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a novel and simple method for the purification of extracellular levansucrase from zymomonas mobilis.a new and simple method for the purification of extracellular levansucrase from zymomonas mobilis from highly viscous fermentation broth was developed. after incubation of the fermentation broth with a fructose-polymer cleaving enzyme preparation (fructozyme, novozymes, dk) for 48 h, levansucrase precipitated as aggregates and was redissolved in a 3 m urea solution. by ongoing size-exclusion chromatography on sephacryl s-300 the final levansucrase preparation was purified 100-fold and exhibited ...200314570269
altered glucose transport and shikimate pathway product yields in e. coli.different glucose transport systems are examined for their impact on phosphoenolpyruvate availability as reflected by the yields of 3-dehydroshikimic acid and byproducts 3-deoxy-d-arabino-heptulosonic acid, 3-dehydroquinic acid, and gallic acid synthesized by escherichia coli from glucose. 3-dehydroshikimic acid is an advanced shikimate pathway intermediate in the syntheses of a spectrum of commodity, pseudocommodity, and fine chemicals. all constructs carried plasmid arof(fbr) and tkta inserts ...200314524706
expression of galp and glk in a escherichia coli pts mutant restores glucose transport and increases glycolytic flux to fermentation products.in escherichia coli, the uptake and phosphorylation of glucose is carried out mainly by the phosphotransferase system (pts). despite the efficiency of glucose transport by pts, the required consumption of 1 mol of phosphoenolpyruvate (pep) for each mol of internalized glucose represents a drawback for some biotechnological applications where pep is a precursor of the desired product. for this reason, there is considerable interest in the generation of strains that can transport glucose efficient ...200312889033
screening of yeasts for cell-free production of (r)-phenylacetylcarbinol.105 yeast strains from 10 genera and 40 species were evaluated for cell-free production of (r)-phenylacetylcarbinol (pac), the chiral precursor in the manufacture of the pharmaceuticals ephedrine and pseudoephedrine. carboligase activity of pyruvate decarboxylase (pdc), forming pac from benzaldehyde and pyruvate, was found in extracts of 98 strains. pac was not formed from benzaldehyde and acetaldehyde, an activity of bacterial pdcs from zymomonas mobilis and zymobacter palmae. two interesting g ...200312889791
an essential role for aspartate 264 in catalysis by trna-guanine transglycosylase from escherichia coli.trna-guanine transglycosylase (tgt) catalyzes a post-transcriptional base-exchange reaction involved in the incorporation of the modified base queuine (q) into the wobble position of certain trnas. catalysis by tgt occurs through a double-displacement mechanism that involves the formation of a covalent enzyme-rna intermediate (kittendorf, j. d., barcomb, l. m., nonekowski, s. t., and garcia, g. a. (2001) biochemistry 40, 14123-14133). the tgt chemical mechanism requires the protonation of the di ...200312909636
metabolic engineering of escherichia coli: construction of an efficient biocatalyst for d-mannitol formation in a whole-cell biotransformation.a whole-cell biotransformation system for the conversion of d-fructose to d-mannitol was developed in escherichia coli by construction of a recombinant oxidation/reduction cycle. first, the mdh gene encoding for the mannitol dehydrogenase of leuconostoc pseudomesenteroides atcc 12291 (mdh) was expressed, effecting a strong catalytic activity of a nadh-dependent reduction of d-fructose to d-mannitol in cell extracts of the recombinant e. coli strain but not enabling whole cells of the strain to p ...200315296170
catalytic activity of zymomonas mobilis extracellular "levan-levansucrase" complex in sucrose medium.the fructan biosynthesis by ethanol sedimented "levan-levansucrase" complex from zymomonas mobilis fermentation broth as well as purified levansucrase was investigated. the fructooligosaccharide (fos) producing activity of "levan-levamsucrase" sediment was investigated in 55% sucrose syrup at 45 degrees c. it was shown that fos in the syrup were presented by 1-kestose, 6-kestose, neokestose and nystose. the increase of gluconic acid concentration was observed in the reaction mixture during the i ...200315296187
inhibition of thiamin diphosphate dependent enzymes by 3-deazathiamin diphosphate.3-deazathiamin diphosphate (deazatpp) and a second thiamin diphosphate (tpp) analogue having a benzene ring in place of the thiazolium ring have been synthesised. these compounds are both extremely potent inhibitors of pyruvate decarboxylase from zymomonas mobilis; binding is competitive with tpp and is essentially irreversible even though no covalent linkage is formed. deazatpp binds approximately seven-fold faster than tpp and at least 25,000-fold more tightly (k(i) less than 14 pm). deazatpp ...200415188040
use of zymomonas mobilis and saccharomyces cerevisiae mixed with kluyveromyces fragilis for improved ethanol production from jerusalem artichoke tubers.jerusalem artichoke mashed tubers were fermented using single yeasts and a bacterium as well as mixed culture of microorganisms. kluyveromyces fragilis, a yeast with an active inulinase, was used together with either a commercial distillery yeast, saccharomyces cerevisiae, or the bacterium zymomonas mobilis. after batch fermentation the best ethanol concentration of 0.48 g g(-1) for the mixed population and 0.46 g g(-1) for the single population can be obtained. the theoretical yield of the mixe ...200415269559
metabolic engineering of corynebacterium glutamicum for fuel ethanol production under oxygen-deprivation conditions.the central metabolic pathway of corynebacterium glutamicum was engineered to produce ethanol. a recombinant strain which expressed the zymomonas mobilis genes coding for pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhb) was constructed. both genes placed under the control of the c. glutamicum ldha promoter were expressed at high levels in c. glutamicum, resulting, under oxygen-deprivation conditions, in a significant yield ofethanol from glucose in a process characterized by the abs ...200416179801
biphasic aqueous/organic biotransformation of acetaldehyde and benzaldehyde by zymomonas mobilis pyruvate decarboxylase.zymomonas mobilis pyruvate decarboxylase (pdc) transformed acetaldehyde and benzaldehyde into (r)-phenylacetylcarbinol (pac), the precursor for the synthesis of ephedrine and pseudoephedrine. organic solvents were screened for a biphasic biotransformation with the enzyme in an aqueous phase and the toxic substrates delivered through the organic phase. in the absence of substrates a second phase of 1-pentanol, hexadecane or mtbe (methyl tertiary-butyl ether) stabilized the pdc activity in compari ...200415162454
the effect of zymomonas mobilis culture on experimental schistosoma mansoni infection.c57bl/10 male mice infected with schistosoma mansoni were distributed into mixed, prophylactic and curative groups. a culture of zymomonas mobilis was orally administered to mice. a 61% protection from the infection was observed in the curative group (p <0.05). histopathological study of the livers and intestines showed similar results.200415765603
