Detection, Isolation and Partial Characterization of Antifungal Compound (s) Produced by Pseudomonas aeruginosa CMG1055

The use of microorganisms for biocontrol agents has become an effective alternative technology. Bacteria from marine environment are an underutilized source of novel antibiotics. The bacterial strain CMG1055 which showed strong antifungal activity against pathogenic fungi was isolated from surface water of Arabian Sea of Pakistan. Based on the physiological and biochemical characteristics and 16S ribosomal RNA sequence analysis, the bacterial strain CMG1055 was identified as Pseudomonas aeruginosa. This bacterium exhibited varying degrees of antifungal activities against a number of pathogenic fungi, such as A. niger, Helimanthosporium sp, T. entagrophytes, C. albicans, S. cerevisiae, and Rhizpopus sp. The production of antifungal activity showed a great degree of media specificity and it was strictly restricted to King B agar supplemented with 20 % glycerol. No production of antifungal activity was detected in Tris glucose minimal medium. Antifungal compound(s) produced by CMG1055 was extracted using 80% acetone and ethyl acetate from the growth medium and purified by silica gel column chromatography. The minimal inhibitory concentration ranged from 50 to 75μ g/mL. Chemically the antifungal substance was a phenolic compound with aromatic unsaturation, as confirmed by UV and IR spectroscopy.