phnD genes in 100 m (CRX1066027; CRA016611)
DNA was extracted from the filter using the FastDNA Spin Kit for soil (Mo Bio Laboratories, USA) according to the manufacturer's instructions. Quantification of the phnJ and phnD gene copies was performed by quantitative polymerase chain reaction (qPCR) on the total extracted DNA.  The primer pair used for the phnD gene consisted of the forward primer phnD-F TCGGNGCMATYCCSGATCAGAACCCSG and the reverse primer phnD -R GGNCGNGCCACCCAGTGGTARTC.