RESUMO
Hexavalent Chromium [Cr(VI)], a toxic inorganic pollutant of agriculture soil derived from variousanthropogenic industrial sources, disturbs vegetation and contaminates the food chain. Chromate microbialtoxicity was studied using plant growth-promoting chromate reducing Pseudomonas aeruginosa ATCCP15442 (P15). With a minimum inhibitory concentration of 1,250 µg/ml Cr(VI), the isolate is capable of 98%bioreduction of 100 µg/ml Cr(VI) in 24 hours and 83% of 500 µg/ml Cr(VI) in 72 hours. Additionally, P15shows tolerance to cross heavy metal pollutants (Cd, Pb, and Zn), halotolerance, and the production of plantgrowth-promoting substance, such as indole acetic acid (IAA), siderophore, and phosphate solubilization in thepresence and absence of Cr(VI). This study also reports that 100 and 250 µg/ml Cr(VI) decreases the productionof IAA, siderophore, and phosphate solubilization without affecting the growth or Cr(VI) bioreduction ability.In Vigna mungo seed bacterization assay, P15 is capable of enhancing root and shoot length in absence ofCr(VI) and reversing toxic effects of 100 µg/ml Cr(VI). No enhancement of plant parameters was observed athigher Cr(VI) concentrations, except reversal of Cr toxicity. These data are indication of the detrimental effectof Cr(VI) pollution on rhizospheric microbial flora associated with plant growth-promoting activities.