SCREENING OF ANTAGONISTIC ACTIVITY OF SOIL ISOLATES AGAINST PHYTOPATHOGENIC FUNGI

Background: Present study aims to screen some bacterial strains isolated from soil samples of different places in India for their antagonistic activity against certain phytopathogenic fungi. Five strains of phytopathogenic fungi were used in the investigation viz. Fusarium oxysporum, Alternaria solani, Aspergillus niger, Mucor indicus and Sclerotinia sp. A total of forty strains were isolated from different soil samples, out of which four strains namely BV-1, BV-2, BV-3 and BV-4 successfully showed antagonistic activity against phytopathogens.

Results: Strains BV-1, BV-2 and BV-3 showed the gram positive whereas BV-4 showed gram negative reaction. All strains showed good growth at pH 4 while only BV-1 and BV-2 showed no growth at pH 2. Strain BV-4 was found to be maximum tolerant whereas strain BV-2 was least tolerant towards antibiotics attempted in the investigation. All strains were able to utilize calcium nitrate, potassium nitrate and ammonium sulphate. All of four strains did not show any inhibition of Alternaria solani and Mucor indicus. Strain BV-1 showed maximum antagonism against Aspergillus niger (40% inhibition) and Sclerotinia sp (75% inhibition). Strain BV-2 exhibited 72% inhibition of Aspergillus niger and 82% inhibition of Sclerotinia sp. Strain BV-3 showed its antagonism only against Fusarium oxysporum (37% inhibition).

Conclusions: Four isolated bacterial strains BV-1, BV-2, BV-3 and BV-4 can be applied widely as a broad spectrum biological fungicide due to their property to inhibit phytopathogenic fungi used in the current investigation.