Indian Journal of Microbiology

Seventy six P-solubilizing bacteria, isolated from the chickpea rhizopshere using Pikovaskaya's medium, showed phosphate solubilization efficiency from 6 to 118% on solid and 22–248 µg mL⁻¹ in liquid medium. Only four out of 18 isolates, showing complementary antibiotic resistance to donor strains, were selected on the basis of P-solubilization efficiency, for transfer of lacZ marker. A stable chromogenic marker (lacZ) from E. coli was introduced into selected PSB isolates by random Tn5 mutagenesis. The transconjugants were selected based on blue colonies appearing on medium containing 50 µg mL⁻¹ each of kanamycin, chloramphenicol and X-gal. The P-solubilization activity of PSB was not affected by transconjugation.