Wickerhamiella kiyanii f.a., sp. nov. and Wickerhamiella fructicola f.a., sp. nov., two yeasts isolated from native plants of Atlantic rainforest in Brazil.

Two novel species, Wickerhamiella kiyanii f.a., sp. nov. (type strain FB1-1DASP(T) = CBS 12905(T) = CBMAI 1613(T)) and Wickerhamiella fructicola f.a., sp. nov. (type strain H10Y(T) = CBS 12902(T) = CBMAI 1614(T)) are proposed in the Wickerhamiella clade (Saccharomycetes, Saccharomycetales) to accommodate three strains isolated from flowers and fruits typical of the Brazilian Atlantic rainforest. The novel status of these yeast species was established by sequence divergence observed in the D1/D2 domains of the LSU rRNA gene from the most closely related, described species as well as by phylogenetic analysis. Wickerhamiella kiyanii sp. nov. differs from its nearest phylogenetic neighbours W. pagnoccae CBS 12178(T), Candida jalapaonensis CBS 10935(T) and Candida drosophilae CBS 8459(T) by 2.2-4.2% in the D1/D2 sequences. By contrast, a sequence divergence of 13.2-13.8% was observed between W. fructicola sp. nov. and its closest, described phylogenetic relative Candida kazoui JCM 12558(T) and Candida hasegawae JCM 12559(T). Taxonomic descriptions of the two novel species are given.

Generation of Nutrients and Detoxification: Possible Roles of Yeasts in Leaf-Cutting Ant Nests.

The possible roles played by yeasts in attine ant nests are mostly unknown. Here we present our investigations on the plant polysaccharide degradation profile of 82 yeasts isolated from fungus gardens of Atta and Acromyrmex species to demonstrate that yeasts found in ant nests may play the role of making nutrients readily available throughout the garden and detoxification of compounds that may be deleterious to the ants and their fungal cultivar. Among the yeasts screened, 65% exhibited cellulolytic enzymes, 44% exhibited pectinolytic activity while 27% and 17% possess enzyme systems for the degradation of protease and amylase, respectively. Galacturonic acid, which had been reported in previous work to be poorly assimilated by the ant fungus and also to have a negative effect on ants' survival, was assimilated by 64% and 79% of yeasts isolated from nests of A. texana and Acromyrmex respectively. Our results suggest that yeasts found in ant nests may participate in generation of nutrients and removal of potentially toxic compounds, thereby contributing to the stability of the complex microbiota found in the leaf-cutting ant nests.