Alternating Current Influences Anaerobic Electroactive Biofilm Activity

Area of Science:

• Microbial electrochemistry
• Biofilm science
• Applied microbiology

Background:

• Alternating current (AC) is known to inhibit microbial growth in suspension.
• The impact of AC on anaerobic biofilm activity remains largely uninvestigated.
• Microbial electrochemical reactors (M বিপ্ল) rely on biofilms for function.

Purpose of the Study:

• To systematically investigate the effects of varying AC frequencies on anaerobic biofilm activity.
• To understand the mechanisms behind AC-induced biofilm inactivation.
• To explore potential applications in controlling biofilms in M বিপ্ল and related technologies.

Main Methods:

• Utilized Geobacter-dominated anaerobic biofilms grown on electrodes in M বিপ্ল.
• Applied AC with frequencies ranging from 1 MHz to 1 Hz at different amplitudes (1.2 V, 5 V) for 30 minutes.
• Measured changes in limiting current to quantify biofilm activity.
• Employed confocal microscopy to visualize biofilm structure and electrode interface.

Main Results:

• High-frequency AC (1 MHz to 1 kHz) caused only temporary inhibition of biofilm activity.
• Low-frequency AC (100 Hz) at 1.2 or 5 V resulted in a permanent 47 ± 19% decrease in limiting current.
• Biofilm inactivation at 100 Hz was attributed to electrohydrodynamic forces damaging the biofilm and intercellular electron transfer network at the electrode interface.
• 1 Hz AC induced water electrolysis, generating gas bubbles that detached the biofilm from the electrode.

Conclusions:

• AC frequency is a critical parameter for controlling anaerobic biofilm activity.
• Low-frequency AC can permanently inactivate biofilms by disrupting their structure and function at the electrode interface.
• Findings offer insights for biofouling control, waste treatment, and energy recovery in M বিপ্ল.
• The study provides a foundation for understanding microbial physiology and ecology under electrical stimulation.