Int.J.Curr.Microbiol.App.Sci (2019) 8(11): 1986-1991 1986 Original Research Article https://doi.org/10.20546/ijcmas.2019.811.232 Pseudomonas fluorescens: A Proficient Plant Growth Promoting Rhizobacteria Isolated from Organic Farm Harshada S. Kitey * and Vijay N. Charde Department of Microbiology, Taywade College, Koradi, Nagpur, 441111, MS, India *Corresponding author ABSTRACT Introduction Due to excessive use of chemical fertilizers in agricultural field, the soil loses the microbial activity. It is reported that Organic applications in agricultural farms increases the microbial activity drastically as compare to soil with chemical fertilizers [3]. In rhizosphere, siderophore producing Pseudomonas plays a central role in improvement of the plant development. These bacteria act as biocontrol agent by limiting iron nutrition to the pathogen. Many bacteria synthesize siderophore that has an high affinity for ferric iron, resulting in ferric- siderophore complex which is transported into the cell and thus facilitates iron uptake under low iron condition making unavailable to the other organisms and restrict the growth of deleterious bacteria and fungi at the root [1]. International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 8 Number 11 (2019) Journal homepage: http://www.ijcmas.com In the present study, strains of Pseudomonas fluorescens designated as OrgS63 and OrgS49 isolated from soybean rhizosphere of an organic farm. Siderophore production was detected by using modified Fiss Minimal medium and estimation was done by CAS assay. Both the strains were found to produce good amount of siderophores. These Pseudomonas strains were screened for their other plant growth promoting traits like IAA production, production of Ammonia, HCN production, Phosphate solubilization and antifungal activity. OrgS63 was the most efficient phosphate solubilizer on NBRIP plates with a solubilization index of 6.10. In liquid NBRIP medium, significantly higher Phosphate solubilization was recorded for both the strains OrgS63 and OrgS49 (440 and 450 μg/ml) after 5 days of incubation. Both the strains OrgS63 (90.00%) and OrgS49 (90.44%) has shown high % inhibition against Fusarium oxysporum. These isolates also showed positive results for Indole 3-acetic acid (IAA), ammonia production, hydrogen cyanide (HCN) production and ammonia production. Thus, the present study concludes that these Siderophore producing Pseudomonas fluorescens strains could serve as a proficient Plant growth promoting Rhizobacterial inoculants for improving the cropping systems and enhancing metal remediation of polluted environments. Keywords Pseudomonas fluorescens, OrgS63, OrgS49, Fusarium oxysporum Accepted: 17 October 2019 Available Online: 10 November 2019 Article Info