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Metabolic Engineering

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https://www.readbyqxmd.com/read/28645641/homogenizing-bacterial-cell-factories-analysis-and-engineering-of-phenotypic-heterogeneity
#1
REVIEW
Dennis Binder, Thomas Drepper, Karl-Erich Jaeger, Frank Delvigne, Wolfgang Wiechert, Dietrich Kohlheyer, Alexander Grünberger
In natural habitats, microbes form multispecies communities that commonly face rapidly changing and highly competitive environments. Thus, phenotypic heterogeneity has evolved as an innate and important survival strategy to gain an overall fitness advantage over cohabiting competitors. However, in defined artificial environments such as monocultures in small- to large-scale bioreactors, cell-to-cell variations are presumed to cause reduced production yields as well as process instability. Hence, engineering microbial production toward phenotypic homogeneity is a highly promising approach for synthetic biology and bioprocess optimization...
June 20, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28625755/multilevel-engineering-of-the-upstream-module-of-aromatic-amino-acid-biosynthesis-in-saccharomyces-cerevisiae-for-high-production-of-polymer-and-drug-precursors
#2
Miguel Suástegui, Chiam Yu Ng, Anupam Chowdhury, Wan Sun, Mingfeng Cao, Emma House, Costas D Maranas, Zengyi Shao
A multilevel approach was implemented in Saccharomyces cerevisiae to optimize the precursor module of the aromatic amino acid biosynthesis pathway, which is a rich resource for synthesizing a great variety of chemicals ranging from polymer precursor, to nutraceuticals and pain-relief drugs. To facilitate the discovery of novel targets to enhance the pathway flux, we incorporated the computational tool YEASTRACT for predicting novel transcriptional repressors and OptForce strain-design for identifying non-intuitive pathway interventions...
June 15, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28624535/atp-free-biosynthesis-of-a-high-energy-phosphate-metabolite-fructose-1-6-diphosphate-by-in-vitro-metabolic-engineering
#3
Wei Wang, Meixia Liu, Chun You, Zhimin Li, Yi-Heng Percival Zhang
Fructose 1,6-diphosphate (FDP) is a widely used medicine and is also a precursor of two important three-carbon phosphates -- glyceraldehyde 3-phosphate (GA3P) and dihydroxyacetone phosphate (DHAP) for the biosynthesis of numerous fine chemicals. An in vitro synthetic cofactor-free enzymatic pathway comprised of four hyperthermophilic enzymes was designed to produce FDP from starch and pyrophosphate. All of four hyperthermophilic enzymes (i.e., alpha-glucan phosphorylase from Thermotaga maritima, phosphoglucomutase from Thermococcus kodakarensis, glucose 6-phosphate isomerase from Thermus thermophilus, and pyrophosphate phosphofructokinase from T...
June 14, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28627452/engineering-of-unconventional-yeast-yarrowia-lipolytica-for-efficient-succinic-acid-production-from-glycerol-at-low-ph
#4
Zhiyong Cui, Cuijuan Gao, Jiaojiao Li, Jin Hou, Carol Sze Ki Lin, Qingsheng Qi
Yarrowia lipolytica is considered as a potential candidate for succinic acid production because of its innate ability to accumulate citric acid cycle intermediates and its tolerance to acidic pH. Previously, a succinate-production strain was obtained through the deletion of succinate dehydrogenase subunit encoding gene Ylsdh5. However, the accumulation of by-product acetate limited further improvement of succinate production. Meanwhile, additional pH adjustment procedure increased the downstream cost in industrial application...
June 13, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28619444/single-step-production-of-the-simvastatin-precursor-monacolin-j-by-engineering-of-an-industrial-strain-of-aspergillus-terreus
#5
Xuenian Huang, Yajing Liang, Yong Yang, Xuefeng Lu
Monacolin J is a key precursor for the synthesis of simvastatin (Zocor), an important drug for treating hypercholesterolemia. Industrially, monacolin J is manufactured through alkaline hydrolysis of lovastatin, a fungal polyketide produced by Aspergillus terreus. Multistep chemical processes for the conversion of lovastatin to simvastatin are laborious, cost expensive and environmentally unfriendly. A biocatalysis process for monacolin J conversion to simvastatin has been developed. However, direct bioproduction of monacolin J has not yet been achieved...
