Effect of fairy ring bacteria on the growth of Tricholoma matsutake in vitro culture

Tricholoma matsutake (pine mushroom) (Basidiomycota, Agaricales) is a valuable edible fungal species that cannot be cultivated artificially. As an ectomycorrhizal fungus, T. matsutake interacts with trees belonging to the Pinaceae and Fagaceae, and forms fairy rings around host trees that are arc-shaped areas with dense hyphae of T. matsutake in the soil. Because the fairy rings maintain their dense hyphae for several years and form fruiting bodies, the characteristics of the fairy ring may be important in understanding the ecology of T. matsutake. Recent studies have shown that diverse bacteria co-exist in the fairy ring, and suggest that the fairy ring bacteria may influence on the growth of T. matsutake. However, the effect of the fairy ring bacteria on the growth of T. matsutake is largely unknown. In this study, we isolated fairy ring bacteria and investigated their effect on the growth of T. matsutake in co-culture experiments. In addition, the relationship between bacterial effects and nutrient conditions was tested using different media with varying glucose concentrations. A total of 237 bacteria (28 species) were isolated from fairy rings of four different T. matsutake producing areas: Proteobacteria (17 species), Firmicutes (7 species), and Actinobacteria (4 species). Burkholderiaceae (Burkholderia and Paraburkholderia) was most abundant in the fairy ring bacteria communities. Most bacteria showed a negative effect on the growth of T. matsutake when it grew on glucose rich medium (20g/L). In glucose deficient medium (2g/L), however, some bacteria promoted the growth of T. matsutake. In addition, the mode of interaction between bacteria and T. matsutake is different, depending on the glucose concentration.