High culturable diversity and climate-associated seasonal dynamics of Saccharomycotina yeasts in subtropical forest leaf litter

Forest-associated Saccharomycotina yeasts are present in low relative abundance, which hampers our ability to accurately assess their diversity and behavior. To gain a better understanding, researchers conducted weekly sampling of leaf litter over a 47-week period in a subtropical forest in northern Taiwan. Through enrichment, isolation, and ITS sequencing, they successfully recovered 687 isolates, comprising 613 Saccharomycotina species and 77 putative novel operational taxonomic units. However, rarefaction tests revealed that the cultivated diversity likely remains unexplored.

When comparing different litter traps, the researchers found high community dissimilarity, primarily driven by taxon replacement. Interestingly, neither topography nor geographic distance appeared to influence the community composition. Moreover, the turnover rates were in line with what would be expected from random distribution.

The variability in Saccharomycotina yeasts' richness was closely linked to the weather conditions. The researchers observed a peak in richness during warm and wet periods, with a noticeable decline during the winter months. Among the factors associated with richness, minimum temperature emerged as the strongest statistical predictor.

Furthermore, the researchers found that the community composition was influenced by various environmental factors, including maximum temperature, minimum relative humidity, precipitation, and solar radiation.

Finally, the researchers identified a strong association between selected isolates' thermal optima and the temperature recorded during their collection week. Specifically, two isolates of Magnusiomyces magnusii collected in October exhibited higher thermal optima compared to four isolates collected during the winter months. This finding suggests that temperature plays a crucial role in shaping the community structure and dynamics of Saccharomycotina yeasts in subtropical forest leaf litter.