1. Cofactor engineering in Thermoanaerobacterium aotearoense SCUT27 for maximizing ethanol yield and revealing an enzyme complex with high ferredoxin-NAD + reductase activity.
- Author
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Dai K, Qu C, Li X, Lan Y, Fu H, and Wang J
- Subjects
- Fermentation, NAD metabolism, Oxidation-Reduction, Ethanol metabolism, Thermoanaerobacterium metabolism, Thermoanaerobacterium genetics, Thermoanaerobacterium enzymology
- Abstract
Thermoanaerobacterium aotearoense SCUT27 is a prominent producer of biofuels from lignocellulosic materials. To provide sufficient NAD(P)H for ethanol production, redox-related genes, including lactate dehydrogenase (ldh), redox-sensing transcriptional repressor (rex), and hydrogenase (hfsB), were knocked out. However, the growth of strain PRH (Δldh/Δrex/ΔhfsB) was suppressed due to the intracellular redox state imbalance with the increased NADH concentration. Coincidentally, when the Bcd-EtfAB (BCD) complex was overexpressed, the resulting strain PRH-B3 (Δldh/Δrex/ΔhfsB::BCD) grew rapidly and produced ethanol with a high yield. With lignocellulosic hydrolysates, PRH-BA (Δldh/Δrex/ΔhfsB::BCD::adhE) demonstrated high ethanol productivity and yield, reaching levels of 0.45-0.51 g/L/h and 0.46-0.53 g/g sugars, respectively. The study results shed light on the cofactor balance for cell stability and the high ferredoxin-NAD
+ reductase activity of the BCD complex under an intracellular low redox state. They also provide an essential reference for developing strains for improved biofuel production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
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