sequences of bacteria
DNA was extracted from the collected enrichment culture samples with the E.Z.N.A. Mag-Bind Soil DNA Kit (M5635-02, Omega, USA), following the manufacturer's instructions. The V4 region of 16S rRNA gene were PCR amplified by the primer 515F/806R. Sequencing was performed using the Illumina MiSeq system (Illumina MiSeq, USA) following the manufacturers protocol at Sangon Biotech Co., Ltd. (Shanghai, China).