Cross Megan C Gruenberg, Aboulnaga Elhussiny, TerAvest Michaela A
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA.
Faculty of Agriculture, Mansoura University, Mansoura, Egypt.
Appl Environ Microbiol. 2025 May 21;91(5):e0196824. doi: 10.1128/aem.01968-24. Epub 2025 Apr 10.
Microbial electrosynthesis (MES) is a sustainable approach to chemical production from CO and clean electricity. However, limitations in electron transfer efficiency and gaps in understanding of electron transfer pathways in MES systems prevent full realization of this technology. could serve as an MES biocatalyst because it has a well-studied, efficient transmembrane electron transfer pathway. A key first step in MES in this organism could be CO reduction to formate. However, we report that wild-type does not tolerate high levels of formate. In this work, we created and characterized formate-tolerant strains of for further engineering and future use in MES systems through adaptive laboratory evolution. Two different point mutations in a gene encoding a predicted sodium-dependent bicarbonate transporter and a DUF2721-containing protein separately confer formate tolerance to . The mutations were further evaluated to understand their role in improving formate tolerance. We also show that the wild-type and mutant versions of the putative sodium-dependent bicarbonate transporter improve formate tolerance of , indicating the potential of transferring this formate tolerance phenotype to other organisms.
is a bacterium with a well-studied, efficient extracellular electron transfer pathway. This capability could make this organism a suitable host for microbial electrosynthesis using CO or formate as feedstocks. However, we report here that formate is toxic to , limiting the potential for its use in these systems. In this work, we evolve several strains of that have improved formate tolerance, and we investigate some mutations that confer this phenotype. The phenotype is confirmed to be attributed to several single point mutations by transferring the wild-type and mutant versions of each gene to the wild-type strain. Finally, the formate tolerance mechanism of one variant is studied using structural modeling and expression in another host. This study, therefore, presents a simple method for conferring formate tolerance to bacterial hosts.
微生物电合成（MES）是一种利用一氧化碳和清洁电力进行化学生产的可持续方法。然而，MES系统中电子转移效率的限制以及对电子转移途径理解的不足阻碍了该技术的全面实现。[具体微生物名称]可作为MES生物催化剂，因为它具有经过充分研究的高效跨膜电子转移途径。在该生物体中MES的关键第一步可能是将一氧化碳还原为甲酸盐。然而，我们报告野生型[具体微生物名称]不耐受高水平的甲酸盐。在这项工作中，我们通过适应性实验室进化创建并表征了耐甲酸盐的[具体微生物名称]菌株，以便在MES系统中进一步工程化和未来使用。编码预测的钠依赖性碳酸氢盐转运蛋白和含DUF2721蛋白的基因中的两个不同点突变分别赋予[具体微生物名称]甲酸盐耐受性。对这些突变进行了进一步评估，以了解它们在提高甲酸盐耐受性中的作用。我们还表明，推定的钠依赖性碳酸氢盐转运蛋白的野生型和突变型版本提高了[具体微生物名称]的甲酸盐耐受性，表明将这种甲酸盐耐受性表型转移到其他生物体的潜力。
[具体微生物名称]是一种具有经过充分研究的高效细胞外电子转移途径细菌。这种能力可能使该生物体成为使用一氧化碳或甲酸盐作为原料进行微生物电合成的合适宿主。然而，我们在此报告甲酸盐对[具体微生物名称]有毒，限制了其在这些系统中的使用潜力。在这项工作中，我们进化了几种具有提高的甲酸盐耐受性的[具体微生物名称]菌株，并研究了赋予这种表型的一些突变。通过将每个基因的野生型和突变型版本转移到野生型菌株中，证实该表型归因于几个单点突变。最后，使用结构建模和在另一个宿主中的表达研究了一个变体的甲酸盐耐受机制。因此，本研究提出了一种赋予细菌宿主甲酸盐耐受性的简单方法。
