Prospecting Araucaria-Associated Yeasts for Second-Generation Biorefineries

Native yeasts are a promising microbial resource for the development of sustainable biorefineries. In this study, we isolated 30 yeast strains from soil, decaying wood, and tree bark in a preserved Araucaria Forest in Southern Brazil and characterized them phenotypically and taxonomically. All strains were able to grow on glucose, xylose, and cellobiose, and 50% of them could metabolize arabinose. Several isolates showed high growth rates on xylose (up to 0.47 h−1) and cellobiose (up to 0.45 h−1). Notably, 19 strains (63% of the analyzed yeasts) exhibited xylanase activity at 50 °C (up to 156.84 U/mL), and four strains (13%) showed significant cellulase production. β-Glucosidase activities were particularly high in permeabilized cells of CHAP-258, CHAP-277, and CHAP-278 (up to 584.33 U/mg DCW), with kinetic parameters indicating high enzymatic performance. Twelve strains (40% of the total) were classified as oleaginous, and three (10%) displayed both lipogenic and esterase activity. Lipase activity against p-nitrophenyl palmitate (pNPP) reached 55.55 U/mL in CHAP-260. Taxonomic identification revealed representatives of seven genera, including Meyerozyma, Papiliotrema, Scheffersomyces, and Sugiyamaella, with potential for biotechnological use. Overall, the biochemical diversity observed highlights the value of native yeasts from Araucaria Forests as biocatalysts for lignocellulose-based bioprocesses, particularly due to their ability to grow on pentoses, secrete hydrolytic enzymes, and accumulate lipids.