Potential of rhizobacteria for bioremediation of lead accumulation in rice plants

Abstract

This research was conducted in a greenhouse pot experiment to investigate the efficiency of lead-resistant bacterial inoculation on lead accumulation in rice by comparing a variety of isolated bacteria strains (TK1, TK3, RV2, RV4) and evaluating their growth. Additionally, lead accumulation in different parts of rice plants and the ability in BCF and TF were observed. The results showed in terms of growth performance (height, fresh weight and dry weight) that there was no significant difference between rice plants grown in uncontaminated and lead-contaminated soils. The highest lead accumulation was found in roots of TK3 (57.67 mg kg-1) Enterobacter sp. inoculum, followed by shoots of TK3 (19.50 mg kg-1), and grains of RV2 (0.55 mg kg-1) Pseudomonas chlororaphis subsp. inoculum. Thus, lead concentration in grains on day 95 of the experiment exceeded the European Union Standard (0.2 mg kg-1), which might not be safe for human consumption but did not exceed the standard as animal feed (30 mg kg-1). The experimental rice plants in this study were not suitable for using in cleaning up lead-contaminated soil because the values of BCF and TF values were less than 1, but Bacillus subtilis strain EB31 from TK1 had the highest potential for lead bioremediation.