Background Lignocellulosic biomass has been commonly regarded as a potential feedstock for the production of biofuels and biochemicals. High sugar yields and the complete bioconversion of all the lignocellulosic sugars into valuable products are attractive for the utilization of lignocelluloses. It is essential to pretreat and hydrolyze lignocelluloses at high solids loadings during industrial processes, which is more economical and environmentally friendly as capital cost, energy consumption, and water usage can be reduced. However, oligosaccharides are inevitably released during the high solids loading enzymatic hydrolysis and they are more recalcitrant than monosaccharides for microorganisms. Results A fed-batch enzymatic hydrolysis of corn stover pretreated by the sodium hydroxide-methanol solution (SMs) at high solids loading was demonstrated to reach the high concentrations and yields of fermentable sugars. Glucose, xylose, cello-oligosaccharides, and xylo-oligosaccharides achieved 146.7 g/L, 58.7 g/L, 15.6 g/L, and 24.7 g/L, respectively, when the fed-batch hydrolysis was started at 12% (w/v) solids loading, and 7% fresh substrate and a standardized blend of cellulase, β-glucosidase, and hemicellulase were fed consecutively at 3, 6, 24, and 48 h to achieve a final solids loading of 40% (w/v). The total conversion of glucan and xylan reached 89.5% and 88.5%, respectively, when the oligosaccharides were taken into account. Then, a fed-batch culture on the hydrolysates was investigated for lipid production by Cutaneotrichosporon oleaginosum. Biomass, lipid content, and lipid yield were 50.7 g/L, 61.7%, and 0.18 g/g, respectively. The overall consumptions of cello-oligosaccharides and xylo-oligosaccharides reached 74.1% and 68.2%, respectively. Conclusions High sugars concentrations and yields were achieved when the enzyme blend was supplemented simultaneously with the substrate at each time point of feeding during the fed-batch enzymatic hydrolysis. Oligosaccharides were co-utilized with monosaccharides during the fed-batch culture of C. oleaginosum. These results provide a promising strategy to hydrolyze alkaline organosolv-pretreated corn stover into fermentable sugars with high concentrations and yields for microbial lipid production.

中文翻译：

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碱性有机溶剂预处理的玉米秸秆的分批补料酶水解促进了用于微生物脂质生产的高浓度和高产量的可发酵糖。

背景木质纤维素生物质通常被认为是生产生物燃料和生物化学品的潜在原料。高糖产率和将所有木质纤维素糖完全生物转化为有价值的产品对于木质纤维素的利用具有吸引力。在工业过程中，必须在高固含量下预处理和水解木质纤维素，因为可以降低资本成本、能源消耗和用水量，从而更加经济和环保。然而，在高固体负荷酶水解过程中，寡糖不可避免地会释放出来，并且它们比单糖对微生物更难对付。结果证明，在高固体负荷下，用氢氧化钠-甲醇溶液 (SMs) 预处理的玉米秸秆的补料分批酶水解可达到高浓度和高产率的可发酵糖。当以 12%（w/ v) 固体负载，7% 新鲜底物和纤维素酶、β-葡糖苷酶和半纤维素酶的标准化混合物在 3、6、24 和 48 小时连续进料，以实现 40% (w/v) 的最终固体负载. 当考虑寡糖时，葡聚糖和木聚糖的总转化率分别达到 89.5% 和 88.5%。然后，研究了水解产物上的补料分批培养物通过 Cutaneotrichosporon oleaginosum 产生脂质。生物量、脂质含量和脂质产量分别为 50.7 g/L、61.7% 和 0.18 g/g。纤维寡糖和木寡糖的总消费量分别达到74.1%和68.2%。结论 在补料分批酶水解过程中，在每个补料时间点同时向酶混合物补充底物时，可获得高糖浓度和产量。在 C. oleaginosum 的补料分批培养过程中，寡糖与单糖共同使用。这些结果为将碱性有机溶剂预处理的玉米秸秆水解成高浓度和高产率的可发酵糖类用于微生物脂质生产提供了一种有前景的策略。脂肪产量分别为 50.7 g/L、61.7% 和 0.18 g/g。纤维寡糖和木寡糖的总消费量分别达到74.1%和68.2%。结论 在补料分批酶水解过程中，在每个补料时间点同时向酶混合物补充底物时，可获得高糖浓度和产量。在 C. oleaginosum 的补料分批培养过程中，寡糖与单糖共同使用。这些结果为将碱性有机溶剂预处理的玉米秸秆水解成高浓度和高产率的可发酵糖类用于微生物脂质生产提供了一种有前景的策略。脂肪产量分别为 50.7 g/L、61.7% 和 0.18 g/g。纤维寡糖和木寡糖的总消费量分别达到74.1%和68.2%。结论 在补料分批酶水解过程中，在每个补料时间点同时向酶混合物补充底物时，可获得高糖浓度和产量。在 C. oleaginosum 的补料分批培养过程中，寡糖与单糖共同使用。这些结果为将碱性有机溶剂预处理的玉米秸秆水解成高浓度和高产率的可发酵糖类用于微生物脂质生产提供了一种有前景的策略。分别。结论 在补料分批酶水解过程中，在每个补料时间点同时向酶混合物补充底物时，可获得高糖浓度和产量。在 C. oleaginosum 的补料分批培养过程中，寡糖与单糖共同使用。这些结果为将碱性有机溶剂预处理的玉米秸秆水解成高浓度和高产率的可发酵糖类用于微生物脂质生产提供了一种有前景的策略。分别。结论 在补料分批酶水解过程中，在每个补料时间点同时向酶混合物补充底物时，可获得高糖浓度和产量。在 C. oleaginosum 的补料分批培养过程中，寡糖与单糖共同使用。这些结果为将碱性有机溶剂预处理的玉米秸秆水解成高浓度和高产率的可发酵糖类用于微生物脂质生产提供了一种有前景的策略。