title: Beta-galactosidase production by Streptococcus thermophilus is higher in the small intestine than in the caecum of human-microbiota-associated mice after lactose supplementation.
abstract: Transit kinetics and survival rates of a bacterial species from yoghurt (i.e. Streptococcus thermophilus strain FBI3) were examined in different digestive compartments of gnotoxenic and human-microbiota-associated mice. The production of the lactose-hydrolysing enzyme (i.e. beta-galactosidase) was also investigated within the digestive tract, using a chromosomal reporter system based on luciferase genes from Photorhabdus luminescens under the control of the plac promoter. In both mice models, S. thermophilus cells transited within 2 h from the stomach to the caecum-colon compartment of the digestive tract where they displayed a survival rate of nearly 100 %. In gnotoxenic mice, luciferase activity was found to increase in the second half of the small intestine and in the caecum-colon compartment when lactose was added to the drinking water provided to the animals. In human-microbiota-associated mice drinking lactose, luciferase activity was similarly increased in the second half of the small intestine but was drastically reduced in the caecum-colon compartment. This feature could be ascribed to the presence of the resident human microbiota.
authors.affiliation: Unité d'Ecologie et de Physiologie du Système Digestif, Institut National de la Recherche Agronomique, 78352 Jouy en Josas Cedex, France.
authors.forename: Denis D G
authors.initials: DD
authors.lastname: Mater
authors.forename: Sophie
authors.initials: S
authors.lastname: Drouault-Holowacz
authors.forename: Raish
authors.initials: R
authors.lastname: Oozeer
authors.forename: Philippe
authors.initials: P
authors.lastname: Langella
authors.forename: Jamila
authors.initials: J
authors.lastname: Anba
authors.forename: Gérard
authors.initials: G
authors.lastname: Corthier
mesh_terms: D000818:Animals; D002432:Cecum / Q000201:enzymology*; D015169:Colony Count, Microbial; D019587:Dietary Supplements; D005260:Female; D007421:Intestine, Small / Q000201:enzymology* / Q000382:microbiology; D007785:Lactose / Q000008:administration & dosage*; D007787:Lactose Intolerance / Q000382:microbiology; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D048249:Streptococcus thermophilus / Q000201:enzymology* / Q000502:physiology; D015014:Yogurt / Q000382:microbiology; D001616:beta-Galactosidase / Q000096:biosynthesis*
chemical_list: D008156:Luciferases; D001616:beta-Galactosidase; D007785:Lactose