RHIZOBACTERIA OF MAIZE ANTAGONISTIC TO FUSARIUM-MONILIFORME, A SOIL-BORNE FUNGAL PATHOGEN - ISOLATION AND IDENTIFICATION

The species of bacteria associated with rhizosphere and roots of maize exhibited varying degrees of antagonism towards Fusarium moniliforme, which was dependent upon the soils from which the bacteria were isolated. Pseudomonas fluorescens, P. putida, P. cepacia, Flavobacterium/CDC group II, Enterobacter cloacae, E. agglomerans, Acinetobacter calcoaceticus, Bacillus spp, and various actinomycetes were the antagonistic bacteria most frequently isolated from maize-growing soils. In vitro inhibition depended on the agar medium used and also on the age of the bacterial culture. Bacteria belonging to the group Pseudomonas such as P.fluorescens, P. putida and P. cepacia, which formed 88% of the antagonistic Gram-negative bacteria isolated were more inhibitory to F. moniliforme than the other antagonists and were isolated in high numbers from both maize seedlings and mature plants. Isolation of antagonists from surface sterilized roots indicate their close association with maize roots. Antibiotic production rather than siderophores seem to be responsible for the antifungal activity of antagonistic bacteria.