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Ka-yiu San - One of the best experts on this subject based on the ideXlab platform.
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Metabolic engineering of the anaerobic central metabolic pathway in Escherichia coli for the simultaneous anaerobic production of Isoamyl Acetate and succinic acid
Biotechnology progress, 2009Co-Authors: Cheryl R. Dittrich, George N Bennett, Ka-yiu SanAbstract:An in vivo method of producing Isoamyl Acetate and succinate simultaneously has been developed in Escherichia coli to maximize yields of both high value compounds as well as maintain the proper redox balance between NADH and NAD(+). Previous attempts at producing the ester Isoamyl Acetate anaerobically did not produce the compound in high concentrations because of competing pathways and the need for NAD(+) regeneration. The objective of this study is to produce succinate as an example of a reduced coproduct to balance the ratio of NADH/NAD(+) as a way of maximizing Isoamyl Acetate production. Because the volatility of the two compounds differs greatly, the two could be easily separated in an industrial setting. An ldhA, adhE double mutant strain (SBS110MG) served as the control strain to test the effect of an additional ackA-pta mutation as found in SBS990MG. Both strains overexpressed the two heterologous genes pyruvate carboxylase and alcohol acetyltransferase (for ester production). The triple mutant SBS990MG was found to produce higher levels of both Isoamyl Acetate and succinate. At the optimal condition of 25 degrees C, the culture produced 9.4 mM Isoamyl Acetate and 45.5 mM succinate. SBS990MG produced 36% more ester and over 700% more succinate than SBS110MG. In addition, this study demonstrated that a significantly higher Isoamyl Acetate concentration can be attained by simultaneously balancing the carbon and cofactor flow; the Isoamyl Acetate concentration of 9.4 mM is more than seven times higher than an earlier report of about 1.2 mM.
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Aerobic production of Isoamyl Acetate by overexpression of the yeast alcohol acetyl-transferases AFT1 and AFT2 in Escherichia coli and using low-cost fermentation ingredients.
Bioprocess and biosystems engineering, 2007Co-Authors: R. Singh, P. V. Vadlani, M. L. Harrison, George N Bennett, Ka-yiu SanAbstract:Isoamyl Acetate, produced via fermentation, is a natural flavor chemical with applications in the food industry. Two alcohol acetyltransferases from Saccharomyces cerevisiae (ATF1 and ATF2) can catalyze the esterification of Isoamyl alcohol with acetyl coenzyme A. The respective genes were cloned and expressed in an appropriate ack-pta(-) strain of Escherichia coli. The engineered strains produce Isoamyl Acetate when Isoamyl alcohol is added to the culture medium. Aerobic shake flask experiments examined Isoamyl Acetate production over various growth times, temperatures, and initial optical densities. The strain carrying the pBAD-ATF1 plasmid exhibited a high molar ester yield from glucose (1.13) after 48 h of aerobic growth at 25 degrees C. Low-cost media components, such as fusel oil, sorghum glucose and corn steep liquor, were found to give a high yield of Isoamyl Acetate. High-cell-density gave an increased Isoamyl Acetate yield of 0.18 g/g of glucose consumed.
