title: Metabolic adaptation of Lactococcus lactis in the digestive tract: the example of response to lactose.
abstract: Lactococcus lactis is a model of food-grade lactic acid bacterium, which can durably colonize the digestive tract of germ-free mice. To study in vivo the bacterial adaptation to a novel nutritional resource brought by alimentation, the lactose-catabolizing strain IL2661 of L. lactis was established in monoxeny in mice. Half of the mice then received a lactose-rich diet. The mouse has no efficient intestinal lactase and is well adapted to a follow-up of the metabolic activity of microbial origin. The analysis of lactose and lactate in the feces suggested that L. lactis was able to use lactose in vivo. We developed a proteomic approach to evaluate in deeper details the metabolic response of the bacterium. We observed that L. lactis switched its metabolism to use the novel carbon source and reduced the level of proteins involved in an alternative mode of ATP production. In parallel, we also found that the amount of proteins involved in transcriptional regulation, transport and catabolism decreased in the presence of lactose. The proteome analysis informed us about the resources used by the bacteria in absence of lactose. In competition experiments, we found that the metabolic adaptation gives a strong ecological advantage to the bacteria able to efficiently utilize lactose.
authors.affiliation: Unité Biochimie Bactérienne, Institut National de la Recherche Agronomique, Centre de Recherches de Jouy-en-Josas, Jouy-en-Josas, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Roy
authors.forename: Jamila
authors.initials: J
authors.lastname: Anba
authors.forename: Gérard
authors.initials: G
authors.lastname: Corthier
authors.forename: Lionel
authors.initials: L
authors.lastname: Rigottier-Gois
authors.forename: Véronique
authors.initials: V
authors.lastname: Monnet
authors.forename: Michel-Yves
authors.initials: MY
authors.lastname: Mistou
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D005856:Germ-Free Life; D013294:Lactococcus lactis / Q000254:growth & development / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D020543:Proteome
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D007785:Lactose