Yasuo Asada | Nihon University (original) (raw)
Papers by Yasuo Asada
Journal of Bioscience and Bioengineering, 1999
Cationic polyelectrolytes (chitosan, poly-l-lysine (PLL), polyethyleneimine (PEI) and trimethylam... more Cationic polyelectrolytes (chitosan, poly-l-lysine (PLL), polyethyleneimine (PEI) and trimethylammonium glycol chitosan iodide (TGCI)) were used to entrap anoxygenic phototrophic bacteria in order to prevent the inhibitory effect of NH4+ on hydrogen production. When combined with agar gel, chitosan and PLL demonstrated no obvious repressive effect on hydrogen production by Rhodobacter sphaeroides under light-anaerobic conditions with lactate and glutamate as the
International Journal of Biological Macromolecules, 1999
Regulatory mechanism in PHB [poly-(hydroxybutyrate)] accumulation by cyanobacteria, especially by... more Regulatory mechanism in PHB [poly-(hydroxybutyrate)] accumulation by cyanobacteria, especially by a thermophilic isolate, Synechococcus MA19 was reviewed in comparison with a genetically engineered strain. The strain, MA19 accumulates PHB under nitrogen starved and photoautotrophic conditions (MA19-N). Little PHB synthase activity was detected in crude extracts from the cells grown in nitrogen sufficient conditions (MA19+N). The activity was detected exclusively in
Biotechnology Letters, 1995
Effect of pH of culture media on intracellular accumulation of poly-(hydroxybutyrate) (PHB) by a ... more Effect of pH of culture media on intracellular accumulation of poly-(hydroxybutyrate) (PHB) by a non-sulfur photosynthetic bacterium, Rhodobacter sphaeroides strain RV was studied in pH-stat cultures. Sub-optimal pH for growth, 8.0 or 8.5 gave the higher content of PHB rather than optimal pH 7.5 for growth. These results show that growth and PHB accumulation of the bacteria can be controlled
Biochimica Et Biophysica Acta-gene Structure and Expression, 2000
The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus... more The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus PCC7942. The Shine–Dalgarno sequence of the structural gene encoding hydrogenase I from C. pasteurianum was changed to that of the cat (chloramphenicol acetyltransferase) gene. The hydrogenase gene was cloned downstream of a strong promoter, isolated from Synechococcus PCC7942, with the cat gene as a reporter gene. Expression of
Biotechnology Techniques, 1997
Clostridial hydrogenase was introduced into a cyanobacterium, Synechococcus elongatus, by direct ... more Clostridial hydrogenase was introduced into a cyanobacterium, Synechococcus elongatus, by direct electroporation. The introduced hydrogenase activity was 11 nmol H evolved with reduced Methyl Viologen per mg chlorophyll. The cells with clostridial hydrogenase showed simultaneous light-dependent evolution of H and O . This method will be applicable to assess a variety of hydrogenases for hydrogen production coupled with cyanobacterial photo-synthesis.
Biotechnology Techniques, 1993
A method for improving the adsorption of bacteria on glass surfaces was developed. The modificati... more A method for improving the adsorption of bacteria on glass surfaces was developed. The modification of a glass surface by LS-2480 greatly increased the number of bacteria that were immobilized. The conditions for bacteria immobilization on the modified glass surface were optimized.
Journal of Fermentation and Bioengineering, 1996
A thermophilic cyanobacterium strain MA19 that photoautotrophically accumulates a high amount of ... more A thermophilic cyanobacterium strain MA19 that photoautotrophically accumulates a high amount of poly-β-hydroxybutyrate (PHB) was isolated and identified as Synechococcus sp. This strain accumulated PHB at more than 20% of the dry cell weight after the cells were cultivated in a nitrogen-free inorganic medium aerated with 2% CO2. The PHB content was the highest in all the photoautotrophic organisms. PHB
International Journal of Hydrogen Energy, 2006
Hydrogen production with glucose by using co-immobilized cultures of a lactic acid bacterium, Lac... more Hydrogen production with glucose by using co-immobilized cultures of a lactic acid bacterium, Lactobacillus delbrueckii NBRC13953, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. Glucose was converted to hydrogen gas in a yield of 7.1mol of hydrogen per mole of glucose at a maximum under illuminated conditions.