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applicability of coa acetyl coa manipulation system to enhance Isoamyl Acetate production in escherichia coli
Metabolic Engineering, 2004Co-Authors: R. V. Vadali, George N Bennett, Ka-yiu SanAbstract:Coenzyme A (CoA) and its thioester derivatives are important precursor molecules for many industrially useful compounds such as esters, PHBs, lycopene and polyketides. Previously, in our lab we could increase the intracellular levels of CoA and acetyl-Coenzyme A (acetyl-CoA) by overexpressing one of the upstream rate-controlling enzymes pantothenate kinase with a concomitant supplementation of the precursor pantothenic acid to the cell culture medium. In this study, we showed that the CoA/acetyl-CoA manipulation system could be used to increase the productivity of industrially useful compounds derived from acetyl-CoA. We chose the production of Isoamyl Acetate as a model system. Isoamyl Acetate is an important flavor component of sake yeast and holds a great commercial value. Alcohol acetyl transferase (AAT) condenses Isoamyl alcohol and acetyl-CoA to produce Isoamyl Acetate. The gene ATF2, coding for this AAT was cloned and expressed in Escherichia coli. This genetic engineered E. coli produces Isoamyl Acetate, an ester, from intracellular acetyl-CoA when Isoamyl alcohol is added externally to the cell culture medium. In the current study, we showed that in a strain bearing ATF2 gene, an increase in intracellular CoA/acetyl-CoA by overexpressing panK leads to an increase in Isoamyl Acetate production. Additionally, the cofactor manipulation technique was combined with more traditional approach of competing pathway deletions to further increase Isoamyl Acetate production. The Acetate production pathway competes with Isoamyl Acetate production for the common intracellular metabolite acetyl-CoA. Earlier we have shown that Acetate pathway deletion (ackA-pta) increases Isoamyl Acetate production. The Acetate production pathway was inactivated under elevated CoA/acetyl-CoA conditions, which lead to a further increase in Isoamyl Acetate production.
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Enhanced Isoamyl Acetate production upon manipulation of the acetyl-CoA node in Escherichia coli.
Biotechnology progress, 2004Co-Authors: R. V. Vadali, George N Bennett, Ka-yiu SanAbstract:Coenzyme A (CoA) and its thioester derivative acetyl-Coenzyme A (acetyl-CoA) participate in over 100 different reactions in intermediary metabolism of microorganisms. Earlier results indicated that overexpression of upstream rate-limiting enzyme pantothenate kinase with simultaneous supplementation of precursor pantothenic acid to the culture media increased intracellular CoA levels significantly ( approximately 10-fold). The acetyl-CoA levels also increased ( approximately 5-fold) but not as much as that of CoA, showing that the carbon flux from the pyruvate node is rate-limiting upon an increase in CoA levels. In this study, pyruvate dehydrogenase was overexpressed under elevated CoA levels to increase carbon flux from pyruvate to acetyl-CoA. This coexpression did not increase intracellular acetyl-CoA levels but increased the accumulation of extracellular Acetate. The production of Isoamyl Acetate, an industrially useful compound derived from acetyl-CoA, was used as a model reporter system to signify the beneficial effects of this metabolic engineering strategy. In addition, a strain was created in which the Acetate production pathway was inactivated to relieve competition at the acetyl-CoA node and to efficiently channel the enhanced carbon flux to the ester production pathway. The synergistic effect of cofactor CoA manipulation and pyruvate dehydrogenase overexpression in the Acetate pathway deletion mutant led to a 5-fold increase in Isoamyl Acetate production. Under normal growth conditions the Acetate pathway deletion mutant strains accumulate intracellular pyruvate, leading to excretion of pyruvate. However, upon enhancing the carbon flux from pyruvate to acetyl-CoA, the excretion of pyruvate was significantly reduced.
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production of Isoamyl Acetate in acka pta and or ldh mutants of escherichia coli with overexpression of yeast atf2
Applied Microbiology and Biotechnology, 2004Co-Authors: R. V. Vadali, Catherine Emily Horton, George N Bennett, F. B. Rudolph, Ka-yiu SanAbstract:The gene coding for alcohol acetyltransferase (ATF2), which catalyzes the esterification of Isoamyl alcohol and acetyl coenzyme A (acetyl-CoA), was cloned from Saccharomyces cerevisiae and expressed in Escherichia coli. This genetically engineered strain of E. coli produced the ester Isoamyl Acetate when Isoamyl alcohol was added externally to the cell culture medium. Various competing pathways at the acetyl-CoA node were inactivated to increase the intracellular acetyl-CoA pool and divert more carbon flux to the ester synthesis pathway. Several strains with deletions in the ackA-pta and/or ldh pathways and bearing the ATF2 on a high-copy-number plasmid were constructed and studied. Compared to the wild-type, ackA-pta and nuo mutants produced higher amounts of ester and an ackA-pta-ldh-nuo mutant lower amounts. Isoamyl Acetate production correlated well with intracellular coenzyme A (CoA) and acetyl-CoA levels. The ackA-pta-nuo mutant had the highest intracellular CoA/acetyl-CoA level and hence produced the highest amount of ester (1.75 mM) during the growth phase under oxic conditions and during the production phase under anoxic conditions.
