Isolation and Characterization of Novel Apple Rhizosphere Bacterium as Fungal Antagonist.

Strain An-F was isolated from the rhizosphere soil of replant site of apple orchard at Shimla district H.P. and identiûed as Pseudomonas aeruginosa on the basis of biochemical tests and by 16S rRNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards phytopathogenic fungi. The antifungal metabolite by An-F was extracted and characterized using TLC and HPLC (High pressure liquid chromatography). Production of siderophores, phosphatase, HCN, ammonia, indole-3-acetic acid (IAA), gibberellins and cytokinins in An-F were determined. The antifungal metabolite produced by An-F has been identiûed as 2, 4-diacetylphloroglucinol on the basis of TLC and HPLC data. Present study reports the production of 2,4-diacetylphloroglucinol as well as IAA, gibberellins and cytokinins for the ûrst time by a saprophytic P. aeruginosa strain An-F isolated from the replant site of apple. Because of the production of siderophore, growth hormone, protease and phosphatase and its innate fungicidal potential, this strain can be used as biofertilizer and antagonist against a range of phytopathogenic fungi. [ABSTRACT FROM AUTHOR]