Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
National key Laboratory of Non-food Biomass Energy Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China.
Nat Commun. 2024 Oct 28;15(1):9288. doi: 10.1038/s41467-024-53609-3.
Exploring microorganisms with downstream synthetic advantages in lignin valorization is an effective strategy to increase target product diversity and yield. This study ingeniously engineers the non-lignin-degrading bacterium Ralstonia eutropha H16 (also known as Cupriavidus necator H16) to convert lignin, a typically underutilized by-product of biorefinery, into valuable bioplastic polyhydroxybutyrate (PHB). The aromatic metabolism capacities of R. eutropha H16 for different lignin-derived aromatics (LDAs) are systematically characterized and complemented by integrating robust functional modules including O-demethylation, aromatic aldehyde metabolism and the mitigation of by-product inhibition. A pivotal discovery is the regulatory element PcaQ, which is highly responsive to the aromatic hub metabolite protocatechuic acid during lignin degradation. Based on the computer-aided design of PcaQ, we develop a hub metabolite-based autoregulation (HMA) system. This system can control the functional genes expression in response to heterologous LDAs and enhance metabolism efficiency. Multi-module genome integration and directed evolution further fortify the strain's stability and lignin conversion capacities, leading to PHB production titer of 2.38 g/L using heterologous LDAs as sole carbon source. This work not only marks a leap in bioplastic production from lignin components but also provides a strategy to redesign the non-LDAs-degrading microbes for efficient lignin valorization.
利用在木质素增值方面具有下游合成优势的微生物来增加目标产物的多样性和产量是一种有效的策略。本研究巧妙地对非木质素降解细菌罗尔斯通氏菌 H16（也称为贪铜菌 H16）进行了工程改造，使其能够将木质素这种生物炼制过程中通常未得到充分利用的副产物转化为有价值的生物塑料聚羟基丁酸酯（PHB）。本研究系统地描述了 R. eutropha H16 对不同木质素衍生芳烃（LDA）的芳香族代谢能力，并通过整合包括 O-去甲基化、芳香醛代谢和减轻副产物抑制在内的强大功能模块进行了补充。一个关键的发现是调节元件 PcaQ，它对木质素降解过程中的芳香族枢纽代谢物原儿茶酸高度响应。基于 PcaQ 的计算机辅助设计，我们开发了一种基于枢纽代谢物的自动调节（HMA）系统。该系统可以根据异源 LDA 控制功能基因的表达，从而提高代谢效率。多模块基因组整合和定向进化进一步增强了菌株的稳定性和木质素转化能力，使得该菌株能够以异源 LDA 作为唯一碳源生产 PHB，产量达到 2.38 g/L。这项工作不仅标志着生物塑料生产从木质素成分上的飞跃，还为重新设计非 LDA 降解微生物以实现高效木质素增值提供了一种策略。
