Enhanced Production of Antimicrobial Pyocyanin Using Electromagnetic Fields and Carbon Nanotubes

Pseudomonas aeruginosa produces pyocyanin, a phenazine antimicrobial agent against drug-resistant microorganisms. Multi-walled carbon nanotubes (MWCNTs) were shown to stimulate pyocyanin production. Since they are known for their conductivity, their stimulatory properties could be affected by electromagnetic fields (EMFs). Therefore, this study aimed to verify whether EMFs, alone or in combination with MWCNT, could serve as a process simulator for pyocyanin production, and whether the production process is optimizable.

The Design of Experiment method was employed to optimize pyocyanin production by the cultures exposed to different types of EMFs alone or in combination with MWCNTs. This allowed for identifying the setup with the highest improvement in pyocyanin production. In this setup, additional assays, including conductivity, magnetic induction, ROS level, and membrane potential measurements, were performed. The antibacterial properties of the purified pigment were also assessed.

The rotating magnetic field (RMF) combined with MWCNT was identified as the most effective setup for pyocyanin production (production improved by 143% compared to the control), which can be further enhanced by aeration. Significant changes in conductivity, magnetic induction, membrane potential, and ROS levels were observed. The purified pigment exhibited strong antibacterial properties, particularly against Staphylococcus aureus and Acinetobacter baumannii, which are often recognized as drug-resistant microorganisms.

This research proposes a novel approach to bioprocessing, where the production of the desired metabolite can be stimulated through a combination of stressors.