Luuc Mur - Academia.edu (original) (raw)
Papers by Luuc Mur
Journal of General Microbiology, 1979
Limnology and Oceanography, 1982
Physiological information from chemostat-cultured Oscillatoria agardhii Gomont has been used to a... more Physiological information from chemostat-cultured Oscillatoria agardhii Gomont has been used to assess the nature of factors limiting growth rate in a natural population of this cyanobacterium, which dominates the phytoplankton in Lake Wolderwijd. Phosphorus, light (E), and nitrogen limited the growth rate of the population at different times of year: E and P limitation, alternately during January', February, and March; P limitation during April and May; N followed by E limitation in June; N limitation in July until mid-August, followed by P limitation until October; E limitation in October, November, and December. In winter, however, an effect of temperature on the phytoplankton growth could not be excluded. Internal nutrient and pigment contents cannot be used as physiological indicators without prior knowledge of the growth rates and light conditions in nature. Similarly, N:P ratios (internal or external) are not reliable indicators of Nor P-limited phytoplankton growth. On the other hand, nutrient uptake capacity values (
Limnology and Oceanography, 1986
Phosphate uptake capacity of natural phytoplankton populations was used as a physiological indica... more Phosphate uptake capacity of natural phytoplankton populations was used as a physiological indicator of P limitation in the Loosdrecht lakes. During a substantial period of the growth season of 1983, P-limited growth was observed in Lake fireukeleveen and Lake Loosdrecht, but P limitation was less severe in the latter. In Lake Breukeleveen the maximum initial phosphate uptake rate (V,,) varied between 0.3 and 5.7 pg P (pg Chl)-' h-l during P-limited growth, whereas in Lake Loosdrecht, V,, varied between 0.3 and 2.1 pg P (pg Chl)-' h-l. Both at the end of June and the beginning of July, growth was not P limited in either lake. Phytoplankton in Lake Loosdrccht was not limited by phosphorus in September. The frequent occurrence of P limitation led to the prediction that reduction of the P loadings of Lake Loosdrecht will result in a reduction of the phytoplankton biomass.
Journal of Plankton Research, 1991
Page 1. Journal of Plankton Research Vol 13 no 2 pp 419-436, 1991 Diurnal changes in buoyancy and... more Page 1. Journal of Plankton Research Vol 13 no 2 pp 419-436, 1991 Diurnal changes in buoyancy and vertical distribution in populations of Microcystis in two shallow lakes Bas W.Ibelings, Luuc R.Mur and Anthony E.Walsby1 ...
Journal of Plankton Research, 1985
Page 1. Journal of Plankton Research Vol.7 no.4 pp.487-495, 1985 Interactions between temperature... more Page 1. Journal of Plankton Research Vol.7 no.4 pp.487-495, 1985 Interactions between temperature and light intensity on growth and photosynthesis of the cyanobacterium OscUlatoria agardhii Anton F.Post, Rutger de Wit ...
Journal of Hypertension - J HYPERTENSION, 1997
Computer models can be helpful tools to provide abetter understanding of the mechanisms responsib... more Computer models can be helpful tools to provide abetter understanding of the mechanisms responsible forthe complex movements of cyanobacteria resulting fromchanges in buoyancy and mixing of the water column ina lake. Kromkamp & Walsby (1990) developed a verticalmigration model for Oscillatoria, that wasbased on the experimentally determinedrelationship between the rates of density change andphoton irradiance in this cyanobacterium. To adaptthis model to Microcystis, we determinedrelated changes in carbohydrate content in cultures ofMicrocystis. Samples were incubated at variousconstant values of photon irradiance and then placedin the dark. The changes in carbohydrate content ofthe cells during these incubations were investigated.The relationship between the ratio of carbohydrate toprotein and cell density in Microcystis wasestablished to permit conversion of the rates ofcarbohydrate change to rates of density change. Byplotting the calculated rates of density changeagainst the valu...
