Electron Transfer Beyond the Outer Membrane: Putting Electrons to Rest.

Area of Science:

• Microbiology
• Biochemistry
• Environmental Science

Background:

• Extracellular electron transfer (EET) is a microbial process for redox reactions beyond the cell.
• Shewanella and Geobacter were the first identified bacteria utilizing EET for mineral respiration.
• EET requires transferring electrons across the cell membrane, distinguishing it from other respiratory processes.

Purpose of the Study:

• To review the current understanding of EET mechanisms in Shewanella and Geobacter.
• To highlight the strategies microbes use to conduct electrons across the outer membrane.
• To discuss the broader implications of EET for diverse extracellular acceptors.

Main Methods:

• Literature review of studies on Shewanella and Geobacter.
• Analysis of research on electron transport chains and outer membrane proteins.
• Synthesis of findings on EET to various mineral and non-mineral acceptors.

Main Results:

• Well-conserved pathways for inner-to-outer membrane electron transfer are established.
• Emerging evidence points to a wider array of EET mechanisms than previously known.
• EET enables the reduction of diverse extracellular targets, including minerals, electrodes, and other organisms.

Conclusions:

• Microbial EET is crucial for biogeochemical cycling and has diverse applications.
• Understanding EET mechanisms is key to harnessing microbial capabilities for environmental and technological purposes.
• Further research is needed to fully elucidate the less understood EET pathways and their scope.