Background: Contamination of groundwater with nitrate has become an important environmental issue... more Background: Contamination of groundwater with nitrate has become an important environmental issue. Microalgae are especially effective agents for the removal of nitrate and nitrite from wastewaters, leading to a variety of bioremediation scenarios where algae assimilate nitrogen and convert it to biomass thus reclaiming contaminated water. This study evaluates the effects of high nitrate and nitrite concentrations on the kinetics of cell growth and nitrogen removal by Chlorella vulgaris. Methods: Algal growth and nitrate removal from media containing initial nitrate concentrations ranging from 1094 to 3000 mg L-1 were monitored in batch growth. Nitrite as the sole N source and simultaneous removal of nitrate and nitrite was also investigated. Results: Maximum growth and nitrate removal rates were 3.6 g L-1 and 16.4 mg L-1 h-1 respectively at a nitrate concentration of 2400 mg L-1 while 3000 mg L-1 nitrate appeared to inhibit growth yield but not nitrate uptake. Nitrite as the sole N source (400 mg L-1) resulted in optimal growth of Chlorella vulgaris with a maximum biomass of 3.16 g L-1. Nitrate and nitrite concentrations of 800 and 150 mg L-1 produced maximum growth rate and biomass production of 7.8 g L-1 biomass. Conclusion: This study demonstrate the potential of Chlorella vulgaris to efficiently remove and utilize both nitrate and nitrite from culture medium even at high initial concentrations while achieving high biomass productivity.
Microalgae have been used commercially as a feed-stock for the production of high-value compounds... more Microalgae have been used commercially as a feed-stock for the production of high-value compounds, pigments, cosmetics, and nutritional supplements. In addition, because of their rapid growth rates, high photosynthetic efficiency, and high lipid and protein content, commodity products including biodiesel, feed supplements, and polyunsaturated fatty acids derived from algal biomass are of current interest. Since microalgae lack non-photosynthetic structures and float in water , they do not need massive amounts of structural cellulose found in land plants. Thus, under optimal culture conditions, some oleaginous species can allocate up to 70 % of their bio-mass to lipids. Lipid production and its regulation in microalgae are species-specific and influenced by environmental conditions. Various strategies have been developed to improve lipid productivity and fatty acid composition to meet specific production goals. Manipulation of physiochemical parameters, tro-phic modes, and nutrient levels, known as process engineering, is a simple approach that leads to desired alterations in the biochemical composition of algal biomass, including lipid quantity and quality. In this paper, we review the effects of manipulating biochemical parameters such as necessary nutrients (C, N, P, S, Fe, and Si), NaCl concentration, and pH of culture medium to optimize lipid content and profile in some algae strains with commercial potential.
Many animals, plants, and microorganisms are harmed by ultraviolet-B radiation. In particular, se... more Many animals, plants, and microorganisms are harmed by ultraviolet-B radiation. In particular, several members of class amphibia are negatively affected by exposure to ultraviolet-B radiation. Exposure to ultraviolet-B radiation can cause death or various types of sublethal damage in amphibians. One mechanism to lessen the effect of harmful ultraviolet-B radiation is to limit exposure to sunlight behaviorally. Few studies have examined the behavioral sensitivity of adult amphibians to ultraviolet-B radiation. Using both field experiments and field observations, we found that two species of diurnal poison-dart frogs in Costa Rica (Dendrobates pumilio, D. auratus) consistently preferred areas in the field and within experimental testing chambers that offered low levels of ultraviolet-B radiation. In field observations, vocalizing D. pumilio were found at locations with significantly lower levels of ambient ultraviolet-B compared to random locations throughout their natural habitat. Ultraviolet-B avoidance behavior may be an important behavioral response for tropical frogs in light of recent evidence suggesting a significant increase in the levels of ambient ultraviolet-B radiation in the tropics over the past decade. Abstract in French is available at http://www.blackwell-synergy.com/loi/btp.
