Functional Diversity and Oleaginous Potential of Fungal Strains From Hawaiian Soil Ecosystems

Fungi represent an important but underexplored resource for microbial lipid production, including nutritionally valuable polyunsaturated fatty acids. Hawaiian soils, shaped by volcanic parent materials and strong environmental gradients, provide a unique setting for discovering functionally diverse fungal strains with distinct metabolic traits. In this study, we performed the first quantitative lipid screening of 22 culturable fungal isolates collected from Hawaiian soils to evaluate their growth performance, lipid accumulation, and fatty acid composition. Substantial variation was observed across the collection, with multiple isolates exceeding 20% lipid content (dry weight). Among these, UHC1797, assigned to the Trichoderma guizhouense clade, emerged as a standout strain, combining rapid radial growth (~ 17-19 mm/day) with > 20% lipid accumulation and elevated α-linolenic acid (ALA; ~11% of total fatty acids). Confocal imaging confirmed intracellular lipid accumulation across representative isolates. Comparative analysis showed that UHC1797 lies at the upper range of reported Trichoderma growth and remains competitive with representative oleaginous fungi, including Mortierella strains. Genome-informed analysis further supports the presence of conserved lipid biosynthesis pathways underlying this phenotype. Together, these findings highlight Hawaiian soils as a promising reservoir of oleaginous fungi and support an ecology-informed framework for identifying strains with potential for sustainable lipid production and biotechnological applications.