A comparative evaluation towards the potential of Klebsiella sp. and Enterobacter sp. in plant growth promotion, oxidative stress tolerance and chromium uptake in Helianthus annuus (L.).

Prevalence of metal pollutants exerts negative effects on human health and environment, thus propounding an urgent need for a safer substitute. This study was conducted to compare the chromium bioremediation and plant growth promotion ability of two bacterial strains, Klebsiella sp. strain CPSB4 (MH266218) and Enterobacter sp. strain CPSB49 (MH532567), isolated from the rhizospheric soils. A pot scale experiment was setup with Helianthus annuus (L.) as a test plant to compare the efficiency of both isolates in enhancement of plant growth, nutrients uptake, anti-oxidative enzymes production, lipid peroxidation, and chromium bioremediation. Inoculation of strains, CPSB4 and CPSB49 enhanced plant biomass, plant growth, nutrient uptake, anti-oxidative enzymes, and chromium bioremediation, while reduction in lipid peroxidation was observed compared to uninoculated control under chromium stress. The maximum increase in plant growth and nutrient uptake was found in treatments inoculated with CPSB49, while maximum chromium uptake by sunflower was observed in treatments inoculated with CPSB4. Moreover, an increase in anti-oxidative enzyme production and decrease in lipid peroxidation was observed on inoculation of the selected strains. Thus, the strains Klebsiella sp. and Enterobacter sp. can be effectively used in chromium bioremediation and plant growth promotion under chromium stress conditions.