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Fluorescence-based detection of lacZ reporter gene expression in intact and viable bacteria including Mycobacterium
B Rowland1, A Purkayastha, C Monserrat
1David Axelrod Institute, Wadsworth Center, New York State Department of Health, P.O. Box 22002, 120 New Scotland Ave, Albany, NY 12208, USA.
Abstract:
A variety of fluorescein di-beta-D-galactopyranoside (FDG)-based substrates were evaluated for measuring beta-galactosidase expression in bacteria. One substrate, 5-acetylamino-FDG (C2FDG), performed well in all bacteria tested, including the slow growing mycobacterium, Mycobacterium bovis BCG. The sensitivity of C2FDG in intact, viable BCG was similar to that of o-nitrophenyl-beta-D-galactopyranoside in cell lysates when used to measure lacZ reporter gene activity. C2FDG was approximately 70-fold more sensitive than green fluorescent protein (GFP) in BCG when assayed in a fluorescence plate reader, 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.