Improvement of economic Phytoremediation with heavy metal tolerant Rhizosphere Bacteria

Phytoremediation is an emerging low-cost and ecologically benign technology for decontamination of soils. Heavy metals are continuously being added to soils through various agricultural and industrial activities such as the use of agrochemicals and the long-term deposition of urban sewage sludge on agricultural soils, waste disposal, waste incineration and vehicle exhausts. All these sources cause accumulation of these elements in agricultural soils and pose a threat to food safety and potential health risks. A number of plant growthpromoting rhizobacteria (PGPR) belonging to various taxonomic groups contain the enzyme l-aminocyclopropane-l-carboxylate (ACe) deaminase, which hydrolyses ACC, the immediate precursor of the plant hormone ethylene. The application of heavy metal solubilizing microorganism is a promising approach for increasing heavy metal bioavailablity in heavy metal amended soils. This work is highly focused on isolating heavy metal tolerant bacteria and isolated 5 cadmium tolerant bacteria (Proteus sp., Bacillus sp., Clostridium sp., Alcaligenes sp. and Coccobacillus sp.) and studying deaminase activity of methionine and alanine by estimating the level of a-Ketobutyrate which helps us to know the mechanism of plant growth promotion. It was observed that deaminase activity was comparatively high in Proteus sp. and it was found to be 0.78 (Deaminase assay of methionine) and 0.69 (Deaminase assay of alanine) at 360 nm. Even though cadmium is a toxic heavy metal, the cadmium tolerant organisms like Alcaligenes sp. (0.8, 2.2 cm), Bacillus sp. (004, 1.2 cm), Coccobacillus sp. (0.3, 1.0 cm), Clostridium sp. (0.7, 2.8 cm) and Proteus sp. (1A, 1.8 cm) helped the seedlings to grow and it was observed by the elongation of both root and shoot length. Moreover, it helped in the remediation of cadmium present in the environment.