Beneficial rhizospheric associated traits of chromate resistant bacteria for remediation of Cr (VI) contaminated soil

Agricultural fields are polluted with Cr (VI) due to the excessive use of industrial effluent for irrigation purposes. The current study was focused on evaluating and comparing the impact of chromate stress on wheat growth with distilled water and industrial effluent, with and without inoculation of bacteria. All chromate-resistant bacteria (UT8, UT25, AKR2, LM3, LM8, and NY2) isolated from polluted environments proficiently resisted K2CrO4 (1500 mu g/ml). Staphylococcus simulans UT8 significantly produced plant-growth-promoting compounds such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase (365.05 nmol alpha-ketobutyrate mg/protein/h), indole acetic acid (IAA) production (77.14 mu g/ml), and hydrogen cyanide (HCN). Strain UT8 showed an increment in the germination of seeds (38.47%), and root and shoot length (95.19 and 119.29%, respectively) under chromate stress (350 mu g/ml) as compared to uninoculated controls. Similarly, UT8 inoculated seedlings also exhibited remarkable augmentation in the plant height (49.18%), tiller number/plant (87.96%), and grain yield/pot (108.96%) under chromate as compared to inoculum free treatment (control). Scanning electron micrographs of S. simulans UT8 treated seedlings root exhibited enhanced colonization in the presence of Cr (VI). Chromate removal potential of strain UT8 and the competence to secrete active phytohormones make it among the agronomically potent microorganisms to enhance wheat growth in metal-polluted soils.

Automated summary

This study evaluated the impact of chromate stress on wheat growth by comparing the effects of distilled water and industrial effluent, with and without bacterial inoculation. The results showed that chromate-resistant bacteria significantly promoted wheat growth, especially in terms of seed germination and root and shoot length. Staphylococcus simulans UT8, in particular, showed promising results with increased germination and enhanced plant height, tiller number, and grain yield under chromate stress.