title: Intrinsic characteristics of Cr⁶⁺-resistant bacteria isolated from an electroplating industry polluted soils for plant growth-promoting activities.
abstract: The Cr(6+)-resistant plant growth-promoting bacteria was isolated from soil samples that were collected from an electroplating industry at Coimbatore, India, that had tolerated chromium concentrations up to 500 mg Cr(6+)/L in Luria-Bertani medium. Based on morphology, physiology, and biochemical characteristics, the strain was identified as Bacillus sp. following the Bergey's manual of determinative bacteriology. Evaluation of plant growth-promoting parameters has revealed the intrinsic ability of the strain for the production of indole-3-acetic acid (IAA), siderophore, and solubilization of insoluble phosphate. Bacillus sp. have utilized tryptophan as a precursor for their growth and produced IAA (122 μg/mL). Bacillus sp. also exhibited the production of siderophore that was tested qualitatively using Chrome Azurol S (CAS) assay solution and utilized the insoluble tricalcium phosphate as the sole source of phosphate exhibiting higher rate of phosphate solubilization after 72 h of incubation (1.45 μg/mL). Extent of Cr(6+) uptake and accumulation of Cr(6+) in the cell wall of Bacillus sp. was investigated using atomic absorption spectrophotometer and scanning electron microscope-energy dispersive spectroscopy, respectively. The congenital capability of this Cr(6+)-resistant plant growth-promoting Bacillus sp. could be employed as bacterial inoculum for the improvement of phytoremediation in heavy metal contaminated soils.
authors.affiliation: Rhizosphere Biology Laboratory, Department of Microbiology, School of Life Sciences, Bharathidasan University, Tiruchchirappalli, 620 024 Tamil Nadu, India.
authors.forename: B
authors.initials: B
authors.lastname: Hemambika
authors.forename: V Rajesh
authors.initials: VR
authors.lastname: Kannan
mesh_terms: D001407:Bacillus / Q000187:drug effects*; D002857:Chromium / Q000378:metabolism / Q000633:toxicity*; D024881:Drug Resistance, Bacterial; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000378:metabolism; D063245:Plant Development / Q000187:drug effects*; D012989:Soil Pollutants / Q000633:toxicity*; D012995:Solubility; D013054:Spectrophotometry, Atomic
chemical_list: D010710:Phosphates; D012989:Soil Pollutants; D002857:Chromium