Mutants of Anabaena sp. PCC 7120 with O2-sensitive acetylene-reducing activity were studied to id... more Mutants of Anabaena sp. PCC 7120 with O2-sensitive acetylene-reducing activity were studied to identify envelope components that contribute to the barrier limiting diffusion of oxygen into the heterocyst. Mutant strain EF114, deficient in a heterocyst-specific glycolipid, reduced acetylene only under strictly anaerobic conditions. Analysis of in vivo O2 uptake as a function of dissolved pO2 showed that EF114 has lost
Mutants of Anabaena sp. strain PCC 7120 unable to grow aerobically on dinitrogen were isolated by... more Mutants of Anabaena sp. strain PCC 7120 unable to grow aerobically on dinitrogen were isolated by mutagenesis with UV irradiation, followed by a period of incubation in yellow light and then by penicillin enrichment. A cosmid vector, pRL25C, containing replicons functional in Escherichia coli and in Anabaena species was constructed. DNA from wild-type Anabaena sp. strain PCC 7120 was partially digested with Sau3AI, and size-fractionated fragments about 40 kilobases (kb) in length were ligated into the phosphatase-treated unique BamHI site of pRL25C. A library of 1,054 cosmid clones was generated in E. coli DH1 bearing helper plasmid pDS4101. A derivative of conjugative plasmid RP-4 was transferred to this library by conjugation, and the library was replicated to lawns of mutant Anabaena strains with defects in the polysaccharide layer of the envelopes of the heterocysts. Mutant EF116 was complemented by five cosmids, three of which were subjected to detailed restriction mapping; a 2...
Thesis (Ph. D. in Plant Physiology)--University of California, Berkeley, Dec. 1980. Bibliography:... more Thesis (Ph. D. in Plant Physiology)--University of California, Berkeley, Dec. 1980. Bibliography: leaves 245-266.
This report covers the progress during the third year of this project. The state-of-the-art of bi... more This report covers the progress during the third year of this project. The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The conclusions were that practical biophotolysis systems are feasible; however, they will require, in most cases, relatively long-term R and D. The biophotolysis system developed under this project, utilizing heterocystous blue-green algae, was demonstrated both indoors and outdoors with a model converter system using the heterocystous blue-green alga Anabaena cylindrica. Maximal light energy conversion efficiencies were 2.5% indoors and about 0.2% outdoors, averaged for periods of about two weeks. Achievement of such rates required optimization of N/sub 2/ supply and culture density. A small amount of N/sub 2/ in the argon gas phase used to sparge the cultures was beneficial to the stability of a long-term hydrogen-production activity. A relatively small amount of the hydrogen produced by these cultures can be ascribed...
The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The... more The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The conclusions were that practical biophotolysis systems are feasible; however, they will require, in most cases, relatively long-term R and D. The biophotolysis system developed, utilizing heterocystous blue-green algae, was demonstrated both indoors and outdoors with a model converter system using the heterocystous blue-green alga Anabaena cylindrica. Maximal light energy conversion efficiencies were 2.5 percent indoors and about 0.2 percent outdoors, averaged for periods of about two weeks. Achievement of such rates required optimization of N2 supply and culture density.
The regulation of nitrogenase. biosynthesis in the heterocystous blue-green alga, Anabaena cylind... more The regulation of nitrogenase. biosynthesis in the heterocystous blue-green alga, Anabaena cylindrica was studied in vivo. The action of ammonia on nitrogenase activity during heterocyst induction and in fully differentiated cultures was compared with that of selective inhibitors of transcription and translation. The process of heterocyst differentiation is known to become refractory to inhibition by ammonia at some intermediate stage. We now report that nitrogenase induction is also inhibited only in the early stages of heterocyst development. Later in the differentiation process, nitrogenase activity continued to increase in the presence of ammonia. The addition of ammonia to logarithmically growing cultures had little effect on nitrogenase activity on a volume basis; however, no new heterocysts were formed and specific activity declined as the cultures grew. Nitrogenase under these conditions is not stable since inhibition of protein synthesis resulted in rapid loss of enzyme act...
Kinetics of growth and nitrogenase induction inFrankia sp. Ar13 were studied in batch culture. Gr... more Kinetics of growth and nitrogenase induction inFrankia sp. Ar13 were studied in batch culture. Growth on defined medium with NH
... Marcia A. Murry 1,* ,; Anastasia S. Konopka 1 ,; S. Diane Pratt 2 ,; Thomas L. Vandergon 2. .... more ... Marcia A. Murry 1,* ,; Anastasia S. Konopka 1 ,; S. Diane Pratt 2 ,; Thomas L. Vandergon 2. ... M. & Normand, P. 1993. ... MEGA Molecular Evolutionary Genetics Analysis, version 1.01, Institute of Molecular Evolutionary Genetics, Pennsylvania State Univ., University Park PA . ...