Journal of Experimental Marine Biology and Ecology, 2000
During the stationary phase of a batch culture of the epipelic diatom Cylindrotheca closterium, a... more During the stationary phase of a batch culture of the epipelic diatom Cylindrotheca closterium, accumulation of exopolysaccharides and intracellular carbohydrates was observed. When nitrogen was added to the culture in the stationary phase, growth was resumed and the accumulation of exopolysaccharides was delayed. This indicated that nitrogen depletion caused cessation of growth, and stimulated exopolysaccharide accumulation. Exopolysaccharide accumulation was also stimulated when cells were either resuspended in medium lacking N or P, or when they were inoculated in medium with low concentrations of N or P. Growth was not immediately affected by low N or P concentrations. S depletion only resulted in exopolysaccharide accumulation when growth was affected. Si or Fe depletion did not stimulate exopolysaccharide accumulation, even when growth rates were lowered. Apparently, stimulation of exopolysaccharide accumulation is dependent on the type of nutrient depletion. Intracellular storage carbohydrates did not accumulate when cells were incubated at low N or P concentrations. Cells grown with ammonium as nitrogen source produced more carbohydrates (both extracellular and intracellular) than cells grown with nitrate as nitrogen source, indicating that both exopolysaccharides and intracellular carbohydrates accumulated as a result of overflow metabolism.
Journal of Biotechnology, 1999
The specific growth rate of Chlamydomonas reinhardtii and Chlorella sorokiniana decreased under s... more The specific growth rate of Chlamydomonas reinhardtii and Chlorella sorokiniana decreased under square-wave light/dark cycles of medium duration, 13-87 s, in comparison to continuous illumination. Three experiments were done in three different turbidostats at saturating and sub-saturating light intensities during the light period, 240-630 mmol m − 2 s − 1. Within each experiment the light intensity during the light periods of the intermittent light regimes was equal and this intensity was also applied under continuous illumination. The specific growth rate decreased proportional or more than proportional to the fraction of time the algae were exposed to light; this light fraction ranged from 0.32 to 0.88. We conclude that under these light regimes the chlorophyta C. reinhardtii and C. sorokiniana are not able to store light energy in the light period to sustain growth in the dark period at the same rate as under continuous illumination. C. reinhardtii increased its specific light absorbing surface by increasing its chloropyll-a content under light/dark cycles of 13 s duration and a light fraction of 0.67 at 240 mmol m − 2 s − 1 ; the chloropyll-a content was twice as high under intermittent illumination in comparison to continuous illumination. The combination of a higher specific light absorption together with a lower specific growth rate led to a decrease of the yield of biomass on light energy under intermittent illumination.
Journal of Biotechnology, 2000
The light regime inside a photobioreactor is characterized by a light gradient with full (sun)lig... more The light regime inside a photobioreactor is characterized by a light gradient with full (sun)light at the light-exposed surface and darkness in the interior of the bioreactor. Consequently, depending on the mixing characteristics, algae will be exposed to certain light/dark cycles. In this study the green alga Chlamydomonas reinhardtii was cultivated under five different light regimes: (1) continuous illumination; (2) a square-wave light/dark cycle with a light fraction (m) of 0.5 and a duration (t c) of 6.1 s; (3) m =0.5, t c = 14.5 s; (4) m= 0.5, t c = 24.3 s and (5) m = 0.8, t c =15.2 s. The biomass yield on light energy, protein per photons, decreased under light/dark cycles (m =0.5) in comparison to continuous light (CL), from 0.207 (CL) to 0.117-0.153 g mol − 1 (m = 0.5). Concomitantly, the maximal specific photosynthetic activity, oxygen production per protein, decreased from 0.94 (CL) to 0.64-0.66 g g − 1 h − 1 (m=0.5). Also the quantum yield of photochemistry, yield of the conversion of light energy into chemical energy, decreased from 0.47 (CL) to 0.23 (m=0.5, t c =24.3 s). Apparently, C. reinhardtii is not able to maintain a high photosynthetic capacity under medium-duration light/dark cycles and since specific light absorption did not change, light utilization efficiency decreased in comparison to continuous illumination.
