Electron acceptor-dependent respiratory and physiological stratifications in biofilms

Area of Science:

• Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Bacterial respiration drives biogeochemical cycles and bioremediation.
• Bacteria often encounter coexisting solid and soluble electron acceptors.
• Understanding sessile bacteria's response to multiple acceptors is crucial.

Purpose of the Study:

• Investigate bacterial respiration strategies with multiple electron acceptors.
• Examine how Shewanella decolorationis biofilms interact with anode and azo dye.

Main Methods:

• Utilized microbial fuel cells (MFCs) with Shewanella decolorationis.
• Introduced azo dye as an alternative electron acceptor in the anode chamber.
• Compared respiration patterns of biofilm and planktonic cells.

Main Results:

• Planktonic cells preferred azo dye, while biofilm cells used both anode and azo dye.
• Simultaneous respiration enhanced biofilm viability and dissipated proton accumulation.
• Biofilm potential was less affected by cathodic conditions than anode potential.

Conclusions:

• Shewanella exhibits distinct respiration strategies based on cell state (biofilm vs. planktonic).
• Co-respiration with multiple electron acceptors can enhance bacterial viability.
• Results support an electron-hopping mechanism in Shewanella electrode-respiring biofilms.