Georgieva Tania I, Ahring Birgitte K
BioScience and Technology Group, BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark.
Appl Microbiol Biotechnol. 2007 Nov;77(1):61-8. doi: 10.1007/s00253-007-1149-8.
Dilute sulfuric acid pretreated corn stover is potential feedstock of industrial interest for second generation fuel ethanol production. However, the toxicity of corn stover hydrolysate (PCS) has been a challenge for fermentation by recombinant xylose fermenting organisms. In this work, the thermophilic anaerobic bacterial strain Thermoanaerobacter BG1L1 was assessed for its ability to ferment undetoxified PCS hydrolysate in a continuous immobilized reactor system at 70 degrees C. The tested strain showed significant resistance to PCS, and substrate concentrations up to 15% total solids (TS) were fermented yielding ethanol of 0.39-0.42 g/g-sugars consumed. Xylose was nearly completely utilized (89-98%) for PCS up to 10% TS, whereas at 15% TS, xylose conversion was lowered to 67%. The reactor was operated continuously for 135 days, and no contamination was seen without the use of any agent for preventing bacterial infections. This study demonstrated that the use of immobilized thermophilic anaerobic bacteria for continuous ethanol fermentation could be promising in a commercial ethanol process in terms of system stability to process hardiness and reactor contamination. The tested microorganism has considerable potential to be a novel candidate for lignocellulose bioconversion into ethanol.
稀硫酸预处理的玉米秸秆是第二代燃料乙醇生产中具有工业应用潜力的原料。然而，玉米秸秆水解液（PCS）的毒性一直是重组木糖发酵微生物发酵面临的挑战。在本研究中，对嗜热厌氧细菌菌株嗜热栖热菌BG1L1在70℃的连续固定化反应器系统中发酵未解毒的PCS水解液的能力进行了评估。测试菌株对PCS表现出显著抗性，能发酵高达15%总固体（TS）的底物浓度，消耗的糖产乙醇量为0.39 - 0.42 g/g。对于TS含量高达10%的PCS，木糖几乎完全被利用（89 - 98%），而在TS含量为15%时，木糖转化率降至67%。该反应器连续运行135天，在未使用任何防止细菌感染试剂的情况下未出现污染。本研究表明，就系统稳定性、工艺耐受性和反应器污染而言，利用固定化嗜热厌氧细菌进行连续乙醇发酵在商业乙醇生产过程中具有前景。所测试的微生物有很大潜力成为将木质纤维素生物转化为乙醇的新型候选菌株。
