APPLICATION OF FLOW-CYTOMETRY FOR RAPID-DETERMINATION OF CELL NUMBER OF VIABLE BACTERIA

The application of the Flow cytometry (FCM) technique for rapid determ ination of cell number of viable bacteria suspended in seawater is des cribed. A fluorescein diacetate was used to distinguish between viable cells and dead cells for various bacteria. The FCM technique was also used to discriminate between Gram-positive and Gram-negative bacteria using the LIVE BacLight(TM) Bacterial gram stain kit. A difference in the fluorescence scattergram between the two bacterial groups was obs erved. The FCM method provided rapid determination of cell number of v iable bacteria in seawater. A good correlation was observed between th e values determined by the FCM method and the colony counting method i n the range of 10(5)-10(9) cells/ml. One FCM assay could be completed within 60 s and the total assay time including the preparation of bact eria was within 35 min.