PDF(Pubmed)
Abstract：
The platform chemical cis,cis-muconic acid (ccMA) provides facile access to a number of monomers used in the synthesis of commercial plastics. It is also a metabolic intermediate in the β-ketoadipic acid pathway of many bacteria and, therefore, a current target for microbial production from abundant renewable resources via metabolic engineering. This study investigates Novosphingobium aromaticivorans DSM12444 as a chassis for the production of ccMA from biomass aromatics. The N. aromaticivorans genome predicts that it encodes a previously uncharacterized protocatechuic acid (PCA) decarboxylase and a catechol 1,2-dioxygenase, which would be necessary for the conversion of aromatic metabolic intermediates to ccMA. This study confirmed the activity of these two enzymes in vitro and compared their activity to ones that have been previously characterized and used in ccMA production. From these results, we generated one strain that is completely derived from native genes and a second that contains genes previously used in microbial engineering synthesis of this compound. Both of these strains exhibited stoichiometric production of ccMA from PCA and produced greater than 100% yield of ccMA from the aromatic monomers that were identified in liquor derived from alkaline pretreated biomass. Our results show that a strain completely derived from native genes and one containing homologs from other hosts are both capable of stoichiometric production of ccMA from biomass aromatics. Overall, this work combines previously unknown aspects of aromatic metabolism in N. aromaticivorans and the genetic tractability of this organism to generate strains that produce ccMA from deconstructed biomass.IMPORTANCEThe production of commodity chemicals from renewable resources is an important goal toward increasing the environmental and economic sustainability of industrial processes. The aromatics in plant biomass are an underutilized and abundant renewable resource for the production of valuable chemicals. However, due to the chemical composition of plant biomass, many deconstruction methods generate a heterogeneous mixture of aromatics, thus making it difficult to extract valuable chemicals using current methods. Therefore, recent efforts have focused on harnessing the pathways of microorganisms to convert a diverse set of aromatics into a single product. Novosphingobium aromaticivorans DSM12444 has the native ability to metabolize a wide range of aromatics and, thus, is a potential chassis for conversion of these abundant compounds to commodity chemicals. This study reports on new features of N. aromaticivorans that can be used to produce the commodity chemical cis,cis-muconic acid from renewable and abundant biomass aromatics.
摘要：
目标：利用可再生资源生产商品化学品是提高工业过程的环境和经济可持续性的重要目标。植物生物质中的芳烃是用于生产有价值的化学品的未充分利用和丰富的可再生资源。然而,由于植物生物质的化学成分，许多解构方法产生芳烃的异质混合物，因此，使用目前的方法很难提取有价值的化学物质。因此,最近的努力集中在利用微生物的途径将一组不同的芳香族化合物转化为单一的产品。新鞘氨醇芳香剂DSM12444具有代谢多种芳香剂的天然能力，因此，是将这些丰富的化合物转化为商品化学品的潜在底盘。这项研究报告了N.aromaticivorans的新特征，可用于生产商品化学品顺式，来自可再生和丰富的生物质芳烃的顺式粘康酸。
