Draft Genome and Comparative Analysis of a Cutaneotrichosporon jirovecii-Related Yeast Recovered from a Human Fecal Sample.

BACKGROUND

Cutaneotrichosporon jirovecii is an under-characterized basidiomycetous yeast within the family Trichosporonaceae. Its taxonomic placement, ecological distribution, and functional potential remain incompletely understood because genome-scale resources for C. jirovecii and closely related lineages are limited.

METHODS

We characterized strain H0426_7, a C. jirovecii-related yeast recovered from a human fecal sample, using ITS-based type-strain comparison, ITS phylogenetic analysis, whole-genome sequencing, average nucleotide identity analysis, read-level assessment of public C. jirovecii-labeled datasets, and comparative functional annotation. Antifungal susceptibility was assessed using the Sensititre YeastOne plate.

RESULTS

The ITS sequence of H0426_7 closely matched type-strain material of C. jirovecii, including CBS 6864 and its equivalent deposits. The ITS-based tree placed H0426_7 adjacent to CBS 6864 with bootstrap support of 87%. The final draft genome comprised 38.66 Mb in 1974 contigs, with a GC content of 63.76% and BUSCO completeness of 80.0%. ANI analysis showed that H0426_7 was genomically distinct from the recognized Cutaneotrichosporon species included in the ANI analysis but highly similar to two unclassified feces-derived strains, P10-008 and PK4640, with ANI values exceeding 98.8%. Two public datasets labeled as C. jirovecii showed anomalously low ANI values with H0426_7; read-level taxonomic profiling indicated low target-fungal read proportions, suggesting that these datasets are unsuitable as definitive genome-level references. CAZyme annotation identified 285 family assignments in H0426_7, representing 278 non-redundant predicted proteins, including relatively high GH5 and GH31 counts, suggesting candidate carbohydrate-utilization features shared with the H0426_7/P10-008/PK4640 lineage.

CONCLUSIONS

H0426_7 is best described as a C. jirovecii-related Cutaneotrichosporon isolate pending availability of a high-quality genome assembly from the C. jirovecii type strain. This study expands genome-scale resources for underrepresented basidiomycetous yeasts and provides a comparative framework for future taxonomic, ecological, and functional studies of feces-associated Cutaneotrichosporon lineages.