Bacterial lignin degradation: characterization and biocatalytic applications

细菌是生物圈中自然和人造化合物降解的主要原因。这种退化是全球碳循环的一个重要环节，对维持地球上的生命至关重要。细菌降解活动也代表了丰富的，几乎没有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资助的研究项目对细菌酶的功能提供了新的见解，这些酶参与了芳香化合物和污染物的降解，以及这些酶是如何被调节的。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，约占陆地生物量的25%。木质素与纤维素和半纤维素紧密结合，形成坚固的刚性结构，非常不易降解。解构这种木质纤维素对于利用木质生物质作为化学物质、材料和其他生物产品的可再生来源至关重要。虽然真菌降解木质素的酶已经研究了很多年，但细菌降解木质素的酶在很大程度上被忽视了，尽管它们更适合于工业过程。我的研究将集中于两种类型的细菌酶：(a)分解聚合木质素；(b)降解木质素解聚产物。这些酶代表了一类重要的含金属酶，但我们对它们的了解还不够透彻。拟议中的研究将增加我们对这些酶的作用以及它们如何起作用的理解。这将反过来为重要生物过程的分子机制以及大自然如何利用金属催化这些过程提供基本的见解。所获得的知识还将促进酶和细菌的工程应用于生物技术。更具体地说，它将有助于设计生物催化剂，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。研究目标将采用涉及各种尖端技术的跨学科方法来实现。这项研究将受益于Eltis实验室开发的许多工具和方法。最后，该研究项目为学员提供广泛的技能，为他们在学术界、工业界和政府的职业生涯做好准备。

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.