16S of hexavalent chromium polluted soil at depth of 20-40 cm, initial time
DNA was isolated using an effective protocol for DNA extraction from difficult samples standardized in our lab.  Extracted metagenomic DNA was used to prepare libraries for sequencing of V3V4 hypervariable regions from 16S rRNA, for PCR amplification were used Phusion High-Fidelity. Amplicons were pooled at equimolar concentrations and cleaned using a MoBio Ultraclean PCR Clean-Up Kit, paired-end libraries sequencing was performed by UUSMB UNAM