Background: Contamination of groundwater with nitrate has become an important environmental issue... more Background: Contamination of groundwater with nitrate has become an important environmental issue. Microalgae are especially effective agents for the removal of nitrate and nitrite from wastewaters, leading to a variety of bioremediation scenarios where algae assimilate nitrogen and convert it to biomass thus reclaiming contaminated water. This study evaluates the effects of high nitrate and nitrite concentrations on the kinetics of cell growth and nitrogen removal by Chlorella vulgaris. Methods: Algal growth and nitrate removal from media containing initial nitrate concentrations ranging from 1094 to 3000 mg L-1 were monitored in batch growth. Nitrite as the sole N source and simultaneous removal of nitrate and nitrite was also investigated. Results: Maximum growth and nitrate removal rates were 3.6 g L-1 and 16.4 mg L-1 h-1 respectively at a nitrate concentration of 2400 mg L-1 while 3000 mg L-1 nitrate appeared to inhibit growth yield but not nitrate uptake. Nitrite as the sole N source (400 mg L-1) resulted in optimal growth of Chlorella vulgaris with a maximum biomass of 3.16 g L-1. Nitrate and nitrite concentrations of 800 and 150 mg L-1 produced maximum growth rate and biomass production of 7.8 g L-1 biomass. Conclusion: This study demonstrate the potential of Chlorella vulgaris to efficiently remove and utilize both nitrate and nitrite from culture medium even at high initial concentrations while achieving high biomass productivity.
Microalgae have been used commercially as a feed-stock for the production of high-value compounds... more Microalgae have been used commercially as a feed-stock for the production of high-value compounds, pigments, cosmetics, and nutritional supplements. In addition, because of their rapid growth rates, high photosynthetic efficiency, and high lipid and protein content, commodity products including biodiesel, feed supplements, and polyunsaturated fatty acids derived from algal biomass are of current interest. Since microalgae lack non-photosynthetic structures and float in water , they do not need massive amounts of structural cellulose found in land plants. Thus, under optimal culture conditions, some oleaginous species can allocate up to 70 % of their bio-mass to lipids. Lipid production and its regulation in microalgae are species-specific and influenced by environmental conditions. Various strategies have been developed to improve lipid productivity and fatty acid composition to meet specific production goals. Manipulation of physiochemical parameters, tro-phic modes, and nutrient levels, known as process engineering, is a simple approach that leads to desired alterations in the biochemical composition of algal biomass, including lipid quantity and quality. In this paper, we review the effects of manipulating biochemical parameters such as necessary nutrients (C, N, P, S, Fe, and Si), NaCl concentration, and pH of culture medium to optimize lipid content and profile in some algae strains with commercial potential.
Many animals, plants, and microorganisms are harmed by ultraviolet-B radiation. In particular, se... more Many animals, plants, and microorganisms are harmed by ultraviolet-B radiation. In particular, several members of class amphibia are negatively affected by exposure to ultraviolet-B radiation. Exposure to ultraviolet-B radiation can cause death or various types of sublethal damage in amphibians. One mechanism to lessen the effect of harmful ultraviolet-B radiation is to limit exposure to sunlight behaviorally. Few studies have examined the behavioral sensitivity of adult amphibians to ultraviolet-B radiation. Using both field experiments and field observations, we found that two species of diurnal poison-dart frogs in Costa Rica (Dendrobates pumilio, D. auratus) consistently preferred areas in the field and within experimental testing chambers that offered low levels of ultraviolet-B radiation. In field observations, vocalizing D. pumilio were found at locations with significantly lower levels of ambient ultraviolet-B compared to random locations throughout their natural habitat. Ultraviolet-B avoidance behavior may be an important behavioral response for tropical frogs in light of recent evidence suggesting a significant increase in the levels of ambient ultraviolet-B radiation in the tropics over the past decade. Abstract in French is available at http://www.blackwell-synergy.com/loi/btp.
