TitleAbstractYear(sorted descending)
Conceptual design of cost-effective and environmentally-friendly configurations for fuel ethanol production from sugarcane by knowledge-based process synthesis.In this work, the hierarchical decomposition methodology was used to conceptually design the production of fuel ethanol from sugarcane. The decomposition of the process into six levels of analysis was carried out. Several options of technological configurations were assessed in each level considering economic and environmental criteria. The most promising alternatives were chosen rejecting the ones with a least favorable performance. Aspen Plus was employed for simulation of each one of the tech ...201222137752
electron transport and oxidative stress in zymomonas mobilis respiratory mutants.the ethanol-producing bacterium zymomonas mobilis is of great interest from a bioenergetic perspective because, although it has a very high respiratory capacity, the respiratory system does not appear to be primarily required for energy conservation. to investigate the regulation of respiratory genes and function of electron transport branches in z. mobilis, several mutants of the common wild-type strain zm6 (atcc 29191) were constructed and analyzed. mutant strains with a chloramphenicol-resist ...201222228443
adaptive evolution of escherichia coli inactivated in the phosphotransferase system operon improves co-utilization of xylose and glucose under anaerobic conditions.modification of the phosphoenolpyruvate/sugar phosphotransferase system (pts) has shown improvement in sugar coassimilation in escherichia coli production strains. however, in preliminary experiments under anaerobic conditions, e. coli strains with an inactive pts and carrying ploi1594, which encodes pyruvate decarboxylase and alcohol dehydrogenase from zymomonas mobilis, were unable to grow. these pts⁻ strains were previously evolved under aerobic conditions to grow rapidly in glucose (pts⁻ glu ...201120740380
conditioning of dilute-acid pretreated corn stover hydrolysate liquors by treatment with lime or ammonium hydroxide to improve conversion of sugars to ethanol.dilute-acid pretreatment of lignocellulosic biomass enhances the ability of enzymes to hydrolyze cellulose to glucose, but produces many toxic compounds that inhibit fermentation of sugars to ethanol. the objective of this study was to compare the effectiveness of treating hydrolysate liquor with ca(oh)2 and nh4oh for improving ethanol yields. corn stover was pretreated in a pilot-scale reactor and then the liquor fraction (hydrolysate) was extracted and treated with various amounts of ca(oh)2 o ...201120801647
evaluation and optimization of ethanol production from carob pod extract by zymomonas mobilis using response surface this research, ethanol production from carob pod extract (extract) using zymomonas mobilis with medium optimized by plackett-burman (p-b) and response surface methodologies (rsm) was studied. z. mobilis was recognized as useful for ethanol production from carob pod extract. the effects of initial concentrations of sugar, peptone, and yeast extract as well as agitation rate (rpm), ph, and culture time in nonhydrolyzed carob pod extract were investigated. significantly affecting variables (p = ...201120820859
physiological importance of cytochrome c peroxidase in ethanologenic thermotolerant zymomonas mobilis.zymomonas mobilis zmcytc as a peroxidase bearing three heme c-binding motifs was investigated with ?zmcytc constructed. the mutant exhibited filamentous shapes and reduction in growth under a shaking condition at a high temperature compared to the parental strain and became hypersensitive to exogenous h(2)o(2). under the same condition, the mutation caused increased expression of genes for three other antioxidant enzymes. peroxidase activity, which was detected in membrane fractions with ubiquin ...201121422762
identification of mutation points in cupriavidus necator ncimb 11599 and genetic reconstitution of glucose-utilization ability in wild strain h16 for polyhydroxyalkanoate production.although the facultative chemolithoautotrophic cupriavidus necator (formerly ralstonia eutropha) wild strain h16 is potentially useful as a host for metabolic engineering aimed at polyhydroxyalkanoate production, this organism is deficient in assimilating glucose, a major sugar in non-edible cellulosic resources. growth properties of c. necator h16 harboring heterologous glf (encoding glucose-facilitated diffusion transporter) and glk (encoding glucokinase) from zymomonas mobilis strongly sugges ...201122014784
activation-independent cyclization of monoterpenoids.biosynthesis of cyclic monoterpenes (c(10)) generally requires cyclization of an activated linear precursor (geranyldiphosphate) by specific terpene cyclases. cyclic triterpenes (c(30)) on the other hand originate from the linear precursor squalene by the action of squalene-hopene cyclases (shcs) or oxidosqualene cyclases (oscs). here, we report on a novel terpene cyclase from zymomonas mobilis (zmo1548-shc) with the unique property to cyclize citronellal to isopulegol. to our knowledge zmo1548- ...201122156419
design and construction of improved new vectors for zymomonas mobilis recombinants.zymomonas mobilis is a very important gram-negative bacterium having a potential application to simultaneous co-production of biofuel and other high value-added products through biorefinery process technology development. up to now, ploi193 has been used as the plasmid of choice for z. mobilis strains. however, its application has been limited due to its relatively low transformation efficiency, a large plasmid size (13.4 kb), and limited choice of cloning sites for gene manipulations. some of t ...201121337340
genome sequence of the ethanol-producing zymomonas mobilis subsp. mobilis lectotype strain atcc 10988.zymomonas mobilis atcc 10988 is the type strain of the z. mobilis subsp. mobilis taxon, members of which are some of the most rigorous ethanol-producing bacteria. isolated from agave cactus fermentations in mexico, atcc 10988 is one of the first z. mobilis strains to be described and studied. its robustness in sucrose-substrate fermentations, physiological characteristics, large number of plasmids, and overall genomic plasticity render this strain important to the study of the species. here we r ...201121725006
metabolic engineering of escherichia coli for improving l: -3,4-dihydroxyphenylalanine (l: -dopa) synthesis from glucose.l: -3,4-dihydroxyphenylalanine (l: -dopa) is an aromatic compound employed for the treatment of parkinson's disease. metabolic engineering was applied to generate escherichia coli strains for the production of l: -dopa from glucose by modifying the phosphoenolpyruvate:sugar phosphotransferase system (pts) and aromatic biosynthetic pathways. carbon flow was directed to the biosynthesis of l: -tyrosine (l: -tyr), an l: -dopa precursor, by transforming strains with compatible plasmids carrying gene ...201121512819
functional characterization of a putative ß-lactamase gene in the genome of zymomonas mobilis.zymomonas mobilis zm4 is resistant to ß-lactam antibiotics but there are no reports of a ß-lactam resistance gene and its regulation. a putative ß-lactamase gene sequence (zmo0103) in the genome of z. mobilis showed a 55% amino acid sequence identity with class c ß-lactamase genes. qpcr analysis of the ß-lactamase transcript indicated a higher level expression of the ß-lactamase compared to the relative transcript quantities in antibiotic-susceptible bacteria. the putative ß-lactamase gene was c ...201121796435