Journal of Biotechnology, 1999
The study of biological hydrogen production by using photosynthetic bacteria and cyanobacteria is... more The study of biological hydrogen production by using photosynthetic bacteria and cyanobacteria is described based on a national R&D project in Japan. We describe here the subjects examined in the research for photosynthetic bacteria: analysis of the relationship between the penetration of light to photobioreactor and hydrogen production, genetic engineering of photosynthetic bacteria to control the pigment content for making
Chinese Journal of Oceanology and Limnology, 1998
Our efforts have been aimed at the technological basis of photosynthetic-microbial production of ... more Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium,Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilicSynechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes fromAlcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted.In vitro andin vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation ofSynechococcus PCC7942 with the hydrogenase gene fromClostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture ofRhodobacter andClostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium,Rhodobacter sphaeroides RV. A mutant acquired by UV irradiation will be characterized for the mutation and for hydrogen productivity in comparison with the wild type strain. Some basic studies to develop photobioreactors are also introduced.
Hydrogen evolution by a nitrogen-fixing cyanobacterium, Anabaena sp. strain N-7363, was tested in... more Hydrogen evolution by a nitrogen-fixing cyanobacterium, Anabaena sp. strain N-7363, was tested in order to develop a water biophotolysis system under aerobic conditions. A culture of the strain supplemented with carbon dioxide under an air atmosphere evolved hydrogen and oxygen gas, which reached final concentrations of 9.7 and 69.8%, respectively, after 12 days of incubation. Hydrogen uptake activity was not
Methods of illumination to simulate the dally sunlight irradiation pattern were studied in relati... more Methods of illumination to simulate the dally sunlight irradiation pattern were studied in relation to photohydrogen production using the photosynthetic bacterium Rhodobacter sphueroides RV. Three illumination patterns were compared, in which the light intensity was changed in 1, 3, or 6 steps. As a control, outdoor experiments were also carried out over a 3-d period in Tsukuba, August 1996. Outdoors, hydrogen production by Rba. sphaeroides RV was dependent on the sunlight intensity: the total volume of hydrogen produced per day varied from 14 to 28 Z-m-2, while the total light energy ranged from 5.5 to 6.4 kWh.m-2=d-1. The maximum hydrogen production rate was 2.8 Z*m-2-h-1 under a 4.5cm light path and the average light energy conversion efficiency was 1.1%. Indoors, the hydrogen production rate was found to be independent of the mode of illumination among the three patterns employed. The maximum hydrogen production rate was 3.3 1. rnm2.h-' with a light energy conversion efficiency of l.O%, and it was concluded that the single-step illumination method provides an appropriate simulation of sunlight. Saturation of hydrogen production occurs during high light intensity around noon and this plays a key role in the simulation.
ABSTRACT In order to use photosynthetic bacteria for efficient hydrogen production after anaerobi... more ABSTRACT In order to use photosynthetic bacteria for efficient hydrogen production after anaerobic hydrogen and acetate fermentation, hydrogen-producing activity from acetate by agar-immobilized photosynthetic bacteria was evaluated under light-illuminated conditions. Among the tested 5 strains, Rhodobacter sphaeroides RV gave similar rate of hydrogen production as the case of lactate, and the yield was as high as 2.65–2.81 mol of hydrogen per mol of acetate consumed. R. sphaeroides IL106 gave the highest yield of 3.03 mol of hydrogen per acetate when acetate concentration was low.
Journal of Fermentation and Bioengineering, 1997
The non nitrogen-fixing and 6lamentous cyanobacterium Spirulina platensis NIES-46 produced hydrog... more The non nitrogen-fixing and 6lamentous cyanobacterium Spirulina platensis NIES-46 produced hydrogen gas, ethanol, and low molecular organic acids auto-fermentatively under dark and anaerobic conditions. The fermentative productivity was enhanced by incubating the cyanobacterium under nitrogen-starved conditions. Cell-free extracts of the cyanobacterium catalyzed hydrogen production by the addition of acetyl-coenzyme A and pyruvate. Pyruvate-degrading and acetaldehyde dehydrogenase activities were observed in the cell-free extracts. These results suggest that the fermentation was dependent on the anaerobic degradation of endogenous glycogen via pyruvate.
