Gonçalves Geisa A L, Takasugi Yusaku, Jia Lili, Mori Yutaro, Noda Shuhei, Tanaka Tsutomu, Ichinose Hirofumi, Kamiya Noriho
Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Japan.
Biomass Engineering Program, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Enzyme Microb Technol. 2015 May;72:16-24. doi: 10.1016/j.enzmictec.2015.01.007. Epub 2015 Jan 25.
Recently, the new trend in the second-generation ethanol industry is to use mild pretreatments, in order to reduce costs and to keep higher content of hemicellulose in the biomass. Nevertheless, a high enzyme dosage is still required in the conversion of (hemi)cellulose. The interaction between cellulases and xylanases seems to be an effective alternative to reduce enzyme loading in the saccharification process. At first, to evaluate the synergism of xylanases on bagasse degradation, we have produced two xylanases from glycoside hydrolase family 10 (GH10) and three xylanases from glycoside hydrolase family 11 (GH11), from two thermophilic organisms, Thermobifida fusca and Clostridium thermocellum, and one mesophilic organism, Streptomyces lividans. Peracetic acid (PAA) pretreated bagasse was used as substrate. The combination of XynZ-C (GH10, from C. thermocellum), and XlnB (GH11, from S. lividans) presented the highest degree of synergy after 6h (3.62). However, the combination of XynZ-C and Xyn11A (GH11, from T. fusca) resulted in the highest total yield of reducing sugars. To evaluate the synergism between xylanases and cellulases, commercial cellulase preparation from Trichoderma reesei was combined with the selected xylanases, XynZ-C and Xyn11A. About 2-fold increase was observed in the concentration of reducing sugars, when both xylanases, XynZ-C and Xyn11A, were added together with T. reesei cellulases in the reaction mixture.
最近，第二代乙醇产业的新趋势是采用温和预处理，以降低成本并保持生物质中较高的半纤维素含量。然而，在（半）纤维素转化过程中仍需要高酶用量。纤维素酶和木聚糖酶之间的相互作用似乎是降低糖化过程中酶负载量的有效替代方法。首先，为了评估木聚糖酶对甘蔗渣降解的协同作用，我们从嗜热栖热放线菌和热纤梭菌这两种嗜热生物以及淡紫链霉菌这种嗜温生物中分别生产了两种来自糖苷水解酶家族10（GH10）的木聚糖酶和三种来自糖苷水解酶家族11（GH11）的木聚糖酶。过氧乙酸（PAA）预处理的甘蔗渣用作底物。XynZ-C（来自热纤梭菌的GH10）和XlnB（来自淡紫链霉菌的GH11）的组合在6小时后表现出最高的协同程度（3.62）。然而，XynZ-C和Xyn11A（来自嗜热栖热放线菌的GH11）的组合产生了最高的还原糖总产量。为了评估木聚糖酶和纤维素酶之间的协同作用，将里氏木霉的商业纤维素酶制剂与选定的木聚糖酶XynZ-C和Xyn11A组合。当XynZ-C和Xyn11A这两种木聚糖酶与里氏木霉纤维素酶一起添加到反应混合物中时，观察到还原糖浓度增加了约2倍。
