Interactions of Phlebopus spongiosus with several soil fungi and antibacterial activity of its culture broth

An edible ectomycorrhizal fungus Phlebopus spongiosus have been found in pomelo orchards (Citrus maxima). The culture broth of Ph. spongiosus became darker after ca. 3 weeks of inoculation. The dry production of culture broth extract (culture extract) was 0.30 ± 0.09 g per culture (20 ml broth in a 50 ml flask). Both 5% and 10% solution of the culture extract shows the antibacterial activities on growth of all tested Gram positive bacteria Bacillus subtilis, Bacillus thuringiensis and a Gram negative bacterium Gluconobacter oxydans but not on the other Gram negative bacteria Escherichia coli and Asaia bogorensis. On PDA plates, Ph. spongiosus showed the inhibition on the growth of soil fungi Penicillium citrinum and Aspergillus niger, whereas it was invaded by that of a mycoparasite Trichoderma viride. Further studies on physiological and ecological characteristics and principal components for the activities of culture exudates in laboratory is necessary to find the applicable profits from this fungus.