Turgut Cabaroğlu - One of the best experts on this subject based on the ideXlab platform.
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Research Article Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
2016Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Copyright © 2013 Murat Yilmaztekin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeastwhich can produce Isoamyl Acetate by esterification of amyl alcoholswith acetyl coenzymeAvia fermentation.The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15∘C and 25∘C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate byWilliopsis saturnus var. saturnus from sugar beetmolasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25∘C than at 15∘C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703mg L−1 h−1 and a specific productivity of 0.0297mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25∘C. The maximum amount of Isoamyl Acetate reached with these conditions was 118mg/L. 1
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Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
BioMed research international, 2013Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeast which can produce Isoamyl Acetate by esterification of amyl alcohols with acetyl coenzyme A via fermentation. The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15°C and 25°C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate by Williopsis saturnus var. saturnus from sugar beet molasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25°C than at 15°C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703 mg L−1 h−1 and a specific productivity of 0.0297 mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25°C. The maximum amount of Isoamyl Acetate reached with these conditions was 118 mg/L.
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Enhanced production of Isoamyl Acetate from beet molasses with addition of fusel oil by Williopsis saturnus var. saturnus
Food Chemistry, 2009Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Abstract Fusel oil which contains high level of amyl alcohols (approximately 45–55%) is a by-product obtained from the distillation of alcohol made by fermentation of molasses. Williopsis saturnus is a yeast which is able to convert Isoamyl alcohol into Isoamyl Acetate. The aim of this study was to increase the formation of Isoamyl Acetate by the addition of fusel oil at the ratios of 1%, 2% and 3% (v/v) to molasses based fermentation medium using W. saturnus . It was found out that bioconversion of added fusel oil into Isoamyl Acetate was possible and an addition of 1% fusel oil led to an increase in Isoamyl Acetate concentration from 118 to 354 mg/L.
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Production of Isoamyl Acetate from Sugar Beet Molasses by Williopsis saturnus var. saturnus
Journal of the Institute of Brewing, 2008Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Three strains of Williopsis saturnus var. saturnus were employed for the production of natural Isoamyl Acetate (the character impact compound of banana flavour) using sugar beet molasses as the carbon source and batch cultivation at 25°C under anaerobic conditions. Of the three strains, strain HUT 7087 was the best producer of Isoamyl Acetate, producing 20.7 mg/L. Sugar beet molasses was deemed to be an acceptable carbon source for the production of this flavour compound.
Murat Yilmaztekin - One of the best experts on this subject based on the ideXlab platform.
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Research Article Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
2016Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Copyright © 2013 Murat Yilmaztekin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeastwhich can produce Isoamyl Acetate by esterification of amyl alcoholswith acetyl coenzymeAvia fermentation.The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15∘C and 25∘C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate byWilliopsis saturnus var. saturnus from sugar beetmolasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25∘C than at 15∘C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703mg L−1 h−1 and a specific productivity of 0.0297mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25∘C. The maximum amount of Isoamyl Acetate reached with these conditions was 118mg/L. 1
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Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
BioMed research international, 2013Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeast which can produce Isoamyl Acetate by esterification of amyl alcohols with acetyl coenzyme A via fermentation. The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15°C and 25°C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate by Williopsis saturnus var. saturnus from sugar beet molasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25°C than at 15°C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703 mg L−1 h−1 and a specific productivity of 0.0297 mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25°C. The maximum amount of Isoamyl Acetate reached with these conditions was 118 mg/L.
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Enhanced production of Isoamyl Acetate from beet molasses with addition of fusel oil by Williopsis saturnus var. saturnus
Food Chemistry, 2009Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Abstract Fusel oil which contains high level of amyl alcohols (approximately 45–55%) is a by-product obtained from the distillation of alcohol made by fermentation of molasses. Williopsis saturnus is a yeast which is able to convert Isoamyl alcohol into Isoamyl Acetate. The aim of this study was to increase the formation of Isoamyl Acetate by the addition of fusel oil at the ratios of 1%, 2% and 3% (v/v) to molasses based fermentation medium using W. saturnus . It was found out that bioconversion of added fusel oil into Isoamyl Acetate was possible and an addition of 1% fusel oil led to an increase in Isoamyl Acetate concentration from 118 to 354 mg/L.