Journal of Fermentation and Bioengineering, 1997
A stable photoreaction system was developed using cactus chloroplasts coupled with the fused enzy... more A stable photoreaction system was developed using cactus chloroplasts coupled with the fused enzyme between rat cytochrome P4501Al (CYPlAl) and yeast NADPH-cytochrome P450 oxidoreductase expressed in yeast microsomes. The fused enzyme catalyzed o-deethylation of 'I-ethoxycoumarin to 7-hydroxycoumarin using molecular oxygen and NADPH produced by photosystems I and II. Cactus chloroplast were found to constitute a good material for use as a NADPH-regenerating system in bioreactors. For NADPH formation, cactus chloroplasts showed twice as much activity as those of spinach when the same chlorophyll concentration was used at 30°C, as well as being more thermostable. The optimal temperature for NADPH formation with cactus chloroplasts was 42S°C, whereas for spinach it ranged from 20 to 30°C. Cactus chloroplasts can thus be applied in bioreactor NADPH-regenerating systems using oxido-reductive enzymes like P45Os.
Journal of Fermentation and Bioengineering, 1995
The penetration of light into a photobioreactor and its relation to hydrogen production were anal... more The penetration of light into a photobioreactor and its relation to hydrogen production were analyzed using a photosynthetic bacterium, Rhodobacter sphaeroides. A photobioreactor composed of four compartments aligned along the light penetration axis, each with a OS-cm light path, was used to examine the hydrogen evolution at various light penetration depths. The light energy decreased quasi-exponentially upon passage through the bacterial suspension (1.5 mg dry wt./ml). In the first compartment (O-O.5 cm), 69% of the incident light energy was absorbed, 21% in the second one (OS-l.0 cm) and 7% in the third one (1.0-1.5 cm). However, the hydrogen evolution rates did not decrease as the light energy. The efficiency of the conversion of light to hydrogen increased with the depth in the reactor and the third compartment showed the highest efficiency. Excess absorption of light energy in the shaliow region reduced the total efficiency of the reactor. Alteration of the light spectrum upon passage of the light through the bacterial suspension greatly affected the hydrogen production. In the deep region of the reactor, energy of light of wavelength around the absorption maxima of the bacterium (800-850 nm) was lost. Light reaching the deep region was mainly of wavelength between 600 and 780 nm, and was also used for hydrogen production.
International Journal of Hydrogen Energy, 1999
Hydrogen production from the wastewater of tofu factory was examined by using anoxygenic phototro... more Hydrogen production from the wastewater of tofu factory was examined by using anoxygenic phototrophic bacterium Rhodobacter sphaeroides immobilized in agar gels[ The maximum rate of hydrogen production observed from the wastewater was 1[0 l h −0 m 1 gel which was even slightly higher than that from a glucose medium "as control#[ The hydrogen production lasted up to 49 h[ The yield of hydrogen was 0[8 ml:ml wastewater or 9[13 ml:mg carbohydrates contained in the wastewater[ This yield corresponds to 42) or 54) of that from the glucose medium\ according to the di}erent expressions of the yield[ The TOC "total organic carbon# removal ratio in 74 h reached 30) which was comparable to that from the glucose medium[ The immobilization protected the bacterium from the inhibitory e}ect of ammonium ion[ Þ 0888 International Association for Hydrogen Energy[ Published by Elsevier Science Ltd[ All rights reserved[
Journal of Bioscience and Bioengineering, 1999
A stable mutant of the photosynthetic bacterium Rhodobacter sphaeroides with an altered light-har... more A stable mutant of the photosynthetic bacterium Rhodobacter sphaeroides with an altered light-harvesting (LH) system (P3 mutant) was obtained by UV irradiation and characterized. The mutant exhibited a 2.7-fold decrease in the core antennal (LH1) content and 1.6-fold increase in peripheral antennal (LH2) content compared to the wild-type strain. The H2 evolution rates in the P3 mutant under 800- and
Journal of Bioscience and Bioengineering, 1999
The principles and recent progress in the research and development of photobiological hydrogen pr... more The principles and recent progress in the research and development of photobiological hydrogen production are reviewed. Cyanobacteria produce hydrogen gas using nitrogenase and/or hydrogenase. Hydrogen production mediated by native hydrogenases in cyanobacteria occurs under in the dark under anaerobic conditions by degradation of intracellular glycogen. In vitro and in vivo coupling of the cyanobacterial photosynthetic system with a clostridial hydrogenase
