Epsilon Archive for Student Projects

Abstract

Rhodotorula toruloides is an oleaginous yeast recognized for its high lipid content, high production of oils and carotenoids and favorable fatty acid profile, making it a valuable candidate for food, feed, and biofuel applications. However, the robust structure of its cell wall poses a major challenge for cost-effective lipid extraction. This study aimed to identify soil-derived microbial strains capable of enzymatically degrading R. toruloides cell walls to improve biomass accessibility and processing efficiency.
Ten microbial isolates, including bacteria, filamentous fungi, and yeasts were cultivated in media containing R. toruloides cell wall material as the sole carbon source. Growth was assessed via optical density measurements (OD₆₀₀), results were further validated and assessed through biomass quantification using dry cell weight (DCW) analysis. The two methods produced consistent trends, reinforcing the observed differences in growth performance.
Among the isolates, Streptomyces seoulensis (strain 5) demonstrated the highest growth across both OD₆₀₀ and DCW measurements. 16S rRNA gene sequencing confirmed its identity with >99% sequence similarity to S. seoulensis. Genome annotation revealed a broad spectrum of cell wall-degrading enzymes, including multiple glucanases, chitinases, proteases, and GPI-cleaving enzymes, but no mannan-degrading enzymes were detected.
These findings suggest that S. seoulensis is a promising candidate for enzymatic pretreatment of R. toruloides, supporting more sustainable lipid extraction methods in biotechnological