BACTERIAL-ACTIVITY MEASUREMENTS BY MEDIATED AMPEROMETRY IN A FLOW-INJECTION SYSTEM

This report describes a method for enumerating microorganisms which co mbines electrochemical detection with flow injection analysis. It is b ased on the measurement of electrical currents generated by active mic robes in the presence of redox mediators (i.e., low molecular weight e lectron acceptors) that are permeable to the bacterial cell membrane. Analysis of samples could be done in 10 min, at a lower limit of detec tion of 10(5)-10(6) bacteria per milliliter. The results also provided new insights into factors that limit the lower limits of sensitivity of the mediated amperometric detection system. Information for the des ign of a convenient and semi-automated test format for use by laborato ry personnel, or for an automated system which could function on-line for bioprocess or quality control, was obtained.