Electrochemical measurement of catalase activity of Eschelida coli with use of H_2O_2 selective sol-gel film-modified electrode

摘要

The catalase activity of Escherichia coli (E coli) was detected by using H2O2-selective sol-gel film modified platinum electrode. This sol-gel film is composed of three kinds of organosilanes and two biopolymers (i.e., chitosan and bovine serum albumin). This protein/polysaccharide/hybrid sol-gel membrane showed an excellent permselectivity to H2O2, based on a size exclusive mechanism. The steady-state anodic current obtained in the presence of 0.1 mM H2O2 was diminished by the addition of E. coli samples, due to the catalase activity of E. coli. The time-dependent decrease in current (I/t) was dependent on the E. coli density in the range from 106 to 107 CFU (colony forming units). Although the sensitivity is not sufficient, this electrochemical method may be applicable to discriminate calatase-positive and catalase-negative bacteria within 30 min.