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Zvi Cohen - One of the best experts on this subject based on the ideXlab platform.
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the effect of phosphate starvation on the lipid and fatty acid composition of the fresh water eustigmatophyte Monodus subterraneus
Phytochemistry, 2006Co-Authors: Inna Khozingoldberg, Zvi CohenAbstract:Abstract Phosphate limitation caused significant changes in the fatty acid and lipid composition of Monodus subterraneus . With decreasing phosphate availability from 175 to 52.5, 17.5 and 0 μM (K 2 HPO 4 ), the proportion of the major VLC-PUFA, eicosapentaenoic acid (EPA), gradually decreased from 28.2 to 20.8, 19.4 and 15.5 mol% (of total fatty acids), respectively. The cellular total lipid content of starved cells increased, mainly due to the dramatic increase in triacylglycerols (TAG) levels. Among polar lipids, cellular contents of digalactosyldiacylglycerol (DGDG) and diacylglyceroltrimethylhomoserine (DGTS) increased sharply from 0.29 and 0.19 to 0.60 and 0.38 fg cell −1 , respectively, while that of monogalactosyldiacylglycerol (MGDG) was not significantly changed. In the absence of phosphate, the proportion of phospholipids was significantly reduced from 8.3% to 1.4% of total lipids, and the proportion of triacylglycerols (TAG) increased from 6.5% up to 39.3% of total lipids. The share of MGDG was substantially reduced, from 35.7% to 13.3%, while that of DGDG and DGTS reduced less from 18.3% to 15.1%, and 12.2% to 8.6%, respectively. The most distinctive change in the fatty acid composition was noted in that of DGDG, where the proportion of EPA, located exclusively at the sn -1 position, increased from 11.3% to 21.5% at the expense of 16:0, 16:1 and 18:1. In MGDG, however, the proportion of EPA did not change appreciably. In contrast to higher plants, DGDG accumulated under P-deprivation in M. subterraneus , did not resemble PC and the positional distribution of its fatty acids was not altered, preserving the C20/C16 structure of its molecular species. We suggest that under phosphate starvation DGTS is a likely source of C 20 acyl groups that can be exported to the sn -1 position of DGDG and can partially compensate for the decrease in PE, the apparent source of C 20 acyl-containing diacylglycerols in this alga. Moreover, accumulation of non-esterified 18:0 indicates that no polar lipid can replace PC, which appears to be the only lipid capable of C 18 desaturation in this alga.
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biosynthesis of eicosapentaenoic acid epa in the freshwater eustigmatophyte Monodus subterraneus eustigmatophyceae 1
Journal of Phycology, 2002Co-Authors: Inna Khozingoldberg, Shoshana Didicohen, Intyk Shayakhmetova, Zvi CohenAbstract:In an attempt to elucidate the biosynthesis of the polyunsaturated fatty acid eicosapentaenoic acid (20:5 � 3, EPA), we treated cultures of the eustigmatophyte Monodus subterraneus Peterson with either salicylhydroxamic acid or the herbicide SAN 9785. Labeled linoleic acid was incorporated into the cultures in the presence and absence of the latter inhibitor, and the redistribution of label was followed. Our results suggest that the major biosynthetic pathway leading to EPA involves fatty acids of the � 6 family. In the early stages of the biosynthesis, 18:1 is predominantly incorporated to the sn -2 position of phosphatidylcholine, where it is stepwise desaturated by the � 12 and � 6 desaturases to 18:3 � 6. The latter is released from the lipid, elongated to 20:3 � 6 and reincorporated to both positions of phosphatidylethanolamine (PE) where it is further desaturated by the � 5 and � 3 desaturases to EPA. We suggest that PE is the donor of the 20:5/20:5 diacylglycerol that is imported to the chloroplast to form the eukaryotic-like molecular species of monogalactosyldiacylglycerol. Likewise, 20:3 � 6 can be also incorporated into diacylglyceryltrimethylhomoserine, mostly to the sn -2 position and similarly desaturated to 20:4 � 6 and 20:5 � 3. These