sorbitol can be produced not only chemically but also biotechnologically.sorbitol, a polyol found in many fruits, is attracting increasing industrial interest as a sweetener, humectant, texturizer, and softener. it is principally produced by chemical means. the bacterium zymomonas mobilis is able to produce sorbitol together with gluconic acid from fructose and glucose, respectively. this is possible in a one-step reaction via the enzyme glucose-fructose oxidoreductase, so far only known from z. mobilis. the possibilities for the production of sorbitol by z. mobilis ...200415304760
novel xylose dehydrogenase in the halophilic archaeon haloarcula marismortui.during growth of the halophilic archaeon haloarcula marismortui on d-xylose, a specific d-xylose dehydrogenase was induced. the enzyme was purified to homogeneity. it constitutes a homotetramer of about 175 kda and catalyzed the oxidation of xylose with both nadp+ and nad+ as cosubstrates with 10-fold higher affinity for nadp+. in addition to d-xylose, d-ribose was oxidized at similar kinetic constants, whereas d-glucose was used with about 70-fold lower catalytic efficiency (kcat/km). with the ...200415342590
crystal structure of 1-deoxy-d-xylulose-5-phosphate reductoisomerase from zymomonas mobilis at 1.9-a resolution.1-deoxy-d-xylulose-5-phosphate reductoisomerase (dxr) is the second enzyme in the non-mevalonate pathway of isoprenoid biosynthesis. the structure of the apo-form of this enzyme from zymomonas mobilis has been solved and refined to 1.9-a resolution, and that of a binary complex with the co-substrate nadph to 2.7-a resolution. the subunit of dxr consists of three domains. residues 1-150 form the nadph binding domain, which is a variant of the typical dinucleotide-binding fold. the second domain c ...200415063313
antitumor activity of levan polysaccharides from selected microorganisms.levans were isolated from the cultures of gluconoacetobacter xylinus (g-levan; mw = 40,000), microbacterium laevaniformans (m; mw = 710,000), rahnella aquatilis (r; mw = 380,000), and zymomonas mobilis (z; mw = 570,000). the levans were composed mainly of fructose residues when analyzed by tlc and hplc, and their main backbones were beta-(2,6)-linkages with beta-(2,1)-branches by gc-ms and nmr. in the in vitro antitumor activity test of the levans against eight different tumor cell lines, relati ...200415178007
inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass.an overview of the different inhibitors formed by pre-treatment of lignocellulosic materials and their inhibition of ethanol production in yeast and bacteria is given. different high temperature physical pre-treatment methods are available to render the carbohydrates in lignocellulose accessible for ethanol fermentation. the resulting hydrolyzsates contain substances inhibitory to fermentation-depending on both the raw material (biomass) and the pre-treatment applied. an overview of the inhibito ...200415300416
parameter oscillations in a very high gravity medium continuous ethanol fermentation and their attenuation on a multistage packed column bioreactor system.the quasi-steady-states, marked by small fluctuations of residual glucose, ethanol, and biomass concentrations, and sustainable oscillations marked by big fluctuations of these monitored fermentation parameters were observed during the continuous ethanol fermentation of saccharomyces cerevisiae when very high gravity media were fed and correspondingly high ethanol concentrations reached. a high ethanol concentration was shown to be one of the main factors that incited these oscillations, althoug ...200415470717
the genome sequence of the ethanologenic bacterium zymomonas mobilis zm4.we report the complete genome sequence of zymomonas mobilis zm4 (atcc31821), an ethanologenic microorganism of interest for the production of fuel ethanol. the genome consists of 2,056,416 base pairs forming a circular chromosome with 1,998 open reading frames (orfs) and three ribosomal rna transcription units. the genome lacks recognizable genes for 6-phosphofructokinase, an essential enzyme in the embden-meyerhof-parnas pathway, and for two enzymes in the tricarboxylic acid cycle, the 2-oxoglu ...200415592456
disruption of the zymomonas mobilis extracellular sucrase gene (sacc) improves levan production.disruption of the extracellular zymomonas mobilis sucrase gene (sacc) to improve levan production.200415012804
crystallographic study of inhibitors of trna-guanine transglycosylase suggests a new structure-based pharmacophore for virtual screening.the enzyme trna-guanine transglycosylase (tgt) is involved in the pathogenicity of shigellae. as the crystal structure of this protein is known, it is a putative target for the structure-based design of inhibitors. here we report a crystallographic study of several new ligands exhibiting a 2,6-diamino-3h-quinazolin-4-one scaffold, which has been shown recently to be a promising template for tgt-inhibitors. crystal structure analysis of these complexes has revealed an unexpected movement of the s ...200415050823
metabolic engineering of escherichia coli: construction of an efficient biocatalyst for d-mannitol formation in a whole-cell biotransformation.a whole-cell biotransformation system for the conversion of d-fructose to d-mannitol was developed in escherichia coli by constructing a recombinant oxidation/reduction cycle. first, the mdh gene, encoding mannitol dehydrogenase of leuconostoc pseudomesenteroides atcc 12291 (mdh), was expressed, effecting strong catalytic activity of an nadh-dependent reduction of d-fructose to d-mannitol in cell extracts of the recombinant e. coli strain. by contrast whole cells of the strain were unable to pro ...200414586579
performance of a newly developed integrant of zymomonas mobilis for ethanol production on corn stover hydrolysate.efficient conversion of lignocellulosic biomass requires biocatalysts able to tolerate inhibitors produced by many pretreatment processes. recombinant zymomonas mobilis 8b, a recently developed integrant of zymomonas mobilis 31821(pzb5), tolerated acetic acid up to 16 g l(-1) and achieved 82%-87% (w/w) ethanol yields from pure glucose/xylose solutions at ph 6 and temperatures of 30 degrees c and 37 degrees c. an ethanol yield of 85% (w/w) was achieved on glucose/xylose from hydrolysate produced ...200415055769
ethanol fermentation on the move. 200515637618
over-expression of xylulokinase in a xylose-metabolising recombinant strain of zymomonas mobilis.the broad host range vector pbbr1mcs-2 has been evaluated as an expression vector for zymomonas mobilis. the transformation efficiency of this vector was 2 x 10(3) cfu per mug of dna in a recombinant strain of z. mobilis zm4/acr containing the plasmid pzb5. stable replication for this expression vector was demonstrated for 50 generations. this vector was used to study xylose metabolism in acetate resistant z. mobilis zm4/acr (pzb5) by over-expression of xylulokinase (xk), as previous studies had ...200515727825
genome update: base skews in 200+ bacterial chromosomes. 200515758208
zymomonas mobilis subspecies identification by amplified ribosomal dna restriction analysis.to identify strains of zymomonas mobilis at the subspecies level by a fast and reliable technique.200515644116
