Removal of aspirin from aqueous solution using electroactive bacteria induced by alternating current

Area of Science:

• Biotechnology and Environmental Science
• Microbial Electrochemistry

Background:

• Acetylsalicylic acid (ASA) biodegradation is crucial for environmental remediation.
• Bacterial enzyme activities, such as laccase (LEA) and dehydrogenase (DHA), are key to this process.
• Enhancing these enzyme activities can improve biodegradation efficiency.

Purpose of the Study:

• To investigate the effect of alternating current (AC) on bacterial LEA and DHA.
• To optimize AC parameters for enhanced enzyme activity in ASA biodegradation.
• To evaluate the potential of an electroactive bioreactor for stimulating enzyme activities.

Main Methods:

• A microbial consortium was cultured in an electroactive bioreactor.
• AC stimulation was applied using a function generator with varying voltage amplitude (2-10 Vpp), optical fiber splice tray (OFST) of 0.1 V, and frequency of 10 Hz.
• Enzyme activities (LEA, DHA), cell viability, permeability, and by-product profiles (LC-MS, GC-MS) were analyzed.

Main Results:

• Optimal AC stimulation at 8 Vpp and 0.1 V OFST for 12 hours maximized bacterial LEA (30.6 U/mL) and DHA (75.5 micro grTF/cm2.gr biomass).
• Cell viability remained high (95.7%) with minimal permeability (0.3%) at 8 Vpp.
• LC-MS and GC-MS analyses indicated reduced by-product intensity at 8 Vpp compared to 2 Vpp.

Conclusions:

• Alternating current effectively stimulates bacterial LEA and DHA, promoting ASA biodegradation.
• An electroactive bioreactor with optimized AC parameters offers a novel approach for enhancing microbial enzyme activities.
• This method shows potential for efficient and cleaner biodegradation of pharmaceutical pollutants.