scholarly journals Deletion ofnfnABin Thermoanaerobacterium saccharolyticum and Its Effect on Metabolism

2015 ◽  
Vol 197 (18) ◽  
pp. 2920-2929 ◽  
Author(s):  
Jonathan Lo ◽  
Tianyong Zheng ◽  
Daniel G. Olson ◽  
Natalie Ruppertsberger ◽  
Shital A. Tripathi ◽  
...  
Keyword(s):  
Ethanol Yield ◽  
Oxidoreductase Activity ◽  
Fermentation Products ◽  
Content Type ◽  
Ferredoxin Oxidoreductase ◽  
Ethanol Formation ◽  
Cell Extracts ◽  
Thermoanaerobacterium Saccharolyticum ◽  
Adh Activity ◽  
Reversible Transfer

ABSTRACTNfnAB catalyzes the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP+. The NfnAB complex has been hypothesized to be the main enzyme for ferredoxin oxidization in strains ofThermoanaerobacterium saccharolyticumengineered for increased ethanol production. NfnAB complex activity was detectable in crude cell extracts ofT. saccharolyticum. Activity was also detected using activity staining of native PAGE gels. ThenfnABgene was deleted in different strains ofT. saccharolyticumto determine its effect on end product formation. In wild-typeT. saccharolyticum, deletion ofnfnABresulted in a 46% increase in H2formation but otherwise little change in other fermentation products. In two engineered strains with 80% theoretical ethanol yield, loss ofnfnABcaused two different responses: in one strain, ethanol yield decreased to about 30% of the theoretical value, while another strain had no change in ethanol yield. Biochemical analysis of cell extracts showed that the ΔnfnABstrain with decreased ethanol yield had NADPH-linked alcohol dehydrogenase (ADH) activity, while the ΔnfnABstrain with unchanged ethanol yield had NADH-linked ADH activity. Deletion ofnfnABcaused loss of NADPH-linked ferredoxin oxidoreductase activity in all cell extracts. Significant NADH-linked ferredoxin oxidoreductase activity was seen in all cell extracts, including those that had lostnfnAB. This suggests that there is an unidentified NADH:ferredoxin oxidoreductase (distinct fromnfnAB) playing a role in ethanol formation. The NfnAB complex plays a key role in generating NADPH in a strain that had become reliant on NADPH-ADH activity.IMPORTANCEThermophilic anaerobes that can convert biomass-derived sugars into ethanol have been investigated as candidates for biofuel formation. Many anaerobes have been genetically engineered to increase biofuel formation; however, key aspects of metabolism remain unknown and poorly understood. One example is the mechanism for ferredoxin oxidation and transfer of electrons to NAD(P)+. The electron-bifurcating enzyme complex NfnAB is known to catalyze the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP+and is thought to play key roles linking NAD(P)(H) metabolism with ferredoxin metabolism. We report the first deletion ofnfnABand demonstrate a role for NfnAB in metabolism and ethanol formation inThermoanaerobacterium saccharolyticumand show that this may be an important feature among other thermophilic ethanologenic anaerobes.

scholarly journals The Bifunctional Alcohol and Aldehyde Dehydrogenase Gene,adhE, Is Necessary for Ethanol Production in Clostridium thermocellum and Thermoanaerobacterium saccharolyticum

2015 ◽  
Vol 197 (8) ◽  
pp. 1386-1393 ◽  
Author(s):  
Jonathan Lo ◽  
Tianyong Zheng ◽  
Shuen Hon ◽  
Daniel G. Olson ◽  
Lee R. Lynd
Keyword(s):  
Ethanol Production ◽  
Aldehyde Dehydrogenase ◽  
Clostridium Thermocellum ◽  
Deletion Strain ◽  
Aldh Activity ◽  
Content Type ◽  
Ethanol Formation ◽  
Cell Extracts ◽  
Thermoanaerobacterium Saccharolyticum ◽  
Dehydrogenase Gene