Engineering yield and rate of reductive biotransformation in Escherichia coli by partial cyclization of the pentose phosphate pathway and PTS-independent glucose transport.Optimization of yields and productivities in reductive whole-cell biotransformations is an important issue for the industrial application of such processes. In a recent study with Escherichia coli, we analyzed the reduction of the prochiral ß-ketoester methyl acetoacetate by an R-specific alcohol dehydrogenase (ADH) to the chiral hydroxy ester (R)-methyl 3-hydroxybutyrate (MHB) using glucose as substrate for the generation of NADPH. Deletion of the phosphofructokinase gene pfkA almost doubled th ...201122002070
analysis of experimental errors in bioprocesses. 1. production of lactobionic acid and sorbitol using the gfor (glucose-fructose oxidoreductase) enzyme from permeabilized cells of zymomonas mobilis.the proper determination of experimental errors in bioprocesses can be very important because experimental errors can exert a major impact on the analysis of experimental results. despite this, the effect of experimental errors on the analysis of bioprocess data has been largely overlooked in the literature. for this reason, we performed detailed statistical analyses of experimental errors obtained during the production of lactobionic acid and sorbitol in a system utilizing as catalyst the gfor ...201121328074
a highly efficient adh-coupled nadh-recycling system for the asymmetric bioreduction of carbon-carbon double bonds using enoate reductases.the asymmetric bioreduction of activated alkenes catalyzed by flavin-dependent enoate reductases from the oye-family represents a powerful method for the production of optically active compounds. for its preparative-scale application, efficient and economic nadh-recycling is crucial. a novel enzyme-coupled nadh-recycling system is proposed based on the concurrent oxidation of a sacrificial sec-alcohol catalyzed by an alcohol dehydrogenase (adh-a). due to the highly favorable position of the equi ...201121328323
optimization of process parameters for ethanol production from sugar cane molasses by zymomonas mobilis using response surface methodology and genetic algorithm.ethanol is a potential energy source and its production from renewable biomass has gained lot of popularity. there has been worldwide research to produce ethanol from regional inexpensive substrates. the present study deals with the optimization of process parameters (viz. temperature, ph, initial total reducing sugar (trs) concentration in sugar cane molasses and fermentation time) for ethanol production from sugar cane molasses by zymomonas mobilis using box-behnken experimental design and gen ...201121336926
respiration-deficient mutants of zymomonas mobilis show improved growth and ethanol fermentation under aerobic and high temperature conditions.respiration-deficient mutant (rdm) strains of zymomonas mobilis were isolated from antibiotic-resistant mutants. these rdm strains showed various degrees of respiratory deficiency. all rdm strains exhibited much higher ethanol fermentation capacity than the wild-type strain under aerobic conditions. the strains also gained thermotolerance and exhibited greater ethanol production at high temperature (39°c), under both non-aerobic and aerobic conditions, compared with the wild-type strain. microar ...201121236727
structures of iron-dependent alcohol dehydrogenase 2 from zymomonas mobilis zm4 with and without nad+ cofactor.the ethanologenic bacterium zymomonas mobilis zm4 is of special interest because it has a high ethanol yield. this is made possible by the two alcohol dehydrogenases (adhs) present in z. mobilis zm4 (zmadhs), which shift the equilibrium of the reaction toward the synthesis of ethanol. they are metal-dependent enzymes: zinc for zmadh1 and iron for zmadh2. however, zmadh2 is inactivated by oxygen, thus implicating zmadh2 as the component of the cytosolic respiratory system in z. mobilis. here, we ...201121295587
cloning, expression, purification, crystallization and preliminary x-ray diffraction analysis of an asch domain-containing protein from zymomonas mobilis zm4.the human activating signal cointegrator 1 (asc-1) homology (asch) domain is frequently observed in many organisms, although its function has not yet been clearly defined. in zymomonas mobilis zm4, the zmo0922 gene encodes a polypeptide that includes an asch domain (zmasch). to provide a better structural background for the probable role of asch domain-containing proteins, the zmo0922 gene was cloned and expressed. the purified protein was crystallized from 30%(w/v) polyethylene glycol 400, 0.1ô ...201121393833
de novo biosynthesis of biodiesel by escherichia coli in optimized fed-batch cultivation.biodiesel is a renewable alternative to petroleum diesel fuel that can contribute to carbon dioxide emission reduction and energy supply. biodiesel is composed of fatty acid alkyl esters, including fatty acid methyl esters (fames) and fatty acid ethyl esters (faees), and is currently produced through the transesterification reaction of methanol (or ethanol) and triacylglycerols (tags). tags are mainly obtained from oilseed plants and microalgae. a sustainable supply of tags is a major bottleneck ...201121629774
mini-mu transposon mutagenesis of ethanologenic zymomonas mobilis.zymomonas mobilis is a facultatively anaerobic a-proteobacterium with a considerable potential for industrial ethanol production. an important tool in the generation of stable mutants for this organism is described in this chapter; it entails insertional mutagenesis with the help of the transposable element mini-mu. the latter is delivered into z. mobilis with the use of plasmid pulb113 (rp4::mini-mu) that self-transfers in the organism at notable frequencies and remains highly stable even under ...201121815107
genome sequence of the ethanol-producing zymomonas mobilis subsp. pomaceae lectotype strain atcc 29192.zymomonas mobilis is an alphaproteobacterium studied for bioethanol production. different strains of this organism have been hitherto sequenced; they all belong to the z. mobilis subsp. mobilis taxon. here we report the finished and annotated genome sequence of strain atcc 29192, a cider-spoiling agent isolated in the united kingdom. atcc 29192 is the lectotype of the second-best-characterized subspecies of z. mobilis, z. mobilis subsp. pomaceae. the nucleotide sequence of atcc 29192 deviates fr ...201121742897
Discovery and characterization of a xylose reductase from Zymomonas mobilis ZM4.Formation of xylitol, a byproduct from xylose fermentation, is a major limiting factor in ethanol production from xylose in engineered Zymomonas strains, yet the postulated xylose reductase remains elusive. We report here the discovery of xylose reductase in Zymomonas mobilis and, for the first time, to associate the enzyme function with its gene. Besides xylose and xylulose, the enzyme was active towards benzaldehyde, furfural, 5-hydroxymethyl furfural, and acetaldehyde, exhibiting nearly 150-t ...201121720846
Biochemical and molecular characterization of NAD(+) -dependent isocitrate dehydrogenase from the ethanologenic bacterium Zymomonas mobilis.An isocitrate dehydrogenase from Zymomonas mobilis was overexpressed in Escherichia coli as a fused protein (ZmIDH). The molecular mass of recombinant ZmIDH, together with its 6× His partner, was estimated to be 74 kDa by gel filtration chromatography, suggesting a homodimeric structure. The purified recombinant ZmIDH displayed maximal activity at 55 °C, pH 8.0 with Mn(2+) and pH 8.5 with Mg(2+) . Heat inactivation studies showed that the recombinant ZmIDH was rapidly inactivated above 40 °C. I ...201122117777
