Characterization of a novel Cr6+ reducing Pseudomonas sp with plant growth-promoting potential

The isolate RNP4 obtained from a long-term tannery waste contaminated soil was characterized and presumptively identified as Pseudomonas sp. The strain RNP4 tolerated concentrations up to 450 mg Cr6+/L on a Luria-Bartani (LB) agar medium and reduced a substantial amount of Cr6+, to Cr3+, in the LB liquid medium. The ability of performing multifarious activities in tandem suggested the uniqueness of isolate RNP4. The strain produced a substantial amount of indole acetic acid (IAA) in tryptophan-supplemented medium. The strain also exhibited the production of siderophore and solubilization of phosphorus in mineral salt medium and SRSI medium, respectively. Concurrent production of IAA and siderophore and the solubilization of phosphorus revealed its plant growth promotion potential. Furthermore, the strain was able to promote the growth of black gram, Indian mustard, and pearl millet in the presence of Cr. Thus, the innate capability of this novel isolate for parallel bioremediation and plant growth promotion has significance in the management of environmental and agricultural problems.