Chromium tolerant plant growth promoting rhizobacteria from the rhizosphere of Trifolium pratense and Melilotus albus

Industrialization and ever-growing population are resulted in exploitation of natural resources and cause flushing of toxic contaminants into the environment. Present study investigates the isolation and identification of beneficial bacterial population from the rhizosphere zone of two plants – red clover (Trifolium pratense) and white sweet clover (Mililotus albus) growing in vicinity of Cr mine, near Verkhnyaya Pyshma town, Russia. Significant number of plant growth promoting rhizobacteria capable to solubilize tri-calcium phosphate and produce indole-3-acetic acid with and without Cr (0, 100 and 200 mg/L) was studied at 24 h and 120 h. For most of the bacterial isolates, the phosphate solubilization and indole-3-acetic acid production was reduced with increase in Cr concentration at 24 h however, enhanced phosphate solubilization and decreased Indole-3-acetic acid was found at 120 h. The study suggests that isolated bacterial strains are capable to tolerate 100 mg/L of Cr without showing any significant change in results and can help in bioremediation of Cr contaminated sites.