high-level acetaldehyde production in lactococcus lactis by metabolic engineering.efficient conversion of glucose to acetaldehyde is achieved by nisin-controlled overexpression of zymomonas mobilis pyruvate decarboxylase (pdc) and lactococcus lactis nadh oxidase (nox) in l. lactis. in resting cells, almost 50% of the glucose consumed could be redirected towards acetaldehyde by combined overexpression of pdc and nox under anaerobic conditions.200515691976
experimental identification and quantification of glucose metabolism in seven bacterial species.the structurally conserved and ubiquitous pathways of central carbon metabolism provide building blocks and cofactors for the biosynthesis of cellular macromolecules. the relative uses of pathways and reactions, however, vary widely among species and depend upon conditions, and some are not used at all. here we identify the network topology of glucose metabolism and its in vivo operation by quantification of intracellular carbon fluxes from 13c tracer experiments. specifically, we investigated a ...200515716428
high efficiency ethanol fermentation by entrapment of zymomonas mobilis into lentikats.to examine the potential of zymomonas mobilis entrapped into polyvinylalcohol (pva) lens-shaped immobilizates in batch and continuous ethanol production.200516238644
transcriptional analysis of a gene cluster involved in glucose tolerance in zymomonas mobilis: evidence for an osmoregulated promoter.exponentially growing cells of zymomonas mobilis normally exhibit a lag period of up to 3 h when they are transferred from a liquid medium containing 2% glucose to a liquid medium containing 10% glucose. a mutant of z. mobilis (cu1) exhibited a lag period of more than 20 h when it was grown under the same conditions, whereas it failed to grow on a solid medium containing 10% glucose. the glucose-defective phenotype of mutant cu1 was due to a spontaneous insertion in a putative gene (orf4) identi ...200516030211
cog3926 and cog5526: a tale of two new lysozyme-like protein families.we have identified two new lysozyme-like protein families by using a combination of sequence similarity searches, domain architecture analysis, and structural predictions. first, the p5 protein from bacteriophage phi8, which belongs to cog3926 and pfam family duf847, is predicted to have a new lysozyme-like domain. this assignment is consistent with the lytic function of p5 proteins observed in several related double-stranded rna bacteriophages. domain architecture analysis reveals two lysozyme- ...200516155206
[research progress of ethanologenic zymomonas mobilis].zymomonas mobilis is one of the natural ethanologenic microbes. with the unique entner-doudoroff pathway and some other special pathways of glycolytic and energetic metabolism, z. mobilis has remarkable characters of higher rate of ethanol production and higher tolerance to ethanol. glycolytic and energetic metabolism, tolerances (e.g., to ethanol, osmotic stress, etc.) and genetic improvements of z. mobilis are reviewed to elucidate the huge potential of z. mobilis in fuel ethanol production.200515989250
recombinant production of zymomonas mobilis pyruvate decarboxylase in the haloarchaeon haloferax volcanii.the unusual physiological properties of archaea (e.g., growth in extreme salt concentration, temperature and ph) make them ideal platforms for metabolic engineering. towards the ultimate goal of modifying an archaeon to produce bioethanol or other useful products, the pyruvate decarboxylase gene of zymomonas mobilis (zm pdc) was expressed in haloferax volcanii. this gene has been used successfully to channel pyruvate to ethanol in various gram-negative bacteria, including escherichia coli. altho ...200515876566
exchanging the substrate specificities of pyruvate decarboxylase from zymomonas mobilis and benzoylformate decarboxylase from pseudomonas putida.pyruvate decarboxylase from zymomonas mobilis (pdc) and benzoylformate decarboxylase from pseudomonas putida (bfd) are thiamine diphosphate-dependent enzymes that decarboxylate 2-keto acids. although they share a common homotetrameric structure they have relatively low sequence similarity and different substrate spectra. pdc prefers short aliphatic substrates whereas bfd favours aromatic 2-keto acids. these preferences are also reflected in their carboligation reactions. pdc catalyses the conver ...200515930043
the role of aspartic acid 143 in e. coli trna-guanine transglycosylase: insights from mutagenesis studies and computational modeling.trna guanine transglycosylase (tgt) is a trna-modifying enzyme which catalyzes the posttranscriptional exchange of guanine in position 34 of trna(y,h,n,d) with the modified base queuine in eukaryotes or its precursor, preq(1) base, in eubacteria. thus, tgt must recognize the guanine in trna and the free base queuine or preq(1) to catalyze this exchange. the crystal structure of zymomonas mobilis tgt with preq(1) bound suggests that a key aspartate is critically involved in substrate recognition. ...200515951383
cofactor activation and substrate binding in pyruvate decarboxylase. insights into the reaction mechanism from molecular dynamics simulations.we have performed long-term molecular dynamics simulations of pyruvate decarboxylase from zymomonas mobilis. nine structures were modeled to investigate mechanistic questions related to binding of the cofactor, thiamin diphosphate (thdp), and the substrate in the active site. the simulations reveal that the proposed three thdp-tautomers all can bind in the active site and indicate that the equilibrium is shifted toward 4'-aminopyrimidine thdp in the absence of substrate. 4'-aminopyrimidinium thd ...200516274227
cosmeceutical properties of levan produced by zymomonas mobilis.levan, a polysaccharide that can be produced by both plants and microorganisms, is a sugar polymer composed of fructose, with beta-2,6 linkages. here, we have attempted to assess the possible use of levan produced by zymomonas mobilis as a cosmeceutical ingredient. in service of this goal, we assessed a host of levan's properties, including its moisturizing effects, cell cytotoxicity, cell proliferation effects, and anti-inflammation effects. levan exhibited a moisturizing effect that was almost ...200516538295
ethanol production from cellulosic materials by genetically engineered zymomonas mobilis.to confer the ability to ferment cello-oligosaccharides on the ethanol-producing bacterium, zymomonas mobilis, the beta-glucosidase gene from ruminococcus albus, tagged at its n-terminal with the 53-amino acid tat signal peptide from the periplasmic enzyme glucose-fructose oxidoreductase from z. mobilis, was introduced into the strain. the tag enabled 61% of the beta-glucosidase activity to be transported through the cytoplasmic membrane of the recombinant strain which then produced 0.49 g ethan ...200515742147
intermediates and transition states in thiamin diphosphate-dependent decarboxylases. a kinetic and nmr study on wild-type indolepyruvate decarboxylase and variants using indolepyruvate, benzoylformate, and pyruvate as substrates.the thiamin diphosphate (thdp)-dependent enzyme indolepyruvate decarboxylase (ipdc) is involved in the biosynthetic pathway of the phytohormone 3-indoleacetic acid and catalyzes the nonoxidative decarboxylation of 3-indolepyruvate to 3-indoleacetaldehyde and carbon dioxide. the steady-state distribution of covalent thdp intermediates of ipdc reacting with 3-indolepyruvate and the alternative substrates benzoylformate and pyruvate has been analyzed by (1)h nmr spectroscopy. for the first time, we ...200515835904
