Rapid evaluation of biofilm attachment promoters and biofilm growth orientation using a mini-impedimetric device

Abstract

The time response of the impedance of a thiosulfate oxidizing bacterial strain growing in culture wells containing 10 active gold mini-electrodes was experimentally measured in this study. Based on a proposed RC circuit that describes the electrode-culture well as an equivalent array of capacitors and resistors, the shape of the time response of the observed total capacitance was anticipated to correlate with the preferential biofilm growth direction (perpendicular to or along the gold mini-electrode surface). Based on this correlation and the proposed model, it was found that when pre-coating the electrodes with an aqueous polyethyleneimine (PEI) solution, the spreading of the biofilm was more intense than in the untreated electrodes, which was later observed through confocal laser scanning microscopy. Similar results were obtained when using poly- d-lysine or calf skin collagen as coating agents, though the spreading of the biofilms was always more intense in the PEI coated ones.