Fecha de publicación: 2010.
The effect of eliminating D-lactate synthesis in poly(3-hydroxybutyrate) (PHB)-accumulating recombinant Escherichia coli (K24K) was analyzed using glycerol as a substrate. K24KL, an ldhA derivative, produced more biomass and had altered carbon partitioning among the metabolic products, probably due to the increased availability of carbon precursors and reducing power. This resulted in a significant increase of PHB and ethanol synthesis and a decrease in acetate production. Cofactor measurements revealed that cultures of K24K and K24KL had a high intracellular NADPH content and that the NADPH/NADP+ ratio was higher than the NADH/NAD+ ratio. The ldhA mutation affected cofactor distribution, resulting in a more reduced intracellular state, mainly due to a further increase in NADPH/NADP+. In 60-h fed-batch cultures, K24KL reached 41.9 g · liter-1 biomass and accumulated PHB up to 63% ± 1% (wt/wt), with a PHB yield on glycerol of 0.41 ± 0.03 g · g-1, the highest reported using this substrate. © 2010, American Society for Microbiology.
Afiliación de los autores: De Almeida, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Afiliación de los autores: Pettinari, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Palabras claves: Carbon partitioning; Carbon precursors; Cofactors; D-lactate; Fed-batch cultures; Metabolic products; Poly(3-hydroxybutyrate); Recombinant Escherichia coli; Reducing power; Batch cell culture; Escherichia coli; Ethanol; Substrates; Glycerol; alcohol; carbon; glycerol; hydroxybutyric acid; lactate dehydrogenase; lactic acid; nicotinamide adenine dinucleotide; nicotinamide adenine dinucleotide phosphate; poly(3 hydroxybutyric acid); poly-beta-hydroxybutyrate; polyester; alcohol; biomass; ester; ethanol; fecal coliform; partitioning; recombination; article; biomass; bioreactor; chemistry; Escherichia coli; genetics; growth, development and aging; metabolism; time; Biomass; Bioreactors; Carbon; Escherichia coli; Ethanol; Glycerol; Hydroxybutyrates; Lactate Dehydrogenases; Lactic Acid; Metabolic Networks and Pathways; NAD; NADP; Polyesters; Time Factors; Escherichia coli.
Repositorio: Biblioteca Digital (UBA-FCEN). Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales