(Life Technologies, Carlsbad, CA, USA). PCR amplification was performed using fusion primers targeting V4 regions of the 16S rRNA gene with the extracted DNA. For bacterial amplification, fusion primers of 515F (5′-AATGATACGGCGACCACCGAGATCTACAC-XXXXXXXX-TCGTCGGCAGCGTCAGATGTGTATAAGAGACAG-GT...