Impact of Fecal Microbiota Transplantation in Ulcerative Colitis

Inclusion Criteria: Inclusion Criteria for patients : * Age ≥ 18 years and \< 75 years * Ulcerative colitis (according to the Lennard Jones criteria) diagnosed for at least 3 months and : * Currently active (PMC \> 1) and planned to be treated by systemic corticosteroids (minimum 40mg prednisone equivalent daily) Or * Currently treated by systemic corticosteroid (minimum 40 mg prednisone equivalent daily) within max 3 weeks Or * Steroid dependent patients (at least one unsuccessful attempt to discontinue steroid within the last 6 months before inclusion) * Patient with health insurance (AME excepted) * Informed written consent * Female of child-bearing age with an active contraception and this during at least period of treatment until the end of active follow-up period (week 24) Inclusion Criteria for healthy volunteers donors : * Age ≥ 18 years and \< 50 years * 17 kg/m² \< body mass index \< 30 kg/m² * Regular bowel movement defined as at least 1 stool every other day and maximum 2 stools per day * Subject with health insurance (AME excepted) * Informed Written consent Exclusion Criteria: Exclusion Criteria for patients : * UC complication requiring surgical treatment * Patient treated with high dose corticosteroid more than three weeks before inclusion (≥ 40 mg prednisone equivalent daily) except in case of steroid-dependence * Contraindication to colonoscopy or anesthesia * Pregnancy or breastfeeding during the study * Treatment preceding the colonoscopy with: * intravenous infliximab and/or vedolizumab and/or ustekinumab (\< 6 weeks before the planned date of the colonoscopy) and/or subcutaneous infliximab (\<2 weeks before the planned date of the colonoscopy), and /or adalimumab (\<2 weeks before the planned date of the colonoscopy) and/or golimumab and/or tofacitinib (\<4 weeks before the planned date of the colonoscopy) * immunosuppressant (thiopurine, methotrexate, tacrolimus or other classical immunosuppressant) started or stopped \< 3 months before the planned date of the colonoscopy * Antibiotics, antifungic or probiotics treatment \< 4 weeks before the planned date of the colonoscopy * participation in any other interventional study * patient under legal protection Exclusion Criteria for healthy volunteers donors : \- For details, please see protocol.