Dynamics of yeast populations recovered from decaying leaves in a nonpolluted stream: a 2‐year study on the effects of leaf litter type and decomposition time

Here we report on the results of a survey of the yeast populations occurring on submerged leaves (alder, eucalyptus and oak) in a natural mountain stream, during different phases of their decomposition and through two consecutive years. Leaf litter mass loss, total yeast counts, Shannon–Weiner index ( H ′), yeast community structure and physiologic abilities were analyzed to evaluate the dynamics of yeast communities during decay. Seventy‐two yeast taxa were recorded, and in all litter types, species of basidiomycetous affinity predominated over ascomycetous ones. Discriminant analysis of presence/absence data (yeast species) showed significant differences both among substrate types ( P <0.0026) and with decomposition time ( P <0.0001). Carbon and nitrogen source utilization by yeast strains also varied with the substrate ( P <0.0001) and decomposition time ( P <0.0001). Further conclusions were that: (1) all litter types have in common ubiquitous yeast species, such as Cryptococcus albidus , Debaryomyces hansenii and Rhodotorula glutinis , among the common 20 yeast species; (2) only a few species were dominant, and most species were rare, being recorded once or twice throughout decomposition; and (3) the order of yeast appearance, and their substrate assimilation patterns, strongly suggest a succession phenomenon. Finally, explanations for the distribution patterns and variations in yeast communities are discussed.