Yuan Yufeng, Jiang Bo, Chen Hui, Wu Wenjuan, Wu Shufang, Jin Yongcan, Xiao Huining
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China.
Laboratory of Wood Chemistry, Nanjing Forestry University, 159 Longpan Rd, Nanjing, 210037, China.
Biotechnol Biofuels. 2021 Oct 20;14(1):205. doi: 10.1186/s13068-021-02054-1.
Enzymatic hydrolysis of lignocellulose for bioethanol production shows a great potential to remit the rapid consumption of fossil fuels, given the fact that lignocellulose feedstocks are abundant, cost-efficient, and renewable. Lignin results in low enzymatic saccharification by forming the steric hindrance, non-productive adsorption of cellulase onto lignin, and deactivating the cellulase. In general, the non-productive binding of cellulase on lignin is widely known as the major cause for inhibiting the enzymatic hydrolysis. Pretreatment is an effective way to remove lignin and improve the enzymatic digestibility of lignocellulose. Along with removing lignin, the pretreatment can modify the lignin structure, which significantly affects the non-productive adsorption of cellulase onto lignin. To relieve the inhibitory effect of lignin on enzymatic hydrolysis, enormous efforts have been made to elucidate the correlation of lignin structure with lignin-enzyme interactions but with different views. In addition, contrary to the traditional belief that lignin inhibits enzymatic hydrolysis, in recent years, the addition of water-soluble lignin such as lignosulfonate or low molecular-weight lignin exerts a positive effect on enzymatic hydrolysis, which gives a new insight into the lignin-enzyme interactions. For throwing light on their structure-interaction relationship during enzymatic hydrolysis, the effect of residual lignin in substrate and introduced lignin in hydrolysate on enzymatic hydrolysis are critically reviewed, aiming at realizing the targeted regulation of lignin structure for improving the saccharification of lignocellulose. The review is also focused on exploring the lignin-enzyme interactions to mitigate the negative impact of lignin and reducing the cost of enzymatic hydrolysis of lignocellulose.
鉴于木质纤维素原料丰富、成本效益高且可再生，通过酶促水解木质纤维素生产生物乙醇显示出缓解化石燃料快速消耗的巨大潜力。木质素通过形成空间位阻、纤维素酶在木质素上的非生产性吸附以及使纤维素酶失活，导致酶促糖化率较低。一般来说，纤维素酶在木质素上的非生产性结合是抑制酶促水解的主要原因，这一点广为人知。预处理是去除木质素并提高木质纤维素酶促消化率的有效方法。除了去除木质素外，预处理还可以改变木质素结构，这显著影响纤维素酶在木质素上的非生产性吸附。为了减轻木质素对酶促水解的抑制作用，人们付出了巨大努力来阐明木质素结构与木质素 - 酶相互作用之间的关系，但观点各异。此外，与传统观点认为木质素抑制酶促水解相反，近年来，添加水溶性木质素（如木质素磺酸盐）或低分子量木质素对酶促水解产生了积极影响，这为木质素 - 酶相互作用提供了新的见解。为了阐明它们在酶促水解过程中的结构 - 相互作用关系，本文对底物中残留木质素和水解产物中引入的木质素对酶促水解的影响进行了批判性综述，旨在实现对木质素结构的靶向调控以提高木质纤维素的糖化率。该综述还侧重于探索木质素 - 酶相互作用，以减轻木质素的负面影响并降低木质纤维素酶促水解的成本。
