scholarly journals Pyruvate-to-ethanol pathway in Entamoeba histolytica

1978 ◽  
Vol 171 (1) ◽  
pp. 225-230 ◽  
Author(s):  
H S Lo ◽  
R E Reeves
Keyword(s):  
Enzyme Activity ◽  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Entamoeba Histolytica ◽  
Aldehyde Dehydrogenase ◽  
Pyruvate Decarboxylase ◽  
Acetyl Coa ◽  
Key Enzyme ◽  
Pyruvate Synthase ◽  
Soluble Enzymes

The pyruvate-to-ethanol pathway in Entamoeba histolytica is unusual when compared with most investigated organisms. Pyruvate decarboxylase (EC 4.1.1.1), a key enzyme for ethanol production, is not found. Pyruvate is converted into acetyl-CoA and CO2 by the enzyme pyruvate synthase (EC 1.2.7.1), which has been demonstrated previously in this parasitic amoeba. Acetyl-CoA is reduced to acetaldehyde and CoA by the enzyme aldehyde dehydrogenase (acylating) (EC 1.2.1.10) at an enzyme activity of 9 units per g of fresh cells with NADH as a reductant. Acetaldehyde is further reduced by either a previously identified NADP+-linked alcohol dehydrogenase or by a newly found NAD+-linked alcohol dehydrogenase at an enzyme activity of 136 units per g of fresh cells. Ethanol is identified as the product of soluble enzymes of amoeba acting on pyruvate or acetyl-CoA. This result is confirmed by radioactive isotopic, spectrophotometric and gas-chromatographic methods.

A novel bifunctional aldehyde/alcohol dehydrogenase mediating ethanol formation from acetyl-CoA in hyperthermophiles

2020 ◽  
Author(s):  
Qiang Wang ◽  
Chong Sha ◽  
Hongcheng Wang ◽  
Kesen Ma ◽  
Juergen Wiegel ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Ethanol Fermentation ◽  
Cellulosic Ethanol ◽  
Decarboxylase Activity ◽  
Aldh Activity ◽  
Acetyl Coa ◽  
Ethanol Formation

Abstract Background: Hyperthermophilic fermentation at temperatures above 80 °C allows in situ product removal to mitigate the ethanol toxicity, and reduces microbial contamination without autoclaving/cooling of feedstock. Many species of Thermotoga grow at temperatures up to 90 °C, and have enzymes to degrade and utilize lignocelluloses, which provide advantages for achieving consolidated processes of cellulosic ethanol production. However, no CoA-dependent aldehyde dehydrogenase (CoA-Aldh) from any hyperthermophiles has been documented in literature so far. The pyruvate ferredoxin oxidoreductases from hyperthermophiles have pyruvate decarboxylase activity, which convert about 2% and 98% of pyruvate to acetaldehyde and acetyl-CoA (ac-CoA), respectively. Acetyl-CoA can be converted to acetic acid, if there is no CoA-Aldh to convert ac-CoA to acetaldehyde and further to ethanol. Therefore, the current study aimed to identify and characterize a CoA-Aldh activity that mediates ethanol fermentation in hyperthermophiles.Results: In Thermotoga neapolitana (Tne), a hyperthermophilic iron-acetaldehyde/alcohol dehydrogenase (Fe-AAdh) was, for the first time, revealed to catalyze the ac-CoA reduction to form ethanol via an acetaldehyde intermediate, while the annotated aldh gene in Tne genome only encodes a CoA-independent Aldh that oxidizes aldehyde to acetic acid. Three other Tne alcohol dehydrogenases (Adh) exhibited specific physiological roles in ethanol formation and consumption: Fe-Adh2 mainly catalyzed the reduction of acetaldehyde to produce ethanol, and Fe-Adh1 showed significant activities only under extreme conditions, while Zn-Adh showed special activity in ethanol oxidation. In the in vitro formation of ethanol from ac-CoA, a strong synergy was observed between Fe-Adh1 and Fe-AAdh. The Fe-AAdh gene is highly conserved in Thermotoga spp. and in Pyrococus sp., which is probably responsible for ethanol metabolism in hyperthermophiles.Conclusions: Hyperthermophilic Thermotoga spp. are excellent candidates for biosynthesis of cellulosic ethanol fermentation strains. The finding of a novel hyperthermophilic CoA-Aldh activity of Tne Fe-AAdh revealed the existence of a hyperthermophilic fermentation pathway from ac-CoA to ethanol, which offers a basic frame for in vitro synthesis of a highly active AAdh for effective ethanol fermentation pathway in hyperthermophiles, which is a key element for the approach to the consolidated processes of cellulosic ethanol production.

