How Chromium-Resistant Bacteria Can Improve Corn Growth in Chromium-Contaminated Growing Medium
Hadia-e-Fatima, Ambreen Ahmed
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Department of Botany, University of the Punjab, Quaid-e-Azam Campus,
Lahore 54590, Pakistan
Submission date: 2016-02-16
Final revision date: 2016-05-20
Acceptance date: 2016-05-21
Publication date: 2016-11-24
Pol. J. Environ. Stud. 2016;25(6):2357–2365
Chromium is a heavy metal found in various oxidation states (Cr3+ to Cr6+). It is a highly toxic metal widely used in a number of industries and is generally found to have a carcinogenic impact on living organisms. Although there are chemical and biological approaches for reducing chromium toxicity in the environment, in industrial areas green cover is largely affected by this metal contamination through plant growth retardation. To reduce these toxic effects, some auxin-producing bacterial species living in the rhizosphere have proven to be effective in reducing toxic hexavalent chromium [Cr (VI)] into a less toxic state, i.e., trivalent chromium [Cr (III)]. The present study reveals the potential of chromium-resistant auxin-producing bacteria for bioremediation. For this purpose, plant growth-promoting bacteria that are capable of growing in the presence of chromium were isolated from different industrial areas. The impact of isolated strains on reducing the toxic effects of chromium was analyzed by comparing different growth parameters of inoculated and non-inoculated treatments of Zea mays in the presence and absence of chromium stress. Increments in shoot length of the treated plants was noted up to 23% due to bacterial inoculation with Halomonas sp. (AST) under chromium stress of 1,000 μg/ml (K2CrO4) as compared to control. Similarly amount of auxin produced in the treated corn plants was improved up to 161% in treatments with Bacillus cereus (3a) over respective control. These findings suggest that the above mentioned chromium-resistant auxin-producing bacterial isolates can serve as an ecofriendly tool to improve crop production in soils contaminated with chromium.