June 12, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28606738/engineering-high-level-production-of-fatty-alcohols-by-saccharomyces-cerevisiae-from-lignocellulosic-feedstocks
#6
Leo d'Espaux, Amit Ghosh, Weerawat Runguphan, Maren Wehrs, Feng Xu, Oliver Konzock, Ishaan Dev, Melissa Nhan, Jennifer Gin, Amanda Reider Apel, Christopher J Petzold, Seema Singh, Blake A Simmons, Aindrila Mukhopadhyay, Héctor García Martín, Jay D Keasling
Fatty alcohols in the C12-C18 range are used in personal care products, lubricants, and potentially biofuels. These compounds can be produced from the fatty acid pathway by a fatty acid reductase (FAR), yet yields from the preferred industrial host Saccharomyces cerevisiae remain under 2% of the theoretical maximum from glucose. Here we improved titer and yield of fatty alcohols using an approach involving quantitative analysis of protein levels and metabolic flux, engineering enzyme level and localization, pull-push-block engineering of carbon flux, and cofactor balancing...
June 10, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28603040/a-real-time-control-system-of-gene-expression-using-ligand-bound-nucleic-acid-aptamer-for-metabolic-engineering
#7
Jing Wang, Xun Cui, Le Yang, Zhe Zhang, Liping Lv, Haoyuan Wang, Zhenmin Zhao, Ningzi Guan, Lichun Dong, Rachel Chen
Artificial control of bio-functions through regulating gene expression is one of the most important and attractive technologies to build novel living systems that are useful in the areas of chemical synthesis, nanotechnology, pharmacology, cell biology. Here, we present a novel real-time control system of gene regulation that includes an enhancement element by introducing duplex DNA aptamers upstream promoter and a repression element by introducing a RNA aptamer upstream ribosome binding site. With the presence of ligands corresponding to the DNA aptamers, the expression of the target gene can be potentially enhanced at the transcriptional level by strengthening the recognition capability of RNAP to the recognition region and speeding up the separation efficiency of the unwinding region due to the induced DNA bubble around the thrombin-bound aptamers; while with the presence of RNA aptamer ligand, the gene expression can be repressed at the translational level by weakening the recognition capability of ribosome to RBS due to the shielding of RBS by the formed aptamer-ligand complex upstream RBS...
June 8, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28602523/engineering-biological-systems-using-automated-biofoundries
#8
REVIEW
Ran Chao, Shekhar Mishra, Tong Si, Huimin Zhao
Engineered biological systems such as genetic circuits and microbial cell factories have promised to solve many challenges in the modern society. However, the artisanal processes of research and development are slow, expensive, and inconsistent, representing a major obstacle in biotechnology and bioengineering. In recent years, biological foundries or biofoundries have been developed to automate design-build-test engineering cycles in an effort to accelerate these processes. This review summarizes the enabling technologies for such biofoundries as well as their early successes and remaining challenges...
June 7, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28591561/over-expression-of-groesl-in-cupriavidus-necator-for-heterotrophic-and-autotrophic-isopropanol-production
#9
Jillian Marc, Estelle Grousseau, Eric Lombard, Anthony J Sinskey, Nathalie Gorret, Stéphane E Guillouet
We previously reported a metabolic engineering strategy to develop an isopropanol producing strain of Cupriavidus necator leading to production of 3.4gL(-1) isopropanol. In order to reach higher titers, isopropanol toxicity to the cells has to be considered. A toxic effect of isopropanol on the growth of C. necator has been indeed observed above a critical value of 15gL(-1). GroESL chaperones were first searched and identified in the genome of C. necator. Native groEL and groES genes from C. necator were over-expressed in a strain deleted for PHA synthesis...
June 4, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28587908/elevating-4-hydroxycoumarin-production-through-alleviating-thioesterase-mediated-salicoyl-coa-degradation
#10
Xiaolin Shen, Monika Mahajani, Jia Wang, Yaping Yang, Qipeng Yuan, Yajun Yan, Yuheng Lin
Acyl-CoAs are essential intermediates in the biosynthetic pathways of a number of industrially and pharmaceutically important molecules. When these pathways are reconstituted in a heterologous microbial host for metabolic engineering purposes, the acyl-CoAs may be subject to undesirable hydrolysis by the host's native thioesterases, resulting in a waste of cellular energy and decreased intermediate availability, thus impairing bioconversion efficiency. 4-hydroxycoumarin (4HC) is a direct synthetic precursor to the commonly used oral anticoagulants (e...
