The Brazilian Amazonian rainforest harbors a high diversity of yeasts associated with rotting wood, including many candidates for new yeast species

This study investigated the diversity of yeast species associated with rotting wood in Brazilian Amazonian rainforests. A total of 569 yeast strains were isolated from rotting wood samples collected in three Amazonian areas (Universidade Federal do Amazonas‐Universidade Federal do Amazonas [UFAM], Piquiá, and Carú) in the municipality of Itacoatiara, Amazon state. The samples were cultured in yeast nitrogen base (YNB)‐d‐xylose, YNB‐xylan, and sugarcane bagasse and corncob hemicellulosic hydrolysates (undiluted and diluted 1:2 and 1:5). Sugiyamaella was the most prevalent genus identified in this work, followed by Kazachstania. The most frequently isolated yeast species were Schwanniomyces polymorphus, Scheffersomyces amazonensis, and Wickerhamomyces sp., respectively. The alpha diversity analyses showed that the dryland forest of UFAM was the most diverse area, while the floodplain forest of Carú was the least. Additionally, the difference in diversity between UFAM and Carú was the highest among the comparisons. Thirty candidates for new yeast species were obtained, representing 36% of the species identified and totaling 101 isolates. Among them were species belonging to the clades Spathaspora, Scheffersomyces, and Sugiyamaella, which are recognized as genera with natural xylose‐fermenting yeasts that are often studied for biotechnological and ecological purposes. The results of this work showed that rotting wood collected from the Amazonian rainforest is a tremendous source of diverse yeasts, including candidates for new species. To explore the diversity of the Amazonian rainforest by targeting the group of yeasts with the ability to assimilate lignocellulosic sugars, the authors collected rotting wood samples in three sites of the forest, including both drylands and floodplain areas. Dryland areas in the Brazilian Amazonian rainforest has higher diversity of yeasts associated with rooting wood than floodplain areas. Also, a high number of candidates for novel species is present in rotting wood samples. Take‐away Rotting wood is a great source of yeast species that can assimilate lignocellulosic sugars. Dryland areas in the Brazilian Amazonian rainforest has higher diversity of culturable yeasts associated with rooting wood than floodplain areas. A great number of candidates for novel species is present in rotting wood samples. Universidade Federal do Amazonas and yeast nitrogen base (YNB)‐xylose were the area and medium, respectively, in which the highes