Kim Sun-Ki, Bomble Yannick J, Westpheling Janet
Department of Genetics, University of Georgia, Athens, GA, 30602, USA.
Oak Ridge National Laboratory, The BioEnergy Science Center and The Center for Bioenergy Innovation, Oak Ridge, TN, 37831, USA.
Biotechnol Biofuels Bioprod. 2023 Mar 14;16(1):46. doi: 10.1186/s13068-023-02291-6.
Sensitivity to inhibitors derived from the pretreatment of plant biomass is a barrier to the consolidated bioprocessing of these complex substrates to fuels and chemicals by microbes. Spermidine is a low molecular weight aliphatic nitrogen compound ubiquitous in microorganisms, plants, and animals and is often associated with tolerance to stress. We recently showed that overexpression of the endogenous spermidine synthase enhanced tolerance of the Gram-positive bacterium, Clostridium thermocellum to the furan derivatives furfural and HMF.
Here we show that co-expression with an NADPH-dependent heat-stable butanol dehydrogenase from Thermoanaerobacter pseudethanolicus further enhanced tolerance to furans and acetic acid and most strikingly resulted in an increase in thermotolerance at 65 °C.
Tolerance to fermentation inhibitors will facilitate the use of plant biomass substrates by thermophiles in general and this organism in particular. The ability to grow C. thermocellum at 65 °C has profound implications for metabolic engineering.
对植物生物质预处理产生的抑制剂敏感是微生物将这些复杂底物联合生物加工为燃料和化学品的障碍。亚精胺是一种低分子量脂肪族含氮化合物，普遍存在于微生物、植物和动物中，且常与胁迫耐受性相关。我们最近发现，内源性亚精胺合酶的过表达增强了革兰氏阳性菌热纤梭菌对呋喃衍生物糠醛和5-羟甲基糠醛的耐受性。
在此我们表明，与来自嗜热栖热放线菌的依赖NADPH的热稳定丁醇脱氢酶共表达，进一步增强了对呋喃和乙酸的耐受性，最显著的是导致在65℃时耐热性增加。
对发酵抑制剂的耐受性总体上有助于嗜热菌尤其是该菌株利用植物生物质底物。热纤梭菌在65℃生长的能力对代谢工程具有深远意义。
