斑茅酶解转化可发酵单糖的液氨预处理及参数优化

Optimization of liquid ammonia treatment for enzymatic hydrolysis of Saccharum arundinaceum to fermentable sugars

摘要:

斑茅(Saccharum arundinaceum Retz.)的生物产量高，对土壤条件要求低，可作为纤维素乙醇生产的原料作物在我国南方地区广泛种植。实验以斑茅为原料，采用液氨预处理法克服其水解顽抗性，并添加纤维素酶进行酶解，运用高效液相色谱 (HPLC) 测定了酶解液中的单糖含量。实验结果表明在纤维素酶添加量为15?FPU/(g当量葡聚糖)、预处理原料含水率为80％、预处理温度为130 ℃、预处理驻留时间为10 min、液氨与生物质的质量比例为2∶1时，葡聚糖和木聚糖的总转化率分别为69.34％和82.60％，相比于未作预处理的原料分别提高了573％和1 056％，单糖产量提高8倍。实验结果表明液氨预处理对斑茅是一种有效的预处理方式，并优于稀酸或湿爆法预处理，与酸预处理和氨爆法 (AFEX) 处理效果接近。

Abstract:

China has abundant available marginal land that can be used for cultivation of lignocellulosic energy plants. Saccharum arundinaceum Retz. is a potential energy crop with both high biomass yield and low soil fertility requirements. It can be planted widely as cellulosic ethanol feedstock in southern China. In the present work Saccharum arundinaceum was pretreated by liquid ammonia treatment (LAT) to overcome biomass recalcitrance, followed by enzymatic hydrolysis. The monosaccharide contents (glucose, xylose, and arabinose) of the enzymatic hydrolysate were determined by high performance liquid chromatography. Experimental results show that the optimal LAT pretreatment conditions were 130 °C, 2:1 (W/W) ammonia to biomass ratio, 80% moisture content (dry weight basis) and 5 min residence time. Approximately 69.34% glucan and 82.60% xylan were converted after 72 h enzymatic hydrolysis at 1% glucan loading using 15 FPU/(g of glucan) of cellulase. The yields of glucose and xylose were 573% and 1 056% higher than those of the untreated biomass, and the LAT-pretreated substrates obtained an 8-fold higher of total monosaccharide yield than untreated substrates. LAT pretreatment was an effective to increase the enzymatic digestibility of Saccharum arundinaceum compared to acid impregnated steam explosion and similar to that of acid treatment and ammonia fiber expansion treatment.