ABSTRACTThermoanaerobacterium saccharolyticumandClostridium thermocellumare anaerobic thermophilic bacteria being investigated for their ability to produce biofuels from plant biomass. The bifunctional alcohol and aldehyde dehydrogenase gene,adhE, is present in these bacteria and has been known to be important for ethanol formation in other anaerobic alcohol producers. This study explores the inactivation of theadhEgene inC. thermocellumandT. saccharolyticum. Deletion ofadhEreduced ethanol production by >95% in bothT. saccharolyticumandC. thermocellum, confirming thatadhEis necessary for ethanol formation in both organisms. In bothadhEdeletion strains, fermentation products shifted from ethanol to lactate production and resulted in lower cell density and longer time to reach maximal cell density. InT. saccharolyticum, theadhEdeletion strain lost >85% of alcohol dehydrogenase (ADH) activity. Aldehyde dehydrogenase (ALDH) activity did not appear to be affected, although ALDH activity was low in cell extracts. Adding ubiquinone-0 to the ALDH assay increased activity in theT. saccharolyticumparent strain but did not increase activity in theadhEdeletion strain, suggesting that ALDH activity was inhibited. InC. thermocellum, theadhEdeletion strain lost >90% of ALDH and ADH activity in cell extracts. TheC. thermocellumadhEdeletion strain contained a point mutation in the lactate dehydrogenase gene, which appears to deregulate its activation by fructose 1,6-bisphosphate, leading to constitutive activation of lactate dehydrogenase.IMPORTANCEThermoanaerobacterium saccharolyticumandClostridium thermocellumare bacteria that have been investigated for their ability to produce biofuels from plant biomass. They have been engineered to produce higher yields of ethanol, yet questions remain about the enzymes responsible for ethanol formation in these bacteria. The genomes of these bacteria encode multiple predicted aldehyde and alcohol dehydrogenases which could be responsible for alcohol formation. This study explores the inactivation ofadhE, a gene encoding a bifunctional alcohol and aldehyde dehydrogenase. Deletion ofadhEreduced ethanol production by >95% in bothT. saccharolyticumandC. thermocellum, confirming thatadhEis necessary for ethanol formation in both organisms. In strains withoutadhE, we note changes in biochemical activity, product formation, and growth.

scholarly journals Both adhE and a Separate NADPH-Dependent Alcohol Dehydrogenase Gene, adhA, Are Necessary for High Ethanol Production in Thermoanaerobacterium saccharolyticum

2016 ◽  
Vol 199 (3) ◽  
Author(s):  
Tianyong Zheng ◽  
Daniel G. Olson ◽  
Sean J. Murphy ◽  
Xiongjun Shao ◽  
Liang Tian ◽  
...  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Ethanol Production ◽  
Ethanol Yield ◽  
Single Gene ◽  
Maximum Yield ◽  
Primary Alcohol ◽  
Content Type ◽  
Thermoanaerobacterium Saccharolyticum ◽  
Dehydrogenase Gene ◽  
High Ethanol

ABSTRACT Thermoanaerobacterium saccharolyticum has been engineered to produce ethanol at about 90% of the theoretical maximum yield (2 ethanol molecules per glucose equivalent) and a titer of 70 g/liter. Its ethanol-producing ability has drawn attention to its metabolic pathways, which could potentially be transferred to other organisms of interest. Here, we report that the iron-containing AdhA is important for ethanol production in the high-ethanol strain of T. saccharolyticum (LL1049). A single-gene deletion of adhA in LL1049 reduced ethanol production by ∼50%, whereas multiple gene deletions of all annotated alcohol dehydrogenase genes except adhA and adhE did not affect ethanol production. Deletion of adhA in wild-type T. saccharolyticum reduced NADPH-linked alcohol dehydrogenase (ADH) activity (acetaldehyde-reducing direction) by 93%. IMPORTANCE In this study, we set out to identify the alcohol dehydrogenases necessary for high ethanol production in T. saccharolyticum. Based on previous work, we had assumed that adhE was the primary alcohol dehydrogenase gene. Here, we show that both adhA and adhE are needed for high ethanol yield in the engineered strain LL1049. This is the first report showing adhA is important for ethanol production in a native adhA host, which has important implications for achieving higher ethanol yields in other microorganisms.

scholarly journals High Ethanol Titers from Cellulose by Using Metabolically Engineered Thermophilic, Anaerobic Microbes

