Abstract The massive outdoor culture of microalgae rarely reaches biomass concentrations higher t... more Abstract The massive outdoor culture of microalgae rarely reaches biomass concentrations higher than 1 g/L. The dewatering step is known to be a significant barrier in the large-scale production of microalgae-based commodities and bioproducts. High cost and energy consumption, along with low effectiveness, are still key constraints for commonly used dewatering operations. The potential use of forward osmosis as a membrane-based technology for algae dewatering employing osmotic pressure instead of external hydraulic pressure has several advantages such as low energy use and remarkable algae cell recovery. Nevertheless, the main drawbacks of forward osmosis are membrane fouling, concentration polarization phenomena, and reverse solutes diffusion. A lot of research is being carried out to overcome these limitations by developing new membranes and optimizing the process design. This article aims to review the main studies performed to date on microalgae biomass dewatering with the focus on forward osmosis and critical challenges, particularly fouling phenomenon. The forward osmosis performance evaluation, with respect to water flux behavior and microalgae dewatering efficiency, has been discussed in detail as an integral part of this review. When one appraises the achievements of the research carried out up until now, it becomes clear that we are still far from developing forward osmosis for microalgae dewatering at the industrial scale, and novel solutions are needed to enhance its technological readiness level. Some of the remaining challenges include: improving module design and arrangements to mitigate concentration polarization, lab-scale evaluation of different available draw solutions in relation to the properties and composition of the feed solution (i.e. the pH, microalgae species, etc.) for good dewatering process design, the membrane cleaning method and the pilot-scale validation of forward osmosis for dewatering microalgae, all of which are necessary to evaluate the economic and methodological feasibility of the process in a real setting.
Numero de publicacion: ES2545829 A1 (15.09.2015) Tambien publicado como: ES2545829 B2 (15.01.2016... more Numero de publicacion: ES2545829 A1 (15.09.2015) Tambien publicado como: ES2545829 B2 (15.01.2016) Numero de Solicitud: Consulta de Expedientes OEPM (C.E.O.) P201400232 (12.03.2014)
In central Patagonia, the most important crustaceans caught are the Argentine red shrimp (ARS) (P... more In central Patagonia, the most important crustaceans caught are the Argentine red shrimp (ARS) (Pleoticus muelleri) and the southern king crab (SKC) (Lithodes santolla). Their industrial processing generates large amounts of waste, which cause environmental pollution and ecological imbalances. The recovery of valuable compounds from this waste could bring economic benefits to the region. Comparative dry-basis proximal analysis of shells of ARS and SKC showed similar values of chitin (19 and 20%, respectively), slight but significant differences in proteins and ashes (18 and 48% for SKC and 26 and 55% for ARS), and 8 times higher content of lipids in ARS (4%) than in SKC (0.5%) shells. Nowadays, the waste generated by the processing of ARS (18000 t/year) is almost 180 times higher than that of SKC (100 t/year) and comprises not only shells but also heads (S + H). Nevertheless, taking into account that the amount of waste of SKC could increase in the future, the information about its chemical composition becomes relevant and is thus also reported in this work. The analysis of S + H of ARS showed the highest lipid content (11%), and the wet basis analysis of its fatty acids and carotenoids at different catch times showed a constant high level of the omega-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic and docosahexaenoic (5.0 g kg −1) and statistically significant variation in the carotenoid content, which can reach up to 158.8 mg kg −1. The results suggest potentials for recovering valuable n-3-PUFAs and carotenoids from ARS waste.
The fish processing operations in Patagonia produce large amounts of waste. The main fishery reso... more The fish processing operations in Patagonia produce large amounts of waste. The main fishery resource in Argentina is the Argentine hake (Merluccius hubbsi). The ports of the province of Chubut (the most important of which are Puerto Madryn, Rawson and Comodoro Rivadavia), together with Caleta Paula Port (province of Santa Cruz), in the Argentine Patagonia, capture more than 82,000 tons of hake annualy, 80% of which are of M. hubbsi, which is mostly converted into fillets. From this capture, about 2,296 tons of liver would be available for the extraction of oil. To promote the recovery and industrial use of fish oil, in the present study, we determined the variation in the proximate composition and fatty acid profile of Argentine hake waste from the ports mentioned above at different catch times. Proximate composition was determined according of the Official Methods of Analysis (AOAC). Fatty acid profile was analyzed by gas chromatography of the fatty acid methyl esters (FAMEs). A standard mixture of FAMEs was run under identical conditions to identify the compounds on the basis of their retention times. Fatty acids were quantified using heptadecanoic acid (C17:0) as internal standard. The highest lipid recovery (27.0 to 41.8% of total lipids) was obtained from the liver fraction. Palmitic acid (C16:0), oleic acid (18:1 n9), docosahexaenoic acid (22:6 n3), eicosapentaenoic acid (20:5 n3) and palmitoleic acid (16:1) were the main constituents. Protein levels in viscera without livers (V-L) were higher than those in the liver. The extraction of marine fish oil and the production of fish offal meal from waste from fish factories would contribute to the sustainability of the regional industry, because it would also decrease the volume of waste, with benefits to the environment.
