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Elimination of D-lactate synthesis increases poly(3-hydroxybutyrate) and ethanol synthesis from glycerol and affects cofactor distribution in recombinant Escherichia coli.

Authors :
Nikel PI
Giordano AM
de Almeida A
Godoy MS
Pettinari MJ
Source :
Applied and environmental microbiology [Appl Environ Microbiol] 2010 Nov; Vol. 76 (22), pp. 7400-6. Date of Electronic Publication: 2010 Sep 24.
Publication Year :
2010

Abstract

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.

Details

Language :
English
ISSN :
1098-5336
Volume :
76
Issue :
22
Database :
MEDLINE
Journal :
Applied and environmental microbiology
Publication Type :
Academic Journal
Accession number :
20870794
Full Text :
https://doi.org/10.1128/AEM.02067-10