June 3, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28583672/monascus-ruber-as-cell-factory-for-lactic-acid-production-at-low-ph
#11
Ruud A Weusthuis, Astrid E Mars, Jan Springer, Emil Jh Wolbert, Hetty van der Wal, Truus G de Vrije, Mark Levisson, Audrey Leprince, G Bwee Houweling-Tan, Antoine Pha Moers, Sjon Na Hendriks, Odette Mendes, Yvonne Griekspoor, Marc Wt Werten, Peter J Schaap, John van der Oost, Gerrit Eggink
A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175g/l lactic acid at pH 2.8. Its genome and transcriptomes were sequenced and annotated. Genes encoding lactate dehydrogenase (LDH) were introduced to accomplish lactic acid production and two genes encoding pyruvate decarboxylase (PDC) were knocked out to subdue ethanol formation. The strain preferred lactic acid to glucose as carbon source, which hampered glucose consumption and therefore also lactic acid production...
June 3, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28583673/high-level-de-novo-biosynthesis-of-arbutin-in-engineered-escherichia-coli
#12
Xiaolin Shen, Jia Wang, Jian Wang, Zhenya Chen, Qipeng Yuan, Yajun Yan
Arbutin is a hydroquinone glucoside compound existing in various plants. It is widely used in pharmaceutical and cosmetic industries owing to its well-known skin-lightening property as well as anti-oxidant, anti-microbial, and anti-inflammatory activities. Currently, arbutin is usually produced by plant extraction or enzymatic processes, which suffer from low product yield and expensive processing cost. In this work, we established an artificial pathway in Escherichia coli for high-level production of arbutin from simple carbon sources...
June 2, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28552747/the-oxidative-tca-cycle-operates-during-methanotrophic-growth-of-the-type-i-methanotroph-methylomicrobium-buryatense-5gb1
#13
Yanfen Fu, Yi Li, Mary Lidstrom
Methanotrophs are a group of bacteria that use methane as sole carbon and energy source. Type I methanotrophs are gamma-proteobacterial methanotrophs using the ribulose monophosphate cycle (RuMP) cycle for methane assimilation. In order to facilitate metabolic engineering in the industrially promising Type I methanotroph Methylomicrobium buryatense 5GB1, flux analysis of cellular metabolism is needed and (13)C tracer analysis is a foundational tool for such work. This biological system has a single-carbon input and a special network topology that together pose challenges to the current well-established methodology for (13)C tracer analysis using a multi-carbon input such as glucose, and to date, no (13)C tracer analysis of flux in a Type I methanotroph has been reported...
May 25, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28550000/reversal-of-%C3%AE-oxidative-pathways-for-the-microbial-production-of-chemicals-and-polymer-building-blocks
#14
REVIEW
Nicolai Kallscheuer, Tino Polen, Michael Bott, Jan Marienhagen
β-Oxidation is the ubiquitous metabolic strategy to break down fatty acids. In the course of this four-step process, two carbon atoms are liberated per cycle from the fatty acid chain in the form of acetyl-CoA. However, typical β-oxidative strategies are not restricted to monocarboxylic (fatty) acid degradation only, but can also be involved in the utilization of aromatic compounds, amino acids and dicarboxylic acids. Each enzymatic step of a typical β-oxidation cycle is reversible, offering the possibility to also take advantage of reversed metabolic pathways for applied purposes...
May 23, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28545807/enhancing-erythritol-productivity-in-yarrowia-lipolytica-using-metabolic-engineering
#15
Frédéric Carly, Marie Vandermies, Samuel Telek, Sébastien Steels, Stéphane Thomas, Jean-Marc Nicaud, Patrick Fickers
Erythritol (1,2,3,4-butanetetrol) is a four-carbon sugar alcohol with sweetening properties that is used by the agrofood industry as a food additive. In this study, we demonstrated that metabolic engineering can be used to improve the production of erythritol from glycerol in the yeast Yarrowia lipolytica. The best results were obtained using a mutant that overexpressed GUT1 and TKL1, which encode a glycerol kinase and a transketolase, respectively, and in which EYK1, which encodes erythrulose kinase, was disrupted; the latter enzyme is involved in an early step of erythritol catabolism...
