Characterization of Rhizosphere Bacteria and Their Potency as Phytoremediation Promoting Agents for Cr (VI) Contaminated Soil

Abstract

Rhizosphere bacteria have an adaptation mechanism in the chromium contaminated environment and produce compounds that promote the heavy metal resistance of plants. Bacteria were isolated from tannery waste contaminated rhizospheric soil of Ficus septica Burm. F. Screening was done based on the level of Cr (VI) tolerance. High tolerant isolates were tested for their potential in phosphate-solubilizing, Indole Acetic Acid (IAA) production, exopolysaccharide (EPS) production, and presence of chromium reductase (ChR) genes. Based on the results of screening, there were four rhizosphere bacterial isolates (R7, R9, R10, and R12) which were tolerant to 800 mg/L of Cr (VI). All isolates were able to produce IAA, EPS, and dissolve phosphate in medium containing 150 mg/L Cr (VI). The highest production capacity of IAA (25.08 μg/mL) and phosphate-solubilizing (150.98 μg/mL) was shown by R9 isolate, while the highest EPS production was found in R12 isolate (0.02 mg/L). ChR gene was found in R10 and R12 isolates. Bacterial isolates obtained from this study were potential to be used as promoting agents for phytoremediation of Cr (VI) contaminated soil.