Marinobacter atlanticus electrode biofilms differentially regulate gene expression depending on electrode potential...

Area of Science:

• Microbiology
• Environmental Science
• Biochemistry

Background:

• Marinobacter spp. are versatile bacteria known for metal interactions and electrode activity.
• Marinobacter atlanticus strain CP1, isolated from a microbial fuel cell, generates electrical current on electrodes.
• The molecular basis for extracellular electron transfer in M. atlanticus remains unclear.

Purpose of the Study:

• To investigate gene expression changes in M. atlanticus in response to different electrode potentials.
• To elucidate the molecular mechanisms underlying extracellular electron transfer and biofilm formation on electrodes.
• To understand the physiological adaptations of M. atlanticus for growth on electrodes.

Main Methods:

• RNA-sequencing was employed to compare gene expression profiles.
• M. atlanticus was cultured as both planktonic and electrode-attached cells.
• Cells were exposed to varying electrode potentials (310, 510 mV for current production; 160 mV for electron uptake).

Main Results:

• Current-producing potentials increased expression of molybdate transport genes.
• Electrode-attached cells at current-producing potentials showed higher expression of type VI secretion system export proteins.
• Electron uptake potentials (160 mV) upregulated stress response, DNA repair (RecBCD, LexA/RecA), and copper homeostasis genes.
• Changes in proteins with extracellular export motifs suggest biofilm matrix remodeling.

Conclusions:

• M. atlanticus exhibits distinct gene expression patterns in response to electrode potentials, impacting electron transfer and biofilm structure.
• Molybdate transport and type VI secretion system appear crucial for current production.
• Stress response and copper homeostasis are important under electron-uptake conditions.
• Metal acquisition may play a role in redox protein function or electron shuttling in M. atlanticus biofilms.