2011 ◽  
Vol 77 (23) ◽  
pp. 8288-8294 ◽  
Author(s):  
D. Aaron Argyros ◽  
Shital A. Tripathi ◽  
Trisha F. Barrett ◽  
Stephen R. Rogers ◽  
Lawrence F. Feinberg ◽  
...  
Keyword(s):  
Ethanol Production ◽  
Wild Type Strain ◽  
Ethanol Yield ◽  
Fold Increase ◽  
Substantial Improvement ◽  
Wild Type ◽  
Content Type ◽  
Thermoanaerobacterium Saccharolyticum ◽  
Lactic Acids ◽  
High Ethanol

ABSTRACTThis work describes novel genetic tools for use inClostridium thermocellumthat allow creation of unmarked mutations while using a replicating plasmid. The strategy employed counter-selections developed from the nativeC. thermocellum hptgene and theThermoanaerobacterium saccharolyticum tdkgene and was used to delete the genes for both lactate dehydrogenase (Ldh) and phosphotransacetylase (Pta). The ΔldhΔptamutant was evolved for 2,000 h, resulting in a stable strain with 40:1 ethanol selectivity and a 4.2-fold increase in ethanol yield over the wild-type strain. Ethanol production from cellulose was investigated with an engineered coculture of organic acid-deficient engineered strains of bothC. thermocellumandT. saccharolyticum. Fermentation of 92 g/liter Avicel by this coculture resulted in 38 g/liter ethanol, with acetic and lactic acids below detection limits, in 146 h. These results demonstrate that ethanol production by thermophilic, cellulolytic microbes is amenable to substantial improvement by metabolic engineering.

scholarly journals Energy Conservation Associated with Ethanol Formation from H2and CO2in Clostridium autoethanogenum Involving Electron Bifurcation

2015 ◽  
Vol 197 (18) ◽  
pp. 2965-2980 ◽  
Author(s):  
Johanna Mock ◽  
Yanning Zheng ◽  
Alexander P. Mueller ◽  
San Ly ◽  
Loan Tran ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Acetyl Coa ◽  
Content Type ◽  
Substrate Level Phosphorylation ◽  
Clostridium Ljungdahlii ◽  
Ethanol Formation ◽  
Cell Extracts ◽  
Substrate Level ◽  
Clostridium Autoethanogenum ◽  
Specific Activities

ABSTRACTMost acetogens can reduce CO2with H2to acetic acid via the Wood-Ljungdahl pathway, in which the ATP required for formate activation is regenerated in the acetate kinase reaction. However, a few acetogens, such asClostridium autoethanogenum,Clostridium ljungdahlii, andClostridium ragsdalei, also form large amounts of ethanol from CO2and H2. How these anaerobes with a growth pH optimum near 5 conserve energy has remained elusive. We investigated this question by determining the specific activities and cofactor specificities of all relevant oxidoreductases in cell extracts of H2/CO2-grownC. autoethanogenum. The activity studies were backed up by transcriptional and mutational analyses. Most notably, despite the presence of six hydrogenase systems of various types encoded in the genome, the cells appear to contain only one active hydrogenase. The active [FeFe]-hydrogenase is electron bifurcating, with ferredoxin and NADP as the two electron acceptors. Consistently, most of the other active oxidoreductases rely on either reduced ferredoxin and/or NADPH as the electron donor. An exception is ethanol dehydrogenase, which was found to be NAD specific. Methylenetetrahydrofolate reductase activity could only be demonstrated with artificial electron donors. Key to the understanding of this energy metabolism is the presence of membrane-associated reduced ferredoxin:NAD+oxidoreductase (Rnf), of electron-bifurcating and ferredoxin-dependent transhydrogenase (Nfn), and of acetaldehyde:ferredoxin oxidoreductase, which is present with very high specific activities in H2/CO2-grown cells. Based on these findings and on thermodynamic considerations, we propose metabolic schemes that allow, depending on the H2partial pressure, the chemiosmotic synthesis of 0.14 to 1.5 mol ATP per mol ethanol synthesized from CO2and H2.IMPORTANCEEthanol formation from syngas (H2, CO, and CO2) and from H2and CO2that is catalyzed by bacteria is presently a much-discussed process for sustainable production of biofuels. Although the process is already in use, its biochemistry is only incompletely understood. The most pertinent question is how the bacteria conserve energy for growth during ethanol formation from H2and CO2, considering that acetyl coenzyme A (acetyl-CoA), is an intermediate. Can reduction of the activated acetic acid to ethanol with H2be coupled with the phosphorylation of ADP? Evidence is presented that this is indeed possible, via both substrate-level phosphorylation and electron transport phosphorylation. In the case of substrate-level phosphorylation, acetyl-CoA reduction to ethanol proceeds via free acetic acid involving acetaldehyde:ferredoxin oxidoreductase (carboxylate reductase).

