Electrochemical sensor for viable microbial cell concentration based on a functional polymer that captures microorganisms alive

Abstract

We prepared an electrochemical sensor that rapidly determines the concentration of viable cells of aerobic and facultatively anaerobic microorganisms in aqueous suspension. It consists of a flow cell containing an oxygen electrode and non-woven cloth coated with 10 mg·g −1 of a copolymer of N-benzyl-4-vinylpyridinium chloride and styrene, a pyridinium-type polymer. When a sample suspension of microorganisms cells is passed through the electrochemical sensor at a constant flow rate, the microbial cells are captured and accumulated on the surface of the non-woven cloth in the living state. The consumption of oxygen by the captured living cells appears as a decrease in the electric current. Rate of decrease of the electric current is proportional to the concentration of viable microbial cells. A control suspension of bacterial cells killed by autoclaving gave a negligible decrease in the electric current. Each measurement required about 10 min. The minimum detectable concentration of living microbial cells expressed as turbidity at 610 nm was 0.005 to 0.023. The minimum detectable concentration in colony count was 3.7 × 10 5 cells·ml −1 in the case of Escherichia coli.