AUTOMATIC ON-LINE ANALYZER OF MICROBIAL GROWTH USING SIMULTANEOUS MEASUREMENTS OF IMPEDANCE AND TURBIDITY

ROSSANA E. MADRID, CARMELO J. FELICE AND MAX E. VALENTINUZZI

MEDICAL AND BIOLOGICAL ENGINEERING AND COMPUTING

Año: 1999 p. 789 - 793

0140-0118

An apparatus for the measurement of bacterial growth is described. This instrument applies alternate adequate sequential currents of two different frequencies through a pair of electrodes immersed in a cultured medium. It monitors, detects and quantifies the growth of microorganisms based on the measurement of the impedance across the two electrodes and, simultaneously, it measures the variation of the medium turbidity. The medium conductivity and the interface electrode impedance changes can be dissected out from the measured impedance. The variations of turbidity can be calibrated in absorbance or optical density units. Moreover, as all these parameters, they are also proportional to bacterial growth. This computer-controlled apparatus processes and displays them on a monitor showing bulk resistance, electrode impedance and turbidity changes as time course events. The equipment can measure aerobic or anaerobic microorganisms and permits the operator to simultaneously assess impedance and turbidity, or it can produce each parameter as a separate event. Time growth curves of different microorganisms are presented in the results.