Nondestructive, reagent-free, low-volume fluidic set-up to study biofilms by using a transparent electrode, allowing simultaneous electrochemical and optical measurements.

Abstract

The aim was to develop an electrochemical/optical set-up and correlate it (as validation) with other chemical and physical methods to obtain a simple and cost-effective system to study biofilm formation. A simple microfluidic cell and methods allowed continuous monitoring of the first, critical steps of microbial attachment. We monitored sulfate-reducing bacteria (SRB) at the early stages of biofilm formation. Herein, we studied the formation and adherence of SRB consortium biofilms over an indium tin oxide (ITO) conducting surface using microbiological and chemical methods, microscopic observations [scanning electron microscopy (SEM) and optical], and electrochemical impedance spectroscopy (EIS) measurements. The SRB biofilm formation was evaluated for 30 d by SEM and EIS. Charge transfer resistance decreased when the microbial population colonized the electrode. The monitoring of early-stage biofilm formation was performed using EIS at a single frequency of 1Hz during the first 36 h. The simultaneous use of optical, analytical, and microbiological methods allowed us to connect the kinetics of the growth of the microbial consortium to the values obtained via the electrochemical technique. The simple setup we present here can help laboratories with limited resources to study biofilm attachment and facilitates the development of various strategies to control biofilm development in order to avoid damage to metallic structures (microbiologically influenced corrosion, MIC) or the colonization of other industrial structures and medical devices.