Isolation and characterization of two bacteria with heavy metal resistance and phosphate solubilizing capability

Two phosphate solubilizing bacteria( T PSB1 and T PSB 2) with high heavy metal resistance were isolated from soil of a lead-zinc mine in Huayuan of Hunan Province,China. These two bacteria were identified as Stenotrophomonas maltophilia and Burkholderia gladioli by 16S rRNA sequencing analysis,respectively. In the media containing insoluble inorganic calcium phosphate,the soluble phosphate amounts reached respectively 402. 9 mg·L-1and 589. 9 mg·L-1with the bacteria T PSB1 and T PSB2 after two weeks' growth. Moreover,the two bacteria developed solubilizing halos on the plates supplemented with the organic phosphate compounds,and the resulting soluble phosphate amounts in the broth media were respectively 2. 97 mg·L-1and 4. 69 mg·L-1. In addition,these two bacteria showed the resistance to up to 2 000 mg·L-1Zn2 +,and their phosphate solubilizing amounts reached respectively 114. 8 mg·L-1and 125. 1 mg·L-1. Similarly,their heavy metal resistance and phosphate solubilizing ability were also found in the Cr and Pb broth media with the concentration of 1 000 mg·L-1. In the Pb media,the soluble phosphate amounts reached respectively 57. 9 mg·L-1and 71. 7 mg·L-1,and the soluble P amounts in the Cr media were 60.1 mg·L-1and 98. 4 mg·L-1at the concentration of 1 000 mg·L-1.