Bacterial lignin degradation: characterization and biocatalytic applications

细菌是生物圈中天然和人造化合物大部分降解的原因。这种退化构成了全球碳循环中的一个重要环节，对维持地球上的生命至关重要。细菌降解活动也代表着一个丰富的、几乎没有被开发的生物催化剂来源，以维持新兴的全球生物经济。在过去的二十年里，我的NSERC资助的研究项目为参与降解芳香化合物和污染物的细菌酶的功能以及这些酶是如何调节的提供了新的见解。在接下来的五年里，我将把我的项目重点放在降解木质素的酶上，木质素是一种复杂的芳香聚合物，约占陆地生物质的25%。木质素与纤维素和半纤维素紧密结合，形成非常耐降解的坚固结构。解构这种木质纤维素对于将木质生物质用作化学品、材料和其他生物制品的可再生来源至关重要。虽然降解木质素的真菌酶已经研究了多年，但细菌木质素降解酶在很大程度上被忽视了，尽管它更适合工业过程。我的研究将集中在两种类型的细菌酶上：(A)分解聚合木质素；(B)降解木质素解聚产物。这些酶代表了人们还不太了解的重要的含金属酶类。这项拟议的研究将增加我们对这些酶的作用以及它们如何做到这一点的理解。这反过来将提供对重要生物过程的分子机制以及自然如何利用金属催化这些过程的基本见解。所获得的知识还将促进用于生物技术应用的酶和细菌的工程。更具体地说，它将有助于生物催化剂的设计，将低价值的木质素转化为高价值的材料，如润滑剂、化妆品和生物塑料。研究目标将采用跨学科方法实现，涉及各种尖端技术。这项研究将受益于ELTIS实验室开发的一些工具和方法。最后，该研究计划为学员提供广泛的技能，为他们在学术界、工业界和政府部门实现职业生涯做好准备。

Bacteria are responsible for most of the degradation of natural and human-made compounds in the biosphere. This degradation constitutes an essential link in the global carbon cycle and is critical to sustaining life on our planet. Bacterial degradation activities also represent a rich, barely tapped source of biocatalysts to sustain the emerging global bioeconomy. Over the past two decades, my NSERC-funded research program has provided novel insights into the function of bacterial enzymes involved in the degradation of aromatic compounds and pollutants as well as into how these enzymes are regulated. Over the next five years, I will focus my program on enzymes that degrade lignin, a complex aromatic polymer that comprises about 25% of the land-based biomass. Lignin occurs in tight association with cellulose and hemicellulose to form the strong, rigid structure that is very resistant to degradation. Deconstructing this lignocellulose is critical to using woody biomass as a renewable source of chemicals, materials and other bioproducts. While fungal enzymes that degrade lignin have been studied for years, bacterial lignin-degrading enzymes have been largely overlooked despite being more amenable for industrial processes. My research will focus on two types of bacterial enzymes that: (a) breakdown the polymeric lignin; and (b) degrade the lignin depolymerization products. These enzymes represent important classes of metal-containing enzymes that are not well understood. The proposed research will increase our understanding of what these enzymes do and how they do it. This will in turn provide fundamental insights into the molecular mechanism of important biological processes as well as how Nature uses metals to catalyze these processes. The knowledge gained will also facilitate the engineering of enzymes and bacteria for biotechnological applications. More particularly, it will help in the design of biocatalysts to transform low-value lignin into high-value materials, such lubricants, cosmetics and bioplastics. The research objectives will be achieved using an interdisciplinary approach involving a variety of cutting-edge techniques. The research will benefit from a number of tools and approaches developed in the Eltis lab. Finally, the research program provides trainees with a wide range of skills, preparing them for fulfilling careers in academia, industry and government.