Comparative proteomics implicates a role for multiple secretion systems in electrode-respiring Geobacter...

Area of Science:

• Microbial physiology
• Bioelectrochemistry
• Proteomics

Background:

• Geobacter sulfurreducens forms electron-conducting biofilms on electrodes.
• Understanding adaptation from planktonic to biofilm states is crucial for bioelectrochemical applications.

Purpose of the Study:

• To identify physiological changes in Geobacter sulfurreducens during adaptation to electrode respiration.
• To compare protein expression in planktonic cells versus electron-conducting biofilms.

Main Methods:

• Comparative proteomics was used to analyze protein expression.
• Geobacter sulfurreducens cells were cultured under fumarate-respiring planktonic conditions and on electrodes.

Main Results:

• Biofilms showed increased levels of proteins involved in outer membrane biogenesis, cell motility, and secretion.
• Proteins associated with Type I, II, V, and Type IV pili secretion systems were upregulated in biofilms.
• Enzymes for lipopolysaccharide and peptidoglycan biosynthesis were also elevated in biofilms.

Conclusions:

• Secretion systems play a significant role in Geobacter sulfurreducens adaptation to electrode respiration.
• Observed mechanisms suggest similarities in long-range electron transfer with Shewanella oneidensis.
• This study expands the known functions of secretion systems in microbial adaptation to extracellular electron transfer.