fatty acids can be exported and incorporated into the sn -1 position of the prokaryoticlike molecular species of the chloroplastic lipids. We thus suggest that both the eukaryotic-like and the prokaryotic-like molecular species are biosynthesized by different extraplastidial lipids. Key index words: algal lipids; EPA biosynthesis; eukaryotic pathway; fatty acid desaturation; LC-PUFA; Monodus subterraneus ; salicylhydroxamic acid; SAN 9785 Abbreviations: C n fatty acid, fatty acid with n carbon atoms; � n D, a fatty acid desaturase that introduces a double bond at the n th carbon atom from the carboxylic end; DAG, diacylglycerol; DGDG, digalactosyldiacylglycerol; DGTS, diacylglyceryltrimethylhomoserine; EPA, eicosapentaenoic acid (20:5 � 3); MGDG, monogalactosyldiacylglycerol; MLC, medium to long chain (14‐18 carbon atoms); PC, phosphatidylcholine; PE, phosphatidylethanolamine; PUFA, polyunsaturated fatty acid; SHAM, salicylhydroxamic acid; TAG, triacylglycerols; � 3D, a fatty acid desaturase that introduces a double bond at a distance of 3 carbon atoms from the methyl end of the chain. In the shorthand numbering system used for identifying fatty acids, the figure preceding the colon indicates the number of carbon atoms in the fatty acid, whereas that after the colon represents the number of double bonds present. Pairs of numbers representing the fatty acids, when separated by a slash, designate the acyl groups residing in the sn -1 and sn -2 positions, respectively, of the molecular species. Unless otherwise mentioned, 20:4 and 20:5 designate the � 6 and � 3 isomers, respectively.
Inna Khozingoldberg - One of the best experts on this subject based on the ideXlab platform.
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the effect of phosphate starvation on the lipid and fatty acid composition of the fresh water eustigmatophyte Monodus subterraneus
Phytochemistry, 2006Co-Authors: Inna Khozingoldberg, Zvi CohenAbstract:Abstract Phosphate limitation caused significant changes in the fatty acid and lipid composition of Monodus subterraneus . With decreasing phosphate availability from 175 to 52.5, 17.5 and 0 μM (K 2 HPO 4 ), the proportion of the major VLC-PUFA, eicosapentaenoic acid (EPA), gradually decreased from 28.2 to 20.8, 19.4 and 15.5 mol% (of total fatty acids), respectively. The cellular total lipid content of starved cells increased, mainly due to the dramatic increase in triacylglycerols (TAG) levels. Among polar lipids, cellular contents of digalactosyldiacylglycerol (DGDG) and diacylglyceroltrimethylhomoserine (DGTS) increased sharply from 0.29 and 0.19 to 0.60 and 0.38 fg cell −1 , respectively, while that of monogalactosyldiacylglycerol (MGDG) was not significantly changed. In the absence of phosphate, the proportion of phospholipids was significantly reduced from 8.3% to 1.4% of total lipids, and the proportion of triacylglycerols (TAG) increased from 6.5% up to 39.3% of total lipids. The share of MGDG was substantially reduced, from 35.7% to 13.3%, while that of DGDG and DGTS reduced less from 18.3% to 15.1%, and 12.2% to 8.6%, respectively. The most distinctive change in the fatty acid composition was noted in that of DGDG, where the proportion of EPA, located exclusively at the sn -1 position, increased from 11.3% to 21.5% at the expense of 16:0, 16:1 and 18:1. In MGDG, however, the proportion of EPA did not change appreciably. In contrast to higher plants, DGDG accumulated under P-deprivation in M. subterraneus , did not resemble PC and the positional distribution of its fatty acids was not altered, preserving the C20/C16 structure of its molecular species. We suggest that under phosphate starvation DGTS is a likely source of C 20 acyl groups that can be exported to the sn -1 position of DGDG and can partially compensate for the decrease in PE, the apparent source of C 20 acyl-containing diacylglycerols in this alga. Moreover, accumulation of non-esterified 18:0 indicates that no polar lipid can replace PC, which appears to be the only lipid capable of C 18 desaturation in this alga.
