Organic acid, phosphate, sulfate and ammonium co-metabolism releasing insoluble phosphate by Klebsiella aerogenes to simultaneously stabilize lead and cadmium

Here, a novel phosphate-solubilizing bacterium (PSB), Klebsiella aerogenes Wn was applied to develop an environmental-friendly method to simultaneously stabilize Pb and Cd. The maximum dissolved phosphate was up to 701.36 mg/L by the strain Wn. The high performance liquid chromatography (HPLC) and Pearson correlation analyses showed that the acetic acid produced by the strain Wn was significantly positively associated with the released phosphate. Moreover, 100% of 500 mg/L of Pb and 100 mg/L of Cd were simultaneously stabilized in the classical NBRIP medium and the major products were Pb5(PO4)3Cl, Ca7.7Cd0.8(PO4)8(H2O)2.4 and CdS, respectively. In addition, the bacterial genome and transcriptome analyses showed that the pentose phosphate pathway (PPP), pyruvate metabolism pathway, thiamine metabolic pathway, sulfate reduction and ammonium bio-transformation were coupled to promote releasing insoluble phosphate and stabilizing Pb and Cd. In the metabolism networks, the critical genes of gcd, aceE, thiE, thiS and cysH, etc. were significantly up-regulated. Our results are beneficial to deeper understand the molecular mechanisms of releasing insoluble inorganic phosphate by PSBs and develop a technology prototype to simultaneously stabilize Pb and Cd using the PSBs.