Mouse gut metagenome
The extracted DNA from fecal sample of each mouse was used as template to                  amplify the V3 region of 16S rRNA gene. The forward primer was 5'-NNNNNNCCTACGGGAGGCAGCAG-3',                  and the reverse primer was 5'-NNNNNNATTACCGCGGCTGCT-3', where the underlined sequence                 is the universal bacterial primer P1 and P2. The NNNNNN is the unique 6nt barcode used                  to distinguish PCR product from different samples.                 The products from different samples were mixed at equal ratios for pyrosequencing.