MESSAI.iO

AI summary

75% confidence

This study investigates how exogenous flavin mononucleotide (FMN) restores electroactive biofilm formation and extracellular electron transfer in Geobacter sulfurreducens mutants lacking conductive pili or exopolysaccharides. Spectroscopic and electrochemical analyses reveal that FMN incorporates into the biofilm to bind outer membrane c-type cytochromes, functioning as both an electron shuttle and a cofactor.

Generated by MESSAI extraction pipeline · review against source PDF

Extraction

Reported parameters

1 extracted value

View extracted values

No 3D model is mapped to this paper yet. Parameter ranges above still place reported values on the literature distribution.

Abstract

Electroactive biofilms (EABs) are essential for the performance of bioelectrochemical systems (BESs), but their formation in Geobacter, critically on conductive pili and exopolysaccharides, limits application under conditions where these components are deficient. Herein, we investigated the restorative effects of exogenous flavin mononucleotide (FMN) on EAB formation and extracellular electron transfer (EET) in two defective mutants of Geobacter sulfurreducens: the pili-deficient PCAΔ1496 and exopolysaccharides-deficient PCAΔ1501. Results show that FMN significantly promoted biofilm thickness in PCAΔ1496 (250%) and PCAΔ1501 (33%), while boosting maximum current outputs by 175-fold and 317.7%, respectively. Spectroscopic and electrochemical analyses revealed that FMN incorporates into biofilms, binds to outer membrane c-type cytochromes (c-Cyts), and enhances electron exchange capacity. Differential pulse voltammetry further confirmed that FMN did not exist independently in the biofilm but bound to outer membrane c-Cyts as a cofactor. Collectively, exogenous FMN plays dual roles (electron shuttle and cytochrome-bound cofactor) in defective Geobacter EABs, effectively restoring biofilm formation and enhancing EET efficiency. This study expands the understanding of the formation mechanism of Geobacter EABs and provides a novel strategy for optimizing BES performance.

Key findings

  • FMN treatment increased biofilm thickness by 250% in pili-deficient mutants and by 33% in exopolysaccharides-deficient mutants.
  • Maximum current outputs were boosted by 175-fold in pili-deficient strains and 317.7% in exopolysaccharides-deficient strains upon FMN addition.
  • Differential pulse voltammetry confirmed that FMN does not exist independently but binds to outer membrane c-type cytochromes as a cofactor.

Keywords

Geobacter sulfurreducensBiofilmElectron transferFlavin mononucleotideGeobacterFlavin group

Identifiers

DOI
10.3390/microorganisms14010214
Journal
Microorganisms
Year
2026