The present invention relates to methods of using fungal mycobiome as a means of treating and/or diagnosing diseases in a subject. In one embodiment, the present invention provides a method of diagnosing inflammatory bowel disease based on the composition of fungal strains present in the gut of a subject, and treating the subject by administering a probiotic biotherapy. In another embodiment, the present invention provides a method of diagnosing a severe form of ulcerative colitis by detecting the presence of a deficiency in dectin-1 expression in s. fibuligera in the gut of a subject.