Journal of Bioscience and Bioengineering, 1999
Cationic polyelectrolytes (chitosan, poly-l-lysine (PLL), polyethyleneimine (PEI) and trimethylam... more Cationic polyelectrolytes (chitosan, poly-l-lysine (PLL), polyethyleneimine (PEI) and trimethylammonium glycol chitosan iodide (TGCI)) were used to entrap anoxygenic phototrophic bacteria in order to prevent the inhibitory effect of NH4+ on hydrogen production. When combined with agar gel, chitosan and PLL demonstrated no obvious repressive effect on hydrogen production by Rhodobacter sphaeroides under light-anaerobic conditions with lactate and glutamate as the
International Journal of Biological Macromolecules, 1999
Regulatory mechanism in PHB [poly-(hydroxybutyrate)] accumulation by cyanobacteria, especially by... more Regulatory mechanism in PHB [poly-(hydroxybutyrate)] accumulation by cyanobacteria, especially by a thermophilic isolate, Synechococcus MA19 was reviewed in comparison with a genetically engineered strain. The strain, MA19 accumulates PHB under nitrogen starved and photoautotrophic conditions (MA19-N). Little PHB synthase activity was detected in crude extracts from the cells grown in nitrogen sufficient conditions (MA19+N). The activity was detected exclusively in
Biotechnology Letters, 1995
Effect of pH of culture media on intracellular accumulation of poly-(hydroxybutyrate) (PHB) by a ... more Effect of pH of culture media on intracellular accumulation of poly-(hydroxybutyrate) (PHB) by a non-sulfur photosynthetic bacterium, Rhodobacter sphaeroides strain RV was studied in pH-stat cultures. Sub-optimal pH for growth, 8.0 or 8.5 gave the higher content of PHB rather than optimal pH 7.5 for growth. These results show that growth and PHB accumulation of the bacteria can be controlled
Biochimica Et Biophysica Acta-gene Structure and Expression, 2000
The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus... more The Clostridium pasteurianum hydrogenase I has been expressed in the cyanobacterium Synechococcus PCC7942. The Shine–Dalgarno sequence of the structural gene encoding hydrogenase I from C. pasteurianum was changed to that of the cat (chloramphenicol acetyltransferase) gene. The hydrogenase gene was cloned downstream of a strong promoter, isolated from Synechococcus PCC7942, with the cat gene as a reporter gene. Expression of
Biotechnology Techniques, 1997
Clostridial hydrogenase was introduced into a cyanobacterium, Synechococcus elongatus, by direct ... more Clostridial hydrogenase was introduced into a cyanobacterium, Synechococcus elongatus, by direct electroporation. The introduced hydrogenase activity was 11 nmol H evolved with reduced Methyl Viologen per mg chlorophyll. The cells with clostridial hydrogenase showed simultaneous light-dependent evolution of H and O . This method will be applicable to assess a variety of hydrogenases for hydrogen production coupled with cyanobacterial photo-synthesis.
Biotechnology Techniques, 1993
A method for improving the adsorption of bacteria on glass surfaces was developed. The modificati... more A method for improving the adsorption of bacteria on glass surfaces was developed. The modification of a glass surface by LS-2480 greatly increased the number of bacteria that were immobilized. The conditions for bacteria immobilization on the modified glass surface were optimized.
Journal of Fermentation and Bioengineering, 1996
A thermophilic cyanobacterium strain MA19 that photoautotrophically accumulates a high amount of ... more A thermophilic cyanobacterium strain MA19 that photoautotrophically accumulates a high amount of poly-β-hydroxybutyrate (PHB) was isolated and identified as Synechococcus sp. This strain accumulated PHB at more than 20% of the dry cell weight after the cells were cultivated in a nitrogen-free inorganic medium aerated with 2% CO2. The PHB content was the highest in all the photoautotrophic organisms. PHB
International Journal of Hydrogen Energy, 2006
Hydrogen production with glucose by using co-immobilized cultures of a lactic acid bacterium, Lac... more Hydrogen production with glucose by using co-immobilized cultures of a lactic acid bacterium, Lactobacillus delbrueckii NBRC13953, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. Glucose was converted to hydrogen gas in a yield of 7.1mol of hydrogen per mole of glucose at a maximum under illuminated conditions.
