Individual and combinatorial application of Kocuria rhizophila and citric acid on phytoextraction of multi-metal contaminated soils by Glycine max L

Plant-microbe-chelator synergy has been considered as an important phytoremediation strategy to enhance heavy metal extraction from contaminated soil. Plant growth promoting bacteria (PGPB) and organic acids such as citric acid (CA) are important regarding the plant growth and induction of antioxidative defense under abiotic stress conditions. The current study was conducted to investigate the possibility of phytoextraction potential and stress tolerance of Glycine max L. in multi-metal contaminated soil by the manipulation of plant growth promoting endophyte Kocuria rhizophila and citric acid. CA. It was observed that the application of K. rhizophila or CA showed significant influence on growth promotion and metal accumulation capability of G. max L. in industrial contaminated and cadmium spiked (100 and 200 mg kg(-1)) soils. The individual application of K. rhizophila and CA led to a significant increase in biomass (both fresh and dry) and metal uptake, but the effects of K. rhizophila and CA synergy were more noticeable. The co-application of K. rhizophila and CA enhanced plant biomass by about 38.73% and the accumulation of Cd, Cr, Cu and Ni about 40.63%, 56.39%, 59.1% and 39.76%, respectively as compared to non-inoculated and non-treated plants. The analysis of bioconcentration (BCF) and translocation factor (TF) revealed that G. max L. had a phytoextraction capability. It is concluded that microbechelator co-application is an efficient strategy to further improve the efficiency of phytoremediation.