PBS tryp-
GF mice (C57BL/6) received either tryptophan (trp)-free or trp-sufficient diets. The trp-sufficient diet (0.2% trp) matched proportions of the trp-deficient diet in macronutrients, with added mineral and vitamin supplements (35 and 1.5 g/kg, respectively). After two weeks, mice were gavaged with LGG (108 CFU/ml in 200 l PBS) or PBS, and diets were maintained until sacrifice 21 days post-inoculation.