Effects of manipulation of pyruvate decarboxylase and alcohol dehydrogenase levels on the submergence tolerance of rice

2001 ◽  
Vol 28 (12) ◽  
pp. 1231 ◽  
Author(s):  
Musrur Rahman ◽  
Anil Grover ◽  
W. James Peacock ◽  
Elizabeth S. Dennis ◽  
Marc H. Ellis
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Rice Variety ◽  
Pyruvate Decarboxylase ◽  
Inducible Promoter ◽  
Moderate Increase ◽  
Sense Orientation ◽  
Transgenic Lines ◽  
Hybrid Lines ◽  
Adh Activity

A transgenic approach was taken to manipulate the levels of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in rice, in order to investigate whether alteration of ethanol fermentation can affect anaerobic tolerance. A line transformed with an antisense Adh1 construct had only 4–8% of the ADH activity of untransformed plants. This line showed reduced ethanol production and coleoptile growth under anoxia. Mature plants had reduced survival when submerged in water and exposed to anoxia, suggesting that ADH plays an essential role in seed germination and plant survival in the absence of O2. A transgenic line transformed with a cotton Adh2 cDNA in the sense orientation relative to a constitutive promoter, showed 3–4-fold more ADH activity than either untransformed controls, or a flooding-tolerant rice variety (FR13A), both in air and under hypoxia. However, ethanol production by this line was only slightly higher than that of untransformed controls, and there was no increase in survival following anoxia treatments. Three independent transgenic lines containing the ricePdc1 cDNA driven by an anaerobically-inducible promoter (6XARE) showed an increase in PDC1 polypeptide in shoots, but not in roots or endosperm. A moderate increase in PDC activity and ethanol production was observed in shoots of these lines under anaerobic conditions, as well as decreased survival of shoots when submerged and exposed to anoxia. F1 plants containing both the PDC and ADH constructs showed levels of anoxia-tolerance similar to those of untransformed plants. These results suggest that over-production of PDC may be toxic to rice plants because of increased acetaldehyde. Consistent with this view, acetaldehyde levels were appreciably higher in plants over-producing PDC, compared with untransformed plants, or hybrid lines containing both the PDC and ADH constructs.

Fusion of Pyruvate Decarboxylase and Alcohol Dehydrogenase Increases Ethanol Production inEscherichia coli

2014 ◽  
Vol 3 (12) ◽  
pp. 976-978 ◽  
Author(s):  
Aleksandra J. Lewicka ◽  
Jan J. Lyczakowski ◽  
Gavin Blackhurst ◽  
Christiana Pashkuleva ◽  
Kyle Rothschild-Mancinelli ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Pyruvate Decarboxylase ◽  
Inescherichia Coli

scholarly journals Zymobacter palmae pyruvate decarboxylase is less efficient than that of Zymomonas mobilis for ethanol production in metabolically engineered Synechocystis sp PCC6803

2019 ◽  
Author(s):  
Lorraine Quinn ◽  
Patricia Armshaw ◽  
Tewfik Soulimane ◽  
Con Sheehan ◽  
Michael P Ryan ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Zymomonas Mobilis ◽  
Pyruvate Decarboxylase ◽  
Inducible Promoter ◽  
Control Strain ◽  
Zymobacter Palmae ◽  
Synechocystis Sp ◽  
Pcc 6803

AbstractPyruvate decarboxylase (PDC) from Zymobacter palmae (ZpPDC) has been reported to have a lower Km the Zymomonas mobilis PDC (ZmPDC). ZpPDC was combined with native slr1192 alcohol dehydrogenase (adh) in an attempt to increase ethanol production in the photoautotrophic cyanobacterium Synechocystis sp. PCC 6803 over constructs created with Zmpdc. Native (Zppdc) and codon optimised (ZpOpdc) versions of the ZpPDC were cloned into a construct where the pdc expression was controlled via the psbA2 light inducible promoter from Synechocystis PCC 6803. These constructs were transformed into wildtype Synechocystis PCC 6803. Ethanol levels were then compared with identical constructs containing the Zmpdc. While strains with the Zppdc (UL071) and ZpOpdc (UL072) constructs did produce ethanol, levels were lower compared to a control strain (UL004) expressing the pdc from Zymomonas mobilis. The utilisation of a PDC with a lower Km from Zymobacter palmae did not result in enhanced ethanol production in Synechocystis PCC 6803.

