BACTERIAL ANTAGONISTS TO VERTICILLIUM-DAHLIAE KLEB

Bacteria were isolated from the rhizosphere of Verticillium dahliae ho sts and from environments. A total of 1394 bacterial isolates were scr eened for their ability to inhibit in vitro the growth of the phytopat hogenic fungi V. dahliae; 15% (203 of the isolates) showed antifungal effects. Seventeen isolates were selected and determined for further i nvestigations, seven different species were identified. Several of the bacterial species listed, e.g. Erwinia herbicola, Pseudomonas chloror aphis, Pseudomonas paucimobilis and Xanthomonas maltophilia have not b een reported previously as bacterial antagonists of V. dahliae. Bacill us subtilis, Pseudomonas fluorescens and Xanthomonas maltophilia are s trong antagonists. We proved that lytic enzymes and siderophores are i nvolved in the inhibition of growth. Ultrastructural and morphological changes were induced in Verticillium dahliae by the antagonistic bact eria.