production of lactobionic acid and sorbitol from lactose/fructose substrate using gfor/gl enzymes from zymomonas mobilis cells: a kinetic this work, we have investigated the kinetics of the biotechnological production of lactobionic acid (lba) and sorbitol by the catalytic action of glucose-fructose oxidoreductase (gfor) and glucono-δ-lactonase (gl) enzymes. the cells of bacterium zymomonas mobilis atcc 29191 containing this enzymatic complex were submitted to permeabilization and reticulation procedures. the effect of the concentration of substrates on the rate of product formation using a mobilized cell system was investigate ...201122112407
optical mapping and sequencing of the escherichia coli ko11 genome reveal extensive chromosomal rearrangements, and multiple tandem copies of the zymomonas mobilis pdc and adhb genes.escherichia coli ko11 (atcc 55124) was engineered in 1990 to produce ethanol by chromosomal insertion of the zymomonas mobilis pdc and adhb genes into e. coli w (atcc 9637). ko11fl, our current laboratory version of ko11, and its parent e. coli w were sequenced, and contigs assembled into genomic sequences using optical ncoi restriction maps as templates. e. coli w contained plasmids prk1 (102.5 kb) and prk2 (5.4 kb), but ko11fl only contained prk2. ko11fl optical maps made ...201122075923
Cyclohexane-1,2-dione hydrolase from denitrifying Azoarcus sp. strain 22Lin, a novel member of the thiamine diphosphate enzyme family.Alicyclic compounds with hydroxyl groups represent common structures in numerous natural compounds, such as terpenes and steroids. Their degradation by microorganisms in the absence of dioxygen may involve a C-C bond ring cleavage to form an aliphatic intermediate that can be further oxidized. The cyclohexane-1,2-dione hydrolase (CDH) (EC from denitrifying Azoarcus sp. strain 22Lin, grown on cyclohexane-1,2-diol as a sole electron donor and carbon source, is the first thiamine diphosph ...201121965568
a scalable microfluidic chip for bacterial suspension culture.microfluidic systems could, in principle, enable high-throughput breeding and screening of microbial strains for industrial applications, but parallel and scalable culture and detection chips are needed before complete microbial selection systems can be integrated and tested. here we demonstrate a scalable multi-channel chip that is capable of bacterial suspension culture. the key invention is a multi-layered chip design, which enables a single set of control channels to function as serial peris ...201122030862
Biotransformation of pineapple juice sugars into dietetic derivatives by using a cell free oxidoreductase from Zymomonas mobilis together with commercial invertase.An easy procedure for cell free biotransformation of pineapple juice sugars into dietetic derivatives was accomplished using a commercial invertase and an oxidoreductase from Zymomonas mobilis. First, pineapple juice sucrose was quantitatively converted into glucose and fructose by invertase, thus increasing the concentration of each monosaccharide in the original juice to almost twice. In a second step, glucose-fructose oxidoreductase (GFOR) transformed glucose into gluconolactone, and fructose ...201122112775
Fermentation of Reactive-Membrane-Extracted and Ammonium-Hydroxide-Conditioned Dilute-Acid-Pretreated Corn Stover.Acid-pretreated biomass contains various compounds (acetic acid, etc.) that are inhibitory to fermentative microorganisms. Removing or deactivating these compounds using detoxification methods such as overliming or ammonium hydroxide conditioning (AHC) improves sugar-to-ethanol yields. In this study, we treated the liquor fraction of dilute-acid-pretreated corn stover using AHC and a new reactive membrane extraction technique, both separately and in combination, and then the sugars in the treate ...201122161211
irre, an exogenous gene from deinococcus radiodurans, improves the growth of and ethanol production by a zymomonas mobilis strain under ethanol and acid stress.during ethanol fermentation, bacterial strains may encounter various stresses, such as ethanol and acid shock, which adversely affect cell viability and the production of ethanol. therefore, ethanologenic strains that tolerate abiotic stresses are highly desirable. bacteria of the genus deinococcus are extremely resistant to ionizing radiation, ultraviolet light, and desiccation, and therefore constitute an important pool of extreme resistance genes. the irre gene encodes a general switch respon ...201020668411
heterologous expression and extracellular secretion of cellulolytic enzymes by zymomonas mobilis.development of the strategy known as consolidated bioprocessing (cbp) involves the use of a single microorganism to convert pretreated lignocellulosic biomass to ethanol through the simultaneous production of saccharolytic enzymes and fermentation of the liberated monomeric sugars. in this report, the initial steps toward achieving this goal in the fermentation host zymomonas mobilis were investigated by expressing heterologous cellulases and subsequently examining the potential to secrete these ...201020693448
simultaneous consumption of pentose and hexose sugars: an optimal microbial phenotype for efficient fermentation of lignocellulosic biomass.lignocellulosic biomass is an attractive carbon source for bio-based fuel and chemical production; however, its compositional heterogeneity hinders its commercial use. since most microbes possess carbon catabolite repression (ccr), mixed sugars derived from the lignocellulose are consumed sequentially, reducing the efficacy of the overall process. to overcome this barrier, microbes that exhibit the simultaneous consumption of mixed sugars have been isolated and/or developed and evaluated for the ...201020838789
genome-scale modeling and in silico analysis of ethanologenic bacteria zymomonas mobilis.bioethanol has been recognized as a potential alternative energy source. among various ethanol-producing microbes, zymomonas mobilis has acquired special attention due to its higher ethanol yield and tolerance. however, cellular metabolism in z. mobilis remains unclear, hindering its practical application for bioethanol production. to elucidate such physiological characteristics, we reconstructed and validated a genome-scale metabolic network (izm363) of z. mobilis atcc31821 (zm4) based on its a ...201020967753
improvement of ethanol production by electrochemical redox coupling of zymomonas mobilis and saccharomyces cerevisiae.zymomonas mobilis was immobilized in a modified graphite felt cathode with neutral red (nr-graphite cathode) and saccharomyces cerevisiae was cultivated on a platinum plate anode to electrochemically activate ethanol fermentation. electrochemical redox reaction was induced by 3 approximately 4 volt of electric potential charged to a cathode and an anode. z. mobilis produced 1.3 approximately 1.5 m of ethanol in the cathode compartment and s. cerevisiae did 1.7 approximately 1.9 m in the anode co ...201020134239
