SRP005633 Milk and formula feeding; 16S rRNA based bacterial community profiling Diet Creates Metabolic Niches in the “Immature Gut” and Shaping Microbial Communities Although diet composition has been implicated as a major factor in the etiology of various gastrointestinal diseases, conclusive evidence remains elusive. This is particularly true in diseases such as necrotizing enterocolitis where breast milk as opposed to commercial formula appears to confer a “protective effect” to the “immature gut” or juvenile intestinal ecosystem of “immature gut,” yet the mechanism by which this occurs continues to be speculative in nature. In the present study we hypothesize that basic chemical composition of diet fundamentally selects for specific intestinal microbiota which may help explain disparate disease outcome and have therapeutic implications. Complimentary animal and human studies were conducted on young piglets (21 d.)(n=8) (IACUC protocols 08070 and 08015) and premature infants (adjusted gestational age 34-36 weeks) (n=11) (IRB Protocol 15895A). In each study, cecal or stool contents from two groups (Breast milk-fed (BF) vs. Formula-fed (FF)) were analyzed by 16S rRNA gene amplicon pyrosequencing. Milk and formula feeding; neonatal piglet, 16S rRNA based bacterial community profiling This submission comprises the amplified piglet cecal 16S rRNA gene sequences generated for this project.