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Development of a Rhodococcus opacus Cell Factory for Valorizing Lignin to Muconate
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-01-23 , DOI: 10.1021/acssuschemeng.9b06571
Chenggu Cai 1 , Zhaoxian Xu 1 , Meilin Xu 1 , Mufeng Cai 1 , Mingjie Jin 1
Affiliation  

As multiple biochemical pathways exist in nature for lignin synthesis and degradation, lignin valorization through biological pathways has attracted much attention. cis,cis-Muconate, a common metabolic intermediate in lignin biodegradation, is an important platform chemical for the synthesis of a variety of polymers. In this work, Rhodococcus opacus PD630, which is efficient in the assimilation of aromatic compounds, was modified for the first time to accumulate cis,cis-muconate from lignin and lignin-derived aromatics. To achieve efficient genome modification for R. opacus PD630, a markerless gene deletion/insertion system was constructed based on a mutant phenylalanyl-tRNA synthase gene as a counter-selection marker. With the developed gene deletion/insertion system, several R. opacus PD630 mutants were successfully constructed for cis,cis-muconate production from lignin-derived aromatics using catechol and protocatechuate as two key funnel nodes. Results indicated the constructed strains could assimilate at least 15 types of lignin-derived aromatics and real lignin for cis,cis-muconate production. Moreover, both laccase addition and H2SO4 + NaOH combinatorial pretreatment enhanced real lignin valorization to cis,cis-muconate. Ultimately, 1.63 g/L cis,cis-muconate was produced using lignin from corn stover as the substrate by a fed-batch fermentation process. Overall, these results highlight the great potential of using R. opacus as a cell factory for valorizing lignin to cis,cis-muconate and other valuable products.

中文翻译:

建立不透明红球菌细胞工厂以平衡木质素为粘液

由于自然界中存在多种用于木质素合成和降解的生化途径,因此通过生物途径进行木质素增值引起了人们的广泛关注。顺式顺式-Muconate是木质素生物降解中常见的代谢中间体,是合成多种聚合物的重要平台化学物质。在这项工作中,首次修饰了有效吸收芳香族化合物的不透明红球菌PD630,以从木质素和木质素衍生的芳香族化合物中积累顺式顺式-粘康酸酯。为了实现对R. opacus的有效基因组修饰基于突变的苯丙氨酰-tRNA合酶基因作为反选择标记,构建了PD630无标记基因缺失/插入系统。通过开发的基因缺失/插入系统,成功地构建了几种不饱和球菌PD630突变体,利用儿茶酚和原儿茶酸作为两个关键的漏斗节点,从木质素衍生的芳族化合物中顺式顺式粘液生产。结果表明,所构建的菌株可以吸收至少15种类型的木质素衍生的芳族化合物和真正的木质素,以产生顺式顺式-粘康酸酯。此外,漆酶的添加和H 2 SO 4 + NaOH组合预处理均增强了木质素的实际价顺式顺式-粘康酸酯。最终,通过分批补料发酵法,以玉米秸秆中的木质素为底物,生产了1.63 g / L的顺式顺式-粘康酸酯。总的来说,这些结果突显了将不透明芽孢杆菌用作细胞工厂将木质素增值为顺式顺式-粘康酸酯和其他有价值产品的巨大潜力。
更新日期:2020-01-24
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