physiological regulation of the properties of alcohol dehydrogenase ii (adh ii) of zymomonas mobilis: nadh renders adh ii resistant to cyanide and aeration.the variable cyanide-sensitivity of the iron-containing alcohol dehydrogenase isoenzyme (adh ii) of the ethanol-producing bacterium zymomonas mobilis was studied. in aerobically grown permeabilized cells, cyanide caused gradual inhibition of adh ii, which was largely prevented by externally added nadh. cyanide-sensitivity of adh ii was highest in cells grown under conditions of vigorous aeration, in which intracellular nadh concentration was low. anaerobically grown bacteria, as well as those cu ...200516027951
kinetic control of thiamin diphosphate activation in enzymes studied by proton-nitrogen correlated nmr spectroscopy.proton-nitrogen correlated nmr studies were performed on thiamin diphosphate, which has been specifically labeled with (15)n at the 4'-amino group. after reconstitution of the labeled coenzyme with the apoenzymes of both wild-type pyruvate decarboxylase from zymomonas mobilis and the e50q variant, a high-field shift of the (15)n signal of approximately 4 ppm is observed at ph 5.9 when compared to that of the free coenzyme, indicating a higher electron density at the 4'-amino nitrogen in the enzy ...200515952776
respiratory behaviour of a zymomonas mobilis adhb::kan(r) mutant supports the hypothesis of two alcohol dehydrogenase isoenzymes catalysing opposite reactions.perturbation of the aerobic steady-state in a chemostat culture of the ethanol-producing bacterium zymomonas mobilis with a small pulse of ethanol causes a burst of ethanol oxidation, although the reactant ratio of the alcohol dehydrogenase (adh) reaction ([nadh][acetaldehyde][h(+)])/([ethanol][nad(+)]) remains above the k(eq) value. simultaneous catalysis of ethanol synthesis and oxidation by the two adh isoenzymes, residing in different redox microenvironments, has been proposed previously. in ...200616950260
physiology of zymomonas mobilis: some unanswered questions.the ethanol-producing bacterium zymomonas mobilis can serve as a model organism for the study of rapid catabolism and inefficient energy conversion in bacteria. some basic aspects of its physiology still remain poorly understood. here, the energy-spilling pathways during uncoupled growth, the structure and function of electron transport chain, and the possible reasons for the inefficient oxidative phosphorylation are analysed. also, the interaction between ethanol synthesis and respiration is co ...200617010696
polyphasic study of zymomonas mobilis strains revealing the existence of a novel subspecies z. mobilis subsp. francensis subsp. nov., isolated from french cider.zymomonas mobilis strains recently isolated from french 'framboisé' ciders were compared with collection strains of the two defined subspecies, z. mobilis subsp. mobilis and z. mobilis subsp. pomaceae, using a polyphasic approach. six strains isolated from six different regions of france were compared with three strains of z. mobilis subsp. mobilis, including the type strain lmg 404t, and four strains of z. mobilis subsp. pomaceae, including the type strain lmg 448t, using phenotypic and genotyp ...200616403876
ethanol production from dilute-acid softwood hydrolysate by co-culture.dilute-acid softwood hydrolysate, with glucose and xylose as the dominant sugars, was fermented to ethanol by co-cultures. the strains used include saccharomyces cerevisiae 2.535 (1#), pachysolen tannophilis atcc 2.1662 (2#), and recombinant escherichia coli (3#) constructed in our laboratory carrying both pdc and adhb genes derived from zymomonas mobilis. before fermentation, the co-cultures were adapted for five batches. observation under light microscope showed aggregation of adapted strains, ...200616960285
altered mrna expression of hepatic lipogenic enzyme and pparalpha in rats fed dietary levan from zymomonas mobilis.levan or high molecular beta-2,6-linked fructose polymer is produced extracellularly from sucrose-based substrates by bacterial levansucrase. in the present study, to investigate the effect of levan feeding on serum leptin, hepatic lipogenic enzyme and peroxisome proliferation-activated receptor (ppar) alpha expression in high-fat diet-induced obese rats, 4-week-old sprague-dawley male rats were fed high-fat diet (beef tallow, 40% of calories as fat), and, 6 weeks later, the rats were fed 0%, 1% ...200616214330
enhancement of acid tolerance in zymomonas mobilis by a proton-buffering peptide.a portion of the cbpa gene from escherichia coli k-12 encoding a 24 amino acid proton-buffering peptide (pbp) was cloned via the shuttle vector pjb99 into e. coli jm105 and subsequently into zymomonas mobilis cp4. expression of pbp was confirmed in both jm105 and cp4 by hplc. z. mobilis cp4 carrying pjb99-2 (pbp) exhibited increased acid tolerance (p < 0.05) in acidified tsb (hcl [ph 3.0] or acetic acid [ph 3.5]), glycine-hcl buffer (ph 3.0), and sodium acetate-acetic acid buffer (ph 3.5) in com ...200616891663
zymomonas mobilis as catalyst for the biotechnological production of sorbitol and gluconic acid.the conversion of glucose and fructose into gluconic acid (ga) and sorbitol (sor) was conducted in a batch reactor with free (ctab-treated or not) or immobilized cells of zymomonas mobilis. high yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/l (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 u/l. the concentration of the products varied hyperbolically with time according to the eq ...200616915688
microdiesel: escherichia coli engineered for fuel production.biodiesel is an alternative energy source and a substitute for petroleum-based diesel fuel. it is produced from renewable biomass by transesterification of triacylglycerols from plant oils, yielding monoalkyl esters of long-chain fatty acids with short-chain alcohols such as fatty acid methyl esters and fatty acid ethyl esters (faees). despite numerous environmental benefits, a broader use of biodiesel is hampered by the extensive acreage required for sufficient production of oilseed crops. ther ...200616946248
crystal structure of nadp(h)-dependent 1,5-anhydro-d-fructose reductase from sinorhizobium morelense at 2.2 a resolution: construction of a nadh-accepting mutant and its application in rare sugar synthesis.recombinant 1,5-anhydro-d-fructose reductase (afr) from sinorhizobium morelense s-30.7.5 was crystallized in complex with the cofactor nadp(h) and its structure determined to 2.2 a resolution using selenomethionine sad (refined r(work) and r(free) factors of 18.9 and 25.0%, respectively). as predicted from the sequence and shown by the structure, afr can be assigned to the gfo/idh/moca protein family. afr consists of two domains. the n-terminal domain displays a rossmann fold and contains the co ...200616906761
zymomonas mobilis as catalyst for the biotechnological production of sorbitol and gluconic acid.the conversion of glucose and fructose into gluconic acid (ga) and sorbitol (sor) was conducted in a batch reactor with free (ctab-treated or not) or immobilized cells of zymomonas mobilis. high yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/l (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 u/l. the concentration of the products varied hyperbolically with time according to the eq ...200618563654
