Biosorption and Symbiotic Potential of Horse Gram Rhizobia in Soils Contaminated with Cobalt.

The current study aims evaluation of biosorption and symbiotic potential of horse gram plants associated with rhizobia inspite of Cobalt (Co) metal stress, and these rhizobia strains play a pivotal role in the phytoremediation of Co heavy metal-contaminated soils. Horse gram rhizobial isolates HGR-4, HGR-6, HGR-13 and HGR-25 were able to tolerate 1000 µg g Co supplemented in culture media and also 100 µg g in Co supplemented soil. The plants nodulated with the isolates from the study have shown higher nodulation, nitrogen and leghaemoglobin content in the potted experiment on par with the control plants. Atomic absorption spectroscopic analysis of Co content in horse gram plants inoculated with these four isolates showed maximum biosorption of Co among the bacterial root nodules. Application of these strains can be potentially aid the phytoextraction of Co from contaminated soils on association with horse gram plants.