Journal of Biotechnology, 1999
The study of biological hydrogen production by using photosynthetic bacteria and cyanobacteria is... more The study of biological hydrogen production by using photosynthetic bacteria and cyanobacteria is described based on a national R&D project in Japan. We describe here the subjects examined in the research for photosynthetic bacteria: analysis of the relationship between the penetration of light to photobioreactor and hydrogen production, genetic engineering of photosynthetic bacteria to control the pigment content for making
Chinese Journal of Oceanology and Limnology, 1998
Our efforts have been aimed at the technological basis of photosynthetic-microbial production of ... more Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium,Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilicSynechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes fromAlcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted.In vitro andin vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation ofSynechococcus PCC7942 with the hydrogenase gene fromClostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture ofRhodobacter andClostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium,Rhodobacter sphaeroides RV. A mutant acquired by UV irradiation will be characterized for the mutation and for hydrogen productivity in comparison with the wild type strain. Some basic studies to develop photobioreactors are also introduced.
Hydrogen evolution by a nitrogen-fixing cyanobacterium, Anabaena sp. strain N-7363, was tested in... more Hydrogen evolution by a nitrogen-fixing cyanobacterium, Anabaena sp. strain N-7363, was tested in order to develop a water biophotolysis system under aerobic conditions. A culture of the strain supplemented with carbon dioxide under an air atmosphere evolved hydrogen and oxygen gas, which reached final concentrations of 9.7 and 69.8%, respectively, after 12 days of incubation. Hydrogen uptake activity was not
Methods of illumination to simulate the dally sunlight irradiation pattern were studied in relati... more Methods of illumination to simulate the dally sunlight irradiation pattern were studied in relation to photohydrogen production using the photosynthetic bacterium Rhodobacter sphueroides RV. Three illumination patterns were compared, in which the light intensity was changed in 1, 3, or 6 steps. As a control, outdoor experiments were also carried out over a 3-d period in Tsukuba, August 1996. Outdoors, hydrogen production by Rba. sphaeroides RV was dependent on the sunlight intensity: the total volume of hydrogen produced per day varied from 14 to 28 Z-m-2, while the total light energy ranged from 5.5 to 6.4 kWh.m-2=d-1. The maximum hydrogen production rate was 2.8 Z*m-2-h-1 under a 4.5cm light path and the average light energy conversion efficiency was 1.1%. Indoors, the hydrogen production rate was found to be independent of the mode of illumination among the three patterns employed. The maximum hydrogen production rate was 3.3 1. rnm2.h-' with a light energy conversion efficiency of l.O%, and it was concluded that the single-step illumination method provides an appropriate simulation of sunlight. Saturation of hydrogen production occurs during high light intensity around noon and this plays a key role in the simulation.
ABSTRACT In order to use photosynthetic bacteria for efficient hydrogen production after anaerobi... more ABSTRACT In order to use photosynthetic bacteria for efficient hydrogen production after anaerobic hydrogen and acetate fermentation, hydrogen-producing activity from acetate by agar-immobilized photosynthetic bacteria was evaluated under light-illuminated conditions. Among the tested 5 strains, Rhodobacter sphaeroides RV gave similar rate of hydrogen production as the case of lactate, and the yield was as high as 2.65–2.81 mol of hydrogen per mol of acetate consumed. R. sphaeroides IL106 gave the highest yield of 3.03 mol of hydrogen per acetate when acetate concentration was low.
Journal of Fermentation and Bioengineering, 1997
The non nitrogen-fixing and 6lamentous cyanobacterium Spirulina platensis NIES-46 produced hydrog... more The non nitrogen-fixing and 6lamentous cyanobacterium Spirulina platensis NIES-46 produced hydrogen gas, ethanol, and low molecular organic acids auto-fermentatively under dark and anaerobic conditions. The fermentative productivity was enhanced by incubating the cyanobacterium under nitrogen-starved conditions. Cell-free extracts of the cyanobacterium catalyzed hydrogen production by the addition of acetyl-coenzyme A and pyruvate. Pyruvate-degrading and acetaldehyde dehydrogenase activities were observed in the cell-free extracts. These results suggest that the fermentation was dependent on the anaerobic degradation of endogenous glycogen via pyruvate.