adaptation yields a highly efficient xylose-fermenting zymomonas mobilis strain.zymomonas mobilis is a superb ethanol producer with productivity exceeding yeast strains by several fold. although metabolic engineering was successfully applied to expand its substrate range to include xylose, xylose fermentation lagged far behind glucose. in addition, xylose fermentation was often incomplete when its initial concentration was higher than 5%. improvement of xylose fermentation is therefore necessary. in this work, we applied adaptation to improve xylose fermentation in metaboli ...201021154759
three-phase partitioning of hydrolyzed levan.during the fructose and polymerization to synthesize levan, smaller fructooligosaccharide (fos) molecules are produced. fos can also be obtained by levan hydrolysis. three-phase partitioning (tpp) is a separation technique that has been used for polysaccharide precipitation and gathers t-butanol and ammonium sulphate to exclude the polymer from the aqueous solution. in this work tpp was tested to separate levan and fos from aqueous solution. the fos used was obtained from zymomonas mobilis levan ...201020163956
cloning, expression, purification, crystallization and preliminary x-ray diffraction analysis of 2-keto-3-deoxy-6-phosphogluconate aldolase from zymomonas mobilis zm4.zymomonas mobilis zm4 is an organism optimized for ethanol production which uses the entner-doudoroff (ed) pathway for the breakdown of glucose. the key enzyme in this process is 2-keto-3-deoxy-6-phosphogluconate (kdpg) aldolase, which produces glyceraldehyde 3-phosphate and pyruvate. in order to provide a molecular background for the kdpg aldolase from this ethanologenic organism (zmkdpg aldolase), the zmo0997 gene of z. mobilis zm4 coding for zmkdpg aldolase was cloned and expressed and the pu ...201020383025
bacterial supersystem for alginate import/metabolism and its environmental and bioenergy applications.distinct from most alginate-assimilating bacteria that secrete polysaccharide lyases extracellularly, a gram-negative bacterium, sphingomonas sp. a1 (strain a1), can directly incorporate alginate into its cytoplasm, without degradation, through a "superchannel" consisting of a mouth-like pit on the cell surface, periplasmic binding proteins, and a cytoplasmic membrane-bound atp-binding cassette transporter. flagellin homologues function as cell surface alginate receptors essential for expressing ...201021326935
development and application of co-culture for ethanol production by co-fermentation of glucose and xylose: a systematic review.this article reviews current co-culture systems for fermenting mixtures of glucose and xylose to ethanol. thirty-five co-culture systems that ferment either synthetic glucose and xylose mixture or various biomass hydrolysates are examined. strain combinations, fermentation modes and conditions, and fermentation performance for these co-culture systems are compared and discussed. it is noted that the combination of pichia stipitis with saccharomyces cerevisiae or its respiratory-deficient mutant ...201021104106
the bacterial community in 'taberna' a traditional beverage of southern characterize the bacterial community of taberna, an alcoholic traditional beverage from the southern part of mexico produced by the fermentation of the coyol palm sap (acrocomia aculeate).201021039665
enabling unbalanced fermentations by using engineered electrode-interfaced bacteria.cellular metabolism is a series of tightly linked oxidations and reductions that must be balanced. recycling of intracellular electron carriers during fermentation often requires substrate conversion to undesired products, while respiration demands constant addition of electron acceptors. the use of electrode-based electron acceptors to balance biotransformations may overcome these constraints. to test this hypothesis, the metal-reducing bacterium shewanella oneidensis was engineered to stoichio ...201021060736
single amino acid residue changes in subsite -1 of levansucrase from zymomonas mobilis 10232 strongly influence the enzyme activities and products.the -1 subsite of bacterial fructansucrases (fss) (levansucrases and inulosucrases) plays an important role in the substrate recognition, binding and catalysis. three residues (for example w47, w118 and r193, zymomonas mobilis levansucrase numbering) at the -1 subsite are completely conserved among fss. site-directed mutational analysis showed that the substitutions of the three strictly conserved amino acid residues, w47n, w47h, w118n, w118h, r193k and r193h, significantly decreased enzyme acti ...201021082263
the genome-scale metabolic network analysis of zymomonas mobilis zm4 explains physiological features and suggests ethanol and succinic acid production strategies.zymomonas mobilis zm4 is a gram-negative bacterium that can efficiently produce ethanol from various carbon substrates, including glucose, fructose, and sucrose, via the entner-doudoroff pathway. however, systems metabolic engineering is required to further enhance its metabolic performance for industrial application. as an important step towards this goal, the genome-scale metabolic model of z. mobilis is required to systematically analyze in silico the metabolic characteristics of this bacteri ...201021092328
importance of stability study of continuous systems for ethanol production.fuel ethanol industry presents different problems during bioreactors operation. one of them is the unexpected variation in the output ethanol concentration from the bioreactor or a drastic fall in the productivity. in this paper, a compilation of concepts and relevant results of several experimental and theoretical studies about dynamic behavior of fermentation systems for bioethanol production with saccharomyces cerevisiae and zymomonas mobilis is done with the purpose of understanding the stab ...201021034786
an economic comparison of different fermentation configurations to convert corn stover to ethanol using z. mobilis and saccharomyces.numerous routes are being explored to lower the cost of cellulosic ethanol production and enable large-scale production. one critical area is the development of robust cofermentative organisms to convert the multiple, mixed sugars found in biomass feedstocks to ethanol at high yields and titers without the need for processing to remove inhibitors. until such microorganisms are commercialized, the challenge is to design processes that exploit the current microorganisms' strengths. this study expl ...201019785041
extension of the substrate utilization range of ralstonia eutropha strain h16 by metabolic engineering to include mannose and glucose.the gram-negative facultative chemolithoautotrophic bacterium ralstonia eutropha strain h16 is known for its narrow carbohydrate utilization range, which limits its use for biotechnological production of polyhydroxyalkanoates and possibly other products from renewable resources. to broaden its substrate utilization range, which is for carbohydrates and related compounds limited to fructose, n-acetylglucosamine, and gluconate, strain h16 was engineered to use mannose and glucose as sole carbon so ...201021169447
efficient production of ethanol from crude glycerol by a klebsiella pneumoniae mutant strain.a mutant strain of klebsiella pneumoniae, termed gem167, was obtained by γ irradiation, in which glycerol metabolism was dramatically affected on exposure to γ rays. levels of metabolites of the glycerol reductive pathway, 1,3-propanediol (1,3-pd) and 3-hydroxypropionic acid (3-hp), were decreased in the gem167 strain compared to a control strain, whereas the levels of metabolites derived from the oxidative pathway, 2,3-butanediol (2,3-bd), ethanol, lactate, and succinate, were increased. notabl ...201021186120
