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Direct Epifluorescence Microscopy (DEFT)

The Direct Epifluorescent Filter Technique (DEFT) is a rapid method for enumerating bacteria. Used widely in the dairy industry for milk and milk products, it has also been applied to beverages, foods, clinical specimens and in environmental research.

deft_micro_smallAn introduction to DEFT

The Direct Epifluorescent Filter Technique involves capturing bacterial cells on the surface of polycarbonate membrane filters, staining with a fluorochrome such as acridine orange, and visualisation using epifluorescence microscopy. Enumeration of bacteria is greatly facilitated by image analysis and using the Sorcerer Image Analysis system.

Semi-automatic enumeration of DEFT by image analysis

The high speed count and feature measurement capabilities of Sorcerer Image Analysis are ideal for the Direct Epifluorescent Filter Technique. Fluorescing cells are viewed in real time by Sorcerer’s high sensitivity CCD video camera and viable & non-viable cells readily distinguished by virtue of contrast differences.

Different parts of the membrane filter are systematically scanned with bacterial counts transferred directly to Microsoft Excel for customised data processing and reporting.

Sorcerer features for Direct Epifluorescence Microscopy

  • Live imaging direct from the microscope
  • Automatic count and sizing of fluorescent cells
  • Discrimination between visible and non-visible cells
  • Data transfer directly to Excel or Oracle databases
  • Electronic signature and GLP compliance
  • Wide range of proven applications

Sorcerer Image Analysis

Find out more about the Sorcerer Image Analysis system.


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