Expression of green fluorescent protein in Lactococcus lactis

The gfp gene from Aequorea victoria. encoding the green fluorescent protein (GFP) has been expressed in Lactococcus lactis subsp. lactic biovar cremor is MG1363, upon construction and introduction of plasmid pLS1GFP into this host. GFP was monitored in living cells during growth to evaluate its use i n molecular and physiological studies. Quantification of the levels of GFP expressed by cultures was feasible by fluorescence spectroscopy. Phase-cont rast and fluorescence microscopy allowed us to distinguish, in mixed cultur es, lactococcal cells expressing GFP. Our results indicate that GFP can be used as a reporter in L. lactis. (C) 2000 Federation of European Microbiolo gical Societies, Published by Elsevier Science B.V. All rights reserved.