Antibiotic activity of bacterial endobionts of basidiomycete fruit bodies

Bacterial strains (93 isolates) capable of growth on full-strength nutrient media were isolated from 86 fungal fruit bodies collected in the Moscow region. Antimicrobial activity of the endobiont isolates against 12 bacterial and fungal test strains (including drug-resistant ones) was studied in submerged cultures. Most of the strains (84.9%) were found to produce antibiotic compounds with different antimicrobial properties, including antifungal activity in 18.3% of the strains. Morphological characteristics and analysis of the 16S rRNA gene sequences were used to determine the taxonomic position of 16 bacterial strains of the following 10 species: Bacillus subtilis , Ewingella americana , Pseudomonas sp., Stenotrophomonas maltophilia , as well as Achromobacter spanius , B. licheniformis , Hafnia paralvei , Micrococcus terreus , Nocardia coeliaca , and St. rhizophila , which have not been previously known to be endobionts of basidiomycete fruit bodies. Antimicrobial activity of A. spanius , E. americana , H. paralvei , M. terreus , N. coeliaca , and St. rhizophila has not been reported previously. Complex mechanisms of symbiotic relations between fungi and bacteria, including those associated with antibiotic formation, probably developed in the course of co-evolution.