Molecular identification of lead-resistant plant growth promoting Bacillus species isolated from lead-contaminated soil

Abstract

Introduction: Soil contamination by heavy metals, including lead, is one of the most important environmental hazards and a major factor in the ecological collapse. Bioremediation by resistant bacteria is one of the suitable methods for the removal of these heavy metals, which has other advantages, including environmental compatibility, low cost and stimulation of plant growth. The present study was conducted to isolate and identify lead-resistant rhizobacteria from long-term lead-contaminated soil based on morphological characteristics, biochemical tests and sequencing of 16SrRNA gene. Materials and Methods: The rhizosphere samples were collected and diluted on the modified LB media.The colonies were studied based on morphological characteristics, biochemical tests, and ultimately molecular identification based on sequencing of the 16SrRNA gene. Results: Five isolates of lead-resistant Rhizobacteria were identified in this study. All strains showed the ability to tolerate high concentrations of lead (3.26 to 5.9 mM), moreover, all samples have the ability to produce indole acetic acid (88.87 to 38.58 mgl-1). Discussion and Conclusion: Inoculation of hyperaccumulator plants with these lead tolerant rhizobacteria can be effective in improvement of the phytoremediation efficiency in lead contaminated soils.

Keywords

• lead-resistant rhizobacteria
• plant growth regulators
• minimum inhibitory concentration
• iaa
• 16srrna