Metabolic engineering chain

The phbA, phbB, and phbC genes from Alcaligenes eutrophus (Ralstonia eutrophus) encoding the biosynthetic enzymes (3-ketothiolase, acetoacetyl-CoA reductase (NADPH-dependent), and PHB synthase, respectively, have been cloned into E. coli (Scheme 19.42).339-342 The use of in vitro evolution using error-prone polymerase chain reaction has led to enhanced accumulation of PHA in a resultant recombinant strain.343 Additional studies to enhance the biosynthesis of PHB through the use of metabolic engineering have been discussed.344... 

Truksa M, Wu G, Vrinten P, Qiu X. (2006) Metabolic engineering of plants to produce very long-chain polyunsaturated fatty acids. Transgenic Res 15 131-137. 

J. A., and Sayanova, O. (2013) Metabolic engineering of Phaeodactylum tricor-nutum for the enhanced accumulation of omega-3 long chain polyunsaturated fatty acids. Metab. Eng., 22C, 3-9. 

Fatty acid synthesis has been engineered as well. Two pathways to very long chain polyunsaturated fatty acids were realized in P. pastoris to demonstrate their feasibility for future reengineering in oilseed crops [163]. Fatty acids and their esters are also interesting potential biofuels. Fatty acid esters with branched chain alcohols are potential low-viscosity biodiesels, and were successfully synthesized in Escherichia coli and P. pastoris by metabolic engineering [164]. 

Tao, H., Guo, D., Zhang, Y, Deng, Z, and Liu, T. (2015) Metabolic engineering of microbes for branched-chain biodiesel production with low-temperature property. BiotechnoL. Biofuels, 8, 92. 

There have been many successful cases of the development of metabolically engineered E. coli strains for the production of P(3HB), which is one of the best characterized PHAs. P(3HB) synthesis is initiated by condensation of two acetyl-CoA molecules into acetoacetyl-CoA, subsequently followed by reduction to 3-hydroxybutyryl-CoA using NADPH as a cofactor, and finally 3-hydroxybutyryl-CoA is incorporated into the growing chain of P(3HB) (Lee 1996). Because the P(3HB) synthesis pathway competes with inherent metabolic pathways needing acetyl-CoA, it is very important to increase the acetyl-CoA pool available for the P(3HB) synthesis reaction, resulting in increased P(3HB) yield and productivity. 

Park SJ, Lee SY (2005) Systems biological approach for the production of various polyhydroxy-alkanoates by metaboUcally engineered Escherichia coli. Macromol Symp 224 1-9 Park SJ, Park JP, Lee SY (2002) Metabolic engineering of Escherichia coli for the production of medium-chain-length polyhydroxyalkanoates rich in specific monomers. FEMS Microbiol... 

Park S J, Park JP, Lee SY, Doi Y (2003) Enrichment of specific monomer in medium-chain-length poly(3-hydroxyalkanoates) by amplification of fadD and fadE genes in recombinant Escherichia coli. Enzyme Microb Technol 33 62-70 Park SJ, Choi JI, Lee SY (2004) Engineering of Escherichia coli fatty acid metabolism for the production of polyhydroxyalkanoates. Enzyme Microb Technol 36 579-588 Park JH, Lee KH, Kim TY, Lee SY (2007) Metabolic engineering of Escherichia coli for the production of L-vafine based on transcriptome analysis and in silico gene knockout simulation. Proc Natl Acad Sci U S A 104 7797-7802... 

Wiechert W (2002) Modeling and simulation tools for metabolic engineering. J Biotechnol 94 37-63 Witholt B, Kessler B (1999) Perspectives of medium chain length poly(hydroxyalkanoates), a versatile set of bacterial bioplastics. CurrOpin Biotechnol 10 279-285... 

Aldor AS, Keasling JD (2003) Process design for microbial plastic factories metabolic engineering of polyhydroxyalkanoates. Curr Opin Biotechnol 14 475-483 Ashby RD, Solaiman DKY, Fogha TA, Liu CK (2001) Glucose/hpid mixed substrates as a means of controUing the properties of medium chain length poly(hydroxyalkanoates). Biomacromolecules 2 211-216... 

Picataggio S, Rohrer T, Deanda K, Lanning D, Reynolds R, Mielenz J, Eirich LD. (1992). Metabolic engineering of Candida tropicalis for the production of long-chain dicarboxylic acids. Biotechnology (N Y), 10, 894-898. 

For example, metabolic engineering and culture condition manipulation were employed to produce modified PHAs with salient features. PHAs with methyl side-chains such as PH6N (poly(3-hydroxy-6-methyl-nonanoate)) was obtained from Pseudomonas oleovorans fed with methylated alkanoic acids or in a mixture with nonanoic acid as a carbon source. PH6N crystallizes much faster than neat PHN (poly-3-hydro g nonanoate), and the melting temperature was higher (I m = 65 °C) than that of PHN [Tm = 58 Studies have shown that PHAs containing an epoxidized... 

Venegas-caleron, M. Sayanova, O, Napier, J. A an alternative to fish oils metabolic engineering of oil-seed crops to produce omega-3 long chain polyunsaturated fatty acids. Prog Lipid Res 2010, 49 108-119. 

Hofiinaim, M. Wagner, M. Abbadi, A. Fulda, M. Feussner I metabolic engineering of omega-3-very long chain polyunsaturated fatty acid production by an exclusively acyl-coA-dependent pathway. JBiol Chem 2008,283 22352-22362. 

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