Biological activity of secondary metabolites produced by a strain of Pseudomonas fluorescens
2002
Deka Boruah, H.P. | Dilep Kumar, B.S. (Council of Scientific and Industrial Research, Jorhat (India). Regional Research Lab.)
The present investigation was taken up to characterize the secondary metabolites responsible for plant growth and control of fungal and bacterial pathogens produced by the Pseudomonas fluorescens strain RRLJ 008. The strain produced antibiotics phenazine (PHE), 2,4-diacetylphloroglucinol (PHL) and siderophore pyoverdin (PYO) in standard King's B and succinic acid media, respectively. After extraction, PYO was identified by comparing the UV-spectra and moss-green color develoment after `diazotized sulfanilic acid' (DSA) spray in TLC. PHE and PHL were identified by comparing standard compounds on TLC and orange-color development immediately after DSA spray. In vitro antibiosis study of the metabolites revealed their antibacterial and antifungal activity against bacterial test organisms Corynebacterium sp., Mycobacterium phlei and M. smegmatis and test fungi Fusarium moniliforme, F. oxysporum, F. semitectum, F. solani and Rhizoctonia solani. A statistically significantly higher plant growth was recorded in siderophore-amended plantlets under gnotobiotic conditions whereas PHE and PHL did not show any plant-growth-promoting activity. These results support the importance of the secondary metabolites produced by the strain P. fluorescens in enhancing plant growth and in controling fungal and bacterial pathogens.
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