kinetic characterization of synechocystis sp. pcc6803 1-deoxy-d-xylulose 5-phosphate reductoisomerase mutants.the methylerythritol phosphate pathway to isoprenoids has been firmly established as an alternate to the mevalonate pathway in many bacteria, plants, algae, and the malaria parasite plasmodium falciparum. the second enzyme in this pathway, deoxy-d-xylulose 5-phosphate reductoisomerase (dxr; e.c. 1.1.1.267), has been the focus of many investigations since it was found to be the target of the antibacterial and antimalarial compound, fosmidomycin. several x-ray crystal structures of the escherichia ...200616219495
[progress on engineered strains for ethanol production].with the 21 century's coming, the era of cheap oil is coming to the end. there has been an increasing worldwide interest in fuel ethanol. in the last two decades, lots of work has been done to develop strains for ethanol producing. research progress on metabolic engineering of strains for fuel ethanol production is summarized, including genetically engineered saccharomyces cerevisiae to utilize starch, pentose and cellulose, zymomonas mobilis to ferment arabinose and xylose, escherichia coli and ...200617037078
bacterial diversity in the active stage of a bioremediation system for mineral oil hydrocarbon-contaminated soils.soils contaminated with mineral oil hydrocarbons are often cleaned in off-site bioremediation systems. in order to find out which bacteria are active during the degradation phase in such systems, the diversity of the active microflora in a degrading soil remediation system was investigated by small-subunit (ssu) rrna analysis. two sequential rna extracts from one soil sample were generated by a procedure incorporating bead beating. both extracts were analysed separately by generating individual ...200617074900
enhanced benzaldehyde tolerance in zymomonas mobilis biofilms and the potential of biofilm applications in fine-chemical production.biotransformation plays an increasingly important role in the industrial production of fine chemicals due to its high product specificity and low energy requirement. one challenge in biotransformation is the toxicity of substrates and/or products to biocatalytic microorganisms and enzymes. biofilms are known for their enhanced tolerance of hostile environments compared to planktonic free-living cells. zymomonas mobilis was used in this study as a model organism to examine the potential of surfac ...200616461720
tfam detects co-evolution of trna identity rules with lateral transfer of histidyl-trna synthetase.we present tfam, an automated, statistical method to classify the identity of trnas. tfam, currently optimized for bacteria, classifies initiator trnas and predicts the charging identity of both typical and atypical trnas such as suppressors with high confidence. we show statistical evidence for extensive variation in trna identity determinants among bacterial genomes due to variation in overall tdna base content. with tfam we have detected the first case of eukaryotic-like trna identity rules i ...200616473847
kinetic modeling to optimize pentose fermentation in zymomonas mobilis.zymomonas mobilis engineered to express four heterologous enzymes required for xylose utilization ferments xylose along with glucose. a network of pentose phosphate (pp) pathway enzymatic reactions interacting with the native glycolytic entner doudoroff (ed) pathway has been hypothesized. we have investigated this putative reaction network by developing a kinetic model incorporating all of the enzymatic reactions of the pp and ed pathways, including those catalyzed by the heterologous enzymes. s ...200616570322
measurement and analysis of intracellular atp levels in metabolically engineered zymomonas mobilis fermenting glucose and xylose mixtures.intracellular adenosine-5'-triphosphate (atp) levels were measured in a metabolically engineered zymomonas mobilis over the course of batch fermentations of glucose and xylose mixtures. fermentations were conducted over a range of ph (5-6) in the presence of varying initial amounts of acetic acid (0-8 g/l) using a 10% (w/v) total sugar concentration (glucose only, xylose only, or 5% glucose/5% xylose mixture). over the design space investigated, ethanol process yields varied between 56.6% and 92 ...200616599547
the 1.9 a resolution structure of mycobacterium tuberculosis 1-deoxy-d-xylulose 5-phosphate reductoisomerase, a potential drug target.1-deoxy-d-xylulose 5-phosphate reductoisomerase catalyzes the nadph-dependent rearrangement and reduction of 1-deoxy-d-xylulose 5-phosphate to form 2-c-methyl-d-erythritol 4-phosphate, as the second step of the deoxyxylulose 5-phosphate/methylerythritol 4-phosphate pathway found in many bacteria and plants. the end product, isopentenyl diphosphate, is the precursor of various isoprenoids vital to all living organisms. the pathway is not found in humans; the mevalonate pathway is instead used for ...200616790937
construction of an escherichia coli k-12 mutant for homoethanologenic fermentation of glucose or xylose without foreign genes.conversion of lignocellulosic feedstocks to ethanol requires microorganisms that effectively ferment both hexose and pentose sugars. towards this goal, recombinant organisms have been developed in which heterologous genes were added to platform organisms such as saccharomyces cerevisiae, zymomonas mobilis, and escherichia coli. using a novel approach that relies only on native enzymes, we have developed a homoethanologenic alternative, escherichia coli strain se2378. this mutant ferments glucose ...200717259366
quantification of lactobionic acid and sorbitol from enzymatic reaction of fructose and lactose by high-performance liquid chromatography.experimental conditions for complete separation and quantification of mixtures containing lactobionic acid, sorbitol, lactose and fructose are discussed for the first time. these mixtures appear in the enzymatic bioconversion of fructose and lactose catalyzed by glucose-fructose oxidoreductase (gfor) and glucono-delta-lactonase (gl) enzymes of zymomonas mobilis cells. the high-performance liquid chromatography (hplc) separation was carried out in a strong cation ion exchange resin (hydrogen form ...200717306812
genetic engineering of zymobacter palmae for production of ethanol from xylose.its metabolic characteristics suggest that zymobacter palmae gen. nov., sp. nov. could serve as a useful new ethanol-fermenting bacterium, but its biotechnological exploitation will require certain genetic modifications. we therefore engineered z. palmae so as to broaden the range of its fermentable sugar substrates to include the pentose sugar xylose. the escherichia coli genes encoding the xylose catabolic enzymes xylose isomerase, xylulokinase, transaldolase, and transketolase were introduced ...200717308178
growth and metabolism in sugarcane are altered by the creation of a new hexose-phosphate sink.an efficient in planta sugarcane-based production system may be realized by coupling the synthesis of alternative products to the metabolic intermediates of sucrose metabolism, thus taking advantage of the sucrose-producing capability of the plant. this was evaluated by synthesizing sorbitol in sugarcane (saccharum hybrids) using the malus domestica sorbitol-6-phosphate dehydrogenase gene (mds6pdh). mature transgenic sugarcane plants were compared with untransformed sugarcane variety q117 by eva ...200717309679