Hydrobiologia, 1992
Page 1. Hydrobiologia 238: 63-70, 1992. T. Berman, HJ Gons & LR Mur (eds), The Daily Grow... more Page 1. Hydrobiologia 238: 63-70, 1992. T. Berman, HJ Gons & LR Mur (eds), The Daily Growth Cycle of Phytoplankton. © 1992 Kluwer Academic Publishers. Printed in Belgium. 63 An algal cyclostat with computer-controlled dynamic light regime ...
Hydrobiologia, 1992
Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most impor... more Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most important parameters for microalgae cultivation. In this paper, the effect of medium frequency intermittent light on Auxenochlorella pyrenoidosa (formerly Chlorella pyrenoidosa) cultivation was investigated. Three parameters of intermittent light, light intensity, light/dark ratio, and light/dark cycle were employed and the influence of these parameters on the productivity of Auxenochlorella pyrenoidosa was studied. The biomass yield and growth rates were mainly affected by the light fraction and cycle time. Light with 220 µE m −2 s −1 light intensity was determined as the optimal light intensity for biomass production. At the light intensity of 420 µE m −2 s −1 , the results indicated that the intermittent light improved the biomass production with larger light/dark ratio compared with the continuous light. At a lower mean light intensity over time, the intermittent light should be more suitable for biomass growth and the decrease in the light/dark ratio (L/D) will lead to a higher biomass productivity. The light/dark cycle time has little influence on the biomass yield.
FEMS Microbiology Letters, 1978
FEMS Microbiology Letters, 1981
FEMS Microbiology Ecology, 1995
The influence of intermittent highlight dosage on Swrchocytis sp. PCC 6803 with respect to oxygen... more The influence of intermittent highlight dosage on Swrchocytis sp. PCC 6803 with respect to oxygen evolution capacity, fluorescence yield and carotenoid pigment pattern was investigated, using highlight and low-light-adapted cultures. The results showed that this cyanobacterium was able to survive high light stress for a full day if this stress was applied on and off with intermittently presented recovery periods in darkness. Enhanced respiratory activity in the highlight adapted cells was detected and this may be an important factor in preventing photodamage under high light stress. Cyanobacterial photosynthetic and respiratory electron transfer pathways are both present within the same membrane, and share common electron carriers. The role of respiratory activity in preventing overexcitation of photosystem 2 is discussed with regard to cyanobacterial ecology.
Enzyme and Microbial Technology, 2001
Inside photobioreactors algae are exposed to light/dark fluctuations. In this study the marine gr... more Inside photobioreactors algae are exposed to light/dark fluctuations. In this study the marine green alga Dunaliella tertiolecta was cultivated under short light/dark cycles of 3/3 s, 94/94 ms and 31/156 ms as found in medium and short light-path reactors. The photon flux density (PFD) during the light period was 440-455 mol m Ϫ2 s Ϫ1 and, under the 31/156 ms cycle only, 1025 mol m Ϫ2 s Ϫ1. The photosynthetic efficiency was determined and expressed as the biomass yield on light energy in gram protein produced per mol of photons absorbed. The yield under the 94/94 ms cycle was higher than the yield under continuous light of 440-455 mol m Ϫ2 s Ϫ1. Apparently a light integration effect occurs under the 94/94 ms cycle together with an increase of the photosynthetic efficiency. On the contrary, at the 3/3 s cycle the efficiency decreased. Also under the 31/156 ms cycle, with 1025 mol m Ϫ2 s Ϫ1 in the light period, the yield was lower than under continuous light. The results obtained under the 31/156 ms light/dark cycle are discussed with respect to the performance of short light-path flat panel photobioreactors operated at high biomass densities.
