Zhu Junjun, Rong Yayun, Yang Jinlong, Zhou Xin, Xu Yong, Zhang Lingling, Chen Jiahui, Yong Qiang, Yu Shiyuan
College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, China,
Appl Biochem Biotechnol. 2015 Jul;176(5):1370-81. doi: 10.1007/s12010-015-1651-x. Epub 2015 May 7.
High-efficiency xylose utilization is one of the restrictive factors of bioethanol industrialization. However, xylonic acid (XA) as a new bio-based platform chemical can be produced by oxidation of xylose with microbial. So, an applicable technology of XA bioconversion was integrated into the process of bioethanol production. After corn stover was pretreated with acid-catalyzed steam-explosion, solid and liquid fractions were obtained. The liquid fraction, also named as acid-catalyzed steam-exploded corn stover (ASC) prehydrolyzate (mainly containing xylose), was catalyzed with Gluconobacter oxydans NL71 to prepare XA. After 72 h of bioconversion of concentrated ASC prehydrolyzate (containing 55.0 g/L of xylose), the XA concentration reached a peak value of 54.97 g/L, the sugar utilization ratio and XA yield were 94.08 and 95.45 %, respectively. The solid fraction was hydrolyzed to produce glucose with cellulase and then fermented with Saccharomyces cerevisiae NL22 to produce ethanol. After 18 h of fermentation of concentrated enzymatic hydrolyzate (containing 86.22 g/L of glucose), the ethanol concentration reached its highest value of 41.48 g/L, the sugar utilization ratio and ethanol yield were 98.72 and 95.25 %, respectively. The mass balance showed that 1 t ethanol and 1.3 t XA were produced from 7.8 t oven dry corn stover.
高效利用木糖是生物乙醇工业化的限制因素之一。然而，木糖酸（XA）作为一种新型生物基平台化学品，可通过微生物氧化木糖来生产。因此，将一种适用的XA生物转化技术整合到生物乙醇生产过程中。玉米秸秆经酸催化蒸汽爆破预处理后，得到固体和液体部分。液体部分，也称为酸催化蒸汽爆破玉米秸秆（ASC）预水解液（主要含木糖），用氧化葡萄糖杆菌NL71催化制备XA。对浓缩的ASC预水解液（含55.0 g/L木糖）进行72 h生物转化后，XA浓度达到峰值54.97 g/L，糖利用率和XA产率分别为94.08%和95.45%。固体部分用纤维素酶水解产生葡萄糖，然后用酿酒酵母NL22发酵生产乙醇。对浓缩的酶解液（含86.22 g/L葡萄糖）进行18 h发酵后，乙醇浓度达到最高值41.48 g/L，糖利用率和乙醇产率分别为98.72%和95.25%。质量平衡表明，7.8 t烘干玉米秸秆可生产1 t乙醇和1.3 t XA。
