Efficient whole-cell-catalyzing cellulose saccharification using engineered Clostridium thermocellum.
Efficient whole-cell-catalyzing cellulose saccharification using engineered Clostridium thermocellum.
复制标题
使用工程热纤梭菌进行高效全细胞催化纤维素糖化
DOI：
10.1186/s13068-017-0796-y
复制
发表时间：
2017
影响因子：
6.3
通讯作者：
Liu YJ
中科院分区：
文献类型：
--
作者：
Zhang J;Liu S;Li R;Hong W;Xiao Y;Feng Y;Cui Q;Liu YJ
研究背景：低成本糖化是制约木质纤维素工业化转化的主要瓶颈之一，热纤维梭菌（Clostridium thermocellulose）利用多蛋白超分子复合体纤维素酶体（cellulosome）天然高效降解木质纤维素，有望成为低成本的木质纤维素糖化催化剂。C.热纤酶的抑制主要是由于水解产物纤维二糖对其纤维素酶体的抑制作用。虽然添加β-葡萄糖苷酶可以解决这一问题，但由于β-葡萄糖苷酶的产生使糖化过程变得非常复杂，同时也增加了糖化成本。热纤菌pyrF：：CaBglA，其使用新开发的无缝基因组编辑系统产生分泌型外切葡聚糖酶CelS-承载异源BGL。在不额外添加酶的情况下，以100 g/L Avicel为碳源，经过两级糖化过程，Delta pyrF：：CaBglA的相对糖化水平比其亲株Delta pyrF提高了两倍以上。随着菌体密度的增加，还原糖产量和相对糖化水平分别提高到490 mM和79.4%.结论：高的纤维素降解能力和糖产量表明，全细胞催化纤维素糖化策略是有前途的，C.热纤维素酶菌株AparpyrF：：CaBglA有可能作为一种高效的全细胞催化剂用于工业纤维素糖化。
Background:Cost-efficient saccharification is one of the main bottlenecks for industrial lignocellulose conversion.Clostridium thermocellumnaturally degrades lignocellulose efficiently using the cellulosome, a multiprotein supermolecular complex, and thus can be potentially used as a low-cost catalyst for lignocellulose saccharification. The industrial use ofC. thermocellumis restrained due largely to the inhibition of the hydrolysate cellobiose to its cellulosome. Although the supplementation of beta-glucosidase may solve the problem, the production of the enzymes greatly complicates the process and may also increase the cost of saccharification.Results:To conquer the feedback inhibition and establish an efficient whole-cell catalyst for highly efficient cellulose saccharification, we constructed a recombinant strain ofC. thermocellum ∆pyrF::CaBglA which produced a secretory exoglucanase CelS-bearing heterologous BGL using a newly developed seamless genome editing system. Without the extra addition of enzymes, the relative saccharification level of∆pyrF::CaBglA was stimulated by over twofolds compared to its parent strain∆pyrFthrough a two-stage saccharification process with 100 g/L Avicel as the carbon source. The production of reducing sugars and the relative saccharification level were further enhanced to 490 mM and 79.4%, respectively, with increased cell density.Conclusions:The high cellulose-degrading ability and sugar productivity suggested that the whole-cell-catalysis strategy for cellulose saccharification is promising, and theC. thermocellumstrain∆pyrF::CaBglA could be potentially used as an efficient whole-cell catalyst for industrial cellulose saccharification.