tapwater 16S rRNA gene samples collected in control tank 2 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 13-base barcode.