The influence of solar irradiance and carbon dioxide molar fraction of injected CO 2-air mixtures... more The influence of solar irradiance and carbon dioxide molar fraction of injected CO 2-air mixtures on the behavior of outdoor continuous cultures of the microalga Phaeodactylum tricornutum in tubular airlift photobioreactors was analyzed. Instantaneous solar irradiance, pH, dissolved oxygen, temperature, biomass concentration, and the mass flow rates of both the inlet and outlet oxygen and carbon with both the liquid and gas phases were measured. In addition, elemental analysis of the biomass and the cell-free culture medium was performed. The oxygen production rate and carbon dioxide consumption rate increased hyperbolically with the incident solar irradiance on the reactor surface. Carbon losses showed a negative correlation with the daily variation of the carbon dioxide consumption rate. The maximum CO 2 uptake efficiency was 63% of the CO 2 supplied when the CO 2 concentration in the gas supplied was 60% v/v. Carbon losses were >100% during the night, due to CO 2 production by respiration, and hyperbolically decreased to values of 10% to 20% in the midday hours. An increase in the carbon fixed in the biomass with the solar cycle was observed. A slight daily decrease of carbon content of the cell-free culture medium indicated the existence of carbon accumulation in the culture. A decrease in CO 2 molar fraction in the injected gas had a double benefit: first, the biomass productivity of the system was enhanced from 2.05 to 2.47 g L −1 day −1 by reduction of CO 2 inhibition and/or pH gradients; and second, the carbon losses during the daylight period were reduced by 60%. The fluid dynamics in the reactor also influenced the carbon losses: the higher the liquid flow rate the higher the carbon losses. By using a previous mass transfer model the experimental results were simulated and the usefulness of this method in the evaluation and scale-up of tubular photobioreactors was established.
The effect of mechanical agitation on the microalgae Phaeodactylum tricornutum and Porphyridium c... more The effect of mechanical agitation on the microalgae Phaeodactylum tricornutum and Porphyridium cruentum was investigated in aerated continuous cultures with and without the added shear protectant Pluronic F68. Damage to cells was quantified through a decrease in the steady state concentration of the biomass in the photobioreactor. For a given aeration rate, the steady state biomass concentration rose with increasing rate of mechanical agitation until an upper limit on agitation speed was reached. This maximum tolerable agitation speed depended on the microalgal species. Further increase in agitation speed caused a decline in the steady state concentration of the biomass. An impeller tip speed of >1.56 m s-1 damaged P. tricornutum in aerated culture. In contrast, the damage threshold tip speed for P. cruentum was between 2.45 and 2.89 m s-1. Mechanical agitation was not the direct cause of cell damage. Damage occurred because of the rupture of small gas bubbles at the surface of the culture, but mechanical agitation was instrumental in generating the bubbles that ultimately damaged the cells. Pluronic F68 protected the cells against damage and increased the steady state concentration of the biomass relative to operation without the additive. The protective effect of Pluronic was concentration-dependent over the concentration range of 0.01-0.10% w/v.
