The present invention is a microbially inert, optimized carrier medium for fresh Fecal Microbiota Transplantation samples, intended for same-day transplantation, in which the carrier material is gastrointestinally active while remaining predominantly microbially inert. The key active agent in the present optimized collection and transplantation medium is polyethylene glycol, and in one embodiment of the invention the 1,000,000 to 10,000,000 grams per mole molecular weight of the polyethylene glycol provides a useful high viscosity to the present collection/carrier medium.
