Streptococcus thermophilus Is Able To Produce a β-Galactosidase Active during Its Transit in the Digestive Tract of Germ-Free Mice

This work presents data on the application of a bacterial luciferase used to monitor gene expression of Streptococcus thermophilus in the digestive tract. The main result is that the bacterium was able to produce an active β-galactosidase in the digestive tract, although it did not multiply during its transit. This production was enhanced when lactose (the inducer) was added to the diet.