With energy prices reaching historical highs, biodiesel as an alternative fuel is increasingly at... more With energy prices reaching historical highs, biodiesel as an alternative fuel is increasingly attracting attention. Currently, biodiesel is made from a variety of feedstocks, including pure vegetable oils, waste cooking oils, and animal fat; however, the limited supply of these feedstocks impedes the further expansion of biodiesel production. Microalgae have long been recognized as potentially good sources for biofuel production because of their high oil content and rapid biomass production. In recent years, use of microalgae as an alternative biodiesel feedstock has gained renewed interest from researchers, entrepreneurs, and the general public. The objective of this publication is to introduce the basics of algal-biofuel production and the current status of this emerging biodiesel source. Current Feedstock for Biodiesel Production Biodiesel can be made from any oil/lipid source; the major components of these sources are tricylglycerol molecules (TAGs, figure 1). In general, biodiesel feedstock can be categorized into three groups:
ABSTRACT Forward osmosis of microalgal suspensions was performed by using a dialysis membrane sub... more ABSTRACT Forward osmosis of microalgal suspensions was performed by using a dialysis membrane submerged in pure glycerol or a simulated crude glycerol of a biodiesel production process. Freshwater, marine and hypersaline microalgae were concentrated from around 1 to 2.5 g·L− 1 within an hour of treatment with crude glycerol. Cultures of marine microalgae could be osmotically dehydrated using crude glycerol as the draw solution at fluxes of around 2.75 L·m− 2·h− 1. This dewatering method was shown to be reliable and may be used in conjunction with other dewatering methods to improve the overall energy efficiency of a biomass recovery process.
Phycoerythrin is the major light-harvesting pigment-protein of the red algae Porphyridium cruentu... more Phycoerythrin is the major light-harvesting pigment-protein of the red algae Porphyridium cruentum and is widely used as fluorescent probe and analytical reagent. Additionally this protein has a potential application as natural dye in food industry. Nevertheless the knowledge of the functional properties of this alga protein is limited, hindering its application as food additive. In this article we report a biophysical characterization of B-phycoerythrin from Porphyridium cruentum (B-PE) in order to study its stability and spectral properties in a broad range of pHs. This information can help in its potential application as colorant in the food industry. Spectroscopic data obtained in this work show that B-PE has a stronger functional stability in the pH range 4.0-10.0, and Size Exclusion Chromatography suggests that the protein maintains a (αβ) 6-γ oligomeric structure in that range of pHs. At pH 7.0, an apparent T m value of 77.5±0.5°C was calculated. At this pH, the protein is highly stable with a loss of only 20 % of its spectral properties (absorbance and fluorescence) after 25 days at room temperature. These results indicate that B-PE is more stable in a broad range of pHs than other phycoerythrin proteins, which would facilitate its use in the food industry.
B-phycoerythrin from the red alga Porphyridium cruentum was crystallized using the technique of c... more B-phycoerythrin from the red alga Porphyridium cruentum was crystallized using the technique of capillary counter-diffusion. Crystals belonging to the space group R3 with almost identical unit cell constants and diffracting to 1.85 and 1.70 Å were obtained at pH values of 5 and 8, respectively. The most important difference between structures is the presence of the residue His88α in two different conformations at pH 8. This residue is placed next to the chromophore phycoerythrobilin PEB82α and the new conformation results in the relocation of the hydrogen-bond network and hydration around PEB82α, which probably contributes to the observed pH dependence of the optical spectrum associated with this chromophore. Comparison with the structures of B-phycoerythrin from other red algae shows differences in the conformation of the A-ring of the chromophore PEB139α. This conformational difference in B-phycoerythrin from P. cruentum enables the formation of several hydrogen bonds that connect PEB139α with the chromophore PEB158β at the (αβ)(3) hexamer association interface. The possible influence of these structural differences on the optical spectrum and the ability of the protein to perform energy transfer are discussed, with the two pH-dependent conformations of His88α and PEB82α being proposed as representing critical structural features that are correlated with the pH dependence of the optical spectrum and transient optical states during energy transfer.
Effects of mechanical and hydrodynamic forces on cells of the microalga Porphyridium cruentum are... more Effects of mechanical and hydrodynamic forces on cells of the microalga Porphyridium cruentum are reported for aerated cultures in stirred vessels. The specific rate of cell death varied linearly with the specific interfacial area, suggesting the importance of bubble-cell contacting in the damaging process. At low rates of mechanical agitation, bubble break-up at the culture surface was the predominant cause
Journal of Chemical Technology & Biotechnology, 2010
BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for... more BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for possible use in producing lipid feedstock for making biofuels. The effects of temperature (10-30 • C) and dilution rate (0.005-0.017 h −1 ) on lipid productivity in a nutrient sufficient medium in a 4 L stirred tank bioreactor under continuous illumination at an incident irradiance level of 550 µE · m −2 s −1 and a controlled pH of 6 under carbon dioxide supplemented conditions are reported.
