Department of Solar Materials, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
Microb Biotechnol. 2021 Jul;14(4):1784-1796. doi: 10.1111/1751-7915.13862. Epub 2021 Jun 11.
Pseudomonas putida (P. putida) is a microorganism of interest for various industrial processes, yet its strictly aerobic nature limits application. Despite previous attempts to adapt P. putida to anoxic conditions via genetic engineering or the use of a bioelectrochemical system (BES), the problem of energy shortage and internal redox imbalance persists. In this work, we aimed to provide the cytoplasmic metabolism with different monosaccharides, other than glucose, and explored the physiological response in P. putida KT2440 during bioelectrochemical cultivation. The periplasmic oxidation cascade was found to be able to oxidize a wide range of aldoses to their corresponding (keto-)aldonates. Unexpectedly, isomerization of the ketose fructose to mannose also enabled oxidation by glucose dehydrogenase, a new pathway uncovered for fructose metabolism in P. putida KT2440 in BES. Besides the isomerization, the remainder of fructose was imported into the cytoplasm and metabolized. This resulted in a higher NADPH/NADP ratio, compared to glucose. Comparative proteomics further revealed the upregulation of proteins in the lower central carbon metabolism during the experiment. These findings highlight that the choice of a substrate in BES can target cytosolic and periplasmic oxidation pathways, and that electrode-driven redox balancing can drive these pathways in P. putida under anaerobic conditions.
铜绿假单胞菌（P. putida）是一种在各种工业过程中受到关注的微生物，但它严格的需氧性质限制了其应用。尽管之前曾尝试通过基因工程或生物电化学系统（BES）使 P. putida 适应缺氧条件，但能量短缺和内部氧化还原失衡的问题仍然存在。在这项工作中，我们旨在为细胞质代谢提供除葡萄糖以外的不同单糖，并探索铜绿假单胞菌 KT2440 在生物电化学培养过程中的生理反应。发现周质氧化级联能够将多种醛糖氧化为相应的（酮-）醛糖。出乎意料的是，酮糖果糖向甘露糖的异构化也能够被葡萄糖脱氢酶氧化，这揭示了在 BES 中铜绿假单胞菌 KT2440 中果糖代谢的新途径。除了异构化之外，剩余的果糖被导入细胞质并代谢。与葡萄糖相比，这导致 NADPH/NADP 比值升高。比较蛋白质组学进一步揭示了实验过程中较低的中心碳代谢中蛋白质的上调。这些发现强调了 BES 中底物的选择可以针对细胞质和周质氧化途径，并且电极驱动的氧化还原平衡可以在厌氧条件下驱动 P. putida 中的这些途径。
