Metabolic Engineering Research Unit, School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
Division of Biopharmacy, Faculty of Pharmaceutical Sciences, Ubon Ratchathani University, Ubon Ratchathani 34190, Thailand.
Bioresour Technol. 2018 Jul;260:348-356. doi: 10.1016/j.biortech.2018.03.107. Epub 2018 Mar 30.
Rice straw was pretreated with sodium hydroxide (NaOH) before subsequent use for succinate production by Escherichia coli KJ122 under simultaneous saccharification and fermentation (SSF). The NaOH pretreated rice straw was significantly enhanced lignin removal up to 95%. With the optimized enzyme loading of 4% cellulase complex + 0.5% xylanase (endo-glucanase 67 CMC-U/g, β-glucosidase 26 pNG-U/g and xylanase 18 CMC-U/g dry biomass), total sugar conversion reached 91.7 ± 0.8% (w/w). The physicochemical analysis of NaOH pretreated rice straw indicated dramatical changes in its structure, thereby favoring enzymatic saccharification. In batch SSF, succinate production of 69.8 ± 0.3 g/L with yield and productivity of 0.84 g/g pretreated rice straw and 0.76 ± 0.02 g/L/h, respectively, was obtained. Fed-batch SSF significantly improved succinate concentration and productivity to 103.1 ± 0.4 g/L and 1.37 ± 0.07 g/L/h with a comparable yield. The results demonstrated a feasibility of sequential saccharification and fermentation of rice straw as a promising process for succinate production in industrial scale.
稻草在用于大肠杆菌 KJ122 通过同步糖化发酵（SSF）生产琥珀酸之前，先用氢氧化钠（NaOH）进行预处理。NaOH 预处理的稻草显著提高了木质素的去除率，达到 95%。通过优化纤维素酶复合物 4%+木聚糖酶 0.5%的酶用量（内切葡聚糖酶 67CMC-U/g、β-葡萄糖苷酶 26pNG-U/g 和木聚糖酶 18CMC-U/g 干生物质），总糖转化率达到 91.7±0.8%（w/w）。NaOH 预处理稻草的物理化学分析表明，其结构发生了剧烈变化，从而有利于酶解糖化。在分批 SSF 中，获得了 69.8±0.3g/L 的琥珀酸产量，产率和生产强度分别为 0.84g/g 预处理稻草和 0.76±0.02g/L/h。补料分批 SSF 显著提高了琥珀酸浓度和生产强度，分别达到 103.1±0.4g/L 和 1.37±0.07g/L/h，产率相当。结果表明，稻草的顺序糖化和发酵是一种在工业规模上生产琥珀酸的有前途的工艺。
