yield enhancement. This could have a significant impact on a high cost, marginal algal biotechnology process. Aspects of novelty have been claimed in provisional patents applications. A provisional demonstration of the feasibility of D.salina production in tannery effluent indicates that algal biotechnology may provide a utility for, and hence the beneficiation of saline effluent wastes.

Background and Aim: Microalgae are a potential economical source of omega-3 fatty acids, which are known for their health benefits. Omega-3 fatty acids derived from microalgae are however still expensive due to high costs involved in production. These costs can partly be attributed to cultivation of microalgae in unialgal cultures, which are prone to contamination, difficult to scale up and require stringent control of growth conditions. This study therefore is aimed to investigate the feasibility of using a mixed microalgae culture for the production of omega-3 fatty acids. Methods and materials: The microalgae were grown under uncontrolled conditions in a hanging-bag photo-bioreactor, with only the phosphorus-nitrogen ratio (P:N-ratio) varied. Variations in the different population proportions in the culture were studied and related to the biomass, total fatty acid and omega-3 fatty acid productivity of the culture. Finally, a comparison was made between the results obtained in this study and similar studies found in literature. Results and discussion: The mixed culture used was composed of several green microalgae, whose proportions varied with P:N-ratio, season, and age of the culture. Different interactions between the populations were observable, and these were thought to influence the culture’s biomass, total fatty acids (TFAs) and omega-3 fatty acid productivity. The TFA content of the culture was ~10-20% by the end of the exponential phase, depending on the nutrients supplied. The fatty acids were composed of mostly unsaturated fatty acids, the majority of which were omega-3 fatty acids; C18:3ω3 (up to 50% of TFA), C16:4ω3 (up to 15%) and C18:4ω3 (up to 5%). Other fatty acids observed included C16:0 (up to 25%), C18:1ω9/C18:1ω8 (up to 20%), C18:2ω6 (up to 5%), traces of C18:0, C18:3ω6, C17:0, C16:3ω3 and C16:1ω7 were also detected. The presence of these fatty acids was found to vary depending on season, P:N-ratio, and age of the culture. When compared to studies in the literature, the mixed culture was found to perform better than, or as well as reported studies, where unialgal cultures were cultivated under controlled laboratory conditions. Conclusion: In view of the reported advantages of cultivating mixed cultures, the production of omega-3 fatty acids via such cultures appears attractive. More research however is needed to optimise the culture; study interactions between the organisms and their effect on biomass, total fatty acid and omega-3 fatty acid productivity. Finally, the economic implications of using mixed cultures need to be evaluated as well.

No description available.

by Po-keung Wong. / Thesis (M.Phil.)--Chinese University of Hongkong. / Bibliography: leaves 265-298.

Experiments were carried out in fall and winter, 1990 and spring and summer, 1991 , to determine growth and mortality of juvenile Pacific oysters {Crassostrea gigas) in effluent from cultured coho salmon {Oncorhynchus kisutch) , and effluent from salmon in which the red macroalga Palmaria mollis was cultured. Ambient sea water from Yaquina Bay was used as a control. Juvenile Manila clams {Tapes japonica) were also tested in summer, to compare the growth response of clams with that of Pacific oysters. Measured growth parameters included: increase in mean individual live weight, specific growth rate (% increase of mean live weight per day) and mean individual organic (ash-free) weight. Temperature, chlorophyll a, phaeopigment, carbon and nitrogen concentrations and C/N ratio for all treatments were also recorded during spring and summer, 1991. The oysters grew significantly faster in effluent from salmon and salmon conditioned by macroalgae than in the control during the Fall Experiment (September 7- 0ctober 31, 1990). Mean water temperature was 13-16°C. Growth rates were significantly greater in oysters cultured in salmon effluent than in the control during the Winter Experiment (December 7, 1990-February 15, 1991). However, growth was very poor due to low water temperatures (7-10°C). Growth of oysters was significantly greater in the control than in effluent from salmon and salmon conditioned by macrolagae in the Spring Experiment (March 7-May 24, 1991). Mean water temperature was 12°C. In the Summer Experiments, (June 3-July 4 and July 19-August 17, 1991) growth of oysters was more rapid in treatments with macroalgae as compared to treatments without macroalgae Comparative experiments with juvenile Manila clams gave similar results. Percentage mortality for both oysters and clams ranged from 0 to 5% and was highest during winter and lowest during summer. Mean chlorophyll values ranged from 1 μg/1 in spring, 1991 to 11 μg/1 summer, 1991. / Graduation date: 1992

