Colonic Mucosa-associated Mycobiota in Individuals With Normal Colons
Abstract To characterize the spatial variation of the mucosa-associated adherent mycobiota along the large intestine in individuals with a normal-colon, we performed eukaryotic rRNA operon’s internal transcribed spacer-2 sequencing to profile fungal community composition and structure in 70 mucosal biopsies taken from the cecum, ascending, transverse, descending colon, and rectum of 14 polyp-free individuals. The bacteriome of these samples was previously characterized by sequencing the V4 region of the 16S rRNA gene. We identified 64 amplicon sequence variants (ASVs) with the relative abundance no less than 0.05% from these colonic mucosa samples. Each individual has a unique community composition of the gut mycobiome (P = 0.001 for beta diversity). Alpha-diversity and beta-diversity did not differ significantly across the colon segments. The most common phyla (relative abundance) were Ascomycota (45.4%) and Basidiomycota (45.3%). The most common genera were Malassezia (28.2%) and Candida (13.4%). Malassezia was found in 13 of 14 individuals. Other fungi genera were sporadically found in the large intestine. The most common species were Malassezia restricta (22.7%), Candida albicans (11.9%), Malasseziales sp. (8.80%), unclassified fungi (7.80%), and Penicillium paneum (5.70%). Malasseziaceae was co-abundant with Enterobacteriaceae and co-exclusive with Barnesiellaceae, Rikenellaceae, and Acidaminococcaceae. Malassezia was widely colonized whereas other fungal genera were sporadically colonized in the large intestine. The physiologic and pathogenic functions of fungi in human gastrointestinal tract including Malasseziaceae that may interact with several bacterial families remain to be fully elucidated.