Isolation and characterization of Frankia strains isolated from Myrica gale

From 20 provenances of field-collected actinorhizae of Myrica gale, more than 3000 test tubes were inoculated with OsO4-treated nodules. Only 30 Frankia strains were isolated from 6 provenances. Most isolates showed an extremely slow growth in the various isolation media tested. For 12 strains whose growth was sufficient, the Frankia nature of isolates was verified by morphological characterization and biochemical analysis, using gas chromatography for the presence of 2-O-methyl-D-mannose. All 12 strains showed infectivity on M. gale and Alnus glutinosa. Five of those strains were ineffective on A. glutinosa but effective on Elaeagnus angustifolia and Hippophae rhamnoides.