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Microb Cell Fact

Title:		Metabolic engineering of Ashbya gossypii for deciphering the de novo biosynthesis of gamma-lactones
Author(s):		Silva R; Aguiar TQ; Coelho E; Jimenez A; Revuelta JL; Domingues L;
Address:		"CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal. Metabolic Engineering Group, Department of Microbiology and Genetics, University of Salamanca, Campus Miguel de Unamuno, 37007, Salamanca, Spain. CEB-Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal. luciliad@deb.uminho.pt"
Journal Title:		Microb Cell Fact
Year:		2019
Volume:		20190328
Issue:		1
Page Number:		62 -
DOI:		10.1186/s12934-019-1113-1
ISSN/ISBN:		1475-2859 (Electronic) 1475-2859 (Linking)
Abstract:		"BACKGROUND: Lactones are highly valuable cyclic esters of hydroxy fatty acids that find application as pure fragrances or as building blocks of speciality chemicals. While chemical synthesis often leads to undesired racemic mixtures, microbial production allows obtaining optically pure lactones. The production of a specific lactone by biotransformation depends on the supply of the corresponding hydroxy fatty acid, which has economic and industrial value similar to gamma-lactones. Hence, the identification and exploration of microorganisms with the rare natural ability for de novo biosynthesis of lactones will contribute to the long-term sustainability of microbial production. In this study, the innate ability of Ashbya gossypii for de novo production of gamma-lactones from glucose was evaluated and improved. RESULTS: Characterization of the volatile organic compounds produced by nine strains of this industrial filamentous fungus in glucose-based medium revealed the noteworthy presence of seven chemically different gamma-lactones. To decipher and understand the de novo biosynthesis of gamma-lactones from glucose, we developed metabolic engineering strategies focused on the fatty acid biosynthesis and the beta-oxidation pathways. Overexpression of AgDES589, encoding a desaturase for the conversion of oleic acid (C18:1) into linoleic acid (C18:2), and deletion of AgELO624, which encodes an elongase that catalyses the formation of C20:0 and C22:0 fatty acids, greatly increased the production of gamma-lactones (up to 6.4-fold; (7.6 +/- 0.8) x 10(3) microg/g(Cell Dry Weight)). Further substitution of AgPOX1, encoding the exclusive acyl-CoA oxidase in A. gossypii, by a codon-optimized POX2 gene from Yarrowia lipolytica, which encodes a specific long chain acyl-CoA oxidase, fine-tuned the biosynthesis of gamma-decalactone to a relative production of more than 99%. CONCLUSIONS: This study demonstrates the potential of A. gossypii as a model and future platform for de novo biosynthesis of gamma-lactones. By means of metabolic engineering, key enzymatic steps involved in their production were elucidated. Moreover, the combinatorial metabolic engineering strategies developed resulted in improved de novo biosynthesis of gamma-decalactone. In sum, these proof-of-concept data revealed yet unknown metabolic and genetic determinants important for the future exploration of the de novo production of gamma-lactones as an alternative to biotransformation processes"
Keywords:		Eremothecium/*genetics/*metabolism Fatty Acids/biosynthesis/metabolism *Lactones/chemistry/metabolism Metabolic Engineering/*methods Oxidation-Reduction Volatile Organic Compounds/*metabolism Ashbya gossypii De novo biosynthesis Fatty acid biosynthesis Me;
Notes:		"MedlineSilva, Rui Aguiar, Tatiana Q Coelho, Eduardo Jimenez, Alberto Revuelta, Jose Luis Domingues, Lucilia eng UID/BIO/04469/2019/Fundacao para a Ciencia e a Tecnologia/ PD/BD/113812/2015/Fundacao para a Ciencia e a Tecnologia/ POCI-01-0145-FEDER-006684/Fundacao para a Ciencia e a Tecnologia/ NORTE-01-0145-FEDER-000004/European Regional Development Fund/ BIO2014-56930-P/Ministerio de Economia, Industria y Competitividad, Gobierno de Espana/ BIO2017-88435-R/Ministerio de Economia, Industria y Competitividad, Gobierno de Espana/ SA016P17/Consejeria de Educacion, Junta de Castilla y Leon/ England 2019/03/30 Microb Cell Fact. 2019 Mar 28; 18(1):62. doi: 10.1186/s12934-019-1113-1"