Rapid Microbial Detection and Enumeration Using Gel Microdroplets and Colorimetric or Fluorescence Indicator Systems.

摘要

A new micromethod employing microdroplets (GMDs) and optical measurements can be used for rapid detection and enumeration of viable microorganisms (J.C. Weaver, G.B. Williams, A.M. Klibanov, and A.L. Demain, Bio/Technology 6:1084-1089, 1988) and has several potential applications in clinical microbiology. This method involves entrapping microorganisms in GMDs (10 to 100 um in diameter) which are surrounded by a hydrophobic (low dielectric) fluid, subsequently distinguishing occupied and unoccupied GMDs with colorimetric or fluorescence indicators, counting both occupied and unoccupied GMDs, and applying Poisson statistical analysis. Acid-producing microorganisms were used to compare colorimetric and fluorescence pH indicator systems. Fluorescence systems were generally superior, particularly for detection before microbial growth occurred. Although colorimetric detection was reasonably fast for fast-growing microorganisms, significantly longer times were needed for slow-growing microorganisms. We investigated the dependence of the detection time on microbial division time, GMD sixe, and buffering capacity of the medium within GMDs. Biochemistry reprints. (js)