Isolation of Cadmium and Lead Tolerant Plant Growth Promoting Rhizobacteria: Lysinibacillus varians and Pseudomonas putida from Indian Agricultural Soil

Abstract

ABSTRACTCadmium and lead tolerant plant growth promoting rhizobacteria can be an eco-friendly option for reclamation of metal-contaminated soil and mitigation of heavy metal stress for phytostimulation to develop sustainable agriculture. Novel heavy metal tolerant PGPR strain isolation is prerequisite in practical scale. The present study was to isolate, characterize and identify cadmium and lead tolerant PGPR strains. Some potent multi heavy metal tolerant PGPRs were isolated from rhizospheric soil contaminated with industrial, sewage or agrochemical waste and two most promising strains were identified as Lysinibacillus varians strain KUBM17 and Pseudomonas putida strain KUBM18 on the basis of 16S rDNA sequencing. These two strains were exhibiting a high degree of Cd and Pb tolerant ability with bioaccumulatory properties to remove Cd and Pb from the medium which was evidenced by AAS study. Furthermore, L. varians strain KUBM17 and P. putida strain KUBM18 showed very promising PGP traits such as ammonia production, IAA production (20–22 µg/ml), Nitrogen fixation, phosphate solubilization (55–515 ppm) and siderophore production (14–40 nmole) capability together with biocontrol properties with survival ability under different agro-climatic conditions. These PGPR isolates improved the early radish plant growth under cadmium and lead stress condition. So, KUBM 17 and KUBM 18 might be concerned as PGPR-biofertilizer in heavy metal-contaminated agricultural soil.