Those aren't particularly new things to study. We have tons of murine data on the subject and quite a few PhD students over the last 4-6 years have done their PhDs on microbiota and diet with themselves as the guinea pig, so to speak (2-4 year longitudinals).
There are a couple mouse papers out that don't directly address the issue in 2, but that permanence (or lack thereof) played prominent roles in their findings.
There are a couple mouse papers out that don't directly address the issue in 2, but that permanence (or lack thereof) played prominent roles in their findings.