Effect of Phytoremediation with Bacillus Pumilus on Pakchoi Growth and Microbial Community Structure in Lead Contaminated Soil

This study aimed to investigate the function and safety of phytoremediation enhanced by inoculating an effective rhizosphere microbe to lead (Pb) contaminated soil.A pot experiment was conducted in a greenhouse with pakchoi planted in soil treated with different Pb level (0~1000 mg kg-1). After Bacillus Pumilus M2 inoculation, the biomass and concentration of Pb in pakchoi were determined to evaluate effects of plant growth promotion and phytoremediation enhancement. The inoculation led to remarkable growth and Pb accumulation in roots. The results showed that the Pb resistant bacteria significantly increased the biomass of pakchoi by 20.9%~28.4% than those of non-inoculated treatment. When soil was contaminated with Pb more than 800 mg/kg, the biomass of the control was decreased due to the toxic stress, but no significant change was found in inoculated pots. Pb concentration in both aboveand under-ground of pakchoi was higher than that of control. PCR-based denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene was used to study the microbial community structure, which proved that inoculating Bacillus Pumilus contributed to sustain microbial community structure and reduced toxic stress from Pb. KeywordsPb Contamination; Phytoremediation; Bacillus Pumilus; PCR-DGGE; Microbial Community Structure