zymomonas mobilis for fuel ethanol and higher value products.high oil prices, increasing focus on renewable carbohydrate-based feedstocks for fuels and chemicals, and the recent publication of its genome sequence, have provided continuing stimulus for studies on zymomonas mobilis. however, despite its apparent advantages of higher yields and faster specific rates when compared to yeasts, no commercial scale fermentations currently exist which use z. mobilis for the manufacture of fuel ethanol. this may change with the recent announcement of a dupont/broin ...200717522816
crystal structures of trna-guanine transglycosylase (tgt) in complex with novel and potent inhibitors unravel pronounced induced-fit adaptations and suggest dimer formation upon substrate binding.the bacterial trna-guanine transglycosylase (tgt) is a trna modifying enzyme catalyzing the exchange of guanine 34 by the modified base preq1. the enzyme is involved in the infection pathway of shigella, causing bacterial dysentery. as no crystal structure of the shigella enzyme is available the homologous zymomonas mobilis tgt was used for structure-based drug design resulting in new, potent, lin-benzoguanine-based inhibitors. thorough kinetic studies show size-dependent inhibition of these com ...200717524419
metabolic engineering of bacillus subtilis for ethanol production: lactate dehydrogenase plays a key role in fermentative metabolism.wild-type bacillus subtilis ferments 20 g/liter glucose in 48 h, producing lactate and butanediol, but not ethanol or acetate. to construct an ethanologenic b. subtilis strain, homologous recombination was used to disrupt the native lactate dehydrogenase (ldh) gene (ldh) by chromosomal insertion of the zymomonas mobilis pyruvate decarboxylase gene (pdc) and alcohol dehydrogenase ii gene (adhb) under the control of the ldh native promoter. the values of the intracellular pdc and adhii enzymatic a ...200717586670
quantifying the metabolic capabilities of engineered zymomonas mobilis using linear programming analysis.the need for discovery of alternative, renewable, environmentally friendly energy sources and the development of cost-efficient, "clean" methods for their conversion into higher fuels becomes imperative. ethanol, whose significance as fuel has dramatically increased in the last decade, can be produced from hexoses and pentoses through microbial fermentation. importantly, plant biomass, if appropriately and effectively decomposed, is a potential inexpensive and highly renewable source of the hexo ...200717349037
a more convenient truth. 200717366694
sampling for metabolome analysis of microorganisms.in the present work we investigated the most commonly applied methods used for sampling of microorganisms in the field of metabolomics in order to unravel potential sources of error previously ignored but of utmost importance for accurate metabolome analysis. to broaden the significance of our study, we investigated different gram-negative and gram-positive bacteria, i.e., bacillus subtilis, corynebacterium glutamicum, escherichia coli, gluconobacter oxydans, pseudomonas putida, and zymononas mo ...200717411014
single-species microbial biofilm screening for industrial applications.while natural microbial biofilms often consist of multiple species, single-species biofilms are of great interest to biotechnology. the current study evaluates biofilm formation for common industrial and laboratory microorganisms. a total of 68 species of biosafety level one bacteria and yeasts from over 40 different genera and five phyla were screened by growing them in microtiter plates and estimating attached biomass by crystal violet staining. most organisms showed biofilm formation on surfa ...200717653709
cloning and transcriptional analysis of groes and groel in ethanol-producing bacterium zymomonas mobilis tistr 548.heat and ethanol had an affect not only on growth and cell viability of an obligatorily fermentative gram-negative bacterium zymomonas mobilis, but also on protein synthesis. analysis by sds-polyacrylamide gel electrophoresis revealed pronounced increasing of two dominant proteins designated as groes and groel. molecular cloning of the gene encoding groes and groel was performed by pcr technique using specific primers synthesized based on the z. mobilis groesl gene. sequencing analysis of 2179 b ...200719069981
growth rate of a non-fermentative escherichia coli strain is influenced by nad+ regeneration.by complementing a non-fermentative escherichia coli (ldha (-) pflb (-)) strain with the recombinant zymomonas mobilis ethanol pathway (pdc, adhb), we evaluated the effect of different levels of enzymatic activity on growth rate demonstrating that there is a direct relationship between anaerobic growth rate and the total specific activity of pyruvate decarboxylase, which is the limiting enzyme of this specific fermentative nad(+) regenerating pathway. this relationship was proved to be useful to ...200717934696
glutamate versus glutamine exchange swaps substrate selectivity in trna-guanine transglycosylase: insight into the regulation of substrate selectivity by kinetic and crystallographic studies.bacterial trna-guanine transglycosylase (tgt) catalyses the exchange of guanine in the wobble position of particular trnas by the modified base preq(1). in vitro, however, the enzyme is also able to insert the immediate biosynthetic precursor, preq(0), into those trnas. this substrate promiscuity is based on a peptide switch in the active site, gated by the general acid/base glu235. the switch alters the properties of the binding pocket to allow either the accommodation of guanine or preq(1). th ...200717949745
biochemical characterization and phylogenetic analysis of udp-glucose dehydrogenase from the gellan gum producer sphingomonas elodea atcc 31461.sphingomonas elodea atcc 31461 synthesizes in high yield the exopolysaccharide gellan, which is a water-soluble gelling agent with many applications. in this study, we describe the cloning and sequence analysis of the ugdg gene, encoding a udp-glucose dehydrogenase (47.2 kda; udpg-dh; ec 1.1.1.22), required for the synthesis of the gellan gum precursor udp-glucuronic acid. ugdg protein shows homology to members of the udp-glucose/gdp-mannose dehydrogenase superfamily. the neighbor-joining method ...200717668199
ethanol production from hydrolysed agricultural wastes using mixed culture of zymomonas mobilis and candida tropicalis.acid, alkaline and enzymatic hydrolysis of agricultural crop wastes were compared for yields of total reducing sugars with the hydrolysates being evaluated for ethanol production using a mixed culture of zymomonas mobilis and candida tropicalis. acid hydrolysis of fruit and vegetable residues gave 49-84 g reducing sugars l(-1) and 29-32 g ethanol l(-1) was then obtained. alkaline hydrolysis did not give significant amount of reducing sugars. enzymatic hydrolysis of fruit and vegetable residues y ...200717657407
expression of glf z.m. increases d-mannitol formation in whole cell biotransformation with resting cells of corynebacterium glutamicum.a recombinant oxidation/reduction cycle for the conversion of d-fructose to d-mannitol was established in resting cells of corynebacterium glutamicum. whole cells were used as biocatalysts, supplied with 250 mm sodium formate and 500 mm d-fructose at ph 6.5. the mannitol dehydrogenase gene (mdh) from leuconostoc pseudomesenteroides was overexpressed in strain c. glutamicum atcc 13032. to ensure sufficient cofactor [nicotinamide adenine dinucleotide (reduced form, nadh)] supply, the fdh gene enco ...200717503033
