Harnessing the potential of LPMO-containing cellulase cocktails poses new demands on processing conditions.
Harnessing the potential of LPMO-containing cellulase cocktails poses new demands on processing conditions.
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DOI：
10.1186/s13068-015-0376-y
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发表时间：
2015
影响因子：
6.3
通讯作者：
Horn SJ
中科院分区：
文献类型：
--
作者：
Müller G;Várnai A;Johansen KS;Eijsink VG;Horn SJ
新兴的生物经济依赖于将木质纤维生物质加工成燃料和化学品的改进方法。将木质纤维素糖化为可发酵糖是这方面的关键步骤，其中酶催化起着重要作用，也是主要的成本驱动因素。传统上，将纤维素转化为可发酵糖的酶鸡尾酒主要由纤维素酶组成。然而，最近发现的裂解多糖单加氧酶(LPMOS)利用分子氧和电子供体裂解纤维素，为生物质糖化提供了新的工具。目前市售的酶鸡尾酒中含有LPMO，考虑到这些酶的独特性质，可能会改变最佳的加工条件。在这里，我们展示了这种现代纤维素酶鸡尾酒在有氧条件下从经过预处理的木质纤维基质中释放的葡萄糖比无氧条件下高出60%。这种较高的产率与氧化产物的积累有关，这是LPMO活性的标志。在传统的纤维素酶鸡尾酒中添加LPMO可以提高糖化产率，但只能在有氧条件下进行。LPMO在纯纤维素上的活性依赖于外部电子给体的添加，而LPMO在木质纤维上的活性不是必需的。在这项研究中，我们证明了商业酶鸡尾酒的糖化率和LPMO活性之间存在直接的相关性。重要的是，我们表明，如果工艺条件适应LPMO活性的关键决定因素，即电子给体和分子氧的存在，LPMO对整体效率的贡献可能会很大。因此，LPMO的出现具有巨大的潜力，但需要重新考虑工业生物处理程序。本文的在线版本(doi：10.1186/s13068-0150376-y)包含补充材料，授权用户可以使用。
The emerging bioeconomy depends on improved methods for processing of lignocellulosic biomass to fuels and chemicals. Saccharification of lignocellulose to fermentable sugars is a key step in this regard where enzymatic catalysis plays an important role and is a major cost driver. Traditionally, enzyme cocktails for the conversion of cellulose to fermentable sugars mainly consisted of hydrolytic cellulases. However, the recent discovery of lytic polysaccharide monooxygenases (LPMOs), which cleave cellulose using molecular oxygen and an electron donor, has provided new tools for biomass saccharification. Current commercial enzyme cocktails contain LPMOs, which, considering the unique properties of these enzymes, may change optimal processing conditions. Here, we show that such modern cellulase cocktails release up to 60 % more glucose from a pretreated lignocellulosic substrate under aerobic conditions compared to anaerobic conditions. This higher yield correlates with the accumulation of oxidized products, which is a signature of LPMO activity. Spiking traditional cellulase cocktails with LPMOs led to increased saccharification yields, but only under aerobic conditions. LPMO activity on pure cellulose depended on the addition of an external electron donor, whereas this was not required for LPMO activity on lignocellulose. In this study, we demonstrate a direct correlation between saccharification yield and LPMO activity of commercial enzyme cocktails. Importantly, we show that the LPMO contribution to overall efficiency may be large if process conditions are adapted to the key determinants of LPMO activity, namely the presence of electron donors and molecular oxygen. Thus, the advent of LPMOs has a great potential, but requires rethinking of industrial bioprocessing procedures. The online version of this article (doi:10.1186/s13068-015-0376-y) contains supplementary material, which is available to authorized users.