Characterization of antifungal compounds produced by Pseudomonas stutzeri (EGB3) isolated from gut of earthworm (Eisenia foetida)

Strain EGB3 was isolated from the gut of earthworm fed with sterile soil and identified as Pseudomonas stutzeri on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards soil borne phytopathogenic fungi (Fusarium oxysporum, Fusarium solani, Fusarium moniliformae, Fusarium udum, Macrophomena phaseolina, Rhizoctonia solani, Colletotrichum capsicii, Aspergillus flavus, and Aspergillus niger). The antifungal metabolite produced by EGB3 was extracted and characterized to determine the nature of the active molecules (volatile and non-volatile). The bioactive compound was thermostable upto 80°C for 10 min. The zone of inhibition was observed after 6 h of incubation and increased up to 36 h and there was no change in zone of inhibition after 36 h of incubation. EGB3 was an antagonist against a range of phytopathogenic fungi that infect groundnut plants. Key words: phytopathogenic fungi, EGB3, Pseudomonas stutzeri, antifungal metabolites.