scholarly journals Ferredoxin:NAD+Oxidoreductase of Thermoanaerobacterium saccharolyticum and Its Role in Ethanol Formation

2016 ◽  
Vol 82 (24) ◽  
pp. 7134-7141 ◽  
Author(s):  
Liang Tian ◽  
Jonathan Lo ◽  
Xiongjun Shao ◽  
Tianyong Zheng ◽  
Daniel G. Olson ◽  
...  
Keyword(s):  
Ethanol Production ◽  
Redox Balance ◽  
Wild Type ◽  
Anaerobic Microorganism ◽  
Content Type ◽  
Ethanol Formation ◽  
Thermoanaerobacterium Saccharolyticum ◽  
Different Strains ◽  
Electron Carriers

ABSTRACTFerredoxin:NAD+oxidoreductase (NADH-FNOR) catalyzes the transfer of electrons from reduced ferredoxin to NAD+. This enzyme has been hypothesized to be the main enzyme responsible for ferredoxin oxidization in the NADH-based ethanol pathway inThermoanaerobacterium saccharolyticum; however, the corresponding gene has not yet been identified. Here, we identified the Tsac_1705 protein as a candidate FNOR based on the homology of its functional domains. We then confirmed its activityin vitrowith a ferredoxin-based FNOR assay. To determine its role in metabolism, thetsac_1705gene was deleted in different strains ofT. saccharolyticum. In wild-typeT. saccharolyticum, deletion oftsac_1705resulted in a 75% loss of NADH-FNOR activity, which indicated that Tsac_1705 is the main NADH-FNOR inT.saccharolyticum. When both NADH- and NADPH-linked FNOR genes were deleted, the ethanol titer decreased and the ratio of ethanol to acetate approached unity, indicative of the absence of FNOR activity. Finally, we tested the effect of heterologous expression of Tsac_1705 inClostridium thermocellumand found improvements in both the titer and the yield of ethanol.IMPORTANCERedox balance plays a crucial role in many metabolic engineering strategies. Ferredoxins are widely used as electron carriers for anaerobic microorganism and plants. This study identified the gene responsible for electron transfer from ferredoxin to NAD+, a key reaction in the ethanol production pathway of this organism and many other metabolic pathways. Identification of this gene is an important step in transferring the ethanol production ability of this organism to other organisms.

scholarly journals Isolation of a Gene Responsible for the Oxidation oftrans-Anethole topara-Anisaldehyde by Pseudomonas putida JYR-1 and Its Expression in Escherichia coli

2012 ◽  
Vol 78 (15) ◽  
pp. 5238-5246 ◽  
Author(s):  
Dongfei Han ◽  
Ji-Young Ryu ◽  
Robert A. Kanaly ◽  
Hor-Gil Hur
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Putida ◽  
Hypothetical Protein ◽  
Aldehyde Group ◽  
Agrobacterium Vitis ◽  
T7 Promoter ◽  
Content Type ◽  
E Coli ◽  
Cell Extracts ◽  
Isoeugenol Monooxygenase

