Hydrophilicity boosted extracellular electron transfer in Shewanella loihica PV-4

Abstract

Taking advantage of the abundant redox active C-type cytochromes on their outer membrane (OMCs), the genus Shewanella enables extracellular electron transfer (EET), which is applicable in various bioelectrical devices. For practical applications, high efficient EET is always desirable. Here, we reveal that tailoring the surface wettability of electrodes can drastically alter the EET activity of microbial Shewanella loihica PV-4: the EET current on a superhydrophilic electrode is over 3 and 10 times higher than that on normal hydrophilic and hydrophobic electrodes, respectively. Worth noting is that a cell suspension with a rather small initial cell density was preferentially used, which can exclude the influence of other unfavorable factors in such a dynamic and flexible living system. It is proposed that a hydrophilic electrode favors a reduced state of OMCs, and consequently both the EET activity and cell proliferation are highly facilitated.