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  • 1
    Electronic Resource
    Electronic Resource
    Effect of growth rate on the eicosapentaenoic acid and docosahexaenoic acid content of Isochrysis galbana in chemostat culture (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 23-27 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isochrysis galbana rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been grown as a chemostat culture at 20° C and pH 8.00 controlled by CO2 injection. From a low dilution rate (D) of 0.0024 h−1 to 0.0377 h−1, close to maximum growth, a decrease in EPA content from 5.21% dry weight (d.w.) to 2.80% d.w. was observed, although the percentage of EPA in the total fatty acids increased. Lipids were fractionated, EPA being the major fatty acid found in the glycolipid fraction, whereas in the neutral lipid fraction were mainly palmitic and palmitoleic acids. At the same time, the biomass concentration also decreased from 1015 mg·l−1 to 202 mg·l−1 over the range of Ds mentioned. Nonetheless, EPA productivity had a maximum value of 15.26 mg·l−1·day−1 at D=0.0208 h−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166076
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  • 2
    Electronic Resource
    Electronic Resource
    Biomass and icosapentaenoic acid productivities from an outdoor batch culture of Phaeodactylum tricornutum UTEX 640 in an airlift tubular photobioreactor (1995)
    Springer
    Applied microbiology and biotechnology 42 (1995), S. 658-663 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An outdoor tubular photobioreactor, based on an external-loop airlift, has been used to cultivate the diatom Phaeodactylum tricornutum UTEX 640, rich in icosapentaenoic acid (EPA). The system was operated in batch mode. The specific growth rate in the exponential phase, averaged over the whole day, was 0.254 day−1 · A 25 gl−1 maximum biomass concentration was obtained by the end of the culture period. The dissolved oxygen generated never rose over 210% of air saturation nor was there impediment to biomass generation or inhibition of photosynthesis. Furthermore, around 2 × 1017 quanta cm−2 s−1 light intensity seemed to saturate the photosynthetic activity. Biomass losses during the night could be reduced to less than 5% by maintaining the culture at 16°C at night. The maximum concentration and productivity of EPA were 423 mgl−1 and 13 mgl−1 day−1, respectively, at the end of the culture, although a 21-mgl−1 day−1 net EPA generation rate was obtained at the linear growth phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00171940
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  • 3
    Electronic Resource
    Electronic Resource
    Photolimitation and photoinhibition as factors determining optimal dilution rate to produce eicosapentaenoic acid from cultures of the microalga Isochrysis galbana (1998)
    Springer
    Applied microbiology and biotechnology 50 (1998), S. 199-205 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Eicosapentaenoic acid (EPA) productivity from continuous cultures of the marine microalga Isochrysis galbana was studied, taking into account the irradiance on the reactor surface, that is, the photolimitation/photoinhibition regime to which the cells are exposed. Experiments were conducted under a wide variety of operating conditions. The dilution rate ranged from 0.005 h−1 to 0.040 h−1 at five external irradiances (820, 1620, 2050, 2450 and 3270 μmol photons m−2 s−1) covering photolimited to photoinhibited growth. Under these conditions, the specific growth rate (μ) was found to be the main factor influencing EPA content (ranging from 2.35% to 5.23% dryweight) and productivity (up to 0.88 mg l−1 h−1). The fatty acid content was not significantly affected by the external irradiance, but was influenced by the state of growth of the microalga, depending on whether the light regime was photolimiting or photoinhibiting. It might be suggested that light should no longer be considered an isolated factor affecting EPA synthesis, but an indirect influence through the photolimitation/photoinhibition regime and growth rate. At a given dilution rate, EPA content and biomass concentration are lower under photoinhibiting external irradiances than those corresponding to photolimiting conditions, and consequently EPA productivity decays. Since the effect of photoinhibition is less marked at high biomass concentration, a strategy to optimize EPA productivity from microalgal cultures could consist of reducing the dilution rate when the external irradiance increases above the phoinhibition threshold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051277
