STENOTROPHOMONAS MALTOPHILIA IN THE RHIZOSPHERE OF OILSEED RAPE - OCCURRENCE, CHARACTERIZATION AND INTERACTION WITH PHYTOPATHOGENIC FUNGI

Isolates of Stenotrophomonas maltophilia have been isolated from the r hizosphere of oilseed rape. The percentage of S. maltophilia in this h abitat was determined using a selective medium according to Juhnke and Des Jardin (1989). The average number of S. maltophilia per gramme ro ot (wet weight) was 10(7) cfu, 3.7% of the total bacterial number. Sel ected strains were screened for their ability to inhibit in vitro the growth of Rhizoctonia solani and Verticillium dahliae var. longisporum , important soil borne pathogens of rape. The majority of isolates sho wed an antifungal activity in vitro but the efficiency of strains was different. The antifungal activity was achieved by a combination of se veral known antifungal mechanisms. Direct antifungal effect may be bas ed on antibiosis and production of lytic enzymes. Siderophores were se creted by rhizobacteria to improve the availability of iron. The disea se incidence of several plant pathogens could be reduced in greenhouse by the rhizobacterium significantly.