Faculty of Natural Resource Science, University of Akureyri, Borgir v. Nordurslod, 600 Akureyri, Iceland.
Biotechnol Bioeng. 2012 Mar;109(3):686-94. doi: 10.1002/bit.24346. Epub 2011 Nov 6.
The ethanol production capacity from sugars and lignocellulosic biomass hydrolysates (HL) by Thermoanaerobacterium strain AK(17) was studied in batch cultures. The strain converts various carbohydrates to, acetate, ethanol, hydrogen, and carbon dioxide. Ethanol yields on glucose and xylose were 1.5 and 1.1 mol/mol sugars, respectively. Increased initial glucose concentration inhibited glucose degradation and end product formation leveled off at 30 mM concentrations. Ethanol production from 5 g L(-1) of complex biomass HL (grass, hemp, wheat straw, newspaper, and cellulose) (Whatman paper) pretreated with acid (0.50% H(2) SO(4)), base (0.50% NaOH), and without acid/base (control) and the enzymes Celluclast and Novozyme 188 (0.1 mL g(-1) dw; 70 and 25 U g(-1) of Celluclast and Novozyme 188, respectively) was investigated. Highest ethanol yields (43.0 mM) were obtained on cellulose but lowest on hemp leafs (3.6 mM). Chemical pretreatment increased ethanol yields substantially from lignocellulosic biomass but not from cellulose. The influence of various factors (HL, enzyme, and acid/alkaline concentrations) on end-product formation from 5 g L(-1) of grass and cellulose was further studied to optimize ethanol production. Highest ethanol yields (5.5 and 8.6 mM ethanol g(-1) grass and cellulose, respectively) were obtained at very low HL concentrations (2.5 g L(-1)); with 0.25% acid/alkali (v/v) and 0.1 mL g(-1) enzyme concentrations. Inhibitory effects of furfural and hydroxymethylfurfural during glucose fermentation, revealed a total inhibition in end product formation from glucose at 4 and 6 g L(-1), respectively.
采用分批培养法研究了嗜热厌氧菌菌株 AK(17)从糖和木质纤维素生物质水解物（HL）生产乙醇的能力。该菌株可将各种碳水化合物转化为乙酸、乙醇、氢气和二氧化碳。葡萄糖和木糖的乙醇得率分别为 1.5 和 1.1 mol/mol 糖。初始葡萄糖浓度的增加抑制了葡萄糖的降解，而终产物的形成在 30 mM 浓度时趋于稳定。采用酸（0.50% H(2) SO(4)）、碱（0.50% NaOH）预处理和未经酸碱预处理（对照）的 5 g L(-1)复杂生物质 HL（草、麻、麦秸、报纸和纤维素）（Whatman 纸）以及纤维素酶和 Novozyme 188（0.1 mL g(-1) dw；70 和 25 U g(-1)的纤维素酶和 Novozyme 188），研究了从 HL 生产乙醇的情况。在纤维素上获得了最高的乙醇产率（43.0 mM），而在麻叶上获得了最低的乙醇产率（3.6 mM）。化学预处理大大提高了木质纤维素生物质的乙醇产率，但对纤维素的影响不大。进一步研究了 HL、酶和酸碱浓度等各种因素对 5 g L(-1)草和纤维素终产物形成的影响，以优化乙醇的生产。在 HL 浓度非常低（2.5 g L(-1)）时，获得了最高的乙醇产率（草和纤维素分别为 5.5 和 8.6 mM 乙醇 g(-1)）；酸/碱（v/v）浓度为 0.25%，酶浓度为 0.1 mL g(-1)。在葡萄糖发酵过程中，糠醛和羟甲基糠醛的抑制作用表明，在 4 和 6 g L(-1)时，葡萄糖的终产物形成完全受到抑制。