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of growth rate on the eicosapentaenoic acid and docosahexaenoic acid content of Isochrysis galbana in chemostat culture (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 23-27 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An isolate of Isochrysis galbana rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been grown as a chemostat culture at 20° C and pH 8.00 controlled by CO2 injection. From a low dilution rate (D) of 0.0024 h−1 to 0.0377 h−1, close to maximum growth, a decrease in EPA content from 5.21% dry weight (d.w.) to 2.80% d.w. was observed, although the percentage of EPA in the total fatty acids increased. Lipids were fractionated, EPA being the major fatty acid found in the glycolipid fraction, whereas in the neutral lipid fraction were mainly palmitic and palmitoleic acids. At the same time, the biomass concentration also decreased from 1015 mg·l−1 to 202 mg·l−1 over the range of Ds mentioned. Nonetheless, EPA productivity had a maximum value of 15.26 mg·l−1·day−1 at D=0.0208 h−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166076
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  • 5
    Electronic Resource
    Electronic Resource
    Biomass and icosapentaenoic acid productivities from an outdoor batch culture of Phaeodactylum tricornutum UTEX 640 in an airlift tubular photobioreactor (1995)
    Springer
    Applied microbiology and biotechnology 42 (1995), S. 658-663 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  An outdoor tubular photobioreactor, based on an external-loop airlift, has been used to cultivate the diatom Phaeodactylum tricornutum UTEX 640, rich in icosapentaenoic acid (EPA). The system was operated in batch mode. The specific growth rate in the exponential phase, averaged over the whole day, was 0.254 day-1. A 25 g l-1 maximum biomass concentration was obtained by the end of the culture period. The dissolved oxygen generated never rose over 210% of air saturation nor was there impediment to biomass generation or inhibition of photosynthesis. Furthermore, around 2×1017 quanta cm-2 s-1 light intensity seemed to saturate the photosynthetic activity. Bio-mass losses during the night could be reduced to less than 5% by maintaining the culture at 16°C at night. The maximum concentration and productivity of EPA were 423 mg l-1 and 13 mg l-1 day-1, respectively, at the end of the culture, although a 21-mg l-1day-1 net EPA generation rate was obtained at the linear growth phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050309
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  • 6
    Electronic Resource
    Electronic Resource
    Productivity analysis of outdoor chemostat culture in tubular air-lift photobioreactors (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 369-380 
    Details
    ISSN: 1573-5176
    Keywords: Phaeodactylum tricornutum ; tubular photobioreactor ; outdoor culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Net productivity and biomass night losses in outdoor chemostat cultures ofPhaeodactylum tricornutum were analyzed in two tubular airlift photobioreactors at different dilution rates, photobioreactor surface/volume ratios and incident solar irradiance. In addition, an approximate model for the estimation of light profile and average irradiance inside outdoor tubular photobioreactors was proposed. In both photobioreactors, biomass productivity increased with dilution rate and daily incident solar radiation except at the highest incident solar irradiances and dilution rates, when photoinhibition effect was observed in the middle of the day. Variation of estimated average irradiance vs mean incident irradiance showed two effects: first, the outdoor cultures are adapted to average irradiance, and second, simultaneous photolimitation and photoinhibition took place at all assayed culture conditions, the extent of this phenomena being a function of the (incident)1 irradiance and light regime inside the culture. Productivity ranged between 0.50 and 2.04 g L−1 d−1 in the tubular photobioreactor with the lower surface/volume ratio (S/V = 77.5 m−1) and between 1.08 and 2.76 g L−1 d−1 in the other (S/V = 122.0 m−1). The optimum dilution rate was 0.040 h−1 in both reactors. Night-time biomass losses were a function of the average irradiance inside the culture, being lower in TPB0.03 than TPB0.06, due to a better light regime in the first. In both photobioreactors, biomass night losses strongly decreased when the photoinhibition effect was pronounced. However, net biomass productivity also decreased due to lower biomass generation during the day. Thus, optimum culture conditions were obtained when photolimitation and photoinhibition were balanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02178580
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  • 7
    Electronic Resource
    Electronic Resource
    Growth yield determination in a chemostat culture of the marine microalgaIsochrysis galbana (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 529-534 
    Details
    ISSN: 1573-5176