inhibition of pyruvate decarboxylase from z. mobilis by novel analogues of thiamine pyrophosphate: investigating pyrophosphate mimics.replacement of the thiazolium ring of thiamine pyrophosphate with a triazole gives extremely potent inhibitors of pyruvate decarboxylase from z. mobilis, with k(i) values down to 20 pm; this system was used to explore pyrophosphate mimics and several effective analogues were discovered.200717311134
fermentation of molasses by zymomonas mobilis: effects of temperature and sugar concentration on ethanol production.fermentations utilizing strains of zymomonas mobilis, in place of the traditional yeasts, have been proposed due their ethanol yields being close to theoretical. ethanol production from sugar cane molasses was analyzed under different culture conditions using z. mobilis in batch fermentation. the total reducing sugars (trs) concentrations in the molasses, temperature, agitation and culture time effects were studied simultaneously through factorial design. the best conditions for ethanol producti ...200717420121
asymmetric alkene reduction by yeast old yellow enzymes and by a novel zymomonas mobilis reductase.the genes encoding yeast old yellow enzymes (oye 1, 2, and 3) and nad(p)h-dependent 2-cyclohexen-1-one reductase from zymomonas mobilis (ncr) were expressed separately in escherichia coli. all four recombinant strains reduced the carbon double bond in alpha,beta-unsaturated alkenals and alkenones, however rates and enantio-specificities differed. which of the two possible enantiomers was predominantly formed, was not only dependent on the choice of enzyme but also on the substrate: in addition t ...200717657768
ethanol fermentation technologies from sugar and starch feedstocks.this article critically reviews some ethanol fermentation technologies from sugar and starch feedstocks, particularly those key aspects that have been neglected or misunderstood. compared with saccharomyces cerevisiae, the ethanol yield and productivity of zymomonas mobilis are higher, because less biomass is produced and a higher metabolic rate of glucose is maintained through its special entner-doudoroff pathway. however, due to its specific substrate spectrum as well as the undesirability of ...200817964107
immobilization of recombinant invertase (re-invb) from zymomonas mobilis on d-sorbitol cinnamic ester for production of invert sugar.the recombinant invertase (re-invb) from zymomonas mobilis was immobilized by adsorption onto the totally cinnamoylated derivative of d-sorbitol. the polymerization and cross-linking of the derivative initially obtained was achieved by irradiation in the ultraviolet region, where this prepolymer shows maximum sensitivity. immobilization of re-invb on this support involves a process of physical adsorption and intense hydrophobic interactions between the cinnamoyl groups of the support and related ...200818237126
real-time pcr detection of bacteria belonging to the firmicutes phylum.members of the bacterial phylum firmicutes occupy a wide range of habitats and can be either beneficial or detrimental in diverse settings, including food- and beverage-related industries. firmicutes are responsible for the vast majority of beer-spoilage incidents and, as such, they have a substantial financial impact in the brewing industry. rapid detection and identification of a bacterium as a firmicutes is difficult due to widespread genetic transfer and genome reduction resulting in phenoty ...200818501458
amino acid substitutions of his296 alter the catalytic properties of zymomonas mobilis 10232 levansucrase.his296 of zymomonas mobilis levansucrase (ec 2.4.1.10) is crucial for the catalysis of the transfructosylation reaction. the three-dimensional structures of levansucrases revealed the his296 is involved in the substrate recognition and binding. in this study, nine mutants were created by site-directed mutagenesis, in which his296 was substituted with amino acids of different polarity, charge and length. the substitutions of his296 with arg or trp retained partial hydrolysis and transfructosylati ...200818324341
specific ethanol production rate in ethanologenic escherichia coli strain ko11 is limited by pyruvate decarboxylase.modification of ethanol productivity and yield, using mineral medium supplemented with glucose or xylose as carbon sources, was studied in ethanologenic escherichia coli ko11 by increasing the activity of five key carbon metabolism enzymes. ko11 efficiently converted glucose or xylose to ethanol with a yield close to 100% of the theoretical maximum when growing in rich medium. however, when ko11 ferments glucose or xylose in mineral medium, the ethanol yields decreased to only 70 and 60%, respec ...200818349551
microwave-assisted hydrolysis of zymomonas mobilis levan envisaging oligofructan production.levan, a polysaccharide from zymomonas mobilis, was hydrolyzed to obtain oligofructans or fructooligosaccharides with a degree of polymerization varying from 4 to 14. fructooligosaccharides (fos) are short chain fructans that beneficially affects the host by selective stimulation of growth and activity of one or a number of bacteria including probiotic bacteria in the colon. the hydrolysis was performed in a microwave oven to shorten the reaction time. the experiments showed that it is possible ...200817604160
structures of dimeric dihydrodiol dehydrogenase apoenzyme and inhibitor complex: probing the subunit interface with site-directed mutagenesis.dimeric dihydrodiol dehydrogenase (dd) catalyses the nicotinamide adenine dinucleotide phosphate (nadp+)-dependent oxidation of trans-dihydrodiols of aromatic hydrocarbons to their corresponding catechols. this is the first report of the crystal structure of the dimeric enzyme determined at 2.0 a resolution. the tertiary structure is formed by a classical dinucleotide binding fold comprising of two betaalphabetaalphabeta motifs at the n-terminus and an eight-stranded, predominantly antiparallel ...200817654552
fermentable metabolite of zymomonas mobilis controls collagen reduction in photoaging skin by improving tgf-beta/smad signaling suppression.solar ultraviolet (uv) irradiation causes damages on human skin and premature skin aging (photoaging). uv-induced reduction of type i collagen in dermis is widely considered primarily induction of wrinkled appearance of photoaging skin. type i procollagen synthesis is reduced under uv irradiation by blocking transforming growth factor-beta (tgf-beta)/smad signaling; more specifically, it is down-regulation of tgf-beta type ii receptor (t beta rii). therefore, preventing uv-induced loss of t beta ...200818060420
development of a versatile shuttle vector for gene expression in geobacillus spp.an improved, versatile shuttle vector has been created for the metabolic engineering of geobacillus spp. as kanamycin is the most thermo-tolerant of commonly used antibiotics, the gene encoding a thermostable kanamycin nucleotidyltransferase, together with the origin of replication from the g. stearothermophilus plasmid pbst1 were cloned into the escherichia coli cloning vector puc18. the resulting vector, named pucg18, replicated in both organisms and could be transformed with an efficiency of ...200818501964