-
Production of Isoamyl Acetate from Sugar Beet Molasses by Williopsis saturnus var. saturnus
Journal of the Institute of Brewing, 2008Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Three strains of Williopsis saturnus var. saturnus were employed for the production of natural Isoamyl Acetate (the character impact compound of banana flavour) using sugar beet molasses as the carbon source and batch cultivation at 25°C under anaerobic conditions. Of the three strains, strain HUT 7087 was the best producer of Isoamyl Acetate, producing 20.7 mg/L. Sugar beet molasses was deemed to be an acceptable carbon source for the production of this flavour compound.
George N Bennett - One of the best experts on this subject based on the ideXlab platform.
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Metabolic engineering of the anaerobic central metabolic pathway in Escherichia coli for the simultaneous anaerobic production of Isoamyl Acetate and succinic acid
Biotechnology progress, 2009Co-Authors: Cheryl R. Dittrich, George N Bennett, Ka-yiu SanAbstract:An in vivo method of producing Isoamyl Acetate and succinate simultaneously has been developed in Escherichia coli to maximize yields of both high value compounds as well as maintain the proper redox balance between NADH and NAD(+). Previous attempts at producing the ester Isoamyl Acetate anaerobically did not produce the compound in high concentrations because of competing pathways and the need for NAD(+) regeneration. The objective of this study is to produce succinate as an example of a reduced coproduct to balance the ratio of NADH/NAD(+) as a way of maximizing Isoamyl Acetate production. Because the volatility of the two compounds differs greatly, the two could be easily separated in an industrial setting. An ldhA, adhE double mutant strain (SBS110MG) served as the control strain to test the effect of an additional ackA-pta mutation as found in SBS990MG. Both strains overexpressed the two heterologous genes pyruvate carboxylase and alcohol acetyltransferase (for ester production). The triple mutant SBS990MG was found to produce higher levels of both Isoamyl Acetate and succinate. At the optimal condition of 25 degrees C, the culture produced 9.4 mM Isoamyl Acetate and 45.5 mM succinate. SBS990MG produced 36% more ester and over 700% more succinate than SBS110MG. In addition, this study demonstrated that a significantly higher Isoamyl Acetate concentration can be attained by simultaneously balancing the carbon and cofactor flow; the Isoamyl Acetate concentration of 9.4 mM is more than seven times higher than an earlier report of about 1.2 mM.
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Aerobic production of Isoamyl Acetate by overexpression of the yeast alcohol acetyl-transferases AFT1 and AFT2 in Escherichia coli and using low-cost fermentation ingredients.
Bioprocess and biosystems engineering, 2007Co-Authors: R. Singh, P. V. Vadlani, M. L. Harrison, George N Bennett, Ka-yiu SanAbstract:Isoamyl Acetate, produced via fermentation, is a natural flavor chemical with applications in the food industry. Two alcohol acetyltransferases from Saccharomyces cerevisiae (ATF1 and ATF2) can catalyze the esterification of Isoamyl alcohol with acetyl coenzyme A. The respective genes were cloned and expressed in an appropriate ack-pta(-) strain of Escherichia coli. The engineered strains produce Isoamyl Acetate when Isoamyl alcohol is added to the culture medium. Aerobic shake flask experiments examined Isoamyl Acetate production over various growth times, temperatures, and initial optical densities. The strain carrying the pBAD-ATF1 plasmid exhibited a high molar ester yield from glucose (1.13) after 48 h of aerobic growth at 25 degrees C. Low-cost media components, such as fusel oil, sorghum glucose and corn steep liquor, were found to give a high yield of Isoamyl Acetate. High-cell-density gave an increased Isoamyl Acetate yield of 0.18 g/g of glucose consumed.