Biotechnology and Bioengineering, 1996
Light-emitting diodes (LEDs) were used as the sole light source in continuous culture of the gree... more Light-emitting diodes (LEDs) were used as the sole light source in continuous culture of the green alga Chlorella pyrenoidosa. The LEDs applied show a peak emission at 659 nm with a half-power bandwidth of 30 nm. Selection of this wavelength range, which is optimal for excitation of ...
Biotechnology and Bioengineering, 2002
Enclosed outdoor photobioreactors need to be developed and designed for large-scale production of... more Enclosed outdoor photobioreactors need to be developed and designed for large-scale production of phototrophic microorganisms. Both light regime and photosynthetic efficiency were analyzed in characteristic examples of state-of-the-art pilot-scale photobioreactors. In this study it is shown that productivity of photobioreactors is determined by the light regime inside the bioreactors. In addition to light regime, oxygen accumulation and shear stress limit productivity in certain designs. In short light-path systems, high efficiencies, 10% to 20% based on photosynthetic active radiation (PAR 400 to 700 nm), can be reached at high biomass concentrations (>5 kg [dry weight] m −3). It is demonstrated, however, that these and other photobioreactor designs are poorly scalable (maximal unit size 0.1 to 10 m 3), and/or not applicable for cultivation of monocultures. This is why a new photobioreactor design is proposed in which light capture is physically separated from photoautotrophic cultivation. This system can possibly be scaled to larger unit sizes, 10 to >100 m 3 , and the reactor liquid as a whole is mixed and aerated. It is deduced that high photosynthetic efficiencies, 15% on a PAR-basis, can be achieved. Future designs from optical engineers should be used to collect, concentrate, and transport sunlight, followed by redistribution in a large-scale photobioreactor.
Archives of Microbiology, 1984
Page 1. Arch Microbiol (1984) 139:232-239 Archives of Micrnbielegy 9 Springer-Verlag 1984 Growth ... more Page 1. Arch Microbiol (1984) 139:232-239 Archives of Micrnbielegy 9 Springer-Verlag 1984 Growth and photosynthetic response of the cyanobacterium Microcystis aeruginosa in relation to photoperiodicity and irradiance ...
Journal of General Microbiology, 1979
Limnology and Oceanography, 1982
Physiological information from chemostat-cultured Oscillatoria agardhii Gomont has been used to a... more Physiological information from chemostat-cultured Oscillatoria agardhii Gomont has been used to assess the nature of factors limiting growth rate in a natural population of this cyanobacterium, which dominates the phytoplankton in Lake Wolderwijd. Phosphorus, light (E), and nitrogen limited the growth rate of the population at different times of year: E and P limitation, alternately during January', February, and March; P limitation during April and May; N followed by E limitation in June; N limitation in July until mid-August, followed by P limitation until October; E limitation in October, November, and December. In winter, however, an effect of temperature on the phytoplankton growth could not be excluded. Internal nutrient and pigment contents cannot be used as physiological indicators without prior knowledge of the growth rates and light conditions in nature. Similarly, N:P ratios (internal or external) are not reliable indicators of Nor P-limited phytoplankton growth. On the other hand, nutrient uptake capacity values (
Limnology and Oceanography, 1986
Phosphate uptake capacity of natural phytoplankton populations was used as a physiological indica... more Phosphate uptake capacity of natural phytoplankton populations was used as a physiological indicator of P limitation in the Loosdrecht lakes. During a substantial period of the growth season of 1983, P-limited growth was observed in Lake fireukeleveen and Lake Loosdrecht, but P limitation was less severe in the latter. In Lake Breukeleveen the maximum initial phosphate uptake rate (V,,) varied between 0.3 and 5.7 pg P (pg Chl)-' h-l during P-limited growth, whereas in Lake Loosdrecht, V,, varied between 0.3 and 2.1 pg P (pg Chl)-' h-l. Both at the end of June and the beginning of July, growth was not P limited in either lake. Phytoplankton in Lake Loosdrccht was not limited by phosphorus in September. The frequent occurrence of P limitation led to the prediction that reduction of the P loadings of Lake Loosdrecht will result in a reduction of the phytoplankton biomass.
