Morphological and genetic characterization of novel Sarocladium spinificis strains in association with Coccidioides posadasii

Sarocladium is a fungal genus containing diverse members with roles as pathogens of plants and animals, endophytes, and biocontrol agents. This study characterizes two Sarocladium spinificis strains isolated from patients diagnosed with coccidioidomycosis. Morphological, phylogenetic, and genomic analyses confirmed their classification within the Sarocladium genus, closely related to S. spinificis. Both strains exhibited mycelial growth at 24°C and 37°C, with distinct morphological features. Comparative genomic analysis identified unique orthologous clusters and functional gene families associated with diverse carbon utilization and potential pathogenicity. Notably, these strains’ genomes contain many secreted proteins, carbohydrate-activated enzymes, and peptidases, highlighting their metabolic versatility. Co-cultivation experiments revealed that S. spinificis strains CA16 and CA18 both inhibited the growth of Coccidioides posadasii, suggesting antagonistic interactions and potential antifungal properties. These findings underscore the ecological and clinical significance of S. spinificis and its impact on microbial communities, advancing our understanding of its diversity, pathogenic potential, and antifungal capabilities.