Thermophilic anaerobic bacteria have received increasing interest as a promising bioprocessing platform for bioethanol production due to their broad substrate range and higher operating temperature. However, ethanol concentration is still lower than the commercial requirements on account of the high by-product formation and low ethanol tolerance. Our previous transcriptome analysis showed the gene expression level of pyruvate formate lyase-activating protein (PflA) was significantly down-regulated when Thermoanaerobacterium aotearoense SCUT27/Δldh was stimulated by various concentrations of ethanol. Based on this, we constructed the mutant strain T. aotearoense SCUT27/Δldh/ΔpflA, which not only possesses higher ethanol tolerance and production but also has enhanced ethanol/acetate ratio that is important for economical ethanol production. Compared to T. aotearoense SCUT27/Δldh, the mutant strain could resist to 5% (v/v) exogenous ethanol and produce 49 % more ethanol (38.82 g/L vs. 26.05 g/L) in 5-L bioreactor. In addition, the final concentration of ethanol reached 45.01 g/L by immobilized cell fermentation, which is the highest value obtained in T. aotearoense SCUT27. Simultaneously, the ethanol/acetate ratio of the mutant strain achieved 6.82, which was 2.16-fold higher than that of the parental strain.

由于嗜热厌氧细菌具有广泛的底物范围和较高的操作温度，因此作为有前途的生物乙醇生产生物处理平台已引起越来越多的兴趣。然而，由于高的副产物形成和低的乙醇耐受性，乙醇浓度仍低于商业要求。我们先前的转录组分析显示，当用不同浓度的乙醇刺激嗜热厌氧杆菌AUTaroense SCUT27 / Δldh时，丙酮酸甲酸裂解酶激活蛋白（PflA）的基因表达水平显着下调。基于此，我们构建了突变菌株T. aotearoense SCUT27 / Δldh / ΔpflA不仅具有更高的乙醇耐受性和生产能力，而且还具有提高的乙醇/乙酸盐比，这对于经济地生产乙醇非常重要。与T. aotearoense SCUT27 / Δldh相比，该突变菌株在5升生物反应器中可抵抗5％（v / v）的外源乙醇并产生49％的乙醇（38.82 g / L与26.05 g / L）。此外，通过固定化细胞发酵，乙醇的最终浓度达到45.01 g / L，这是在A.arootearoense SCUT27中获得的最高值。同时，突变菌株的乙醇/乙酸比达到6.82，比亲代菌株高2.16倍。