wastewater 16S rRNA gene samples collected in treatment tank 6 in February
Total DNA was extracted from the water samples using PowerWater DNA Isolation Kit (Mo Bio, CA, USA). DNA from the two filters (1.2-m and 0.22-m) were pooled together as one sample. The V4-V5 hypervariable region of the bacterial 16S rRNA gene was amplied with a forward primer 515F and a reverse primer 909R containing a unique 16-base barcode.