Expanding metabolism for biosynthesis of nonnatural alcohols. Proc Natl Acad Sci USA

Department of Chemical and Biomolecular Engineering and Chemistry, University of California, Los Angeles, CA 90095, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 01/2009; 105(52):20653-8. DOI: 10.1073/pnas.0807157106
Source: PubMed


Nature uses a limited set of metabolites to perform all of the biochemical reactions. To increase the metabolic capabilities of biological systems, we have expanded the natural metabolic network, using a nonnatural metabolic engineering approach. The branched-chain amino acid pathways are extended to produce abiotic longer chain keto acids and alcohols by engineering the chain elongation activity of 2-isopropylmalate synthase and altering the substrate specificity of downstream enzymes through rational protein design. When introduced into Escherichia coli, this nonnatural biosynthetic pathway produces various long-chain alcohols with carbon number ranging from 5 to 8. In particular, we demonstrate the feasibility of this approach by optimizing the biosynthesis of the 6-carbon alcohol, (S)-3-methyl-1-pentanol. This work demonstrates an approach to build artificial metabolism beyond the natural metabolic network. Nonnatural metabolites such as long chain alcohols are now included in the metabolite family of living systems.

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    • "tolerated 1.2 % butanol and it can be used as host for the bio production of butanol. Due to the complex mechanisms involved in butanol-induced stress response, such as inhibiting membrane transport systems, enzymes, and disruption of membranes [9]-[19], butanol tolerance phenotype is still difficult to engineer even in microbes with well defined genetic background such as E. coli. The range of our estimate was mainly due to differences in dry mass percentage of the cells of the six bacterial isolates used. "
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    ABSTRACT: Due to a limited supply of petroleum oils, microbial production of butanol has gained more attention in recent years. However, major road blocks of the current butanol fermentation were low yield, low productivity and most importantly low titer due to the toxicity of butanol to their producing strains. In our current research efforts were made to evaluate the potential butanol tolerance bacterial strains for its possible role as a host for butanol production. Among the thirty screened bacterial strains, only few showed tolerance towards butanol in which AS2 I has the capability to tolerate upto 5 % butanol at 72 h with 30 % of cell growth. Assays for different enzymes involved in butanol production were also carried out. from the present study showed that the best butanol tolerant bacteria was found to be Paneibacillus sp. using 16S rDNA sequencing and had enhanced activity of butanol tolerance enzymes. Overall results shows that the strain AS2 I can be engineered as promising host for enhanced butanol production.
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    • "Recently, biofuels with increased carbon content have gained increasing interest due to their greater compatibility with existing engine and jet fuel transportation technologies. Microbial hydrocarbons are therefore new attractive biofuel targets, especially the extracellular long-chain hydrocarbons have received considerable interest due to the potential application in modern energy means (Hill et al. 2006; Fortman et al. 2008; Zhang et al. 2008). Many microbes are known to produce various alkanes with carbon chain lengths of C16 to C35 (Ladygina et al. 2006). "
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    ABSTRACT: The filamentous fungus, Asperigillus carbonarius, is able to produce a series of hydrocarbons in liquid culture using lignocellulosic biomasses, such as corn stover and switch grass as carbon source. The hydrocarbons produced by the fungus show similarity to jet fuel composition and might have industrial application. The production of hydrocarbons was found to be dependent on type of media used. Therefore, ten different carbon sources (oat meal, wheat bran, glucose, carboxymethyl cellulose, avicel, xylan, corn stover, switch grass, pretreated corn stover, and pretreated switch grass) were tested to identify the maximum number and quantity of hydrocarbons produced. Several hydrocarbons were produced include undecane, dodecane, tetradecane, hexadecane 2,4-dimethylhexane, 4-methylheptane, 3-methyl-1-butanol, ethyl benzene, o-xylene. Oatmeal was found to be the carbon source resulting in the largest amounts of hydrocarbon products. The production of fungal hydrocarbons, especially from lignocellulosic biomasses, holds a great potential for future biofuel production whenever our knowledge on regulators and pathways increases. Copyright © 2015 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
    Fungal Biology 01/2015; 119(4). DOI:10.1016/j.funbio.2015.01.001 · 2.34 Impact Factor
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    • "Chemical Titer Productivity % yield a Reference Isobutanol 22 g/L 0.6 g/L/h 86% Atsumi et al. (2008b) Isobutanol 13 g/L 0.09 g/L/h/OD 100% Bastian et al. (2011) 1-Propanol 7.5 g/L 0.1 g/L/h N/A Shen and Liao (2013) 2-Methyl-1-butanol 1.3 g/L 0.05 g/L/h 44% Cann and Liao (2008) 3-Methyl-1-butanol 9.5 g/L 0.16 g/L/h 33% Connor et al. (2010) Farnesol 0.1 g/L 0.003 g/L/h N/A Wang et al. (2010) Isoprenol 1.3 g/L 0.06 g/L/h 12% Zheng et al. (2013) Prenol 0.2 g/L 0.01 g/L/h Zheng et al. (2013) C12–C18 fatty alcohols 1.7 g/L 0.02 g/gDCW/h N/A Youngquist et al. (2013) C8–C18 fatty alcohols 0.8 g/L 0.06 g/L/h N/A Liu et al. (2014) n-Butanol 30 g/L 0.2 g/L/h 70% Shen et al. (2011) Isopropanol 143 g/L 0.6 g/L/h 67% Inokuma et al. (2010) (E,E,E)-geranylgeraniol 3.3 g/L 0.02 g/L/h 1.7% Tokuhiro et al. (2009) 3-Methyl-1-pentanol 0.8 g/L N/A N/A Zhang et al. (2008) 1-Pentanol 2.2 g/L N/A N/A Marcheschi et al. (2012) 1-Hexanol 0.3 g/L N/A N/A Marcheschi et al. (2012) 1-Heptanol 0.08 g/L N/A N/A Marcheschi et al. (2012) 4-Methyl-1-pentanol 0.2 g/L N/A N/A Zhang et al. (2008) 4-Methyl-1-hexanol 0.06 g/L N/A N/A Zhang et al. (2008) 5-Methyl-1-heptanol 0.02 g/L N/A N/A Zhang et al. (2008) "
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    ABSTRACT: Engineering microbial hosts for the production of higher alcohols looks to combine the benefits of renewable biological production with the useful chemical properties of larger alcohols. In this review we outline the array of metabolic engineering strategies employed for the efficient diversion of carbon flux from native biosynthetic pathways to the overproduction of a target alcohol. Strategies for pathway design from amino acid biosynthesis through 2-keto acids, from isoprenoid biosynthesis through pyrophosphate intermediates, from fatty acid biosynthesis and degradation by tailoring chain length specificity, and the use and expansion of natural solvent production pathways will be covered.
    Metabolic Engineering 09/2014; 25. DOI:10.1016/j.ymben.2014.07.007 · 6.77 Impact Factor
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