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applicability of coa acetyl coa manipulation system to enhance Isoamyl Acetate production in escherichia coli
Metabolic Engineering, 2004Co-Authors: R. V. Vadali, George N Bennett, Ka-yiu SanAbstract:Coenzyme A (CoA) and its thioester derivatives are important precursor molecules for many industrially useful compounds such as esters, PHBs, lycopene and polyketides. Previously, in our lab we could increase the intracellular levels of CoA and acetyl-Coenzyme A (acetyl-CoA) by overexpressing one of the upstream rate-controlling enzymes pantothenate kinase with a concomitant supplementation of the precursor pantothenic acid to the cell culture medium. In this study, we showed that the CoA/acetyl-CoA manipulation system could be used to increase the productivity of industrially useful compounds derived from acetyl-CoA. We chose the production of Isoamyl Acetate as a model system. Isoamyl Acetate is an important flavor component of sake yeast and holds a great commercial value. Alcohol acetyl transferase (AAT) condenses Isoamyl alcohol and acetyl-CoA to produce Isoamyl Acetate. The gene ATF2, coding for this AAT was cloned and expressed in Escherichia coli. This genetic engineered E. coli produces Isoamyl Acetate, an ester, from intracellular acetyl-CoA when Isoamyl alcohol is added externally to the cell culture medium. In the current study, we showed that in a strain bearing ATF2 gene, an increase in intracellular CoA/acetyl-CoA by overexpressing panK leads to an increase in Isoamyl Acetate production. Additionally, the cofactor manipulation technique was combined with more traditional approach of competing pathway deletions to further increase Isoamyl Acetate production. The Acetate production pathway competes with Isoamyl Acetate production for the common intracellular metabolite acetyl-CoA. Earlier we have shown that Acetate pathway deletion (ackA-pta) increases Isoamyl Acetate production. The Acetate production pathway was inactivated under elevated CoA/acetyl-CoA conditions, which lead to a further increase in Isoamyl Acetate production.
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Enhanced Isoamyl Acetate production upon manipulation of the acetyl-CoA node in Escherichia coli.
Biotechnology progress, 2004Co-Authors: R. V. Vadali, George N Bennett, Ka-yiu SanAbstract:Coenzyme A (CoA) and its thioester derivative acetyl-Coenzyme A (acetyl-CoA) participate in over 100 different reactions in intermediary metabolism of microorganisms. Earlier results indicated that overexpression of upstream rate-limiting enzyme pantothenate kinase with simultaneous supplementation of precursor pantothenic acid to the culture media increased intracellular CoA levels significantly ( approximately 10-fold). The acetyl-CoA levels also increased ( approximately 5-fold) but not as much as that of CoA, showing that the carbon flux from the pyruvate node is rate-limiting upon an increase in CoA levels. In this study, pyruvate dehydrogenase was overexpressed under elevated CoA levels to increase carbon flux from pyruvate to acetyl-CoA. This coexpression did not increase intracellular acetyl-CoA levels but increased the accumulation of extracellular Acetate. The production of Isoamyl Acetate, an industrially useful compound derived from acetyl-CoA, was used as a model reporter system to signify the beneficial effects of this metabolic engineering strategy. In addition, a strain was created in which the Acetate production pathway was inactivated to relieve competition at the acetyl-CoA node and to efficiently channel the enhanced carbon flux to the ester production pathway. The synergistic effect of cofactor CoA manipulation and pyruvate dehydrogenase overexpression in the Acetate pathway deletion mutant led to a 5-fold increase in Isoamyl Acetate production. Under normal growth conditions the Acetate pathway deletion mutant strains accumulate intracellular pyruvate, leading to excretion of pyruvate. However, upon enhancing the carbon flux from pyruvate to acetyl-CoA, the excretion of pyruvate was significantly reduced.
