Cytochrome OmcS is not essential for extracellular electron transport via conductive pili in < em > Geobacter sulfurreducens < /em > strain KN400

Appl Environ Microbiol. 2021 Oct 20:AEM0162221. doi: 10.1128/AEM.01622-21. Online ahead of print.ABSTRACTThe multi-heme c-type cytochrome OmcS is one of the central components for extracellular electron transport in Geobacter sulfurreducens strain DL-1, but its role in other microbes, including other strains of G. sulfurreducens is currently a matter of debate. Therefore, we investigated the function of OmcS in G. sulfurreducens strain KN400, which is even more effective in extracellular electron transfer than strain DL-1. We found that deleting omcS from strain KN400 did not negatively impact the rate of Fe(III) oxide reduction and that the cells expressed conductive filaments. Replacing the wild-type pilin gene with the aro-5 pilin gene eliminated the OmcS-deficient strain's ability for electron transport to insoluble electron acceptors and diminished filament conductivity. These results are consistent with the concept that electrically conductive pili are the primary conduit for long-range electron transfer in G. sulfurreducens and closely related species. These findings, coupled with the lack of OmcS homologs in most other microbes capable of extracellular electron transfer, suggest that OmcS is not a common critical component for extracellular electron transfer. Importance OmcS has been widely studied and noted to be one of the key components for extracellular electron exchange by Geobacter sulfurreducens strain DL-1. However, the true importance of OmcS warrants further...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Source Type: research