Antimicrobial activity of Pseudomonas secondary metabolites

Abstract:

Introduction: Phenazines are nitrogen-containing heterocyclic molecules produced by fluorescent Pseudomonas. These compounds have broad-spectrum antibiotic properties including antimicrobial activity against phytopathogenic fungi and pathogenic bacteria. Several mechanisms of action have been proposed, including inhibition of DNA replication, uncoupling of electron, transport and energy production, and disruption of normal membrane functions resulting in the generation of toxic intracellular oxygen species. Methods: Production of antimicrobial metabolites in vitro was assayed in NBY supplemented with glucose to a final concentration of 2%. Results: Extracts of supernatants from liquid cultures completely inhibited phytopathogenic fungi when incorporated into agar culture at a rateof 20 and 40 μg/ml, this crude extracts was active against all tested fungi. In a disc assay, extracts equivalent to 20 μg gave zones of inhibition of 15 mm and 25 mm for the Gram positive bacteria Bacillus subtilis and Paracoccus paratrophus, respectively with disc diffusion technique. The purified extracts were analyzed by UV spectroscopy and GC/MS.

KEY WORDS: Antimicrobial activity, phenazines, secondary metabolites.