MOLECULAR DETECTION, ISOLATION AND IDENTIFICATION OF ANTIFUNGAL METABOLITE PRODUCED BY BIOCONTROL ISOLATE OF Pseudomonas aeruginosa

Antagonistic rhizobacteria, more specifically fluorescent pseudomonads, are known to control fungal root diseases of agronomic crops. In this study, Pseudomonas aeruginosa bacteria were isolated from Hibiscus sabdariffa (roselle) rhizosphere. Bacterial isolate was assayed by dual culture technique for potential biological control agent against Rhizoctonia solani, Fusarium oxysporum, Sclerotium rolfsii and Macrophomina phaseolina as phytopathogenic fungi in vitro. Among P. fluorescens isolates, isolate No 9 exhibited the highest activity and produced blue green pigment. Based on biochemical and physiologic tests and MicroScan, this isolate identified as P. fluorescens No 9. Isolate No 9 was shown to have broad spectrum in vitro antibiotic activity against fungal plant pathogens. It was able to produce considerable amount of dark blue colour pigment (2.3g), which yielded 14 mg of purified greenish-yellow metabolite exhibiting effect on spore production and hyphal morphology of F. oxysporum. phzE gene, which is part of the phenazine biosynthetic pathway, was used as universal and to detect the ability of bacteria to produce phenazine. Results from this study provide comprehensive information on biocontrol mechanisms that can be used for commercial use and appropriate application of this bacterium.