Fluorescence-based detection of lucZ reporter gene expression in intact and viable bacteria including Mycobacterium species

A variety of fluorescein di-beta-D-galactopyranoside (FDG)-based substrates were evaluated for measuring beta-galactosidase expression in bacteria, On e substrate, 5-acetylamino-FDG (C2FDG), performed well in all bacteria test ed, including the slow growing mycobacterium, Mycobacterium bovis BCG. The sensitivity of C2FDG in intact, viable BCG was similar to that of o-nitroph enyl-beta-D-galactopyranoside in cell lysates when used to measure lacZ rep orter gene activity, C2FDG was approximately 70-fold more sensitive than gr een fluorescent protein (GFP) in BCG when assayed in a fluorescence plate r eader, and comparable to GFP when measured by flow cytometry, These assays provide an important new alternative for the rapid measurement of reporter gene expression in viable bacteria. (C) 1999 Federation of European Microbi ological Societies, Published by Elsevier Science B.V. All rights reserved.