Chen Chao, Qi Kuan, Chi Fang, Song Xiaojin, Feng Yingang, Cui Qiu, Liu Ya-Jun
CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Int J Biol Macromol. 2022 May 15;207:784-790. doi: 10.1016/j.ijbiomac.2022.03.158. Epub 2022 Mar 26.
Polysaccharides derived from lignocellulose are promising sustainable carbon sources. Cellulosome is a supramolecular machine integrating multi-function enzymes for effective lignocellulose bio-saccharification. However, how various non-cellulose components of lignocellulose affect the cellulosomal saccharification is hitherto unclear. This study first investigated the stability and oxygen sensitivity of the cellulosome from Clostridium thermocellum during long-term saccharification process. Then, the differential inhibitory effects of non-cellulose components, including lignin, xylan, and arabinoxylan, on the cellulosome-based saccharification were determined. The results showed that lignin played inhibitory roles by non-productively adsorbing extracellular proteins of C. thermocellum. Differently, arabinoxylan preferred to bind with the cellulosomal components. Almost no adsorption of cellulosomal proteins on solid xylan was detected. Instead, xylan in water-dissolved form interacted with the cellulosomal proteins, especially the key exoglucanase Cel48S, leading to the xylan inhibitory effect. Compared to xylan, xylooligosaccharides influenced the cellulosome activity slightly. Hence, this work demonstrates that the timely hydrolysis or removal of dissolved xylan is important for cellulosome-based lignocellulose saccharification.
源自木质纤维素的多糖是很有前景的可持续碳源。纤维小体是一种整合多功能酶以实现高效木质纤维素生物糖化的超分子机器。然而，木质纤维素的各种非纤维素成分如何影响纤维小体介导的糖化作用，目前尚不清楚。本研究首先考察了热纤梭菌纤维小体在长期糖化过程中的稳定性和氧敏感性。然后，确定了木质素、木聚糖和阿拉伯木聚糖等非纤维素成分对基于纤维小体的糖化作用的不同抑制效果。结果表明，木质素通过非生产性吸附热纤梭菌的胞外蛋白发挥抑制作用。不同的是，阿拉伯木聚糖更倾向于与纤维小体成分结合。几乎未检测到纤维小体蛋白在固体木聚糖上的吸附。相反，溶解形式的木聚糖与纤维小体蛋白相互作用，尤其是关键的外切葡聚糖酶Cel48S，从而导致木聚糖的抑制作用。与木聚糖相比，木寡糖对纤维小体活性的影响较小。因此，这项工作表明，及时水解或去除溶解的木聚糖对于基于纤维小体的木质纤维素糖化很重要。
