The recent discovery that LPMOs can work under anaerobic conditions when supplied with low amounts H2O2 opens the possibility of using LPMOs as enzyme aids in biogas reactors to increase methane yields from lignocellulosic materials. We have explored this possibility by studying anaerobic digestion of various lignocellulosic materials: Avicel, milled spruce and birch wood, and a lignin-rich hydrolysis residue from steam-exploded birch. The digestions were added LPMOs and various cellulolytic enzyme cocktails and were carried out with or without addition of H2O2. In several cases, enzyme addition had a beneficial effect on methane production, which was partly due to components present in the enzyme preparations. It was possible to detect LPMO activity during the initial phases of the anaerobic digestions of Avicel, and in some cases LPMO activity could be correlated with improved methane production from lignocellulosic materials. However, a positive effect on methane production was only seen when LPMOs were added together with cellulases, and never upon addition of LPMOs only. Generally, the experimental outcomes showed substrate-dependent variations in process efficiency and the importance of LPMOs and added H2O2. These differences could relate to variations in the type and content of lignin, which again will affect the activity of the LPMO, the fate of the added H2O2 and the generation of potentially damaging reactive-oxygen species. The observed effects showed that the interplay between cellulases and LPMOs is important for the overall efficiency of the process. This study shows that it may be possible to harness the power of LPMOs in anaerobic digestion processes and improve biogas production, but also highlight the complexity of the reaction systems at hand. One complicating factor was that the enzymes themselves and other organic components in the enzyme preparations acted as substrates for biogas production, meaning that good control reactions were essential to detect effects caused by enzyme activity. As also observed during regular aerobic enzymatic digestion of lignocellulosic biomass, the type and contents of lignin in the substrates likely plays a major role in determining the impact of LPMOs and of cellulolytic enzymes in general. More work is needed to unravel the interplay between LPMOs, O2, H2O2, and the multitude of redox-active components found in anaerobic bioreactors degrading lignocellulosic substrates.

中文翻译：

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裂解多糖单加氧酶在木质纤维素材料厌氧消化中的应用

最近发现 LPMO 在提供少量 H2O2 时可以在厌氧条件下工作，这开启了在沼气反应器中使用 LPMO 作为酶助剂以提高木质纤维素材料的甲烷产量的可能性。我们通过研究各种木质纤维素材料的厌氧消化探索了这种可能性：Avicel、碾碎的云杉和桦木，以及来自蒸汽爆破桦木的富含木质素的水解残渣。消化添加 LPMO 和各种纤维素分解酶混合物，并在添加或不添加 H2O2 的情况下进行。在一些情况下，酶的添加对甲烷的产生有有益的影响，这部分是由于酶制剂中存在的成分。可以在 Avicel 厌氧消化的初始阶段检测 LPMO 活性，在某些情况下，LPMO 活性可能与提高木质纤维素材料的甲烷产量有关。然而，只有在将 LPMO 与纤维素酶一起添加时，才能看到对甲烷产生的积极影响，而仅在添加 LPMO 时才看到。一般来说，实验结果显示了工艺效率的底物依赖性变化以及 LPMO 和添加的 H2O2 的重要性。这些差异可能与木质素类型和含量的变化有关，这将再次影响 LPMO 的活性、添加的 H2O2 的命运以及潜在破坏性活性氧物质的产生。观察到的效果表明，纤维素酶和 LPMO 之间的相互作用对于该过程的整体效率很重要。这项研究表明，在厌氧消化过程中利用 LPMO 的力量并提高沼气产量是可能的，但也突出了手头反应系统的复杂性。一个复杂的因素是酶本身和酶制剂中的其他有机成分充当沼气生产的底物，这意味着良好的控制反应对于检测酶活性引起的影响至关重要。正如在木质纤维素生物质的常规需氧酶消化过程中观察到的那样，底物中木质素的类型和含量可能在确定 LPMO 和一般纤维素分解酶的影响方面起主要作用。需要做更多的工作来解开 LPMO、O2、H2O2、