Journal of Plankton Research, 1991
Page 1. Journal of Plankton Research Vol 13 no 2 pp 419-436, 1991 Diurnal changes in buoyancy and... more Page 1. Journal of Plankton Research Vol 13 no 2 pp 419-436, 1991 Diurnal changes in buoyancy and vertical distribution in populations of Microcystis in two shallow lakes Bas W.Ibelings, Luuc R.Mur and Anthony E.Walsby1 ...
Journal of Plankton Research, 1985
Page 1. Journal of Plankton Research Vol.7 no.4 pp.487-495, 1985 Interactions between temperature... more Page 1. Journal of Plankton Research Vol.7 no.4 pp.487-495, 1985 Interactions between temperature and light intensity on growth and photosynthesis of the cyanobacterium OscUlatoria agardhii Anton F.Post, Rutger de Wit ...
Journal of Hypertension - J HYPERTENSION, 1997
Computer models can be helpful tools to provide abetter understanding of the mechanisms responsib... more Computer models can be helpful tools to provide abetter understanding of the mechanisms responsible forthe complex movements of cyanobacteria resulting fromchanges in buoyancy and mixing of the water column ina lake. Kromkamp & Walsby (1990) developed a verticalmigration model for Oscillatoria, that wasbased on the experimentally determinedrelationship between the rates of density change andphoton irradiance in this cyanobacterium. To adaptthis model to Microcystis, we determinedrelated changes in carbohydrate content in cultures ofMicrocystis. Samples were incubated at variousconstant values of photon irradiance and then placedin the dark. The changes in carbohydrate content ofthe cells during these incubations were investigated.The relationship between the ratio of carbohydrate toprotein and cell density in Microcystis wasestablished to permit conversion of the rates ofcarbohydrate change to rates of density change. Byplotting the calculated rates of density changeagainst the valu...
Journal of Experimental Marine Biology and Ecology, 2000
During the stationary phase of a batch culture of the epipelic diatom Cylindrotheca closterium, a... more During the stationary phase of a batch culture of the epipelic diatom Cylindrotheca closterium, accumulation of exopolysaccharides and intracellular carbohydrates was observed. When nitrogen was added to the culture in the stationary phase, growth was resumed and the accumulation of exopolysaccharides was delayed. This indicated that nitrogen depletion caused cessation of growth, and stimulated exopolysaccharide accumulation. Exopolysaccharide accumulation was also stimulated when cells were either resuspended in medium lacking N or P, or when they were inoculated in medium with low concentrations of N or P. Growth was not immediately affected by low N or P concentrations. S depletion only resulted in exopolysaccharide accumulation when growth was affected. Si or Fe depletion did not stimulate exopolysaccharide accumulation, even when growth rates were lowered. Apparently, stimulation of exopolysaccharide accumulation is dependent on the type of nutrient depletion. Intracellular storage carbohydrates did not accumulate when cells were incubated at low N or P concentrations. Cells grown with ammonium as nitrogen source produced more carbohydrates (both extracellular and intracellular) than cells grown with nitrate as nitrogen source, indicating that both exopolysaccharides and intracellular carbohydrates accumulated as a result of overflow metabolism.
Journal of Biotechnology, 1999
The specific growth rate of Chlamydomonas reinhardtii and Chlorella sorokiniana decreased under s... more The specific growth rate of Chlamydomonas reinhardtii and Chlorella sorokiniana decreased under square-wave light/dark cycles of medium duration, 13-87 s, in comparison to continuous illumination. Three experiments were done in three different turbidostats at saturating and sub-saturating light intensities during the light period, 240-630 mmol m − 2 s − 1. Within each experiment the light intensity during the light periods of the intermittent light regimes was equal and this intensity was also applied under continuous illumination. The specific growth rate decreased proportional or more than proportional to the fraction of time the algae were exposed to light; this light fraction ranged from 0.32 to 0.88. We conclude that under these light regimes the chlorophyta C. reinhardtii and C. sorokiniana are not able to store light energy in the light period to sustain growth in the dark period at the same rate as under continuous illumination. C. reinhardtii increased its specific light absorbing surface by increasing its chloropyll-a content under light/dark cycles of 13 s duration and a light fraction of 0.67 at 240 mmol m − 2 s − 1 ; the chloropyll-a content was twice as high under intermittent illumination in comparison to continuous illumination. The combination of a higher specific light absorption together with a lower specific growth rate led to a decrease of the yield of biomass on light energy under intermittent illumination.