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biosynthesis of eicosapentaenoic acid epa in the freshwater eustigmatophyte Monodus subterraneus eustigmatophyceae 1
Journal of Phycology, 2002Co-Authors: Inna Khozingoldberg, Shoshana Didicohen, Intyk Shayakhmetova, Zvi CohenAbstract:In an attempt to elucidate the biosynthesis of the polyunsaturated fatty acid eicosapentaenoic acid (20:5 � 3, EPA), we treated cultures of the eustigmatophyte Monodus subterraneus Peterson with either salicylhydroxamic acid or the herbicide SAN 9785. Labeled linoleic acid was incorporated into the cultures in the presence and absence of the latter inhibitor, and the redistribution of label was followed. Our results suggest that the major biosynthetic pathway leading to EPA involves fatty acids of the � 6 family. In the early stages of the biosynthesis, 18:1 is predominantly incorporated to the sn -2 position of phosphatidylcholine, where it is stepwise desaturated by the � 12 and � 6 desaturases to 18:3 � 6. The latter is released from the lipid, elongated to 20:3 � 6 and reincorporated to both positions of phosphatidylethanolamine (PE) where it is further desaturated by the � 5 and � 3 desaturases to EPA. We suggest that PE is the donor of the 20:5/20:5 diacylglycerol that is imported to the chloroplast to form the eukaryotic-like molecular species of monogalactosyldiacylglycerol. Likewise, 20:3 � 6 can be also incorporated into diacylglyceryltrimethylhomoserine, mostly to the sn -2 position and similarly desaturated to 20:4 � 6 and 20:5 � 3. These fatty acids can be exported and incorporated into the sn -1 position of the prokaryoticlike molecular species of the chloroplastic lipids. We thus suggest that both the eukaryotic-like and the prokaryotic-like molecular species are biosynthesized by different extraplastidial lipids. Key index words: algal lipids; EPA biosynthesis; eukaryotic pathway; fatty acid desaturation; LC-PUFA; Monodus subterraneus ; salicylhydroxamic acid; SAN 9785 Abbreviations: C n fatty acid, fatty acid with n carbon atoms; � n D, a fatty acid desaturase that introduces a double bond at the n th carbon atom from the carboxylic end; DAG, diacylglycerol; DGDG, digalactosyldiacylglycerol; DGTS, diacylglyceryltrimethylhomoserine; EPA, eicosapentaenoic acid (20:5 � 3); MGDG, monogalactosyldiacylglycerol; MLC, medium to long chain (14‐18 carbon atoms); PC, phosphatidylcholine; PE, phosphatidylethanolamine; PUFA, polyunsaturated fatty acid; SHAM, salicylhydroxamic acid; TAG, triacylglycerols; � 3D, a fatty acid desaturase that introduces a double bond at a distance of 3 carbon atoms from the methyl end of the chain. In the shorthand numbering system used for identifying fatty acids, the figure preceding the colon indicates the number of carbon atoms in the fatty acid, whereas that after the colon represents the number of double bonds present. Pairs of numbers representing the fatty acids, when separated by a slash, designate the acyl groups residing in the sn -1 and sn -2 positions, respectively, of the molecular species. Unless otherwise mentioned, 20:4 and 20:5 designate the � 6 and � 3 isomers, respectively.
Hokka, Carlos Osamu - One of the best experts on this subject based on the ideXlab platform.
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Estudo cinetico de tratamento de aguas residuarias de abatedouro avicola por processo de lodo ativado
[s.n.], 2018Co-Authors: Hokka, Carlos OsamuAbstract:Orientador : Iracema de Oliveira MoraesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: O dimensionamento racional de sistemas de tratamento por processo de lodo ativado de efluentes líquidos provenientes de indústria de alimentos exige o conhecimento de expressões descrevendo a cinética de crescimento de microrganismos e degradação de material poluente. Neste trabalho, utilizando-se água residuária de abatedouro avícola determinou-se as constantes das expressões cinéticas derivadas da equação de Monod, levando-se em consideração morte celular e