    Keywords: Quantum yield ; average irradiance ; light absorption ; photobioreactor ; photosynthetic efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth yield of the PUFA-producing marine microalgaIsochrysis galbana ALII-4 grown in a light limited chemostat, was measured under a wide variety of conditions of incident irradiance (I O ) and dilution rates (D). The experiments were conducted under laboratory conditions at 20 °C under continuous light. D ranged from 0.0024 to 0.0410 h−1 at three intensities of Io (820, 1620 and 3270 µmol photon m−2 s−1) close to those found in outdoor cultures. A maximum efficiency Ψ max = 0.616 g mol photon−1 was obtained at I O = 820 µmol photon m−2 s−1 and D = 0.030 h−1 and the maximum capacity of the biomass to metabolize the light harvested was found to be 13.1 µmol photon g−1 s−1. Above this value, a significant drop in the system efficiency was observed. A new approach based in the averaged irradiance is used to assess the photon flux absorbed by the biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186332
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of NaCl in the irrigation water on yield and quality of sweet pepper (Capsicum annuum) (1977)
    Springer
    Plant and soil 46 (1977), S. 405-411 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A field experiment was designed to determine the salt tolerance of three varieties of sweet pepper for paprika, studying the effects of four increasing levels of sodium chloride in the irrigation water (5, 10, 29 and 42 meq/l) on soil salinity, yields, and quality of the fruits. EC5:1 and the soluble sodium and chloride contents increased with increasing salinity. The yields were reduced by 5 per cent for variety ‘Ramillete’, 19 per cent for ‘Tres cascos’, and 40 per cent for ‘Bola’ at the highest level. The fruit quality variables studied (colour index and chloride contents) differed with the variety. re]19750925
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010096
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  • 9
    Electronic Resource
    Electronic Resource
    Salt tolerance of four tomato hybrids (1987)
    Springer
    Plant and soil 97 (1987), S. 233-241 
    Details
    ISSN: 1573-5036
    Keywords: Blossom-end rot ; Fruit quality ; Fruit yield ; Leaf mineral composition ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A greenhouse lysimeter experiment was conducted to evaluate the response of tomato hybrids to varying levels of salinity. Four tomato hybrids F-172, F-150, Bornia and Diego were grown at four salinity levels. The soil was salinized prior to transplanting by irrigating with waters that were prepared by adding NaCl to the tap water. The electrical conductivities of the irrigation waters were 1.8, 4.5, 7.0, and 9.5 dS/m at 25°C. Yield, fruit quality, and leaf mineral composition were measured. Fifty percent fruint yield reduction for all hybrids was associated with a soil salinity of 5.1 dS/m. Each unit increase in salinity above 2 dS/m reduced yield by 14%. This indicates that these tomato hybrids are more salt sensitive than the older varieties. Fruit quality and leaf mineral composition were also affected by salinity and hybrid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374946
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  • 10
    Electronic Resource
    Electronic Resource
    A model for light distribution and average solar irradiance inside outdoor tubular photobioreactors for the microalgal mass culture (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 701-714 
    Details
    ISSN: 0006-3592
    Keywords: tubular photobioreactors ; light distribution ; average solar irradiance ; light attenuation ; microalgae mass culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model to estimate the solar irradiance profile and average light intensity inside a tubular photobioreactor under outdoor conditions is proposed, requiring only geographic, geometric, and solar position parameters. First, the length of the path into the culture traveled by any direct or disperse ray of light was calculated as the function of three variables: day of year, solar hour, and geographic latitude. Then, the phenomenon of light attenuation by biomass was studied considering Lambert-Beer's law (only considering absorption) and the monodimensional model of Cornet et al. (1900) (considering absorption and scattering phenomena). Due to the existence of differential wavelength absorption, none of the literature models are useful for explaining light attenuation by the biomass. Therefore, an empirical hyperbolic expression is proposed. The equations to calculate light path length were substituted in the proposed hyperbolic expression, reproducing light intensity data obtained in the center of the loop tubes. The proposed model was also likely to estimate the irradiance accurately at any point inside the culture. Calculation of the local intensity was thus extended to the full culture volume in order to obtain the average irradiance, showing how the higher biomass productivities in a Phaeodactylum tricornutum UTEX 640 outdoor chemostat culture could be maintained by delaying light limitation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 701-714, 1997.
    Additional Material: 15 Ill.
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