Journal of Fermentation and Bioengineering, 1997
A stable photoreaction system was developed using cactus chloroplasts coupled with the fused enzy... more A stable photoreaction system was developed using cactus chloroplasts coupled with the fused enzyme between rat cytochrome P4501Al (CYPlAl) and yeast NADPH-cytochrome P450 oxidoreductase expressed in yeast microsomes. The fused enzyme catalyzed o-deethylation of 'I-ethoxycoumarin to 7-hydroxycoumarin using molecular oxygen and NADPH produced by photosystems I and II. Cactus chloroplast were found to constitute a good material for use as a NADPH-regenerating system in bioreactors. For NADPH formation, cactus chloroplasts showed twice as much activity as those of spinach when the same chlorophyll concentration was used at 30°C, as well as being more thermostable. The optimal temperature for NADPH formation with cactus chloroplasts was 42S°C, whereas for spinach it ranged from 20 to 30°C. Cactus chloroplasts can thus be applied in bioreactor NADPH-regenerating systems using oxido-reductive enzymes like P45Os.
Journal of Fermentation and Bioengineering, 1995
The penetration of light into a photobioreactor and its relation to hydrogen production were anal... more The penetration of light into a photobioreactor and its relation to hydrogen production were analyzed using a photosynthetic bacterium, Rhodobacter sphaeroides. A photobioreactor composed of four compartments aligned along the light penetration axis, each with a OS-cm light path, was used to examine the hydrogen evolution at various light penetration depths. The light energy decreased quasi-exponentially upon passage through the bacterial suspension (1.5 mg dry wt./ml). In the first compartment (O-O.5 cm), 69% of the incident light energy was absorbed, 21% in the second one (OS-l.0 cm) and 7% in the third one (1.0-1.5 cm). However, the hydrogen evolution rates did not decrease as the light energy. The efficiency of the conversion of light to hydrogen increased with the depth in the reactor and the third compartment showed the highest efficiency. Excess absorption of light energy in the shaliow region reduced the total efficiency of the reactor. Alteration of the light spectrum upon passage of the light through the bacterial suspension greatly affected the hydrogen production. In the deep region of the reactor, energy of light of wavelength around the absorption maxima of the bacterium (800-850 nm) was lost. Light reaching the deep region was mainly of wavelength between 600 and 780 nm, and was also used for hydrogen production.
International Journal of Hydrogen Energy, 1999
Hydrogen production from the wastewater of tofu factory was examined by using anoxygenic phototro... more Hydrogen production from the wastewater of tofu factory was examined by using anoxygenic phototrophic bacterium Rhodobacter sphaeroides immobilized in agar gels[ The maximum rate of hydrogen production observed from the wastewater was 1[0 l h −0 m 1 gel which was even slightly higher than that from a glucose medium "as control#[ The hydrogen production lasted up to 49 h[ The yield of hydrogen was 0[8 ml:ml wastewater or 9[13 ml:mg carbohydrates contained in the wastewater[ This yield corresponds to 42) or 54) of that from the glucose medium\ according to the di}erent expressions of the yield[ The TOC "total organic carbon# removal ratio in 74 h reached 30) which was comparable to that from the glucose medium[ The immobilization protected the bacterium from the inhibitory e}ect of ammonium ion[ Þ 0888 International Association for Hydrogen Energy[ Published by Elsevier Science Ltd[ All rights reserved[
Journal of Bioscience and Bioengineering, 1999
A stable mutant of the photosynthetic bacterium Rhodobacter sphaeroides with an altered light-har... more A stable mutant of the photosynthetic bacterium Rhodobacter sphaeroides with an altered light-harvesting (LH) system (P3 mutant) was obtained by UV irradiation and characterized. The mutant exhibited a 2.7-fold decrease in the core antennal (LH1) content and 1.6-fold increase in peripheral antennal (LH2) content compared to the wild-type strain. The H2 evolution rates in the P3 mutant under 800- and
Journal of Bioscience and Bioengineering, 1999
The principles and recent progress in the research and development of photobiological hydrogen pr... more The principles and recent progress in the research and development of photobiological hydrogen production are reviewed. Cyanobacteria produce hydrogen gas using nitrogenase and/or hydrogenase. Hydrogen production mediated by native hydrogenases in cyanobacteria occurs under in the dark under anaerobic conditions by degradation of intracellular glycogen. In vitro and in vivo coupling of the cyanobacterial photosynthetic system with a clostridial hydrogenase