coeficiente de manutenção. Estas constantes foram determinadas em processos em descontínuo e contínuo sem reciclo. As expressões propostas relacionam a velocidade de crescimento celular e velocidade de consumo de substrato com as concentrações X e S, onde X, concentração celular, foi avaliada como concentração de sólidos em suspensão totais (S.S.T.) e S, concentração de substrato limitante, foi avaliada como concentração de Demanda Química de Oxigênio (D.Q.O.). Os valores das constantes determinadas foram: umax = 0,85 dia-¹; ks = 42 mg/l DQO; yG = 0,50 mg S.S.T./mg D.Q.O.; kd = 0,072 dia-¹; m = 0,079 mg D.Q.O./mg S.S.T. dia. Resultados experimentais em sistemas contínuo com reciclo de lodo foram comparados aos resultados calculados através do modelo proposto, mostrando que o modelo explica satisfatória mente este processo. O efeito da concentração de substrato, em D.Q.O., na taxa específica de respiração, R, foi também examinado obtendo-se expressão relacionando velocidade de consumo de oxigênio com concentração de substrato limitante, S. Os valores das constantes determinadas foram: Rmáx = 10,4 mg 02/mg S.S.T. dia k2 = 444 mg/l D.Q.O. Determinou-se ainda a velocidade de sedimentação de lodo a diferentes concentrações do mesmo, bem como a influência da razão substrato microrganismos (F/M) no índice volumétrico de lodo (I.M.). A relação F/M ótima encontra-se em torno de 0,60 -0,80 mg D.Q.O/mg S.S.T. dia. A aplicação do modelo cinético no dimensionamento de processo de lodo ativado para sistemas utilizando-se tanque de aeração tipo reator de mistura e tipo reator tubular foi examinada e neste último caso é proposto um método para calculo de tempo de residência celular e tempo de resistência hidráulico através de gráficos similares aos utilizados para tanque de aeração tipo reator de misturaAbstract: Rational design of food industry liquid effluent treat-system by activated sludge process requires the knowledge of expressions describing the kinetics of microorganism growth and pollutant material degradation. In this work, utilizing a poultry processing industry wastewater, the constants of the kinetic expressions derived from Monod's equation were determined, considering cell death and maintenance coefficient. These constants were determined in batch process and continuous process without recycle. The proposed expressions relate the growth and the substrate consumption rate with the concentrations, X and S, where X, cellular concentration, was evaluated as total suspended solids (T.S.S.) and S, limiting substrate concentration, was evaluated as chemical oxygen demand (C.O.D.). The values of the constants were determined as: umáx = 0,85 day-¹ ks = 42 mg/l C.O.D. yG = 0,50 mg T.S.S./mg C.O.D. kd = 0,072 day-¹ m = 0,079 mg C.O.D./mg T.S.S. day Experimental results in a continuous system with cell recycle were compared with those calculated by the model. The comparison showed that the model explains quite well this process. The effect of substrate concentration on the specific respiration rate, R, was also examined, and the expression obtained relatex oxygen consumption rate with limiting substrate concentration, S. The value of the constants were determined as:Rmax = 10,4 mg O2/mg T.S.S. day k2 = 444 mg/l C.O.D. Furthermore, sludge sedimentation velocities, at different sludge concentrations, were determined, as well as the influence of the food to microorganism ratio (F/M) on the sludge volume index (S.V.I.). The optimum F/M ratio lies between 0,6 and 0,80 mg D.Q.O./mg T.S.S. day. The use of the kinetic model in the design of the activated sludge process for systems utilizing perfectly mixed reactor and plug-flow reactor type aeration tank was examined. In the latter case, a method for calculation of the celular and hydraulic retention times through graphic plots, similar to those utilized for perfectly mixed reactor, was proposedDoutoradoDoutor em Engenharia de Alimento
Carlos Osamu Hokka - One of the best experts on this subject based on the ideXlab platform.
