16S amplicon Illumina sequencing
PCR amplification for high-throughput 16S rRNA sequencing was carried out with the universal primer pair 515F (5-GTGYCAGCMGCCGCGGTA-3) and 909R (5-CCCCGYCAATTCMTTTRAGT-3) targeting the hypervariable V4-V5 region of the 16S rRNA gene.