ABSTRACTA plasmid, pTA163, inEscherichia colicontained an approximately 34-kb gene fragment fromPseudomonas putidaJYR-1 that included the genes responsible for the metabolism oftrans-anethole to protocatechuic acid. Three Tn5-disrupted open reading frame 10 (ORF 10) mutants of plasmid pTA163 lost their abilities to catalyzetrans-anethole. Heterologously expressed ORF 10 (1,047 nucleotides [nt]) under a T7 promoter inE. colicatalyzed oxidative cleavage of a propenyl group oftrans-anethole to an aldehyde group, resulting in the production ofpara-anisaldehyde, and this gene was designatedtao(trans-anetholeoxygenase). The deduced amino acid sequence of TAO had the highest identity (34%) to a hypothetical protein ofAgrobacterium vitisS4 and likely contained a flavin-binding site. Preferred incorporation of an oxygen molecule from water intop-anisaldehyde using18O-labeling experiments indicated stereo preference of TAO for hydrolysis of the epoxide group. Interestingly, unlike the narrow substrate range of isoeugenol monooxygenase fromPseudomonas putidaIE27 andPseudomonas nitroreducensJin1, TAO fromP. putidaJYR-1 catalyzed isoeugenol,O-methyl isoeugenol, and isosafrole, all of which contain the 2-propenyl functional group on the aromatic ring structure. Addition of NAD(P)H to the ultrafiltered cell extracts ofE. coli(pTA163) increased the activity of TAO. Due to the relaxed substrate range of TAO, it may be utilized for the production of various fragrance compounds from plant phenylpropanoids in the future.

scholarly journals Saccharomyces cerevisiae Fermentation of 28 Barley and 12 Oat Cultivars

Fermentation ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 59
Author(s):  
Timothy J. Tse ◽  
Daniel J. Wiens ◽  
Jianheng Shen ◽  
Aaron D. Beattie ◽  
Martin J. T. Reaney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Succinic Acid ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Cereal Crops ◽  
Fermentation Products ◽  
Barley Cultivars ◽  
Oat Cultivars

As barley and oat production have recently increased in Canada, it has become prudent to investigate these cereal crops as potential feedstocks for alcoholic fermentation. Ethanol and other coproduct yields can vary substantially among fermented feedstocks, which currently consist primarily of wheat and corn. In this study, the liquified mash of milled grains from 28 barley (hulled and hull-less) and 12 oat cultivars were fermented with Saccharomyces cerevisiae to determine concentrations of fermentation products (ethanol, isopropanol, acetic acid, lactic acid, succinic acid, α-glycerylphosphorylcholine (α-GPC), and glycerol). On average, the fermentation of barley produced significantly higher amounts of ethanol, isopropanol, acetic acid, succinic acid, α-GPC, and glycerol than that of oats. The best performing barley cultivars were able to produce up to 78.48 g/L (CDC Clear) ethanol and 1.81 g/L α-GPC (CDC Cowboy). Furthermore, the presence of milled hulls did not impact ethanol yield amongst barley cultivars. Due to its superior ethanol yield compared to oats, barley is a suitable feedstock for ethanol production. In addition, the accumulation of α-GPC could add considerable value to the fermentation of these cereal crops.

scholarly journals Comparative Profiling and Discovery of Novel Glycosylated Mycosporine-Like Amino Acids in Two Strains of the Cyanobacterium Scytonema cf. crispum

2016 ◽  
Vol 82 (19) ◽  
pp. 5951-5959 ◽  
Author(s):  
Paul M. D'Agostino ◽  
Vivek S. Javalkote ◽  
Rabia Mazmouz ◽  
Russell Pickford ◽  
Pravin R. Puranik ◽  
...  
Keyword(s):  
Amino Acids ◽  
New Zealand ◽  
Uv Radiation ◽  
High Performance ◽  
Parent Compound ◽  
Future Research ◽  
Content Type ◽  
Chromatography Analysis ◽  
Paralytic Shellfish Toxins ◽  
Cell Extracts

ABSTRACTThe mycosporine-like amino acids (MAAs) are a group of small molecules with a diverse ecological distribution among microorganisms. MAAs have a range of physiological functions, including protection against UV radiation, making them important from a biotechnological perspective. In the present study, we identified a putative MAA (mys) gene cluster in two New Zealand isolates ofScytonemacf.crispum(UCFS10 and UCFS15). Homology to “Anabaena-type”mysclusters suggested that this cluster was likely to be involved in shinorine biosynthesis. Surprisingly, high-performance liquid chromatography analysis ofS. cf.crispumcell extracts revealed a complex MAA profile, including shinorine, palythine-serine, and their hexose-bound variants. It was hypothesized that a short-chain dehydrogenase (UCFS15_00405) encoded by a gene adjacent to theS. cf.crispummyscluster was responsible for the conversion of shinorine to palythine-serine. Heterologous expression of MysABCE and UCFS15_00405 inEscherichia coliresulted in the exclusive production of the parent compound shinorine. Taken together, these results suggest that shinorine biosynthesis inS. cf.crispumproceeds via anAnabaena-type mechanism and that the genes responsible for the production of other MAA analogues, including palythine-serine and glycosylated analogues, may be located elsewhere in the genome.IMPORTANCERecently, New Zealand isolates ofS. cf.crispumwere linked to the production of paralytic shellfish toxins for the first time, but no other natural products from this species have been reported. Thus, the species was screened for important natural product biosynthesis. The mycosporine-like amino acids (MAAs) are among the strongest absorbers of UV radiation produced in nature. The identification of novel MAAs is important from a biotechnology perspective, as these molecules are able to be utilized as sunscreens. This study has identified two novel MAAs that have provided several new avenues of future research related to MAA genetics and biosynthesis. Further, we have revealed that the genetic basis of MAA biosynthesis may not be clustered on the genome. The identification of the genes responsible for MAA biosynthesis is vital for future genetic engineering.

