A simple chemiluminescence-based method for rapid enumeration of Listeria spp. microcolonies.
OBJECTIVE
Listeria monocytogenes is capable, under certain conditions, of producing chemiluminescence which is amplified by luminol. This property was used to detect and count microcolonies of Listeria spp. in a few hours, without the use of a microscope.


RESULTS
After trapping Listeria cells on polyvinylidene fluoride membranes, a chemiluminescence mixture was sprayed onto the membrane. The chemiluminescent spots emitted were analysed by a charge-coupled device camera connected to a data-processing system, which restored the intensity of the signals into three dimensional images. The intensity of the luminescence of microcolonies was improved by addition of cellobiose, and by brief exposure to u.v. light.


CONCLUSIONS
Microcolonies of Listeria spp. can be imaged and counted by luminol-enhanced chemiluminescence with a photon-counting system.


CONCLUSIONS
This method can be applied to the rapid detection and counting of Listeria spp. in raw milk.
Vidon
D J
DJ
Département des Sciences de l'Aliment, Université Louis Pasteur, Illkirch Cedex, France. dvidon@pharma.u-strasbg.fr
Donze
S
S
Muller
C
C
Entzmann
A
A
Andre
P
P
D000818:Animals; D015169:Colony Count, Microbial / Q000379:methods*; D005516:Food Microbiology; D007089:Image Enhancement / Q000295:instrumentation; D008087:Listeria / Q000302:isolation & purification*; D008163:Luminescent Measurements; D008567:Membranes, Artificial; D008892:Milk / Q000382:microbiology*; D017785:Photons; D011145:Polyvinyls; D005465:Fluorocarbon Polymers
D008567:Membranes, Artificial; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers