PCR amplification and sequencing. The partial DNA fragments of bacterial 16S rDNA genes were amplified by PCR using a forward primer F27 (CCGGATCCAGAGTTGATCCTGGTCAGAACGAACGCT) and a reverse primer R1522 (CGGGATCCTACGGCTACCTTGTTACGACTTCACCCC),which were designed to amplify 16S rDNA fragment from the isolated bacterium (Sangon Company, Shanghai,China). The PCR product was cooled and analyzed by electrophoresis in 1% agarose gel. The desired band was excised with a sterile scalpel, eluted in sterile water overnight at 4 C, and then sent to Sangon Company for sequencing. BLAST searches were performed in public data libraries (GenBank, http://www.ncbi.nlm.nih.gov/blast/) to determine the closest known relatives of the partial 16SrDNA gene sequence obtained. Sequences with 96% or higher identity were considered to represent the same species.