Isolation and Characterization of a Pseudomonas aeruginosa Strain PGP for Plant Growth Promotion

The present study has identified a free living bacterial strain from dump garbage soil, capable of forming large halo zone in National Botanical Research Institute’s Phosphate medium and Pikovskaya agar medium with phosphate solubilization index of 4.0. The phosphate solubilization ranged from 304.08 to 2073.01 ± 0.33 µg ml−1 in 3–12 days in NBRIP broth containing tricalcium phosphate and pH decreased from 7.0 to 3.8. The strain showed growth and color change in different nitrogen free media and nitrogen fixation in the supernatant was estimated to be 3.057 ± 0.34 and 7.87 ± 0.34 mg l−1 on 30th and 45th days of incubation. Indole acetic acid, ammonia, siderophore, and hydrogen cyanide production by the strain were quantified. 16s rDNA analysis confirmed the strain as Pseudomonas aeruginosa. Pot based assay with Indian mustard showed that seed coating of the strain significantly enhanced plant wet weight (up to 140%), plant dry weight (up to 88%), root length (up to 25%) and shoot length (up to 14%) over un-inoculated controls. It also showed that seed bacterization resulted in greater enhancement of plant growth than direct inoculation in the plant rhizoplane. Nitrogen and phosphorous content of the seed treated plants were 40.61 and 100% higher than the untreated controls further confirming the nitrogen fixation and phosphate solubilization efficiency of the strain.