Rapid detection of single cell bacteria as a novel approach in food microbiology.
Solid-phase cytometry (SPC) is a novel technique that allows rapid detection of bacteria at the single cell level, without the need for a growth phase. After filtration of the sample, the retained microorganisms are fluorescently labeled on the membrane filter and automatically counted by a laser scanning device. Each fluorescent spot can be visually inspected with an epifluorescence microscope connected to the ChemScan by a computer-driven moving stage. Depending on the fluorogenic labels used, information on the identity and the physiological status of the microorganisms can be obtained within a few hours. Although SPC was originally recommended for the determination of the total viable microbial count in water and other liquid samples, it may also be a promising technique for the detection and enumeration of bacteria in food samples, provided they can be isolated from the unfilterable matrix. The short detection time inherent in this approach is a considerable advantage over conventional plate counting, especially for slow-growing microorganisms. The basic principles of SPC are discussed as well as its potential for the detection of Mycobacterium paratuberculosis, a model example of a slow-growing bacterium in milk.
D'Haese
Eva
E
Ghent University, Laboratory for Pharmaceutical Microbiology, Belgium. Eva.Dhaese@rug.ac.be
Nelis
Hans J
HJ
D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D005434:Flow Cytometry / Q000379:methods; D005516:Food Microbiology; D008892:Milk / Q000382:microbiology; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification