Kane Aunica L, Bond Daniel R, Gralnick Jeffrey A
BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, MN 55108, USA.
ACS Synth Biol. 2013 Feb 15;2(2):93-101. doi: 10.1021/sb300042w. Epub 2012 Aug 27.
Growth in three-electrode electrochemical cells allows quantitative analysis of mechanisms involved in electron flow from dissimilatory metal reducing bacteria to insoluble electron acceptors. In these systems, gold electrodes are a desirable surface to study the electrophysiology of extracellular respiration, yet previous research has shown that certain Shewanella species are unable to form productive biofilms on gold electrodes. To engineer attachment of Shewanella oneidensis to gold, five repeating units of a synthetic gold-binding peptide (5rGBP) were integrated within an Escherichia coli outer membrane protein, LamB, and displayed on the outer surface of S. oneidensis. Expression of LamB-5rGBP increased cellular attachment of S. oneidensis to unpoised gold surfaces but was also associated with the loss of certain outer membrane proteins required for extracellular respiration. Loss of these outer membrane proteins during expression of LamB-5rGBP decreased the rate at which S. oneidensis was able to reduce insoluble iron, riboflavin, and electrodes. Moreover, poising the gold electrode resulted in repulsion of the engineered cells. This study provides a strategy to specifically immobilize bacteria to electrodes while also outlining challenges involved in merging synthetic biology approaches with native cellular pathways and cell surface charge.
三电极电化学电池中的生长过程允许对异化金属还原菌向不溶性电子受体的电子流动所涉及的机制进行定量分析。在这些系统中，金电极是研究细胞外呼吸电生理学的理想表面，但先前的研究表明，某些希瓦氏菌属物种无法在金电极上形成有效的生物膜。为了设计将希瓦氏菌附着到金上的方法，将一个合成金结合肽（5rGBP）的五个重复单元整合到大肠杆菌外膜蛋白LamB中，并展示在希瓦氏菌的外表面。LamB-5rGBP的表达增加了希瓦氏菌对未平衡金表面的细胞附着，但也与细胞外呼吸所需的某些外膜蛋白的丧失有关。在LamB-5rGBP表达过程中这些外膜蛋白的丧失降低了希瓦氏菌还原不溶性铁、核黄素和电极的速率。此外，平衡金电极会导致工程菌的排斥。这项研究提供了一种将细菌特异性固定到电极上的策略，同时也概述了将合成生物学方法与天然细胞途径和细胞表面电荷相结合所涉及的挑战。
