Live Malassezia strains isolated from the mucosa of patients with ulcerative colitis

The human gut is inhabited by a complex ecosystem of diverse microorganisms. While most studies on the gut microbiota have focused on bacteria, accumulating evidence has underscored the role of the mycobiota in inflammatory bowel disease (IBD). This study is the first to isolate and characterize live Malassezia globosa strains from the intestinal mucosa of patients with ulcerative colitis. Malassezia species primarily inhabit the human skin. We therefore compared the M. globosa gut isolates with the M. globosa skin isolates and noted a striking disparity between them. The gut isolates led to a greater exacerbation of colitis in mice. Transcriptome analysis revealed that the gut isolates were more sensitive to normoxia than the skin isolates, suggesting adaptation to hypoxia prevalent in the intestinal environment. These findings provide novel insights into the potential impact of M. globosa on the pathogenesis of IBD and the influence of niche-specific adaptations on its virulence. ### Competing Interest Statement The authors have declared no competing interest.