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Figure 5 | Biotechnology for Biofuels

Figure 5

From: Combined inactivation of the Clostridium cellulolyticum lactate and malate dehydrogenase genes substantially increases ethanol yield from cellulose and switchgrass fermentations

Figure 5

Key metabolic pathways of glycolysis, fermentation and electron transfer to nicotinamide adenine dinucleotide phosphate (NAD(P)+) cofactors in Clostridium cellulolyticum. L-Malate dehydrogenase (MDH) catalyzes the NADH-dependent reduction of oxaloacetate (OAA), forming the L-malate intermediate, and malic enzyme catalyzes the NADP+-dependent oxidation and decarboxylation of the intermediate to produce pyruvate and NADPH. In a second transhydrogenase system, isocitrate dehydrogenase catalyzes 2-oxoglutarate (2OG) and NADPH formation, while a putative 2-oxoacid dehydrogenase could catalyze the NADH-dependent formation of 2-hydroxyglutarate (2HG). Ferredoxin (Fd) reduced by the pyruvate:ferredoxin oxidoreductase enzyme can be oxidized to produce H2 or coupled to the NADH-dependent reduction of NADP+ catalyzed by the iron-sulfur flavoprotein complex NfnAB. Fermentation products are shown in green, and electron transfer cofactors are shown in blue.

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Biotechnology for Biofuels and Bioproducts

ISSN: 2731-3654

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