scholarly journals METABOLIC CHANGES ASSOCIATED WITH OXYGEN STRESS IN PEAR FRUITS

HortScience ◽  
1990 ◽  
Vol 25 (11) ◽  
pp. 1355F-1356
Author(s):  
George D. Nanos ◽  
Roger J. Romani ◽  
Adel A. Kader
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Ethylene Production ◽  
Pyruvate Decarboxylase ◽  
Insect Control ◽  
Pear Fruit ◽  
Oxygen Stress ◽  
Fruit Tissue ◽  
Subsequent Recovery ◽  
Alcohol Dehydrogenase Activity

The response of pear fruits and suspension-cultured pear fruit cells to 0% or 0.25% O2 is being examined to evaluate the feasibility of using such atmospheres for postharvest insect control. These treatments inhibited ethylene production, had no effect on acetaldehyde content, and increased ethanol production in pears kept at 20C for 10 days. The blossom end area of pear fruits was more prone to anaerobiosis, as indicated by increased alcohol dehydrogenase activity and ethanol content. Pear fruit plugs showed increased respiration and ethylene production rates when skin was present compared to plugs without skin. Methods for measuring activity of alcohol dehydrogenase, pyruvate decarboxylase, and pyruvate kinase have been modified and optimized and will be used to determine changes in pear fruit tissue during low O2 treatment and subsequent recovery in air.

scholarly journals 406 Pyruvate Decarboxylase and Alcohol Dehydrogenase Activities in Sweetpotato under Different Oxygen Atmospheres

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 514A-514
Author(s):  
Yuehe Huang ◽  
David H. Picha ◽  
Anthony W. Kilili
Keyword(s):  
Alcohol Dehydrogenase ◽  
Strong Correlation ◽  
Enzyme Activities ◽  
Ipomoea Batatas ◽  
Alcoholic Fermentation ◽  
Anaerobic Metabolism ◽  
Pyruvate Decarboxylase ◽  
Controlled Atmospheres ◽  
Key Enzyme ◽  
Combined Data

`Beauregard' sweetpotato (Ipomoea batatas L. Lam) roots were maintained under different controlled atmospheres ranging from 0% to 21% O2 at 22 °C in two separate trials for 14 days to study changes in activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH). Trial I showed no difference in activities of PDC and ADH between 0% and 1% O2, or among 2%, 5%, and 21% O2. Both PDC and ADH activities were significantly higher at 0% and 1% O2 compared to the 2%, 5%, and 21% O2 atmospheres. In trial II, both enzyme activities were lower at 1.5% O2 than at 0% O2, but higher than at 10% and 21% O2 atmospheres. The combined data of the two trials showed a very strong correlation between PDC and ADH activities (R2 = 0.86). In addition, a strong correlation existed between PDC activity and acetaldehyde concentration (R2 = 0.95). The maximal activities were at pH 6.5 for PDC and at pH 8.5 for ADH in the direction of acetaldehyde-to-ethanol. The results suggest that 1.5% O2 is the critical point for the transition from aerobic to anaerobic metabolism in CA storage of sweetpotato roots, and PDC is the key enzyme in alcoholic fermentation.

scholarly journals Zymobacter palmae Pyruvate Decarboxylase is Less Effective Than That of Zymomonas mobilis for Ethanol Production in Metabolically Engineered Synechocystis sp. PCC6803

2019 ◽  
Vol 7 (11) ◽  
pp. 494 ◽  
Author(s):  
Lorraine Quinn ◽  
Patricia Armshaw ◽  
Tewfik Soulimane ◽  
Con Sheehan ◽  
Michael P. Ryan ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Zymomonas Mobilis ◽  
Pyruvate Decarboxylase ◽  
Biomass Productivity ◽  
Gene Cassette ◽  
Major Effect ◽  
Zymobacter Palmae ◽  
Synechocystis Sp ◽  
Pcc 6803

