Tang Wei, Wu Xinxing, Huang Caoxing, Ling Zhe, Lai Chenhuan, Yong Qiang
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
Key Laboratory of Forestry Genetics and Biotechnology (Nanjing Forestry University), Ministry of Education, Nanjing, 210037, People's Republic of China.
Biotechnol Biofuels. 2021 Jan 19;14(1):25. doi: 10.1186/s13068-021-01874-5.
Humic acids (HA) have been used in biorefinery process due to its surfactant properties as an aid to the pretreatment of lignocellulose, with results indicating a positive effect on delignification. However, the HA remaining on the surface of the pretreated lignocellulose has also been shown to provide a negative effect on ensuing enzymatic digestibility. Hence, a strategy of complexing metallic cations with HA prior to enzymatic hydrolysis was proposed and demonstrated in this work in an effort to provide a means of HA mitigation that does not involve significant water consumption via extensive washing.
Results showed that the enzymatic hydrolysis efficiency of waste wheat straw decreased from 81.9% to 66.1% when it was pretreated by 10 g/L HA, attributed to the inhibition ability of the residual HA on enzyme activity of cellulase with a debasement of 36.3%. Interestingly, enzymatic hydrolysis efficiency could be increased from 66.1% to 77.3% when 10 mM Fe was introduced to the system and allowed to associate with HA during saccharification.
The addition of high-priced metallic cations (Fe) has successfully alleviated the effect of HA on cellulase activity. It is our hope in demonstrating the complexation affinity between metallic cations and HA, future researchers and biorefinery developers will evaluate this strategy as a unit operation that could allow economic biorefining of WWS to produce valuable biochemicals, biofuels, and biomaterials.
腐殖酸（HA）因其具有表面活性剂特性，已被用于生物精炼过程中，以辅助木质纤维素的预处理，结果表明其对脱木质素具有积极作用。然而，预处理后的木质纤维素表面残留的HA也被证明会对后续的酶解消化率产生负面影响。因此，本研究提出并证明了一种在酶水解之前将金属阳离子与HA络合的策略，旨在提供一种减轻HA影响的方法，该方法不涉及通过大量洗涤而消耗大量水。
结果表明，当用10 g/L HA预处理时，废弃小麦秸秆的酶水解效率从81.9%降至66.1%，这归因于残留HA对纤维素酶活性的抑制能力，其降低了36.3%。有趣的是，当在糖化过程中向系统中引入10 mM铁并使其与HA结合时，酶水解效率可从66.1%提高到77.3%。
高价金属阳离子（铁）的添加成功减轻了HA对纤维素酶活性的影响。我们希望通过证明金属阳离子与HA之间的络合亲和力，未来的研究人员和生物精炼开发者将把这种策略评估为一种单元操作，从而实现废弃小麦秸秆的经济生物精炼，以生产有价值的生物化学品、生物燃料和生物材料。