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Estudo cinetico de tratamento de aguas residuarias de abatedouro avicola por processo de lodo ativado
2017Co-Authors: Carlos Osamu HokkaAbstract:Resumo: O dimensionamento racional de sistemas de tratamento por processo de lodo ativado de efluentes líquidos provenientes de indústria de alimentos exige o conhecimento de expressões descrevendo a cinética de crescimento de microrganismos e degradação de material poluente. Neste trabalho, utilizando-se água residuária de abatedouro avícola determinou-se as constantes das expressões cinéticas derivadas da equação de Monod, levando-se em consideração morte celular e coeficiente de manutenção. Estas constantes foram determinadas em processos em descontínuo e contínuo sem reciclo. As expressões propostas relacionam a velocidade de crescimento celular e velocidade de consumo de substrato com as concentrações X e S, onde X, concentração celular, foi avaliada como concentração de sólidos em suspensão totais (S.S.T.) e S, concentração de substrato limitante, foi avaliada como concentração de Demanda Química de Oxigênio (D.Q.O.). Os valores das constantes determinadas foram: umax = 0,85 dia-¹; ks = 42 mg/l DQO; yG = 0,50 mg S.S.T./mg D.Q.O.; kd = 0,072 dia-¹; m = 0,079 mg D.Q.O./mg S.S.T. dia. Resultados experimentais em sistemas contínuo com reciclo de lodo foram comparados aos resultados calculados através do modelo proposto, mostrando que o modelo explica satisfatória mente este processo. O efeito da concentração de substrato, em D.Q.O., na taxa específica de respiração, R, foi também examinado obtendo-se expressão relacionando velocidade de consumo de oxigênio com concentração de substrato limitante, S. Os valores das constantes determinadas foram: Rmáx = 10,4 mg 02/mg S.S.T. dia k2 = 444 mg/l D.Q.O. Determinou-se ainda a velocidade de sedimentação de lodo a diferentes concentrações do mesmo, bem como a influência da razão substrato microrganismos (F/M) no índice volumétrico de lodo (I.M.). A relação F/M ótima encontra-se em torno de 0,60 -0,80 mg D.Q.O/mg S.S.T. dia. A aplicação do modelo cinético no dimensionamento de processo de lodo ativado para sistemas utilizando-se tanque de aeração tipo reator de mistura e tipo reator tubular foi examinada e neste último caso é proposto um método para calculo de tempo de residência celular e tempo de resistência hidráulico através de gráficos similares aos utilizados para tanque de aeração tipo reator de mistura.Abstract:Rational design of food industry liquid effluent treat-system by activated sludge process requires the knowledge of expressions describing the kinetics of microorganism growth and pollutant material degradation. In this work, utilizing a poultry processing industry wastewater, the constants of the kinetic expressions derived from Monod's equation were determined, considering cell death and maintenance coefficient. These constants were determined in batch process and continuous process without recycle. The proposed expressions relate the growth and the substrate consumption rate with the concentrations, X and S, where X, cellular concentration, was evaluated as total suspended solids (T.S.S.) and S, limiting substrate concentration, was evaluated as chemical oxygen demand (C.O.D.). The values of the constants were determined as: umáx = 0,85 day-¹ ks = 42 mg/l C.O.D. yG = 0,50 mg T.S.S./mg C.O.D. kd = 0,072 day-¹ m = 0,079 mg C.O.D./mg T.S.S. day Experimental results in a continuous system with cell recycle were compared with those calculated by the model. The comparison showed that the model explains quite well this process. The effect of substrate concentration on the specific respiration rate, R, was also examined, and the expression obtained relatex oxygen consumption rate with limiting substrate concentration, S. The value of the constants were determined as:Rmax = 10,4 mg O2/mg T.S.S. day k2 = 444 mg/l C.O.D. Furthermore, sludge sedimentation velocities, at different sludge concentrations, were determined, as well as the influence of the food to microorganism ratio (F/M) on the sludge volume index (S.V.I.). The optimum F/M ratio lies between 0,6 and 0,80 mg D.Q.O./mg T.S.S. day. The use of the kinetic model in the design of the activated sludge process for systems utilizing perfectly mixed reactor and plug-flow reactor type aeration tank was examined. In the latter case, a method for calculation of the celular and hydraulic retention times through graphic plots, similar to those utilized for perfectly mixed reactor, was proposed
Ajay Singh - One of the best experts on this subject based on the ideXlab platform.
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omega 3 6 fatty acids alternative sources of production
Process Biochemistry, 2005Co-Authors: Owen P Ward, Ajay SinghAbstract:Polyunsaturated fatty acids (PUFAs) are essential components of higher eukaryotes. Single cell oils (SCO) are now widely accepted in the market place and there is a growing awareness of the health benefits of PUFAs, such as γ-linolenic acid (GLA), arachidonic acid (ARA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). ARA and DHA have also been used for fortification of infant formulae in many parts of the world. Fish oils are rich sources of DHA and EPA and a limited number of plant oilseeds are good sources of other PUFAs. Marine protists and dinoflagellates, such as species of Thraustochytrium, Schizochytrium and Crypthecodinium are the rich sources of DHA, whereas microalgae like Phaeodactylum and Monodus are good sources of EPA. Species of lower fungi Mortierella accumulate a high percentage of ARA in the lipid fraction. In this paper, various microbiological and enzymatic methods for synthesis of PUFAs are discussed.