[metabolic engineering for microbial production of ethanol from xylose: a review].discovery of an efficient bioconversion of cellulosic biomass and its hydrolysis to ethanol is the key to unlocking in developing of a bioethanol industry. the lack of industrially suitable microorganisms to convert xylose to ethanol fuel has been cited as a major technical bottleneck. in the past decades, many improvements have been made in the metabolic engineering of microorganisms, including zymomonas mobilis, escherichia coli, and yeasts, for the fermentation of xylose to produce ethanol by ...201021218632
ethanol production from sugarcane bagasse by zymomonas mobilis using simultaneous saccharification and fermentation (ssf) process.considerable efforts have been made to utilize agricultural and forest residues as biomass feedstock for the production of second-generation bioethanol as an alternative fuel. fermentation utilizing strains of zymomonas mobilis and the use of simultaneous saccharification and fermentation (ssf) process has been proposed. statistical experimental design was used to optimize the conditions of ssf, evaluating solid content, enzymatic load, and cell concentration. the optimum conditions were found t ...201019876607
impact of recycling stillage on conversion of dilute sulfuric acid pretreated corn stover to ethanol.both the current corn starch to ethanol industry and the emerging lignocellulosic biofuels industry view recycling of spent fermentation broth or stillage as a method to reduce fresh water use. the objective of this study was to understand the impact of recycling stillage on conversion of corn stover to ethanol. sugars in a dilute-acid pretreated corn stover hydrolysate were fermented to ethanol by the glucose-xylose fermenting bacteria zymomonas mobilis 8b. three serial fermentations were perfo ...201019998277
enhanced production of ethanol from glycerol by engineered hansenula polymorpha expressing pyruvate decarboxylase and aldehyde dehydrogenase genes from zymomonas improve production of ethanol from glycerol, the methylotrophic yeast hansenula polymorpha was engineered to express the pdc and adhb genes encoding pyruvate decarboxylase and aldehyde dehydrogenase ii from zymomonas mobilis, respectively, under the control of the glyceraldehyde-3-phosphate dehydrogenase (gapdh) promoter. the ethanol yield was 3.3-fold higher (2.74 g l(-1)) in the engineered yeast compared with the parent strain (0.83 g l(-1)). further engineering to stimulate glycerol utiliz ...201020354759
ethanol production from paper sludge by simultaneous saccharification and co-fermentation using recombinant xylose-fermenting microorganisms.simultaneous saccharification and co-fermentation (sscf) of waste paper sludge to ethanol was investigated using two recombinant xylose-fermenting microbes: zymomonas mobilis 8b and saccharomyces cerevisiae rwb222. s. cerevisiae rwb222 produced over 40 g/l ethanol with a yield of 0.39 g ethanol/g carbohydrate on paper sludge at 37 degrees c, while similar titers and yields were achieved by z. mobilis 8b at 30 degrees c. both s. cerevisiae rwb222 and z. mobilis 8b exhibited decreasing cell viabil ...201020506488
comparing the fermentation performance of escherichia coli ko11, saccharomyces cerevisiae 424a(lnh-st) and zymomonas mobilis ax101 for cellulosic ethanol production.abstract:201020507563
sorbitol production using recombinant zymomonas mobilis strain.a recombinant zymomonas mobilis strain harboring the plasmid phw20a-gfo for over-expression of glucose-fructose oxidoreductase (gfor) was constructed. the specific activity of gfor enzyme in the new recombinant strain was at least two folds greater than that in the wild strain. the maximum gfor activity achieved in terms of the volumetric, and the cellular were 2.59 u ml(-1), and 0.70 u mg(-1), respectively, in the batch cultures. a significant improvement of the bioconversion process for the pr ...201020438775
the zymomonas mobilis regulator hfq contributes to tolerance against multiple lignocellulosic pretreatment inhibitors.zymomonas mobilis produces near theoretical yields of ethanol and recombinant strains are candidate industrial microorganisms. to date, few studies have examined its responses to various stresses at the gene level. hfq is a conserved bacterial member of the sm-like family of rna-binding proteins, coordinating a broad array of responses including multiple stress responses. in a previous study, we observed z. mobilis zm4 gene zmo0347 showed higher expression under anaerobic, stationary phase compa ...201020459639
double duty for a conserved glutamate in pyruvate decarboxylase: evidence of the participation in stereoelectronically controlled decarboxylation and in protonation of the nascent carbanion/enamine intermediate .pyruvate decarboxylase (pdc) catalyzes the nonoxidative decarboxylation of pyruvate into acetaldehyde and carbon dioxide and requires thiamin diphosphate (thdp) and a divalent cation as cofactors. recent studies have permitted the assignment of functional roles of active site residues; however, the underlying reaction mechanisms of elementary steps have remained hypothetical. here, a kinetic and thermodynamic single-step analysis in conjunction with x-ray crystallographic studies of pdc from zym ...201020715795
comparative evaluations of cellulosic raw materials for second generation bioethanol evaluate sugar recoveries and fermentabilities of eight lignocellulosic raw materials following mild acid pretreatment and enzyme hydrolysis using a recombinant strain of zymomonas mobilis.201020849394
kinetic and structural characterization of bacterial glutaminyl cyclases from zymomonas mobilis and myxococcus xanthus.although enzymes responsible for the cyclization of amino-terminal glutamine residues are present in both plant and mammal species, none have yet been characterized in bacteria. based on low sequence homologies to plant glutaminyl cyclases (qcs), we cloned the coding sequences of putative microbial qcs from zymomonas mobilis (zmqc) and myxococcus xanthus (mxqc). the two recombinant enzymes exhibited distinct qc activity, with specificity constants k(cat)/k(m) of 1.47±0.33 mm⁻¹ s⁻¹ (zmqc) and 142 ...201020868223
cellulosic ethanol production by zymomonas mobilis harboring an endoglucanase gene from enterobacter cloacae.enterobactercloacae was isolated from the gut of the wood feeding termite, heterotermes indicola, and a 2.25-kb fragment conferring cellulase activity was cloned in escherichia coli. the cloned fragment contained a 1083-bp orf which could encode a protein belonging to glycosyl hydrolase family 8. the cellulase gene was introduced into zymomonas mobilis strain microbial type culture collection centre (mtcc) on a plasmid and 0.134 filter paper activity unit (fpu)/ml units of cellulase activity was ...201020971639
detrimental effect of increasing sugar concentrations on ethanol production from maize or decorticated sorghum mashes fermented with saccharomyces cerevisiae or zymomonas mobilis: biofuels and environmental biotechnology.the efficiency of ethanol fermentation, as affected by grain source (maize and decorticated red sorghum), total sugar concentration (13 or 20° plato) and type of microorganism (saccharomyces cerevisiae or zymomonas mobilis) was studied. maize mashes yielded 0.32 l ethanol kg(-1) ground grain whereas mashes prepared with decorticated red sorghum produced 0.28 l ethanol kg(-1). both microorganisms yielded similar amounts of ethanol. however, high-gravity mashes (20° plato) yielded lower amounts of ...201020972698
