2.3. Bacterial identification by 16S rRNA gene sequence analysis
A few representative isolates from each distinct RAPD group were identified using 16S rRNA gene sequence analysis. Primers fD1 and rD1 were used to amplify about 1500 base pairs(bp) genome fragment with 16S rRNA gene sequences (Weisburg et al., 1991). The primers are described in Table 1. The amplification reaction was performed under the following conditions: preliminary denaturation for 5 min at 94 °C, then 30 cycles of 94 °C for 30 s, 56 °C for 30 s, and 72 °C for 1 min, and final extension at 72 °C for 10 min. The PCR productswere sequenced by a commercial sequencing facility (Shanghai Sangon Biotechnology Corporation, Shanghai). The 16S rRNA gene sequences were used to identify the isolates using EzTaxonserver aswell as NCBI database