Enumeration of Carnobacterium divergens V41, Carnobacterium piscicola V1 and Lactobacillus brevis LB62 by in situ hybridizationflow cytometry

The specific detection and enumeration of Lactobacillus brevis LB62, Carnobacterium divergens V14 and Carnobacterium piscicola VI were studied by in situ hybridizationflow cytometry. The method was performed on the exponential growth phase with three probes targeting 16S rRNA labelled with fluorescein isothicyanate (FITC) : EUB338 probe universal for Eubacteria, Lb probe specific for Lact. brevis and Cb probe specific for the genus Carnobacterium . EUB338 was used to determine the permeabilization and hybridization conditions for the cells. The Lb probe gave no hybridization signal whereas the Cb probe allowed the detection and quantification by flow cytometry at 520 nm of the two Carnobacterium strains in pure culture or in mixtures with Listeria innocua F.