# Whole-Genome Sequencing and Comparative Genomic Analysis of Three Clinical Bloodstream Infection Isolates of Trichosporon austroamericanum

## TL;DR

This study sequenced the genomes of three Trichosporon austroamericanum isolates and compared them to related species, revealing genomic diversity and pathogenic traits.

## Contribution

The study provides the first whole-genome sequencing and comparative analysis of T. austroamericanum, identifying unique genomic features linked to pathogenicity.

## Key findings

- T. austroamericanum isolates showed moderate intraspecific divergence and formed a distinct clade.
- A unique Zn(II)2Cys6-type transcription factor gene was found only in T. austroamericanum and T. asahii.
- T. austroamericanum strains exhibited virulence in a Galleria mellonella model comparable to T. asahii.

## Abstract

Trichosporon austroamericanum is a recently described yeast species related to Trichosporon inkin and exclusively isolated from clinical specimens. However, its genomic features and pathogenic potential remain poorly understood. In this study, we performed whole-genome sequencing on three blood-derived isolates from patients with invasive fungal infections and comparative analyses with 13 related Trichosporon species. The three isolates yielded high-quality assemblies of 9–10 scaffolds (~21 Mb), facilitating reliable comparisons. While most species had comparable genome sizes, Trichosporon ovoides, Trichosporon coremiiforme, and Cutaneotrichosporon mucoides displayed large, fragmented genomes, suggestive of polyploidy. ANI analysis and phylogenetic trees based on ANI and single-copy orthologs supported the classification of T. austroamericanum as a distinct clade with moderate intraspecific divergence. Using the Galleria mellonella, a model for fungal pathogenicity, all T. austroamericanum strains reduced larval survival, and NIIDF 0077300 exhibited virulence comparable to T. asahii and greater than T. inkin. To explore the gene-level differences associated with pathogenicity, we performed ortholog analysis based on single-copy genes. This revealed a unique Zn(II)2Cys6-type transcription factor gene (OG0010545) present only in NIIDF 0077300 and T. asahii. These findings highlight the genomic diversity and infection-associated traits of T. austroamericanum, providing a framework for future functional studies.