Background Production of value-added materials from lignocellulosic biomass residues is an emerging sector that has attracted much attention as it offers numerous benefits from an environmental and economical point of view. Non-digestible oligosaccharides represent a group of carbohydrates that are resistant to gastrointestinal digestion, and therefore, they are considered as potential prebiotic candidates. Such oligosaccharides can derive from the biomass cellulose fraction through a controlled enzymatic hydrolysis that eliminates the yield of monomers. Results In the present study, hydrolysis of organosolv-pretreated forest residues (birch and spruce) was tested in the presence of four cellulases (EG5, CBH7, CBH6, EG7) and one accessory enzyme (LPMO). The optimal enzyme combinations were comprised of 20% EG5, 43% CBH7, 22% TtLPMO, 10% PaCbh6a and 5% EG7 in the case of birch and 35% EG5, 45% CBH7, 10% TtLPMO, 10% PaCbh6a and 5% EG7 in the case of spruce, leading to 22.3% and 19.1 wt% cellulose conversion into cellobiose, respectively. Enzymatic hydrolysis was applied on scale-up reactions, and the produced oligosaccharides (consisted of > 90% cellobiose) were recovered and separated from glucose through nanofiltration at optimized temperature (50 °C) and pressure (10 bar) conditions, yielding a final product with cellobiose-to-glucose ratio of 21.1 (birch) and 20.2 (spruce). Cellobiose-rich hydrolysates were tested as fermentative substrates for different lactic acid bacteria. It was shown that they can efficiently stimulate the growth of two Lactobacilli strains. Conclusions Controlled enzymatic hydrolysis with processive cellulases, combined with product recovery and purification, as well as enzyme recycling can potentially support the sustainable production of food-grade oligosaccharides from forest biomass.

中文翻译：

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通过使用定制的酶混合物，将废弃的森林生物质用于生产具有潜在益生元活性的纤维寡糖。

背景从木质纤维素生物质残渣生产增值材料是一个备受关注的新兴领域，因为它从环境和经济角度提供了许多好处。不易消化的寡糖代表一组对胃肠道消化有抵抗力的碳水化合物，因此，它们被认为是潜在的益生元候选物。此类寡糖可通过消除单体产量的受控酶水解从生物质纤维素部分衍生。结果在本研究中，在四种纤维素酶（EG5、CBH7、CBH6、EG7）和一种辅助酶（LPMO）存在下测试了有机溶剂预处理的森林残留物（桦树和云杉）的水解。最佳酶组合由 20% EG5、43% CBH7、22% TtLPMO、桦木为 10% PaCbh6a 和 5% EG7，云杉为 35% EG5、45% CBH7、10% TtLPMO、10% PaCbh6a 和 5% EG7，导致 22.3% 和 19.1 wt% 的纤维素转化为纤维二糖， 分别。酶水解应用于放大反应，在优化的温度（50°C）和压力（10bar）条件下，通过纳滤回收产生的寡糖（由> 90%的纤维二糖组成）并与葡萄糖分离，得到最终产品纤维二糖与葡萄糖的比例为 21.1（桦木）和 20.2（云杉）。富含纤维二糖的水解产物被测试为不同乳酸菌的发酵底物。结果表明，它们可以有效地刺激两种乳酸杆菌菌株的生长。结论用加工性纤维素酶控制酶促水解，