Biochemical and molecular characterization of fungal isolates from California annual grassland soil.

Fungi play a pivotal role in ecosystem functionality, driving processes such as decomposition, nutrient cycling, and symbiotic interactions. Their wide enzymatic strategies enable the breakdown of complex organic materials and the valorization of organic waste streams, providing sustainable pathways for bioproduct development. Fungi also exhibit significant potential in industrial applications, particularly in biofuel and nutraceutical production, owing to their high lipid content and adaptability to diverse feedstocks. Genera such as Aspergillus, Mortierella, and Linnemannia have demonstrated exceptional lipid production capabilities and unique fatty acid profiles, including high yields of nutraceuticals like arachidonic acid (ARA) and oleic acid. This study explored uncharacterized fungal strains isolated from California grassland soils, analyzing their phylogeny, morphology, growth rates, lipid content, and fatty acid profiles. Results revealed notable genetic and physiological diversity among the isolates, with Mortierella strains emerging as the most promising for industrial applications due to their superior lipid content and productivity of ARA and oleic acid. Confocal microscopy confirmed consistent lipid droplet morphology, while phylogenetic analysis uncovered novel species-level diversity. Key strains were identified for biofuel and nutraceutical production, highlighting their industrial potential. These findings underscore the versatility of fungi as biotechnological tools and provide a foundation for further exploration and utilization of these promising strains in industrial processes.