Keywords fecal microbiome transplantation microbiome microbiota Introduction The intricate relationship between the human host and its indigenous commensal populations, collectively termed the microbiome, impacts host metabolism,1 immunity,2 and a large variety of communicable and non-communicable diseases, ranging from neurodegenerative diseases (e.g., Parkinson’s disease [PD]) to cancer.1,3,4 One attractive feature of the microbiome and its host regulatory capacity is that, in contrast to...