2.3. PCR Amplification assays
All of the primer sequences targeting the 16S rRNA gene (rDNA) of
the bacterial species or groups were derived from the previously
published studies mentioned in Table 2. The PCR amplification and
optimal annealing temperatures of the PCR primers were initially
optimized with a gradient PCR in a Chromo 4 system (Bio-Rad,
Hercules, CA, USA), and these conditions were used to quantify
bacterial levels from fecal samples.