Letters in Applied Microbiology (2008) 47, 98-105

A. Upadhyay and S. Srivastava (2008)
Characterization of a new isolate of Pseudomonas fluorescens strain Psd as a potential biocontrol agent
Letters in Applied Microbiology 47 (2), 98-105
Abstract: Aims: Evaluation of a new isolate of Pseudomonas fluorescens for its biocontrol properties.
Methods and Results: Strain Psd identified as Ps. fluorescens, produces secondary metabolites that are toxic to some plant-pathogenic fungi. Inhibition of fungal growth of Fusarium oxysporum and Verticillium dahliae in the presence of bacterial culture filtrate provided the first clue to its biocontrol properties. In order to determine the basis for antifungal properties, antibiotics were extracted and analysed by TLC. Both pyrrolnitrin and phenazines could be detected in the culture of Psd. Presence of response regulator gene gacA of the two component regulatory system (GacS/GacA) was established by PCR amplification and sequencing. Sequence comparison of gacA justified the taxonomic position of this strain among the known members of Pseudomonadaceae. Synthesis of other compounds like toxic lipodepsipeptide, siderophores, and HCN was also confirmed by appropriate biochemical tests.
Conclusion: Characterization of strain Psd by various biochemical/plate tests followed by chromatographic identification of antibiotics, demonstrates its multifunctional biocontrol property. Response regulator gene gacA provides an additional genetic marker for the phylogenetic studies.
Significance and Impact of the Study: Ps. fluorescens strain Psd with its multifunctional biocontrol property can be used to bioprotect the crop plants from phytopathogens.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Verticillium dahliae
Pseudomonas fluorescens (antagonist)	Verticillium dahliae