I am writing to you to ask if anybody has any experience with the use of
Gfp in lactic acid bacteria or other Gram-positive bacteria.
Gfp has succesfully been used as a bacterial tag and as a reporter gene in
Gram-negative bacteria by people in my lab, and some time ago we started
trying to express Gfp in Lactococcus lactis. However, this was not as
simple as we expected it to be. The dominant problem is the fluorescence
level, which is lower than in Gram-negatives. Besides, we see some
heterogeneity in fluorescence level between the cells in otherwise
homogeneous populations. We are quite sure that it is not lack of oxygen
that causes the problems. The level of fluorescence is lower and the
heterogeneity is larger at lower pH, as the fluorescence is pH sensitive,
but we also have the problems when we keep pH above 7.
So, if anyone has experience or comments, I should be very grateful.