Bacterial community dynamics during bioremediation of Cr(VI)-contaminated soil

• A successful bioremediation of Cr(VI) contaminated soil was achieved.
• P. phragmitetus BB efficiently remediated Cr(VI) from non-sterile soils.
• P. phragmitetus BB plays a key role in Cr(VI) remediation process.

Pannonibacter phragmitetus BB was utilized to intensify the remediation of Cr(VI)-contaminated soil. The dynamics of indigenous bacterial community and the role of exogenous P. phragmitetus BB in the bioremediation process were investigated. Water soluble Cr(VI) and pH of the contaminated soil were 518.84 and 8.64 mg kg−1, respectively. Cr(VI) in contaminated soil and leachate were completely reduced within two days. Restriction fragment length polymorphism (RFLP) revealed that the relative abundance of P. phragmitetus BB ranged from 35.5 to 74.8% during the bioremediation process, which was dominant in the soil bacterial community. Real-time quantitative PCR revealed that the population of P. phragmitetus BB in soil maintained relatively stable within the first 48 h (about 2.0 × 109 cells per gram soil), and the concentration of P. phragmitetus BB increased dramatically after the first 48 h. The results suggest that P. phragmitetus BB can play a key role and get competitive advantages in the remediation Cr(VI) contaminated soil.