modeling of pyruvate decarboxylases from ethanol producing bacteria.pyruvate decarboxylase (pdc) is a key enzyme in homoethanol fermentation process, which decarboxylates 2-keto acid pyruvate into acetaldehyde and carbon dioxide. pdc enzymes from potential ethanol-producing bacteria such as zymomonas mobilis, zymobacter palmae and sarcina ventriculi have different k(m) and k(cat) values for the substrate pyruvate at their respective optimum ph. in this study, the putative three-dimensional structures of pdc dimer of z. palmae pdc and s. ventriculi pdc were gener ...201020975902
phenotype microarray profiling of zymomonas mobilis this study, we developed a phenotype microarray (pm) protocol to profile cellular phenotypes in zymomonas mobilis, which included a standard set of nearly 2,000 assays for carbon, nitrogen, phosphorus and sulfur source utilization, nutrient stimulation, ph and osmotic stresses, and chemical sensitivities with 240 inhibitory chemicals. we observed two positive assays for c-source utilization (fructose and glucose) using the pm screen, which uses redox chemistry and cell respiration as a univer ...201020012508
adaptation yields a highly efficient xylose-fermenting zymomonas mobilis strain.zymomonas mobilis is a superb ethanol producer with productivity exceeding yeast strains by several fold. although metabolic engineering was successfully applied to expand its substrate range to include xylose, xylose fermentation lagged far behind glucose. in addition, xylose fermentation was often incomplete when its initial concentration was higher than 5%. improvement of xylose fermentation is therefore necessary. in this work, we applied adaptation to improve xylose fermentation in metaboli ...201021404252
structural insights into the prereaction state of pyruvate decarboxylase from zymomonas mobilis .pyruvate decarboxylase (pdc) uses thiamine diphosphate as an essential cofactor to catalyze the formation of acetaldehyde on the pathway of ethanol synthesis. here we report the crystallographic image of a prereaction intermediate of a bacterial pyruvate decarboxylase prepared by cocrystallizing the enzyme with pyruvate and a stable analogue of the cofactor's activated ylid form. a second crystal structure of pdc in complex with fluoride shows that the ion organizes a water molecule that occlude ...201020099870
cloning and characterization of a ribitol dehydrogenase from zymomonas mobilis.ribitol dehydrogenase (rdh) catalyzes the conversion of ribitol to d-ribulose. a novel rdh gene was cloned from zymomonas mobilis subsp. mobilis zm4 and overexpressed in escherichia coli bl21(de3). dna sequence analysis revealed an open reading frame of 795 bp, capable of encoding a polypeptide of 266 amino acid residues with a calculated molecular mass of 28,426 da. the gene was overexpressed in e. coli bl21(de3) and the protein was purified as an active soluble form using glutathione s-transfe ...201020127234
bioreduction of alpha-methylcinnamaldehyde derivatives: chemo-enzymatic asymmetric synthesis of lilial and helional.nonracemic aryl-substituted alpha-methyldihydrocinnamaldehyde derivatives employed as olfactory principles in perfumes (lilial, helional) were obtained via enzymatic reduction of the corresponding cinnamaldehyde precursors using cloned and overexpressed ene-reductases. (r)-enantiomers were obtained using the old-yellow-enzyme (oye) homolog yqjm from bacillus subtilis and 12-oxophytodienoic acid reductase isoenzyme opr1 from tomato (e.e.(max) 53%), and (s)-aldehydes were furnished in up to 97% e. ...201020461254
paradigm for industrial strain improvement identifies sodium acetate tolerance loci in zymomonas mobilis and saccharomyces cerevisiae.the application of systems biology tools holds promise for rational industrial microbial strain development. here, we characterize a zymomonas mobilis mutant (acr) demonstrating sodium acetate tolerance that has potential importance in biofuel development. the genome changes associated with acr are determined using microarray comparative genome sequencing (cgs) and 454-pyrosequencing. sanger sequencing analysis is employed to validate genomic differences and to investigate cgs and 454-pyrosequen ...201020484677
dna restriction-modification systems in the ethanologen, zymomonas mobilis better understand the dna restriction-modification (r-m) systems for more amenable strain development of the alternative industrial ethanologen, zymomonas mobilis, three gene knockout mutants were constructed. the gene knockout mutants were tested for their dna restriction activities by the determination of transformation efficiency using methylated and unmethylated foreign plasmid dnas. inactivation of a putative mrr gene encoded by zmo0028 (zmrr) resulted in a 60-fold increase in the transf ...201020957358
how to replace the residual solvation shell of polar active site residues to achieve nanomolar inhibition of trna-guanine a computational and structural study, we investigated a series of 4-substituted lin-benzoguanines that are potent inhibitors of trna-guanine transglycosylase (tgt), a putative target for the treatment of shigellosis. at first glance, it appears self-evident that the placement of a positively charged ligand functional group between the carboxylate groups of two adjacent aspartate residues in the glycosylase catalytic center leads to enhanced ligand binding. the concomitant displacement of wate ...200919894214
engineering the substrate binding site of benzoylformate decarboxylase.benzoylformate decarboxylase (bfdc) and pyruvate decarboxylase (pdc) are both thiamin diphosphate-dependent enzymes. the two share a common three-dimensional structure and catalyze a similar chemical reaction, i.e., decarboxylation of 2-keto acids. however, they vary significantly in their substrate utilization pattern. in particular, bfdc has extremely limited activity with pyruvate, while pdc has no activity with benzoylformate. here we report our progress, using a semirandom approach, toward ...200919621900
electrochemical and biochemical analysis of ethanol fermentation of zymomonas mobilis electrochemical bioreactor (ecb) composed of a cathode compartment and an air anode was used in this study to characterize the ethanol fermentation of zymomonas mobilis. the cathode and air anode were constructed of modified graphite felt with neutral red (nr) and a modified porous carbon plate with cellulose acetate and porous ceramic membrane, respectively. the air anode operates as a catalyst to generate protons and electrons from water. the growth and ethanol production of z. mobilis were ...200919652513
production of lactosucrose from sucrose and lactose by a levansucrase from zymomonas mobilis.lactosucrose (4(g)-beta-d-galactosylsucrose) is an oligosaccharide consisting of galactose, glucose, and fructose. in this study, we prepared lactosucrose from lactose and sucrose using a levansucrase derived from zymomonas mobilis. optimum conditions for lactosucrose formation were 23 degrees c, ph 7.0, 18.0% (w/v) lactose monohydrate, and 18% (w/v) sucrose as substrates, and 1 unit of enzyme/ml of reaction mixture. under these conditions, the lactosucrose conversion efficiency was 28.5%. the p ...200919884774
