Vuong Thu V, Singh Rahul, Eltis Lindsay D, Master Emma R
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada.
Department of Microbiology and Immunology, BioProducts Institute, The University of British Columbia, Vancouver, BC, Canada.
Front Microbiol. 2021 Oct 18;12:723524. doi: 10.3389/fmicb.2021.723524. eCollection 2021.
The relative ability of the small laccase (sLac) and dye-decoloring peroxidase (DyP2) from sp. 75iv2 to transform a variety of lignins was investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The enzymes modified organosolv hardwood lignin to different extents even in the absence of an added mediator. More particularly, sLac decreased the lignin modification metric S (S-lignin)/Ar (total aromatics) by 58% over 16h, while DyP2 lowered this ratio by 31% in the absence of exogenous HO. When used on their own, both sLac and DyP2 also modified native lignin present in aspen wood powder, albeit to lesser extents than in the organosolv lignin. The addition of ABTS for sLac and Mn as well as HO for DyP2 led to increased lignin modification in aspen wood powder as reflected by a decrease in the G/Ar metric by up to a further 13%. This highlights the importance of exogenous mediators for transforming lignin within its native matrix. Furthermore, the addition of ABTS reduced the selectivity of sLac for S-lignin over G-lignin, indicating that the mediator also altered the product profiles. Finally, when sLac was included in reactions containing DyP2, in part to generate HO , the relative abundance of lignin products differed from individual enzymatic treatments. Overall, these results identify possible routes to tuning lignin modification or delignification through choice of enzyme and mediator. Moreover, the current study expands the application of ToF-SIMS to evaluating enzyme action on technical lignins, which can accelerate the discovery and engineering of industrially relevant enzymes for lignin valorization.
利用飞行时间二次离子质谱（ToF-SIMS）研究了来自sp. 75iv2的小漆酶（sLac）和染料脱色过氧化物酶（DyP2）转化多种木质素的相对能力。即使在不添加介质的情况下，这些酶也能不同程度地修饰有机溶剂法阔叶木木质素。更具体地说，sLac在16小时内使木质素修饰指标S（S-木质素）/Ar（总芳烃）降低了58%，而在没有外源过氧化氢的情况下，DyP2使该比例降低了31%。单独使用时，sLac和DyP2也能修饰杨木粉中存在的天然木质素，尽管程度比有机溶剂法木质素小。添加ABTS用于sLac和添加锰以及过氧化氢用于DyP2，导致杨木粉中木质素修饰增加，这通过G/Ar指标进一步降低高达13%得以体现。这突出了外源介质在其天然基质中转化木质素的重要性。此外，添加ABTS降低了sLac对S-木质素相对于G-木质素的选择性，表明介质也改变了产物分布。最后，当sLac包含在含有DyP2的反应中时，部分是为了生成过氧化氢，木质素产物的相对丰度与单独的酶处理不同。总体而言，这些结果确定了通过选择酶和介质来调节木质素修饰或脱木质素的可能途径。此外，当前研究扩展了ToF-SIMS在评估酶对工业木质素作用方面的应用，这可以加速发现和工程改造用于木质素增值的工业相关酶。
