Exposure to soil in the living environment modifies 1 gut microbiota and supports immune tolerance in a 2 mouse model 3 4

a. Department of Biosciences, University of Helsinki, Helsinki, Finland 9 b. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, 10 Sweden 11 c. Department of Bacteriology and Immunology, University of Helsinki, 12 Helsinki, Finland 13 d. Faculty of Veterinary Medicine, Department of Equine and Small Animal 14 Medicine, University of Helsinki, Finland 15 e. Finnish Institute of Occupational Health, Helsinki, Finland 16 17