Department of Forest Biomaterials, North Carolina State University, Raleigh, NC 27695, USA.
Appl Biochem Biotechnol. 2012 Feb;166(4):839-55. doi: 10.1007/s12010-011-9474-x. Epub 2011 Dec 15.
Process simulation and lab trials were carried out to demonstrate and confirm the efficiency of the concept that recycling hydrolysate at low total solid enzymatic hydrolysis is one of the options to increase the sugar concentration without mixing problems. Higher sugar concentration can reduce the capital cost for fermentation and distillation because of smaller retention volume. Meanwhile, operation cost will also decrease for less operating volume and less energy required for distillation. With the computer simulation, time and efforts can be saved to achieve the steady state of recycling process, which is the scenario for industrial production. This paper, to the best of our knowledge, is the first paper discussing steady-state saccharification with recycling of the filtrate form enzymatic hydrolysis to increase sugar concentration. Recycled enzymes in the filtrate (15-30% of the original enzyme loading) resulted in 5-10% higher carbohydrate conversion compared to the case in which recycled enzymes were denatured. The recycled hydrolysate yielded 10% higher carbohydrate conversion compared to pure sugar simulated hydrolysate at the same enzyme loading, which indicated hydrolysis by-products could boost enzymatic hydrolysis. The high sugar concentration (pure sugar simulated) showed inhibition effect, since about 15% decrease in carbohydrate conversion was observed compared with the case with no sugar added. The overall effect of hydrolysate recycling at WinGEMS simulated steady-state conditions with 5% total solids was increasing the sugar concentration from 35 to 141 g/l, while the carbohydrate conversion was 2% higher for recycling at steady state (87%) compared with no recycling strategy (85%). Ten percent and 15% total solid processes were also evaluated in this study.
进行了过程模拟和实验室试验，以证明和确认以下概念的有效性：在低总固体酶水解时回收水解物是提高糖浓度而不产生混合问题的一种选择。由于保留体积较小，较高的糖浓度可以降低发酵和蒸馏的资本成本。同时，由于操作体积减少和蒸馏所需的能源减少，运营成本也会降低。通过计算机模拟，可以节省时间和精力来实现回收过程的稳态，这是工业生产的情况。据我们所知，本文是第一份讨论通过回收滤液进行稳态糖化以提高糖浓度的论文。与回收失活酶的情况相比，滤液中回收的酶（原始酶加载量的 15-30%）可使碳水化合物转化率提高 5-10%。与使用相同酶加载量的纯糖模拟水解物相比，回收的水解物可使碳水化合物转化率提高 10%，这表明水解副产物可以促进酶水解。高糖浓度（纯糖模拟）表现出抑制作用，因为与不加糖的情况相比，碳水化合物转化率下降了约 15%。在 WinGEMS 模拟稳态条件下，用 5%总固体进行水解物回收的总体效果是将糖浓度从 35 增加到 141 g/l，而在稳态下进行回收时的碳水化合物转化率（87%）比没有回收策略（85%）高 2%。本研究还评估了 10%和 15%总固体工艺。