heterologous expression of pyruvate decarboxylase in geobacillus thermoglucosidasius.expression of a pyruvate decarboxylase (pdc) pathway in metabolically versatile thermophilic bacteria could create novel ethanologenic organisms, but no suitable thermostable pdc is available. we have demonstrated that pdc from zymomonas mobilis can be expressed in an active form in geobacillus thermoglucosidasius at up to 52 degrees c, while expression of pdc polypeptides up to 54 degrees c was evident from western blotting. by using an unstable lactate dehydrogenase (ldh) mutant of g. thermogl ...200818368298
an ethanol-tolerant recombinant escherichia coli expressing zymomonas mobilis pdc and adhb genes for enhanced ethanol production from xylose.an ethanol-tolerant mutant, et1, was isolated by an enrichment method from escherichia coli jm109. strains jm109 and et1 were transformed with expression vector pzy507bc containing zymomonas mobilis alcohol dehydrogenase ii (adhb) and pyruvate decarboxylase (pdc) genes, resulting in an ethanol-sensitive recombinant strain jmbc and an ethanol-tolerant recombinant strain, et1bc. alcohol dehydrogenase and pyruvate decarboxylase activities were 24 and 32% lower, respectively, in jmbc than in et1bc. ...200818034308
improvement of p450(bm-3) whole-cell biocatalysis by integrating heterologous cofactor regeneration combining glucose facilitator and dehydrogenase in e. coli.escherichia coli bl21, expressing a quintuple mutant of p450(bm-3), oxyfunctionalizes alpha-pinene in an nadph-dependent reaction to alpha-pinene oxide, verbenol, and myrtenol. we optimized the whole-cell biocatalyst by integrating a recombinant intracellular nadph regeneration system through co-expression of a glucose facilitator from zymomonas mobilis for uptake of unphosphorylated glucose and a nadp(+)-dependent glucose dehydrogenase from bacillus megaterium that oxidizes glucose to gluconola ...200818057930
analysis of the respiratory chain in ethanologenic zymomonas mobilis with a cyanide-resistant bd-type ubiquinol oxidase as the only terminal oxidase and its possible physiological roles.the respiratory chain of the ethanologenic bacterium zymomonas mobilis was investigated, in which the pyruvate-to-ethanol pathway has been demonstrated to be mainly responsible for nadh oxidation and the tricarboxylic acid cycle is incomplete. membranes from cells cultivated under aerobic or anaerobic growth conditions showed dehydrogenase and oxidase activities for nadh, d-lactate and d-glucose and ubiquinol oxidase activity. intriguingly, the nadh oxidase activity level of membrane fractions f ...200818089934
nadh dehydrogenase deficiency results in low respiration rate and improved aerobic growth of zymomonas mobilis.the respiratory chain of the ethanol-producing bacterium zymomonas mobilis is able to oxidize both species of nicotinamide cofactors, nadh and nadph. a mutant strain with a chloramphenicol-resistance determinant inserted in ndh (encoding an nadh : coq oxidoreductase of type ii) lacked the membrane nadh and nadph oxidase activities, while its respiratory d-lactate oxidase activity was increased. cells of the mutant strain showed a very low respiration rate with glucose and no respiration with eth ...200818310045
metabolic engineering of escherichia coli for l-tyrosine production by expression of genes coding for the chorismate mutase domain of the native chorismate mutase-prephenate dehydratase and a cyclohexadienyl dehydrogenase from zymomonas mobilis.the expression of the feedback inhibition-insensitive enzyme cyclohexadienyl dehydrogenase (tyrc) from zymomonas mobilis and the chorismate mutase domain from native chorismate mutase-prephenate dehydratase (phea(cm)) from escherichia coli was compared to the expression of native feedback inhibition-sensitive chorismate mutase-prephenate dehydrogenase (cm-tyra(p)) with regard to the capacity to produce l-tyrosine in e. coli strains modified to increase the carbon flow to chorismate. shake flask ...200818344329
cloning, solubilization, and characterization of squalene synthase from thermosynechococcus elongatus bp-1.squalene synthase (sqs) is a bifunctional enzyme that catalyzes the condensation of two molecules of farnesyl diphosphate (fpp) to give presqualene diphosphate (pspp) and the subsequent rearrangement of pspp to squalene. these reactions constitute the first pathway-specific steps in hopane biosynthesis in bacteria and sterol biosynthesis in eukarya. the genes encoding sqs were isolated from the hopane-producing bacteria thermosynechococcus elongatus bp-1, bradyrhizobium japonicum, and zymomonas ...200818375558
a comparison of simple rheological parameters and simulation data for zymomonas mobilis fermentation broths with high substrate loading in a 3-l bioreactor.traditionally, as much as 80% or more of an ethanol fermentation broth is water that must be removed. this mixture is not only costly to separate but also produces a large aqueous stream that must then be disposed of or recycled. integrative approaches to water reduction include increasing the biomass concentration during fermentation. in this paper, experimental results are presented for the rheological behavior of high-solids enzymatic cellulose hydrolysis and ethanol fermentation for biomass ...200818425609
analysis of bacterial community during the fermentation of pulque, a traditional mexican alcoholic beverage, using a polyphasic approach.in this study, the characterization of the bacterial community present during the fermentation of pulque, a traditional mexican alcoholic beverage from maguey (agave), was determined for the first time by a polyphasic approach in which both culture and non-culture dependent methods were utilized. the work included the isolation of lactic acid bacteria (lab), aerobic mesophiles, and 16s rdna clone libraries from total dna extracted from the maguey sap (aguamiel) used as substrate, after inoculati ...200818450312
metabolic regulation analysis of an ethanologenic escherichia coli strain based on rt-pcr and enzymatic activities.a metabolic regulation study was performed, based upon measurements of enzymatic activities, fermentation performance, and rt-pcr analysis of pathways related to central carbon metabolism, in an ethanologenic escherichia coli strain (cce14) derived from lineage c. in comparison with previous engineered strains, this e coli derivative has a higher ethanol production rate in mineral medium, as a result of the elevated heterologous expression of the chromosomally integrated genes encoding pdczm and ...200818471274
identification of yeast and bacteria involved in the mezcal fermentation of agave salmiana.aims: to identify the yeast and bacteria present in the mezcal fermentation from agave salmiana. methods and results: the restriction and sequence analysis of the amplified region, between 18s and 28s rdna and 16s rdna genes, were used for the identification of yeast and bacteria, respectively. eleven different micro-organisms were identified in the mezcal fermentation. three of them were the following yeast: clavispora lusitaniae, pichia fermentans and kluyveromyces marxianus. the bacteria foun ...200818489025
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