Mutants of Anabaena sp. PCC 7120 with O2-sensitive acetylene-reducing activity were studied to id... more Mutants of Anabaena sp. PCC 7120 with O2-sensitive acetylene-reducing activity were studied to identify envelope components that contribute to the barrier limiting diffusion of oxygen into the heterocyst. Mutant strain EF114, deficient in a heterocyst-specific glycolipid, reduced acetylene only under strictly anaerobic conditions. Analysis of in vivo O2 uptake as a function of dissolved pO2 showed that EF114 has lost
Mutants of Anabaena sp. strain PCC 7120 unable to grow aerobically on dinitrogen were isolated by... more Mutants of Anabaena sp. strain PCC 7120 unable to grow aerobically on dinitrogen were isolated by mutagenesis with UV irradiation, followed by a period of incubation in yellow light and then by penicillin enrichment. A cosmid vector, pRL25C, containing replicons functional in Escherichia coli and in Anabaena species was constructed. DNA from wild-type Anabaena sp. strain PCC 7120 was partially digested with Sau3AI, and size-fractionated fragments about 40 kilobases (kb) in length were ligated into the phosphatase-treated unique BamHI site of pRL25C. A library of 1,054 cosmid clones was generated in E. coli DH1 bearing helper plasmid pDS4101. A derivative of conjugative plasmid RP-4 was transferred to this library by conjugation, and the library was replicated to lawns of mutant Anabaena strains with defects in the polysaccharide layer of the envelopes of the heterocysts. Mutant EF116 was complemented by five cosmids, three of which were subjected to detailed restriction mapping; a 2...
Thesis (Ph. D. in Plant Physiology)--University of California, Berkeley, Dec. 1980. Bibliography:... more Thesis (Ph. D. in Plant Physiology)--University of California, Berkeley, Dec. 1980. Bibliography: leaves 245-266.
This report covers the progress during the third year of this project. The state-of-the-art of bi... more This report covers the progress during the third year of this project. The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The conclusions were that practical biophotolysis systems are feasible; however, they will require, in most cases, relatively long-term R and D. The biophotolysis system developed under this project, utilizing heterocystous blue-green algae, was demonstrated both indoors and outdoors with a model converter system using the heterocystous blue-green alga Anabaena cylindrica. Maximal light energy conversion efficiencies were 2.5% indoors and about 0.2% outdoors, averaged for periods of about two weeks. Achievement of such rates required optimization of N/sub 2/ supply and culture density. A small amount of N/sub 2/ in the argon gas phase used to sparge the cultures was beneficial to the stability of a long-term hydrogen-production activity. A relatively small amount of the hydrogen produced by these cultures can be ascribed...
The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The... more The state-of-the-art of biophotolysis was reviewed and a bioengineering analysis carried out. The conclusions were that practical biophotolysis systems are feasible; however, they will require, in most cases, relatively long-term R and D. The biophotolysis system developed, utilizing heterocystous blue-green algae, was demonstrated both indoors and outdoors with a model converter system using the heterocystous blue-green alga Anabaena cylindrica. Maximal light energy conversion efficiencies were 2.5 percent indoors and about 0.2 percent outdoors, averaged for periods of about two weeks. Achievement of such rates required optimization of N2 supply and culture density.
The regulation of nitrogenase. biosynthesis in the heterocystous blue-green alga, Anabaena cylind... more The regulation of nitrogenase. biosynthesis in the heterocystous blue-green alga, Anabaena cylindrica was studied in vivo. The action of ammonia on nitrogenase activity during heterocyst induction and in fully differentiated cultures was compared with that of selective inhibitors of transcription and translation. The process of heterocyst differentiation is known to become refractory to inhibition by ammonia at some intermediate stage. We now report that nitrogenase induction is also inhibited only in the early stages of heterocyst development. Later in the differentiation process, nitrogenase activity continued to increase in the presence of ammonia. The addition of ammonia to logarithmically growing cultures had little effect on nitrogenase activity on a volume basis; however, no new heterocysts were formed and specific activity declined as the cultures grew. Nitrogenase under these conditions is not stable since inhibition of protein synthesis resulted in rapid loss of enzyme act...
Kinetics of growth and nitrogenase induction inFrankia sp. Ar13 were studied in batch culture. Gr... more Kinetics of growth and nitrogenase induction inFrankia sp. Ar13 were studied in batch culture. Growth on defined medium with NH
... Marcia A. Murry 1,* ,; Anastasia S. Konopka 1 ,; S. Diane Pratt 2 ,; Thomas L. Vandergon 2. .... more ... Marcia A. Murry 1,* ,; Anastasia S. Konopka 1 ,; S. Diane Pratt 2 ,; Thomas L. Vandergon 2. ... M. & Normand, P. 1993. ... MEGA Molecular Evolutionary Genetics Analysis, version 1.01, Institute of Molecular Evolutionary Genetics, Pennsylvania State Univ., University Park PA . ...
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