characterization of multiple promoters and transcript stability in the sacb-sacc gene cluster in zymomonas zymomonas mobilis, the extracellular levansucrase (sacb) and extracellular sucrase (sacc) are involved in sucrose hydrolysis. genes coding for these two enzymes (sacb and sacc) are arranged in a cluster in the genome and separated by a short intervening sequence. the level of sacc transcript was 12-fold higher than that of sacb transcript. on the other hand, transcript stability analysis in sucrose grown cultures revealed that the half-life of the sacb transcripts (153 s) was more than twofol ...200919415238
reduction of xylose to xylitol catalyzed by glucose-fructose oxidoreductase from zymomonas mobilis.genetic improvements of zymomonas mobilis for pentose utilization have a huge potential in fuel ethanol production. the production of xylitol and the resulting growth inhibition by xylitol phosphate have been considered to be one of the important factors affecting the rates and yields from xylose metabolism by the recombinant z. mobilis, but the mechanism of xylitol formation is largely unknown. here, we reported that glucose-fructose oxidoreductase (gfor), a periplasmic enzyme responsible for s ...200919239494
improved genome annotation for zymomonas mobilis. 200919816441
ethanol production from starch hydrolyzates using zymomonas mobilis and glucoamylase entrapped in polyvinylalcohol hydrogel.the glucoamylase from aspergillus niger, immobilized into poly(vinylalcohol) hydrogel lens-shaped capsules lentikats, was used for simultaneous saccharification and fermentation (ssf) with zymomonas mobilis in free form. this system was stable in both the repeated batch and continuous mode of ssf. the microorganism was found to adsorb on the capsules with immobilized enzyme. this increased the ethanol productivity of the repeated batch system with 5% w/v of immobilized glucoamylase almost 2.1 ti ...200919089646
an evolved xylose transporter from zymomonas mobilis enhances sugar transport in escherichia coli.xylose is a second most abundant sugar component of lignocellulose besides glucose. efficient fermentation of xylose is important for the economics of biomass-based biorefineries. however, sugar mixtures are sequentially consumed in xylose co-fermentation with glucose due to carbon catabolite repression (ccr) in microorganisms. as xylose transmembrance transport is one of the steps repressed by ccr, it is therefore of interest to develop a transporter that is less sensitive to the glucose inhibi ...200920003468
enhanced enzymatic hydrolysis of sugarcane bagasse by n-methylmorpholine-n-oxide pretreatment.the cellulose dissolution solvent used in lyocell process for cellulose fiber preparation, n-methylmorpholine-n-oxide (nmmo) monohydrate, was demonstrated to be an effective agent for sugarcane bagasse pretreatment. bagasse of 20wt% was readily dissolved in nmmo monohydrate at 130 degrees c within 1h. after dissolution, bagasse could be regenerated by rapid precipitation with water as a porous and amorphous mixture of its original components. the regenerated bagasse exhibited a significant enhan ...200918713663
myo-inositol facilitators iolt1 and iolt2 enhance d-mannitol formation from d-fructose in corynebacterium glutamicum.reduction of d-fructose to d-mannitol by whole-cell biotransformation with recombinant resting cells of corynebacterium glutamicum atcc13032 requires the coexpression of mdh and fdh, which encode mannitol and formate dehydrogenases, respectively. however, d-mannitol formation is limited by the uptake of d-fructose in its unphosphorylated form, because additional expression of the sugar facilitator from zymomonas mobilis resulted in a significantly increased productivity. here we identified simil ...200919054080
butanol tolerance in a selection of microorganisms.butanol tolerance is a critical factor affecting the ability of microorganisms to generate economically viable quantities of butanol. current clostridium strains are unable to tolerate greater than 2% 1-butanol thus membrane or gas stripping technologies to actively remove butanol during fermentation are advantageous. to evaluate the potential of alternative hosts for butanol production, we screened 24 different microorganisms for their tolerance to butanol. we found that in general, a barrier t ...200919089652
transcriptomic and metabolomic profiling of zymomonas mobilis during aerobic and anaerobic fermentations.zymomonas mobilis zm4 (zm4) produces near theoretical yields of ethanol with high specific productivity and recombinant strains are able to ferment both c-5 and c-6 sugars. z. mobilis performs best under anaerobic conditions, but is an aerotolerant organism. however, the genetic and physiological basis of zm4's response to various stresses is understood poorly.200919154596
thermophilic bacillus coagulans requires less cellulases for simultaneous saccharification and fermentation of cellulose to products than mesophilic microbial biocatalysts.ethanol production from lignocellulosic biomass depends on simultaneous saccharification of cellulose to glucose by fungal cellulases and fermentation of glucose to ethanol by microbial biocatalysts (ssf). the cost of cellulase enzymes represents a significant challenge for the commercial conversion of lignocellulosic biomass into renewable chemicals such as ethanol and monomers for plastics. the cellulase concentration for optimum ssf of crystalline cellulose with fungal enzymes and a moderate ...200919156365
different biochemical mechanisms ensure network-wide balancing of reducing equivalents in microbial sustain growth, the catabolic formation of the redox equivalent nadph must be balanced with the anabolic demand. the mechanisms that ensure such network-wide balancing, however, are presently not understood. based on 13c-detected intracellular fluxes, metabolite concentrations, and cofactor specificities for all relevant central metabolic enzymes, we have quantified catabolic nadph production in agrobacterium tumefaciens, bacillus subtilis, escherichia coli, paracoccus versutus, pseudomonas f ...200919181802
crystal structure analysis and in silico pka calculations suggest strong pka shifts of ligands as driving force for high-affinity binding to tgt.a novel ligand series is presented to inhibit trna-guanine transglycosylase (tgt), a protein with a significant role in the pathogenicity mechanism of shigella flexneri, the causative agent of shigellosis. the enzyme exchanges guanine in the wobble position of trna(asn,asp,his,tyr) against a modified base. to prevent the base-exchange reaction, several series of inhibitors have already been designed, synthesized, and tested. one aim of previous studies was to address a hydrophobic pocket with di ...200919199329
saccharomycopsis fibuligera and its applications in biotechnology.saccharomycopsis fibuligera is found to actively accumulate trehalose from starch and the gene responsible for biosynthesis of trehalose has been cloned and its expression has been characterized. this yeast is also found to secrete a large amount of amylases, acid protease and beta-glucosidase which have highly potential applications in fermentation industry. the genes encoding amylases, acid protease and beta-glucosidase in s. fibuligera have been cloned and characterized. it is also used to pr ...200919328842
an in vivo, label-free quick assay for xylose transport in escherichia coli.efficient use of xylose is necessary for economic production of biochemicals and biofuels from lignocellulosic materials. current studies on xylose uptake for various microorganisms have been hampered by the lack of a facile assay for xylose transport. in this work, a rapid in vivo, label-free method for measuring xylose transport in escherichia coli was developed by taking advantage of the bacillus pumilus xylosidase (xynb), which cleaved a commercially available xylose analog, p-nitrophenyl-be ...200919351525
