| Abstract: | A search for micro-organisms associated in high numbers with roots or leaves of corn, grapevine, chicory, soybean, sunflower, barley and sugarbeet yielded a collection of over 10 000 bacterial strains. Within this collection, antifungal strains have been selected, using direct or indirect in-vitro assays against one target fungus per crop. The target fungi were selected based on their agronomic relevance as pests. Isolates with antifungal activity were tested for their spectrum of activity against a set of phytopathogenic fungi. In 15 bacterial strains with broad-spectrum activity, belonging to the species Erwinia herbicola. Serratia plymuthica, Pseudomonas fluorescens, P. aureofaciens, P. cepacia and Bacillus subtilis, the active compounds have been identified. Bacterial strains belonging to the same taxon, but isolated from different ecological niches and/or different places in Europe, produce identical compounds. In two bacterial taxa (Erwinia and Serratia) this was reflected in a genetic conservation of the regions coding for antifungal activity. In both cases, the biosynthetic pathways proved to be genetically complex. All of the compounds identified in this study have been described previously in bacterial strains isolated from analogous or completely different ecosystems. |
