BACKGROUND: Heavy metal resistant bacterium Enterobacter sp. C1D was evaluated for cadmium (Cd) mediated exopolysaccharide production, biofilm formation and legume root colonization ability under Cd stress to alleviate metal induced stress. RESULTS:The plant was sensitive to Cd (IC 50 3-4 g mL −1 ), whereas the bacterium showed high Cd tolerance (MIC 99 120 g mL −1 ). Confocal laser scanning microscopy of the Cajanus cajan roots showed heavy loads of green fluorescence protein labelled Enterobacter sp. C1D on the surface of plant root, specifically at the point of root hair/lateral root formation along with cortex, even under metal stress. The root colonizing ability of Enterobacter sp. C1D was not affected by the presence of Rhizobium and the bacteria could be observed after 30 days of incubation in soil. Various plant growth parameters, antioxidant metabolites and oxidative stress indicator were significantly influenced by bacterial treatment, which, overall, reduced the adverse effect of Cd. CONCLUSION: Heavy metal tolerant bacteria may be a good choice for the development of biofertilizers and may work well with the native soil microbes such as Rhizobium under the metal polluted soil. Soil experimentsSterilized soil was amended with 0 or 50 or 100 mg kg −1 of Cd and/or inoculated and incubated in a greenhouse for 30 days. Root length, shoot length, fresh weight, number of pods, number of seeds, dry weight of pods, chlorophyll, H 2 O 2 and malondialdehyde (MDA) content, cellular glutathione, and non-protein thiol, protein and antioxidant enzyme from leaf extract were estimated.

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