18S rRNA sequencing
The bacterial 16S rRNA gene V4 region was targeted using the universal primer pair 338F (5 -ACTCCTACGGGAGGCAGCAG-3) and 806R (5-GGACTACHVGGGTWTCTAAT-3).The 18S rRNA gene was amplified using the universal primer pair 454F (5-CCAGCASCYGCGGTAATTCC-3) and V4r (5-ACTTTCGTTCTTGATYRA-42)