Department of Biology, Washington University in Saint Louis, St. Louis, MO 63130, USA.
Department of Biology, Washington University in Saint Louis, St. Louis, MO 63130, USA.
Bioelectrochemistry. 2018 Aug;122:164-173. doi: 10.1016/j.bioelechem.2018.03.015. Epub 2018 Apr 5.
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 H 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 +100mV 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±0.09μA/cm (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）是一种很有前途的生物电化学方法，可以用来生产生物化学物质。先前的一项研究表明，沼泽红假单胞菌 TIE-1 可以直接将固定电极用作电子供体，在避免电解 H 产生的阴极电位下进行光自养生长（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自养条件下的电子摄取能力和生长能力。由于 TIE-1 在将其用作光自养（光亚铁自养）的电子源时与各种形式的铁相互作用，因此我们测试了铁基氧化还原介体增强直接电子摄取的能力。我们的数据表明，可溶性铁不能作为 TIE-1 从相对于标准氢电极（SHE）为+100mV 电势的阴极摄取电子的氧化还原介体。然后，我们测试了固定化铁基氧化还原介体普鲁士蓝（PB）是否可以增强 TIE-1 的电子摄取。计时安培法表明，TIE-1 对阴极电流的摄取从 1.47±0.04 增加到 5.6±0.09μA/cm（增加了 3.8 倍）。总体而言，我们的数据表明固定化 PB 可以增强 TIE-1 的直接电子摄取。