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production of Isoamyl Acetate in acka pta and or ldh mutants of escherichia coli with overexpression of yeast atf2
Applied Microbiology and Biotechnology, 2004Co-Authors: R. V. Vadali, Catherine Emily Horton, George N Bennett, F. B. Rudolph, Ka-yiu SanAbstract:The gene coding for alcohol acetyltransferase (ATF2), which catalyzes the esterification of Isoamyl alcohol and acetyl coenzyme A (acetyl-CoA), was cloned from Saccharomyces cerevisiae and expressed in Escherichia coli. This genetically engineered strain of E. coli produced the ester Isoamyl Acetate when Isoamyl alcohol was added externally to the cell culture medium. Various competing pathways at the acetyl-CoA node were inactivated to increase the intracellular acetyl-CoA pool and divert more carbon flux to the ester synthesis pathway. Several strains with deletions in the ackA-pta and/or ldh pathways and bearing the ATF2 on a high-copy-number plasmid were constructed and studied. Compared to the wild-type, ackA-pta and nuo mutants produced higher amounts of ester and an ackA-pta-ldh-nuo mutant lower amounts. Isoamyl Acetate production correlated well with intracellular coenzyme A (CoA) and acetyl-CoA levels. The ackA-pta-nuo mutant had the highest intracellular CoA/acetyl-CoA level and hence produced the highest amount of ester (1.75 mM) during the growth phase under oxic conditions and during the production phase under anoxic conditions.
Hüseyin Erten - One of the best experts on this subject based on the ideXlab platform.
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Research Article Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
2016Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Copyright © 2013 Murat Yilmaztekin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeastwhich can produce Isoamyl Acetate by esterification of amyl alcoholswith acetyl coenzymeAvia fermentation.The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15∘C and 25∘C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate byWilliopsis saturnus var. saturnus from sugar beetmolasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25∘C than at 15∘C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703mg L−1 h−1 and a specific productivity of 0.0297mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25∘C. The maximum amount of Isoamyl Acetate reached with these conditions was 118mg/L. 1
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Effects of Fermentation Temperature and Aeration on Production of Natural Isoamyl Acetate by Williopsis saturnus var. saturnus
BioMed research international, 2013Co-Authors: Murat Yilmaztekin, Turgut Cabaroğlu, Hüseyin ErtenAbstract:Isoamyl Acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeast which can produce Isoamyl Acetate by esterification of amyl alcohols with acetyl coenzyme A via fermentation. The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15°C and 25°C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of Isoamyl Acetate by Williopsis saturnus var. saturnus from sugar beet molasses were examined. According to the results obtained, Isoamyl Acetate production rate and specific productivity were higher at 25°C than at 15°C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703 mg L−1 h−1 and a specific productivity of 0.0297 mg L−1 cell−1 h−1 Isoamyl Acetate with semiaerobic condition at 25°C. The maximum amount of Isoamyl Acetate reached with these conditions was 118 mg/L.
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Enhanced production of Isoamyl Acetate from beet molasses with addition of fusel oil by Williopsis saturnus var. saturnus
Food Chemistry, 2009Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Abstract Fusel oil which contains high level of amyl alcohols (approximately 45–55%) is a by-product obtained from the distillation of alcohol made by fermentation of molasses. Williopsis saturnus is a yeast which is able to convert Isoamyl alcohol into Isoamyl Acetate. The aim of this study was to increase the formation of Isoamyl Acetate by the addition of fusel oil at the ratios of 1%, 2% and 3% (v/v) to molasses based fermentation medium using W. saturnus . It was found out that bioconversion of added fusel oil into Isoamyl Acetate was possible and an addition of 1% fusel oil led to an increase in Isoamyl Acetate concentration from 118 to 354 mg/L.
-
Production of Isoamyl Acetate from Sugar Beet Molasses by Williopsis saturnus var. saturnus
Journal of the Institute of Brewing, 2008Co-Authors: Murat Yilmaztekin, Hüseyin Erten, Turgut CabaroğluAbstract:Three strains of Williopsis saturnus var. saturnus were employed for the production of natural Isoamyl Acetate (the character impact compound of banana flavour) using sugar beet molasses as the carbon source and batch cultivation at 25°C under anaerobic conditions. Of the three strains, strain HUT 7087 was the best producer of Isoamyl Acetate, producing 20.7 mg/L. Sugar beet molasses was deemed to be an acceptable carbon source for the production of this flavour compound.