scholarly journals Changing Dietary Calcium-Phosphorus Level and Cereal Source Selectively Alters Abundance of Bacteria and Metabolites in the Upper Gastrointestinal Tracts of Weaned Pigs

2013 ◽  
Vol 79 (23) ◽  
pp. 7264-7272 ◽  
Author(s):  
Barbara U. Metzler-Zebeli ◽  
Evelyne Mann ◽  
Stephan Schmitz-Esser ◽  
Martin Wagner ◽  
Mathias Ritzmann ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Gut Health ◽  
Weaned Pigs ◽  
Fermentation Products ◽  
Content Type ◽  
Young Pigs ◽  
Bacterial Microbiota ◽  
Calcium Phosphorus ◽  
And Performance ◽  
The Stability

ABSTRACTSeveral dietary ingredients may affect the bacterial community structure and metabolism in the porcine gut and may therefore influence animals' health and performance. This study investigated the effects of cereal source and calcium-phosphorus (CaP) level in the diet on bacterial microbiota and metabolites, nutrient intake, and gut environment in weaned pigs. Pigs (n= 8/treatment) were fed wheat-barley- or corn-based diets with an adequate or high CaP level for 14 days. Effects on microbiota in the stomach, ileum, and midcolon were assessed using quantitative PCR. Data showed thatEnterobacteriaceae,Campylobacterspp., andHelicobacterspp., which all contain highly immune reactive lipopolysaccharide (LPS), were abundant at all gut sites. Diet effects on bacteria and metabolites were moderate and occurred mainly in the upper gut, whereas no effects on bacteria, fermentation products, and LPS could be observed in the colon. Differences in carbohydrate intake with corn versus wheat-barley diets selectively stimulatedBifidobacteriumin the stomach and ileum. There was a growth advantage for a few bacterial groups in the stomach and ileum of pigs fed the high versus adequate CaP level (i.e., gastricEnterobacteriaceaeand ilealEnterococcus,Bacteroides-Prevotella-Porphyromonas, andCampylobacter). Interestingly, gastrointestinal pH was not affected by dietary CaP level. The present findings demonstrate the stability of the bacterial community and gut environment toward dietary changes even in young pigs. The results on stimulation of gastric and ilealBifidobacteriumby corn diets may be employed in nutritional strategies to support gut health after weaning.

scholarly journals Clostridium acidurici Electron-Bifurcating Formate Dehydrogenase

2013 ◽  
Vol 79 (19) ◽  
pp. 6176-6179 ◽  
Author(s):  
Shuning Wang ◽  
Haiyan Huang ◽  
Jörg Kahnt ◽  
Rudolf K. Thauer
Keyword(s):  
Uric Acid ◽  
Gene Cluster ◽  
Formate Dehydrogenase ◽  
Specific Activity ◽  
Enzyme Complex ◽  
Content Type ◽  
Cell Extracts

ABSTRACTCell extracts of uric acid-grownClostridium aciduricicatalyzed the coupled reduction of NAD+and ferredoxin with formate at a specific activity of 1.3 U/mg. The enzyme complex catalyzing the electron-bifurcating reaction was purified 130-fold and found to be composed of four subunits encoded by the gene clusterhylCBA-fdhF2.

Sign in / Sign up

Export Citation Format

Share Document