Endophytic bacteria have been found in virtually every plant studied, in which they are reported to help in plant growth promotion and fight against plant pathogens in addition to contribution to yield of crop plants. The colonies of endophytes in the internal tissues also produce a variety of natural products which could be exploited for potential pharmaceutical, agricultural and industrial use.

Bacterial endophytes were isolated from surface sterilized root, stem, leaves and fruits of healthy tomato plants. Several isolates belonging to four bacterial genera viz., Bacillus, Pseudomonas, Klebsiella and Citrobacter were obtained and identified using standard biochemical methods. Of the bacterial endophytes isolated in the study, only 50% of the isolates showed antagonistic activity against Fusarium oxysporum f. sp. lycopersici, the pathogen causing wilt disease in tomato. Bacterial metabolites like siderophore, hydrogen cyanide, indole acetic acid and salicylic acid in the culture media were studied. The result showed that comparatively the maximum quantity of siderophore (53.6%), hydrogen cyanide (45%), and salicylic acid (48.7%) was produced by Pseudomonas and indole acetic acid (48.2%) by Bacillus. Among the isolated endophytes, Pseudomonas was found to exhibit superior antagonistic activity against the test pathogen.