RAPID DETECTION OF ESCHERICHIA-COLI USING A SEPARATED ELECTRODE PIEZOELECTRIC CRYSTAL SENSOR

A separated electrode piezoelectric crystal sensor was used to determi ne Escherichia coli bacteria. This method is based on the fact that th e resonant frequency shifts with the culture time in a culture medium where E. coli is inoculated, and the frequency detection time (FDT) is linearly related to the initial number of E. coli in the range 10-10( 6) cells ml(-1). Factors that affect the determination are discussed. E. coli determination in pure culture was tested by the FDT method and compared with the most probable number technique and standard plate c ounts method. A correlation coefficient of 0.96 was obtained between t he FDT and the decadic logarithm of initial concentration of bacteria. The proposed piezoelectric method is much more rapid and sensitive fo r determining microorganisms than the traditional methods.