STRAINS OF ESCHERICHIA COLI MODIFIED BY METABOLIC ENGINEERING TO PRODUCE CHEMICAL COMPOUNDS FROM HYDROLYZED LIGNOCELLULOSE, PENTOSES, HEXOSES AND OTHER CARBON SOURCES

The present invention relates to novel strains of Escherichia coli known as JU15, JU15A, LL26, MS04 and derivatives that preferentially produce metabolites, particularly D-lactate, L-lactate and also ethanol, in a high yield and with high selectivity, from a variety of carbon sources, such as: xylose-rich culture media (a main carbon source), particularly media formulated with hydrolysates of vegetable fibres, such as sugar cane, agave and fodder bagasse, in addition to a wide variety of agro-industrial waste, such as milk whey or forest, cellulose, fodder or shrub waste, and, in general, any lignocellulose-derived material. The aforementioned strains include inactivated genes of pyruvate formate lyase (pflB), alcohol dehydrogenase (adhE), fumarate reductase (frdA) and genes that code for the ATP-dependent xylose transport system (xylFGH). Said strains can additionally include an inactivated lactate dehydrogenase (IdhA) gene, as well as an inserted gene coding for the synthesis of another chemical product. These strains make use of the production of the metabolite of interest (in particular, D-lactate, L-lactate or ethanol) as sole route for regenerating the reducing power of the microorganism. The invention also relates to fermentation methods for producing said metabolites from media with diverse carbon sources, including glucose, lactose or xylose. La presente invención se refiere a nuevas cepas de Escherichia coli denominadas JU15, JU15A, LL26, MS04 y derivadas que producen metabolitos de forma preferencial, particularmente D-Lactato, L-Lactato e inclusive etanol, con un alto rendimiento y alta selectividad a partir de una variedad de fuentes de carbono como: medios de cultivo abundantes en xilosa (como fuente de carbono principal), particularmente medios formulados con hidrolizados de fibras vegetales, como el bagazo de caña, agave y pastos, además de una amplia variedad de residuos agroindustriales, como el suero de leche o desechos forestales, celulosa, pastos, arbustos y en general cualquier material derivado de lignocelulosa. Estas cepas usan la producción del metabolito de interés (particularmente D-lactato, L- lactato o etanol) como única vía de regeneración del poder reductor del microorganismo. También se refiere a los métodos fermentativos para producir dichos metabolitos a partir de medios con fuentes de carbono diversas, incluyendo glucosa, lactosa o xilosa.