Molecular identification of the selected isolates: Total genome DNA of each isolate was extracted from 5 ml overnight cultures grown in MRS broth at 30°C by CTAB (cetyltrimethylammonium bromide) method 16 with modifications. Purified DNA was diluted to 100 ng/µl for following test. The isolated strains were identified by 16S rRNA sequencing and phylogenetic analysis. For each strain, specific region of 16S rRNA was amplified using the genomic DNA as a template, and primers 27f (5’-AGAGTTTGATCCTGGCTCAG-3’) and 1495R (‘5- CTACGGCTACCTTGTTACGA-3’) 17. PCR amplifying procedure was as follows: 5 min at 94°C, 30 cycles of 1 min at 94°C, 1 min at 58°C, 2 min at 72°C and then 10 min at 72°C. It was carried out on the automatic thermal cycler (MJ Research PTC-200). The purified PCR products were sequenced by Shanghai Sangni Biosciences Corporation of China (Shanghai, China). The sequence of all phylotypes was further used to construct the phylogenetic tree. The obtained sequences of all phylotypes in this study were deposited in the GenBank database.