May 22, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28479191/isotopically-nonstationary-13-c-flux-analysis-of-cyanobacterial-isobutyraldehyde-production
#16
Lara J Jazmin, Yao Xu, Yi Ern Cheah, Adeola O Adebiyi, Carl Hirschie Johnson, Jamey D Young
We applied isotopically nonstationary (13)C metabolic flux analysis (INST-MFA) to compare the pathway fluxes of wild-type (WT) Synechococcus elongatus PCC 7942 to an engineered strain (SA590) that produces isobutyraldehyde (IBA). The flux maps revealed a potential bottleneck at the pyruvate kinase (PK) reaction step that was associated with diversion of flux into a three-step PK bypass pathway involving the enzymes PEP carboxylase (PEPC), malate dehydrogenase (MDH), and malic enzyme (ME). Overexpression of pk in SA590 led to a significant improvement in IBA specific productivity...
May 4, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28479190/biosynthesis-of-plant-derived-ginsenoside-rh2-in-yeast-via-repurposing-a-key-promiscuous-microbial-enzyme
#17
Yu Zhuang, Guang-Yu Yang, Xiaohui Chen, Qian Liu, Xueli Zhang, Zixin Deng, Yan Feng
Ginsenoside Rh2 is a potential anticancer drug isolated from medicinal plant ginseng. Fermentative production of ginsenoside Rh2 in yeast has recently been investigated as an alternative strategy compared to extraction from plants. However, the titer was quite low due to low catalytic capability of the key ginseng glycosyltransferase in microorganisms. Herein, we have demonstrated high-level production of ginsenoside Rh2 in Saccharomyces cerevisiae via repurposing an inherently promiscuous glycosyltransferase, UGT51...
May 4, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28465173/glucose-6-phosphate-dehydrogenase-as-a-target-for-highly-efficient-fatty-acid-biosynthesis-in-microalgae-by-enhancing-nadph-supply
#18
Jiao Xue, Srinivasan Balamurugan, Da-Wei Li, Yu-Hong Liu, Hao Zeng, Lan Wang, Wei-Dong Yang, Jie-Sheng Liu, Hong-Ye Li
Oleaginous microalgae have great prospects in the fields of feed, nutrition, biofuel, etc. However, biomass and lipid productivity in microalgae remain a major economic and technological bottleneck. Here we present a novel regulatory target, glucose-6-phosphate dehydrogenase (G6PD) from the pentose phosphate pathway (PPP), in boosting microalgal lipid accumulation. G6PD, involved in the formation of NADPH demanded in fatty acid biosynthesis as reducing power, was characterized in oleaginous microalga Phaeodactylum tricornutum...
April 30, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28442386/arginine-deiminase-pathway-provides-atp-and-boosts-growth-of-the-gas-fermenting-acetogen-clostridium-autoethanogenum
#19
Kaspar Valgepea, Kim Q Loi, James B Behrendorff, Renato de S P Lemgruber, Manuel Plan, Mark P Hodson, Michael Köpke, Lars K Nielsen, Esteban Marcellin
Acetogens are attractive organisms for the production of chemicals and fuels from inexpensive and non-food feedstocks such as syngas (CO, CO2 and H2). Expanding their product spectrum beyond native compounds is dictated by energetics, particularly ATP availability. Acetogens have evolved sophisticated strategies to conserve energy from reduction potential differences between major redox couples, however, this coupling is sensitive to small changes in thermodynamic equilibria. To accelerate the development of strains for energy-intensive products from gases, we used a genome-scale metabolic model (GEM) to explore alternative ATP-generating pathways in the gas-fermenting acetogen Clostridium autoethanogenum...
April 23, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28438645/releasing-the-potential-power-of-terpene-synthases-by-a-robust-precursor-supply-platform
#20
Guangkai Bian, Yichao Han, Anwei Hou, Yujie Yuan, Xinhua Liu, Zixin Deng, Tiangang Liu
Terpenoids represent the largest family of natural products. Their structural diversity is largely due to variable skeletons generated by terpene synthases. However, terpene skeletons found in nature are much more than those generated from known terpene synthases. Most promiscuous terpene synthases (i.e. those that can generate more than one product) have not been comprehensively characterised. Here, we first demonstrated that the promiscuous terpene synthases can produce more variable terpenoids in vivo by converting precursor polyisoprenoid diphosphates of different lengths (C10, C15, C20, C25)...
April 23, 2017: Metabolic Engineering
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