| Summary: | Resumen del trabajo presentado en el 41 Congreso de la Sociedad Española de Bioquímica y Biología Molecular SEBBM, celebrado en Santander (España) del 10 al 13 de septiembre de 2018. Some marine bacteria, such as Moritella marina, are able to produce certain amounts of the nutraceutical docosahexaenoic acid (DHA) thanks to a specific enzymatic complex called Pfa synthase. Moreover, E.coli heterologously expressing this pfa gene cluster from M. marina is also able to produce DHA [1]. The aim of this study was to find genetic or metabolic conditions to improve DHA production in E. coli or any other microorganism. Firstly, we studied the expression of Pfa promoters in E. coli and replaced these promoters by inducible pBAD promoters in order to increase the production of the final product. Secondly, we altered the canonical carbon flux in E. coli to improve the availability of substrates for Pfa complex by two strategies: using the exogenous compound cerulenin, and deleting a initiation enzyme of a competing pathway, FabH [2]. Both strategies exploit a substrate competition mechanism between the native fatty acid synthase from E. coli and the heterologous Pfa complex from M. marina. Finally, we improved E. coli growth at low temperature by introducing two psychrophilic chaperonins, Cpn10 and Cpn60 from Oleispira antarctica [3], in order to improve protein folding. These approaches have increased the overall efficiency of DHA synthesis in E. coli, and could be used for biotechnological optimization in different organisms to synthesize DHA or other polyunsaturated fatty acids.
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