Abstract The massive outdoor culture of microalgae rarely reaches biomass concentrations higher t... more Abstract The massive outdoor culture of microalgae rarely reaches biomass concentrations higher than 1 g/L. The dewatering step is known to be a significant barrier in the large-scale production of microalgae-based commodities and bioproducts. High cost and energy consumption, along with low effectiveness, are still key constraints for commonly used dewatering operations. The potential use of forward osmosis as a membrane-based technology for algae dewatering employing osmotic pressure instead of external hydraulic pressure has several advantages such as low energy use and remarkable algae cell recovery. Nevertheless, the main drawbacks of forward osmosis are membrane fouling, concentration polarization phenomena, and reverse solutes diffusion. A lot of research is being carried out to overcome these limitations by developing new membranes and optimizing the process design. This article aims to review the main studies performed to date on microalgae biomass dewatering with the focus on forward osmosis and critical challenges, particularly fouling phenomenon. The forward osmosis performance evaluation, with respect to water flux behavior and microalgae dewatering efficiency, has been discussed in detail as an integral part of this review. When one appraises the achievements of the research carried out up until now, it becomes clear that we are still far from developing forward osmosis for microalgae dewatering at the industrial scale, and novel solutions are needed to enhance its technological readiness level. Some of the remaining challenges include: improving module design and arrangements to mitigate concentration polarization, lab-scale evaluation of different available draw solutions in relation to the properties and composition of the feed solution (i.e. the pH, microalgae species, etc.) for good dewatering process design, the membrane cleaning method and the pilot-scale validation of forward osmosis for dewatering microalgae, all of which are necessary to evaluate the economic and methodological feasibility of the process in a real setting.
Numero de publicacion: ES2545829 A1 (15.09.2015) Tambien publicado como: ES2545829 B2 (15.01.2016... more Numero de publicacion: ES2545829 A1 (15.09.2015) Tambien publicado como: ES2545829 B2 (15.01.2016) Numero de Solicitud: Consulta de Expedientes OEPM (C.E.O.) P201400232 (12.03.2014)
In central Patagonia, the most important crustaceans caught are the Argentine red shrimp (ARS) (P... more In central Patagonia, the most important crustaceans caught are the Argentine red shrimp (ARS) (Pleoticus muelleri) and the southern king crab (SKC) (Lithodes santolla). Their industrial processing generates large amounts of waste, which cause environmental pollution and ecological imbalances. The recovery of valuable compounds from this waste could bring economic benefits to the region. Comparative dry-basis proximal analysis of shells of ARS and SKC showed similar values of chitin (19 and 20%, respectively), slight but significant differences in proteins and ashes (18 and 48% for SKC and 26 and 55% for ARS), and 8 times higher content of lipids in ARS (4%) than in SKC (0.5%) shells. Nowadays, the waste generated by the processing of ARS (18000 t/year) is almost 180 times higher than that of SKC (100 t/year) and comprises not only shells but also heads (S + H). Nevertheless, taking into account that the amount of waste of SKC could increase in the future, the information about its chemical composition becomes relevant and is thus also reported in this work. The analysis of S + H of ARS showed the highest lipid content (11%), and the wet basis analysis of its fatty acids and carotenoids at different catch times showed a constant high level of the omega-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic and docosahexaenoic (5.0 g kg −1) and statistically significant variation in the carotenoid content, which can reach up to 158.8 mg kg −1. The results suggest potentials for recovering valuable n-3-PUFAs and carotenoids from ARS waste.
The fish processing operations in Patagonia produce large amounts of waste. The main fishery reso... more The fish processing operations in Patagonia produce large amounts of waste. The main fishery resource in Argentina is the Argentine hake (Merluccius hubbsi). The ports of the province of Chubut (the most important of which are Puerto Madryn, Rawson and Comodoro Rivadavia), together with Caleta Paula Port (province of Santa Cruz), in the Argentine Patagonia, capture more than 82,000 tons of hake annualy, 80% of which are of M. hubbsi, which is mostly converted into fillets. From this capture, about 2,296 tons of liver would be available for the extraction of oil. To promote the recovery and industrial use of fish oil, in the present study, we determined the variation in the proximate composition and fatty acid profile of Argentine hake waste from the ports mentioned above at different catch times. Proximate composition was determined according of the Official Methods of Analysis (AOAC). Fatty acid profile was analyzed by gas chromatography of the fatty acid methyl esters (FAMEs). A standard mixture of FAMEs was run under identical conditions to identify the compounds on the basis of their retention times. Fatty acids were quantified using heptadecanoic acid (C17:0) as internal standard. The highest lipid recovery (27.0 to 41.8% of total lipids) was obtained from the liver fraction. Palmitic acid (C16:0), oleic acid (18:1 n9), docosahexaenoic acid (22:6 n3), eicosapentaenoic acid (20:5 n3) and palmitoleic acid (16:1) were the main constituents. Protein levels in viscera without livers (V-L) were higher than those in the liver. The extraction of marine fish oil and the production of fish offal meal from waste from fish factories would contribute to the sustainability of the regional industry, because it would also decrease the volume of waste, with benefits to the environment.
