Development of heavy metal-resistant mutants of phosphate solubilizing Pseudomonas sp. NBRI 4014 and their characterization.

Pseudomonas sp. NBRI 4014 is a potent phosphorus solubilizer (284 microg/ml). It also produced significant levels of siderophore (143.87 microg/ml) and IAA (5.6 microg/ml). Siderotyping indicated it was P. aeruginosa siderovar 1. Cadmium (180 microM), nickel (420 microM), and chromium (370 microM) resistant mutants were developed and characterized for their PGPR properties. Mutants were stable under non-selective pressure. In cases of nickel and cadmium, there were reductions of the siderophore levels. However, they were able to promote root and shoot elongation in soybeans ( Glycine max PK 564) at a significant level (p < 0.05) in the presence of metals unfamiliar to the wild type. The persistence and stability of mutants were evident in rhizospheric soil, thus their exploitation for polluted/contaminated sites was supported.