Towards lignin consolidated bioprocessing: simultaneous lignin depolymerization and product generation by bacteria
Towards lignin consolidated bioprocessing: simultaneous lignin depolymerization and product generation by bacteria
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DOI：
10.1039/c5gc01165e
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发表时间：
2015-01-01
期刊：
影响因子：
9.8
通讯作者：
Beckham, Gregg T.
中科院分区：
文献类型：
--
作者：
Salvachua, Davinia;Karp, Eric M.;Beckham, Gregg T.
木质素代表木质纤维素生物质中未开发的资源，主要是由于其对解聚的不稳定性和其内在的异质性。在自然界中，微生物已经进化出使用细胞外氧化酶使木质素脱乙酰化和吸收在解聚过程中产生的芳香族物质作为碳源和能源的机制。微生物同时进行这两个过程的能力可以使综合生物加工概念应用于木质素，类似于今天通过产乙醇的纤维素分解微生物将多糖转化为乙醇所做的事情。为此，在这里，我们研究了14种细菌分泌木质素分解酶，降解木质素，吸收芳香族化合物和其他化合物存在于生物质衍生的富含木质素的流中的能力，并且在氮限制条件下，积累可用作燃料，化学品或材料前体的细胞内碳储存化合物。在摇瓶条件下，使用碱预处理过程中产生的底物，我们证明，高达近30%的初始木质素可以解聚和分解代谢的细菌的子集。特别地，拟无枝酸菌属，两种恶臭假单胞菌（Pseudomonasputida）菌株，即不动杆菌ADP 1和贾氏红球菌（Rhodococcusjostii），能够降解高分子量木质素种类，并分解代谢大部分低分子量芳香族化合物，因此代表了用于代谢工程的良好起始宿主。本研究还提供了一套全面的实验工具，同时研究细菌中的木质素解聚和芳香族催化剂，并为木质素整合生物加工的概念提供了基础，这最终可能是生物木质素价值的重要途径。
Lignin represents an untapped resource in lignocellulosic biomass, primarily due to its recalcitrance to depolymerization and its intrinsic heterogeneity. In Nature, microorganisms have evolved mechanisms to both depolymerize lignin using extracellular oxidative enzymes and to uptake the aromatic species generated during depolymerization for carbon and energy sources. The ability of microbes to conduct both of these processes simultaneously could enable a Consolidated Bioprocessing concept to be applied to lignin, similar to what is done today with polysaccharide conversion to ethanol via ethanologenic, cellulolytic microbes. To that end, here we examine the ability of 14 bacteria to secrete ligninolytic enzymes, depolymerize lignin, uptake aromatic and other compounds present in a biomass-derived, lignin-enriched stream, and, under nitrogen-limiting conditions, accumulate intracellular carbon storage compounds that can be used as fuel, chemical, or material precursors. In shake flask conditions using a substrate produced during alkaline pretreatment, we demonstrate that up to nearly 30% of the initial lignin can be depolymerized and catabolized by a subset of bacteria. In particular, Amycolatopsis sp., two Pseudomonas putida strains, Acinetobacter ADP1, and Rhodococcus jostii are able to depolymerize high molecular weight lignin species and catabolize a significant portion of the low molecular weight aromatics, thus representing good starting hosts for metabolic engineering. This study also provides a comprehensive set of experimental tools to simultaneously study lignin depolymerization and aromatic catabolism in bacteria, and provides a foundation towards the concept of Lignin Consolidated Bioprocessing, which may eventually be an important route for biological lignin valorization.