Journal of Biotechnology, 2000
The light regime inside a photobioreactor is characterized by a light gradient with full (sun)lig... more The light regime inside a photobioreactor is characterized by a light gradient with full (sun)light at the light-exposed surface and darkness in the interior of the bioreactor. Consequently, depending on the mixing characteristics, algae will be exposed to certain light/dark cycles. In this study the green alga Chlamydomonas reinhardtii was cultivated under five different light regimes: (1) continuous illumination; (2) a square-wave light/dark cycle with a light fraction (m) of 0.5 and a duration (t c) of 6.1 s; (3) m =0.5, t c = 14.5 s; (4) m= 0.5, t c = 24.3 s and (5) m = 0.8, t c =15.2 s. The biomass yield on light energy, protein per photons, decreased under light/dark cycles (m =0.5) in comparison to continuous light (CL), from 0.207 (CL) to 0.117-0.153 g mol − 1 (m = 0.5). Concomitantly, the maximal specific photosynthetic activity, oxygen production per protein, decreased from 0.94 (CL) to 0.64-0.66 g g − 1 h − 1 (m=0.5). Also the quantum yield of photochemistry, yield of the conversion of light energy into chemical energy, decreased from 0.47 (CL) to 0.23 (m=0.5, t c =24.3 s). Apparently, C. reinhardtii is not able to maintain a high photosynthetic capacity under medium-duration light/dark cycles and since specific light absorption did not change, light utilization efficiency decreased in comparison to continuous illumination.
Hydrobiologia, 1992
Page 1. Hydrobiologia 238: 63-70, 1992. T. Berman, HJ Gons & LR Mur (eds), The Daily Grow... more Page 1. Hydrobiologia 238: 63-70, 1992. T. Berman, HJ Gons & LR Mur (eds), The Daily Growth Cycle of Phytoplankton. © 1992 Kluwer Academic Publishers. Printed in Belgium. 63 An algal cyclostat with computer-controlled dynamic light regime ...
Hydrobiologia, 1992
Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most impor... more Light (wavelength, intensity, and light/dark cycle) have been considered as one of the most important parameters for microalgae cultivation. In this paper, the effect of medium frequency intermittent light on Auxenochlorella pyrenoidosa (formerly Chlorella pyrenoidosa) cultivation was investigated. Three parameters of intermittent light, light intensity, light/dark ratio, and light/dark cycle were employed and the influence of these parameters on the productivity of Auxenochlorella pyrenoidosa was studied. The biomass yield and growth rates were mainly affected by the light fraction and cycle time. Light with 220 µE m −2 s −1 light intensity was determined as the optimal light intensity for biomass production. At the light intensity of 420 µE m −2 s −1 , the results indicated that the intermittent light improved the biomass production with larger light/dark ratio compared with the continuous light. At a lower mean light intensity over time, the intermittent light should be more suitable for biomass growth and the decrease in the light/dark ratio (L/D) will lead to a higher biomass productivity. The light/dark cycle time has little influence on the biomass yield.