To produce bioethanol from model cyanobacteria such as Synechocystis, a two gene cassette consisting of genes encoding pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) are required to transform pyruvate first to acetaldehyde and then to ethanol. However the partition of pyruvate to ethanol comes at a cost, a reduction in biomass and pyruvate availability for other metabolic processes. Hence strategies to divert flux to ethanol as a biofuel in Synechocystis are of interest. PDC from Zymobacter palmae (ZpPDC) has been reported to have a lower Km then the Zymomonas mobilis PDC (ZmPDC), which has traditionally been used in metabolic engineering constructs. The Zppdc gene was combined with the native slr1192 alcohol dehydrogenase gene (adhA) in an attempt to increase ethanol production in the photoautotrophic cyanobacterium Synechocystis sp. PCC 6803 over constructs created with the traditional Zmpdc. Native (Zppdc) and codon optimized (ZpOpdc) versions of the ZpPDC were cloned into a construct where pdc expression was controlled via the psbA2 light inducible promoter from Synechocystis sp. PCC 6803. These constructs were transformed into wildtype Synechocystis sp. PCC 6803 for expression and ethanol production. Ethanol levels were then compared with identical constructs containing the Zmpdc. While strains with the Zppdc (UL071) and ZpOpdc (UL072) constructs did produce ethanol, levels were lower compared to a control strain (UL070) expressing the pdc from Zymomonas mobilis. All constructs demonstrated lower biomass productivity illustrating that the flux from pyruvate to ethanol has a major effect on biomass and ultimately overall biofuel productivity. Thus the utilization of a PDC with a lower Km from Zymobacter palmae unusually did not result in enhanced ethanol production in Synechocystis sp. PCC 6803.

Consolidated Bioprocessing for Bioethanol Production by Metabolically Engineered Bacillus Subtilis Strains

2021 ◽  
Author(s):  
Fatemeh Maleki ◽  
Mohammad Changizian ◽  
Narges Zolfaghari ◽  
Sarah Rajaei ◽  
Kambiz Akbari Noghabi ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Plant Biomass ◽  
Fusion Gene ◽  
Consolidated Bioprocessing ◽  
Gene Dosage ◽  
Pyruvate Decarboxylase ◽  
Single Step ◽  
Bioethanol Production ◽  
Genes Encoding

Abstract Background: Bioethanol produced by fermentative microorganisms is regarded as an alternative to fossil fuel. Bioethanol to be used as a viable energy source must be produced cost-effectively by removing expense-intensive steps such as the enzymatic hydrolysis of substrate. Consolidated bioprocessing (CBP) is believed to be a practical solution combining saccharification and fermentation in a single step catalyzed by a microorganism. Bacillus subtills with innate ability to grow on a diversity of carbohydrates seems promising for affordable CBP bioethanol production using renewable plant biomass and wastes. Results: In this study, the genes encoding alcohol dehydrogenase from Z. mobilis (adhZ) and S. cerevisiae (adhS) were each used with Z. mobilis pyruvate decarboxylase gene (pdcZ) to create ethanologenic operons in a lactate-deficient (Δldh) B. subtilis resulting in NZ and NZS strains, respectively. The S. cerevisiae adhS caused significantly more ethanol production by NZS and therefore was used to make two other operons including one with double copies of both pdcZ and adhS and the other with a single pdcZ but double adhS genes expressed in N(ZS)2 and NZS2 strains, respectively. In addition, two fusion genes were constructed with pdcZ and adhS in alternate orientations and used for ethanol production by the harboring strains namely NZ:S and NS:Z, respectively. While the increase of gene dosage was not associated with elevated carbon flow for ethanol production, the fusion gene adhS:pdcZ resulted in more than two times increase of productivity by strain NS:Z as compared with NZS during 48 h fermentation. The CBP ethanol production by NZS and NS:Z using potatoes resulted in 16.3 g/L and 21.5 g/L ethanol during 96 h fermentation, respectively. Conclusion: In this study for the first time, Bacillus subtilis was successfully used for CBP ethanol production with S. cerevisiae alcohol dehydrogenase. The results of the study provide insights on the potentials of B. subtilis for affordable bioethanol production from inexpensive plant biomass and wastes. However, the potentials need to be improved by metabolic and process engineering for higher yields of ethanol production and plant biomass utilization.

Sign in / Sign up

Export Citation Format

Share Document