Made available in DSpace on 2014-06-11T19:27:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-16Bitstream added on 2014-06-13T19:55:57Z : No. of bitstreams: 1 fioresi_tb_me_jabo.pdf: 1222534 bytes, checksum: 8a60817f69089bec8947b5422404e7c7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Um dos fatores importantes na criacao de larvas de peixes e o uso de alimento natural, tal como o fitoplancton, o qual pode ser cultivado em instalacoes especiais, a baixo custo com alto valor nutricional e elevada taxa de crescimento. Muitos fatores afetam o cultivo de algas como luz, nutrientes, temperatura e pH, sendo esses fatores complexos e dificeis de serem analisados separadamente, principalmente, as interacoes entre incidencia de luz e limitacao de nutrientes. Entretanto, a restricao a luz e mais impactante do que a limitacao de nutrientes, desde que a luz afeta diretamente a utilizacao dos compostos disponiveis no meio de cultura. Estudos tem sido enfatizados focalizando o cultivo de algas para a producao de alimento, utilizando-se meios alternativos como forma de baratear o custo de producao. O objetivo do presente trabalho foi avaliar e comparar o efeito do esterco suino no desenvolvimento de Ankistrodesmus gracilis, cultivada em laboratorio em dois meios: com esterco gin natura e esterco biodigerido. O experimento foi realizado no periodo de 22 dias nos volumes, de 2L e 250L, analisando a biologia, valor nutricional e a qualidade da agua do meio de cultura. Biovolume, teor de cinzas, comprimento total e concentracao de lipideos foram significativos (p<0,05) entre os volumes cultivados. O teor de proteina nao foi significativo (p>0,05) somente no meio com esterco biodigerido. As maiores densidades de A. gracilis foram observadas no volume de 2L, tendo a amostra cultivada em meio com esterco biodigerido ao longo do experimento maior densidade, com o pico ao redor do 5o dia, 6,2 x 107 celulas.ml-1. Ortofosfato, pH, alcalinidade, oxigenio dissolvido e temperatura da agua nao foram significativos (p>0,05) entre volumes e o nitrito nao foi detectado... / One of the most important factors in successfully fish rearing is probably the use of natural feed, such as phytoplankton, which may be grown in specially designed installations. So that high nutritional algae could be produced at low cost it is important to reach light production of algae and high growing rate. Many factors affect algae culture growth such as light, nutrients, temperature and pH since they directly involve algae density interactions between light incidence and limitation of nutrients are very complex and the effect of factor can not be analyzed separately. However, light restriction caused more impact than limiting of nutrients, since energy affected directly the utilization of the compounds available in the medium. Several studies focus on the culture of algae for food production through alternative methods to lower production costs. The effect of swine manure fertilization in the development of Ankistrodesmus gracilis was mensured on two medium: in natura and biodigested, during 22 days, in two volumes, 2L and 250L. The biology, nutritional value and water quality of culture medium were analyzed. Biovolume, ash rate, total length and lipids were higher (p<0.05) between treatments. Protein rate was different (p>0.05) only in the biodigested treatment. Highest A. gracilis densities were reported in 2L throughout the experiment the biodigested treatment had the highest density, 6.2 x 107 cells.ml-1, on the 5th day. Orthophosphate, pH, alkalinity, dissolved oxygen and water temperature were only different (p<0.05) between volumes. Nitrite, however, was not reported in the 2L volume treatment. Significant differences (p<0.05) between media were only reported for DBO5. Light demand was also... (Complete abstract, click electronic access below)

Orientador: Lúcia Helena Sipaúba-Tavares / Banca: Luiz Augusto do Amaral / Banca: Márcia Noélia Eler / Resumo: Um dos fatores importantes na criacao de larvas de peixes e o uso de alimento natural, tal como o fitoplancton, o qual pode ser cultivado em instalacoes especiais, a baixo custo com alto valor nutricional e elevada taxa de crescimento. Muitos fatores afetam o cultivo de algas como luz, nutrientes, temperatura e pH, sendo esses fatores complexos e dificeis de serem analisados separadamente, principalmente, as interacoes entre incidencia de luz e limitacao de nutrientes. Entretanto, a restricao a luz e mais impactante do que a limitacao de nutrientes, desde que a luz afeta diretamente a utilizacao dos compostos disponiveis no meio de cultura. Estudos tem sido enfatizados focalizando o cultivo de algas para a producao de alimento, utilizando-se meios alternativos como forma de baratear o custo de producao. O objetivo do presente trabalho foi avaliar e comparar o efeito do esterco suino no desenvolvimento de Ankistrodesmus gracilis, cultivada em laboratorio em dois meios: com esterco gin natura e esterco biodigerido. O experimento foi realizado no periodo de 22 dias nos volumes, de 2L e 250L, analisando a biologia, valor nutricional e a qualidade da agua do meio de cultura. Biovolume, teor de cinzas, comprimento total e concentracao de lipideos foram significativos (p<0,05) entre os volumes cultivados. O teor de proteina nao foi significativo (p>0,05) somente no meio com esterco biodigerido. As maiores densidades de A. gracilis foram observadas no volume de 2L, tendo a amostra cultivada em meio com esterco biodigerido ao longo do experimento maior densidade, com o pico ao redor do 5o dia, 6,2 x 107 celulas.ml-1. Ortofosfato, pH, alcalinidade, oxigenio dissolvido e temperatura da agua nao foram significativos (p>0,05) entre volumes e o nitrito nao foi detectado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: One of the most important factors in successfully fish rearing is probably the use of natural feed, such as phytoplankton, which may be grown in specially designed installations. So that high nutritional algae could be produced at low cost it is important to reach light production of algae and high growing rate. Many factors affect algae culture growth such as light, nutrients, temperature and pH since they directly involve algae density interactions between light incidence and limitation of nutrients are very complex and the effect of factor can not be analyzed separately. However, light restriction caused more impact than limiting of nutrients, since energy affected directly the utilization of the compounds available in the medium. Several studies focus on the culture of algae for food production through alternative methods to lower production costs. The effect of swine manure fertilization in the development of Ankistrodesmus gracilis was mensured on two medium: in natura and biodigested, during 22 days, in two volumes, 2L and 250L. The biology, nutritional value and water quality of culture medium were analyzed. Biovolume, ash rate, total length and lipids were higher (p<0.05) between treatments. Protein rate was different (p>0.05) only in the biodigested treatment. Highest A. gracilis densities were reported in 2L throughout the experiment the biodigested treatment had the highest density, 6.2 x 107 cells.ml-1, on the 5th day. Orthophosphate, pH, alkalinity, dissolved oxygen and water temperature were only different (p<0.05) between volumes. Nitrite, however, was not reported in the 2L volume treatment. Significant differences (p<0.05) between media were only reported for DBO5. Light demand was also... (Complete abstract, click electronic access below) / Mestre