FEMS Microbiology Letters, 1978
FEMS Microbiology Letters, 1981
FEMS Microbiology Ecology, 1995
The influence of intermittent highlight dosage on Swrchocytis sp. PCC 6803 with respect to oxygen... more The influence of intermittent highlight dosage on Swrchocytis sp. PCC 6803 with respect to oxygen evolution capacity, fluorescence yield and carotenoid pigment pattern was investigated, using highlight and low-light-adapted cultures. The results showed that this cyanobacterium was able to survive high light stress for a full day if this stress was applied on and off with intermittently presented recovery periods in darkness. Enhanced respiratory activity in the highlight adapted cells was detected and this may be an important factor in preventing photodamage under high light stress. Cyanobacterial photosynthetic and respiratory electron transfer pathways are both present within the same membrane, and share common electron carriers. The role of respiratory activity in preventing overexcitation of photosystem 2 is discussed with regard to cyanobacterial ecology.
Enzyme and Microbial Technology, 2001
Inside photobioreactors algae are exposed to light/dark fluctuations. In this study the marine gr... more Inside photobioreactors algae are exposed to light/dark fluctuations. In this study the marine green alga Dunaliella tertiolecta was cultivated under short light/dark cycles of 3/3 s, 94/94 ms and 31/156 ms as found in medium and short light-path reactors. The photon flux density (PFD) during the light period was 440-455 mol m Ϫ2 s Ϫ1 and, under the 31/156 ms cycle only, 1025 mol m Ϫ2 s Ϫ1. The photosynthetic efficiency was determined and expressed as the biomass yield on light energy in gram protein produced per mol of photons absorbed. The yield under the 94/94 ms cycle was higher than the yield under continuous light of 440-455 mol m Ϫ2 s Ϫ1. Apparently a light integration effect occurs under the 94/94 ms cycle together with an increase of the photosynthetic efficiency. On the contrary, at the 3/3 s cycle the efficiency decreased. Also under the 31/156 ms cycle, with 1025 mol m Ϫ2 s Ϫ1 in the light period, the yield was lower than under continuous light. The results obtained under the 31/156 ms light/dark cycle are discussed with respect to the performance of short light-path flat panel photobioreactors operated at high biomass densities.
Biotechnology and Bioengineering, 1996
Light-emitting diodes (LEDs) were used as the sole light source in continuous culture of the gree... more Light-emitting diodes (LEDs) were used as the sole light source in continuous culture of the green alga Chlorella pyrenoidosa. The LEDs applied show a peak emission at 659 nm with a half-power bandwidth of 30 nm. Selection of this wavelength range, which is optimal for excitation of ...
Biotechnology and Bioengineering, 2002
Enclosed outdoor photobioreactors need to be developed and designed for large-scale production of... more Enclosed outdoor photobioreactors need to be developed and designed for large-scale production of phototrophic microorganisms. Both light regime and photosynthetic efficiency were analyzed in characteristic examples of state-of-the-art pilot-scale photobioreactors. In this study it is shown that productivity of photobioreactors is determined by the light regime inside the bioreactors. In addition to light regime, oxygen accumulation and shear stress limit productivity in certain designs. In short light-path systems, high efficiencies, 10% to 20% based on photosynthetic active radiation (PAR 400 to 700 nm), can be reached at high biomass concentrations (>5 kg [dry weight] m −3). It is demonstrated, however, that these and other photobioreactor designs are poorly scalable (maximal unit size 0.1 to 10 m 3), and/or not applicable for cultivation of monocultures. This is why a new photobioreactor design is proposed in which light capture is physically separated from photoautotrophic cultivation. This system can possibly be scaled to larger unit sizes, 10 to >100 m 3 , and the reactor liquid as a whole is mixed and aerated. It is deduced that high photosynthetic efficiencies, 15% on a PAR-basis, can be achieved. Future designs from optical engineers should be used to collect, concentrate, and transport sunlight, followed by redistribution in a large-scale photobioreactor.
Archives of Microbiology, 1984
Page 1. Arch Microbiol (1984) 139:232-239 Archives of Micrnbielegy 9 Springer-Verlag 1984 Growth ... more Page 1. Arch Microbiol (1984) 139:232-239 Archives of Micrnbielegy 9 Springer-Verlag 1984 Growth and photosynthetic response of the cyanobacterium Microcystis aeruginosa in relation to photoperiodicity and irradiance ...