optimization of metabolic pathways for bioconversion of lignocellulose to ethanol through genetic engineering.the optimization of metabolic pathways is of fundamental importance for strategies aimed at improving the economics and yield of the lignocellulose-to-ethanol processes. although escherichia coli is capable of metabolizing a wide variety of substrates including hexoses and pentoses, its hexose metabolism is inferior to that of zymomonas mobilis, an obligate, ethanologenic bacterium. we therefore inserted and expressed z. mobilis genes encoding essential enzymes involved in the fermentation pathw ...200919401227
ferromagnetic levan composite: an affinity matrix to purify lectin.a simple and inexpensive procedure used magnetite and levan to synthesize a composite recovered by a magnetic field. lectins from canavalia ensiformis (con a) and cratylia mollis (cramoll 1 and cramoll 1, 4) did bind specifically to composite. the magnetic property of derivative favored washing out contaminating proteins and recovery of pure lectins with glucose elution. cramoll 1 was purified by this affinity binding procedure in two steps instead of a previous three-step protocol with ammonium ...200919547713
genetic engineering of enterobacter asburiae strain jdr-1 for efficient production of ethanol from hemicellulose hydrolysates.dilute acid pretreatment is an established method for hydrolyzing the methylglucuronoxylans of hemicellulose to release fermentable xylose. in addition to xylose, this process releases the aldouronate methylglucuronoxylose, which cannot be metabolized by current ethanologenic biocatalysts. enterobacter asburiae jdr-1, isolated from colonized wood, was found to efficiently ferment both methylglucuronoxylose and xylose in acid hydrolysates of sweet gum xylan, producing predominantly ethanol and ac ...200919617386
enhanced levan production using chitin-binding domain fused levansucrase immobilized on chitin beads.levan is a homopolymer of fructose which can be produced by the transfructosylation reaction of levansucrase (ec from sucrose. in particular, levan synthesized by zymomonas mobilis has found a wide and potential application in the food and pharmaceutical industry. in this study, the immobilization of z. mobilis levansucrae (encoded by levu) was attempted for repeated production of levan. by fusion levu with the chitin-binding domain (chbd), the hybrid protein was overproduced in a solu ...200919018526
engineering of bio-hybrid materials by electrospinning polymer-microbe fibers.although microbes have been used in industrial and niche applications for several decades, successful immobilization of microbes while maintaining their usefulness for any desired application has been elusive. such a functionally bioactive system has distinct advantages over conventional batch and continuous-flow microbial reactor systems that are used in various biotechnological processes. this article describes the use of polyethylene oxide(99)-polypropylene oxide(67)-polyethylene oxide(99) tr ...200919667172
development of a high-throughput method to evaluate the impact of inhibitory compounds from lignocellulosic hydrolysates on the growth of zymomonas mobilis.overcoming the effects of hydrolysate toxicity towards ethanologens is a key technical barrier in the biochemical conversion process for biomass feedstocks to ethanol. despite its importance, the complexity of the hydrolysate toxicity phenomena and the lack of systematic studies, analysis and tools surrounding this issue have blocked a full understanding of relationships involving toxic compounds in hydrolysates and their effects on ethanologen growth and fermentation. in this study, we develope ...200919683550
complete genome sequence of the ethanol producer zymomonas mobilis ncimb 11163.zymomonas mobilis is an ethanol-producing alphaproteobacterium currently considered a major candidate organism for bioethanol production. here we report the finished and annotated genome sequence of z. mobilis subsp. mobilis strain ncimb 11163, a british ale-infecting isolate. this is the first z. mobilis strain whose genome, chromosomal and plasmid, is presented in its entirety.200919767433
two active forms of zymomonas mobilis levansucrase. an ordered microfibril structure of the enzyme promotes levan polymerization.fructansucrases, members of glycoside hydrolase family 68, catalyze both sucrose hydrolysis and the polymerization of fructose to beta-d-fructofuranose polymers. the resulting fructan polymers are distinguished by the nature of the glycosidic bond: inulin (beta-(2-1)-fructofuranose) and levan (beta-(2-6)-fructofuranose). in this study we demonstrate that zymomonas mobilis levansucrase exists in two active forms, depending on the ph and ionic strength. at ph values above 7.0, the enzyme is mainly ...200818809687
development of a versatile shuttle vector for gene expression in geobacillus 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
[optimization of fuel ethanol production from kitchen waste by plackett-burman design].kitchen garbage was chosen to produce ethanol through simultaneous saccharification and fermentation (ssf) by zymomonas mobilis. plackett-burman design was employed to screen affecting parameters during ssf process. the parameters were divided into two parts, enzymes and nutritions. none of the nutritions added showed significant effect during the experiment, which demonstrated that the kitchen garbage could meet the requirement of the microorganism without extra supplementation. protease and gl ...200818624223
immobilization of the recombinant invertase invb from zymomonas mobilis on nylon-6.the recombinant invertase invb (re-invb) from zymomonas mobilis was immobilized on microbeads of nylon-6, by means of covalent bonding. the enzyme was strongly and successfully bound to the support. the activity of the free and immobilized enzyme was determined, using 10% (w/v) sucrose, at a temperature ranging between 15 and 60 degrees c and a ph ranging between 3.5 and 7. the optimal ph and temperature for the immobilized enzyme were 5.5 and 25 degrees c, respectively. immobilization of re-inv ...200818712547
re-engineering escherichia coli for ethanol production.a lactate producing derivative of escherichia coli ko11, strain sz110, was re-engineered for ethanol production by deleting genes encoding all fermentative routes for nadh and randomly inserting a promoterless mini-tn5 cassette (transpososome) containing the complete zymomonas mobilis ethanol pathway (pdc, adha, and adhb) into the chromosome. by selecting for fermentative growth in mineral salts medium containing xylose, a highly productive strain was isolated in which the ethanol cassette had b ...200818773150
the dihydrolipoamide dehydrogenase of aeromonas caviae st exhibits nadh-dependent tellurite reductase activity.potassium tellurite (k(2)teo(3)) is extremely toxic for most forms of life and only a limited number of organisms are naturally resistant to the toxic effects of this compound. crude extracts prepared from the environmental isolate aeromonas caviae st catalize the in vitro reduction of teo32- in a nadh-dependent reaction. upon fractionation by ionic exchange column chromatography three major polypeptides identified as the e1, e2, and e3 components of the pyruvate dehydrogenase (pdh) complex were ...200818675788
Displaying items 1 - 100 of 707