Ralstonia eutropha is a facultative chemolithoautotrophic aerobic bacterium that grows using organic substrates or H2 and CO2. Hydrogenases (Hyds) are synthesized under lithoautotrophic, or energy-limited heterotrophic conditions and are used in enzyme fuel cells (EFC) as anodic catalysts. The effects of chemically synthesized gold nanoparticles (Au-NPs) on R. eutropha H16 growth, oxidation-reduction potential (ORP) kinetics, and H2-oxidizing Hyd activity were investigated in this study. Atomic force microscopy showed that thin, plate-shaped Au-NPs were in the nanoscale range with an average size of 5.68 nm. Compared with growth in medium without Au-NPs (control), the presence of Au-NPs stimulated growth, and resulted in a decrease in ORP to negative values. H2-oxidizing activity was not detected in the absence of Au-NPs, but activity was significantly induced (12 U/g CDW) after 24 h of growth with 18 ng/mL, increasing a further 4-fold after 72 h of growth. The results demonstrate that Au-NPs primarily influence the membrane-bound Hyd. In contrast to R. eutropha, Au-NPs had a negligible or negative effect on growth, hydrogenase activity, and H2 production of Escherichia coli. The findings of this study offer new perspectives for the production of oxygen-tolerant hydrogenases and the development of EFCs.

中文翻译：

---

金纳米粒子激活氢化酶合成并改善 Ralstonia eutropica H16 的异养生长

真养罗尔斯顿菌是一种兼性化能自养需氧细菌，利用有机底物或氢气和二氧化碳生长。氢化酶 (Hyds) 在岩石自养或能量限制的异养条件下合成，并在酶燃料电池 (EFC) 中用作阳极催化剂。本研究研究了化学合成的金纳米颗粒 (Au-NPs) 对富养罗尔斯克氏菌 H16 生长、氧化还原电位 (ORP) 动力学和 H2 氧化 Hyd 活性的影响。原子力显微镜显示薄板状 Au-NPs 处于纳米级范围内，平均尺寸为 5.68 nm。与不含 Au-NP 的培养基（对照）中的生长相比，Au-NP 的存在刺激了生长，并导致 ORP 降至负值。在没有 Au-NP 的情况下，未检测到 H2 氧化活性，但在 18 ng/mL 的浓度下生长 24 小时后，活性被显着诱导 (12 U/g CDW)，在生长 72 小时后进一步增加了 4 倍。结果表明 Au-NP 主要影响膜结合的 Hyd。与富养罗伯茨菌相比，Au-NPs 对大肠杆菌的生长、氢化酶活性和氢气产生的影响可以忽略不计或具有负面影响。这项研究的结果为耐氧氢化酶的生产和EFC的开发提供了新的视角。