RW_3_3
Stool samples were snap-frozen in liquid nitrogen and stored at -80 C until further analyzed. DNA was extracted from the fecal samples using the DNA isolation kit (Omega Bio-Tek, Norcross, GA). For each fecal sample, the V3-V4 region of the 16S rRNA gene was amplified by PCR using the forward primer (5'- ACTCCTACGGGAGGCAGCAG-3') and the reverse primer (5'- GGACTACHVGGGTWTCTAAT-3').