School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
College of Light Industry and Food Science, Guangdong Provincial Key Laboratory of Science and Technology of Lingnan Special Food Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
Bioresour Technol. 2024 Jun;402:130784. doi: 10.1016/j.biortech.2024.130784. Epub 2024 May 1.
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.
热厌氧菌 SCUT27 是一种从木质纤维素材料生产生物燃料的重要生产者。为了提供足够的 NAD(P)H 用于乙醇生产，已敲除了与氧化还原相关的基因，包括乳酸脱氢酶（ldh）、氧化还原感应转录阻遏物（rex）和氢化酶（hfsB）。然而，由于细胞内氧化还原状态失衡和 NADH 浓度增加，菌株 PRH（Δldh/Δrex/ΔhfsB）的生长受到抑制。巧合的是，当过度表达 Bcd-EtfAB（BCD）复合物时，产生的菌株 PRH-B3（Δldh/Δrex/ΔhfsB::BCD）生长迅速，并以高产率生产乙醇。对于木质纤维素水解物，PRH-BA（Δldh/Δrex/ΔhfsB::BCD::adhE）表现出高乙醇生产率和产率，分别达到 0.45-0.51 g/L/h 和 0.46-0.53 g/g 糖。该研究结果阐明了细胞稳定性的辅酶平衡以及在细胞内低氧化还原状态下 BCD 复合物的高铁氧还蛋白-NAD 还原酶活性。它们还为开发用于提高生物燃料生产的菌株提供了重要参考。