The influence of solar irradiance and carbon dioxide molar fraction of injected CO 2-air mixtures... more The influence of solar irradiance and carbon dioxide molar fraction of injected CO 2-air mixtures on the behavior of outdoor continuous cultures of the microalga Phaeodactylum tricornutum in tubular airlift photobioreactors was analyzed. Instantaneous solar irradiance, pH, dissolved oxygen, temperature, biomass concentration, and the mass flow rates of both the inlet and outlet oxygen and carbon with both the liquid and gas phases were measured. In addition, elemental analysis of the biomass and the cell-free culture medium was performed. The oxygen production rate and carbon dioxide consumption rate increased hyperbolically with the incident solar irradiance on the reactor surface. Carbon losses showed a negative correlation with the daily variation of the carbon dioxide consumption rate. The maximum CO 2 uptake efficiency was 63% of the CO 2 supplied when the CO 2 concentration in the gas supplied was 60% v/v. Carbon losses were >100% during the night, due to CO 2 production by respiration, and hyperbolically decreased to values of 10% to 20% in the midday hours. An increase in the carbon fixed in the biomass with the solar cycle was observed. A slight daily decrease of carbon content of the cell-free culture medium indicated the existence of carbon accumulation in the culture. A decrease in CO 2 molar fraction in the injected gas had a double benefit: first, the biomass productivity of the system was enhanced from 2.05 to 2.47 g L −1 day −1 by reduction of CO 2 inhibition and/or pH gradients; and second, the carbon losses during the daylight period were reduced by 60%. The fluid dynamics in the reactor also influenced the carbon losses: the higher the liquid flow rate the higher the carbon losses. By using a previous mass transfer model the experimental results were simulated and the usefulness of this method in the evaluation and scale-up of tubular photobioreactors was established.
The effect of mechanical agitation on the microalgae Phaeodactylum tricornutum and Porphyridium c... more The effect of mechanical agitation on the microalgae Phaeodactylum tricornutum and Porphyridium cruentum was investigated in aerated continuous cultures with and without the added shear protectant Pluronic F68. Damage to cells was quantified through a decrease in the steady state concentration of the biomass in the photobioreactor. For a given aeration rate, the steady state biomass concentration rose with increasing rate of mechanical agitation until an upper limit on agitation speed was reached. This maximum tolerable agitation speed depended on the microalgal species. Further increase in agitation speed caused a decline in the steady state concentration of the biomass. An impeller tip speed of >1.56 m s-1 damaged P. tricornutum in aerated culture. In contrast, the damage threshold tip speed for P. cruentum was between 2.45 and 2.89 m s-1. Mechanical agitation was not the direct cause of cell damage. Damage occurred because of the rupture of small gas bubbles at the surface of the culture, but mechanical agitation was instrumental in generating the bubbles that ultimately damaged the cells. Pluronic F68 protected the cells against damage and increased the steady state concentration of the biomass relative to operation without the additive. The protective effect of Pluronic was concentration-dependent over the concentration range of 0.01-0.10% w/v.
