C.E. Turick
ElectroBioDyne, LLC,
United States
Keywords: biofilms, real-time, monitoring, electrochemical impedance spectroscopy
Summary:
Background. Biofilms are common problems in industry, environmental and medical fields, resulting in significant costs. Development of novel approaches to study and combat biofilms require quantitative real time biofilm monitoring techniques to precisely determine growth characteristics and treatment efficiency. Non-contact, in-situ sensors offer potential to monitor biofilm density, physiological status, growth dynamics and treatment efficiency in real-time. Electrochemical impedance spectrometry (EIS) is a well-established electrochemical technique that is being adapted as a microbiological method for monitoring biofilm growth in real time with potential to quantify biofilm eradication techniques. Methods. This in-situ approach incorporated electrodes positioned away from biofilms and analyzed them with EIS for detection of biofilms and biofilm behavior during growth. EIS conducted at frequencies from 100 kHz to 10 mHz provided label free monitoring and delivered specific information regarding physiological parameters throughout the growth cycle. This technique is insensitive to non-living matter and reflects factors related to cell density, viability, membrane integrity, and the overall metabolic state of microbes. The use of equivalent circuits provided another means of data analysis that correlated to cellular energy levels and viability over time. Removal of biofilms that may develop on electrodes in-situ during studies was accomplished with an electrochemical stripping technique prior to each analysis. Results. Communication between working and counter electrodes detected biofilms by the tangential flow of signals through biofilms. This approach detected the presence or absence of microbes at cell densities <1.2 µg protein /square cm. Electrochemical cleaning of electrodes removed biofilms as confirmed microscopically. Electrochemical data were linked to physiological status and compared to cultures grown in suspension. Conclusions. EIS provided a means to quantitively monitor biofilms and their physiological status, in-situ and in real time without the need for sample acquisition. Electrochemical stripping techniques removed biofilms successfully and may be a potential means of biofilm removal in other applications. Future studies are aimed at continuous in-situ monitoring of actively growing biofilms and the effects of antifouling treatments.