Microbial electrosynthesis (MES) is a promising bioelectrochemical approach to produce biochemicals. A previous study showed that Rhodopseudomonas palustris TIE-1 can directly use poised electrodes as electron donors for photoautotrophic growth at cathodic potentials that avoid electrolytic H₂ production (photoelectroautotrophy). To make TIE-1 an effective biocatalyst for MES, we need to improve its electron uptake ability and growth under photoelectroautotrophic conditions. Because TIE-1 interacts with various forms of iron while using it as a source of electrons for photoautotrophy (photoferroautotrophy), we tested the ability of iron-based redox mediators to enhance direct electron uptake. Our data show that soluble iron cannot act as a redox mediator for electron uptake by TIE-1 from a cathode poised at +100 mV vs. Standard Hydrogen electrode. We then tested whether an immobilized iron-based redox mediator Prussian blue (PB) can enhance electron uptake by TIE-1. Chronoamperometry indicates that cathodic current uptake by TIE-1 increased from 1.47 ± 0.04 to 5.6 ± 0.09 μA/cm² (3.8 times). Overall, our data show that immobilized PB can enhance direct electron uptake by TIE-1.

微生物电合成（MES）是一种有前途的生物电化学方法，用于生产生物化学物质。先前的研究表明，红假单胞菌TIE-1可以直接使用平衡的电极作为电子供体，以在避免电解H _2的阴极电势下进行光自养生长生产（光电自养）。为了使TIE-1成为MES的有效生物催化剂，我们需要提高其在光电子自养条件下的电子吸收能力和生长。由于TIE-1与多种形式的铁发生相互作用，同时将其用作光致自养（光铁自养）的电子源，因此我们测试了铁基氧化还原介体增强直接电子吸收的能力。我们的数据表明，与标准氢电极相比，可溶性铁不能充当TIE-1从+100 mV平衡的阴极吸收电子的氧化还原介体。然后，我们测试了固定化的铁基氧化还原介体普鲁士蓝（PB）是否可以增强TIE-1的电子吸收。计时电流分析法表明，TIE-1吸收的阴极电流从1.47±0.04增加到5.6±0.09μA/ cm ²（3.8倍）。总体而言，我们的数据表明，固定的PB可以增强TIE-1的直接电子吸收。