With energy prices reaching historical highs, biodiesel as an alternative fuel is increasingly at... more With energy prices reaching historical highs, biodiesel as an alternative fuel is increasingly attracting attention. Currently, biodiesel is made from a variety of feedstocks, including pure vegetable oils, waste cooking oils, and animal fat; however, the limited supply of these feedstocks impedes the further expansion of biodiesel production. Microalgae have long been recognized as potentially good sources for biofuel production because of their high oil content and rapid biomass production. In recent years, use of microalgae as an alternative biodiesel feedstock has gained renewed interest from researchers, entrepreneurs, and the general public. The objective of this publication is to introduce the basics of algal-biofuel production and the current status of this emerging biodiesel source. Current Feedstock for Biodiesel Production Biodiesel can be made from any oil/lipid source; the major components of these sources are tricylglycerol molecules (TAGs, figure 1). In general, biodiesel feedstock can be categorized into three groups:
ABSTRACT Forward osmosis of microalgal suspensions was performed by using a dialysis membrane sub... more ABSTRACT Forward osmosis of microalgal suspensions was performed by using a dialysis membrane submerged in pure glycerol or a simulated crude glycerol of a biodiesel production process. Freshwater, marine and hypersaline microalgae were concentrated from around 1 to 2.5 g·L− 1 within an hour of treatment with crude glycerol. Cultures of marine microalgae could be osmotically dehydrated using crude glycerol as the draw solution at fluxes of around 2.75 L·m− 2·h− 1. This dewatering method was shown to be reliable and may be used in conjunction with other dewatering methods to improve the overall energy efficiency of a biomass recovery process.
Phycoerythrin is the major light-harvesting pigment-protein of the red algae Porphyridium cruentu... more Phycoerythrin is the major light-harvesting pigment-protein of the red algae Porphyridium cruentum and is widely used as fluorescent probe and analytical reagent. Additionally this protein has a potential application as natural dye in food industry. Nevertheless the knowledge of the functional properties of this alga protein is limited, hindering its application as food additive. In this article we report a biophysical characterization of B-phycoerythrin from Porphyridium cruentum (B-PE) in order to study its stability and spectral properties in a broad range of pHs. This information can help in its potential application as colorant in the food industry. Spectroscopic data obtained in this work show that B-PE has a stronger functional stability in the pH range 4.0-10.0, and Size Exclusion Chromatography suggests that the protein maintains a (αβ) 6-γ oligomeric structure in that range of pHs. At pH 7.0, an apparent T m value of 77.5±0.5°C was calculated. At this pH, the protein is highly stable with a loss of only 20 % of its spectral properties (absorbance and fluorescence) after 25 days at room temperature. These results indicate that B-PE is more stable in a broad range of pHs than other phycoerythrin proteins, which would facilitate its use in the food industry.
B-phycoerythrin from the red alga Porphyridium cruentum was crystallized using the technique of c... more B-phycoerythrin from the red alga Porphyridium cruentum was crystallized using the technique of capillary counter-diffusion. Crystals belonging to the space group R3 with almost identical unit cell constants and diffracting to 1.85 and 1.70 Å were obtained at pH values of 5 and 8, respectively. The most important difference between structures is the presence of the residue His88α in two different conformations at pH 8. This residue is placed next to the chromophore phycoerythrobilin PEB82α and the new conformation results in the relocation of the hydrogen-bond network and hydration around PEB82α, which probably contributes to the observed pH dependence of the optical spectrum associated with this chromophore. Comparison with the structures of B-phycoerythrin from other red algae shows differences in the conformation of the A-ring of the chromophore PEB139α. This conformational difference in B-phycoerythrin from P. cruentum enables the formation of several hydrogen bonds that connect PEB139α with the chromophore PEB158β at the (αβ)(3) hexamer association interface. The possible influence of these structural differences on the optical spectrum and the ability of the protein to perform energy transfer are discussed, with the two pH-dependent conformations of His88α and PEB82α being proposed as representing critical structural features that are correlated with the pH dependence of the optical spectrum and transient optical states during energy transfer.
Effects of mechanical and hydrodynamic forces on cells of the microalga Porphyridium cruentum are... more Effects of mechanical and hydrodynamic forces on cells of the microalga Porphyridium cruentum are reported for aerated cultures in stirred vessels. The specific rate of cell death varied linearly with the specific interfacial area, suggesting the importance of bubble-cell contacting in the damaging process. At low rates of mechanical agitation, bubble break-up at the culture surface was the predominant cause
Journal of Chemical Technology & Biotechnology, 2010
BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for... more BACKGROUND: Continuous culture of the freshwater microalga Choricystis minor was investigated for possible use in producing lipid feedstock for making biofuels. The effects of temperature (10-30 • C) and dilution rate (0.005-0.017 h −1 ) on lipid productivity in a nutrient sufficient medium in a 4 L stirred tank bioreactor under continuous illumination at an incident irradiance level of 550 µE · m −2 s −1 and a controlled pH of 6 under carbon dioxide supplemented conditions are reported.
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