Ecology and characterization of yeasts from aquatic regions of South Florida

Mycological investigations, entailing over 400 samples from 120 separate collection stations, of the composite aquatic regions of southern Florida and adjacent areas have been developed. A collection of over 1000 yeasts, representing more than 50 taxa, has been characterized and studied. Highest yeast densities were found in freshwaters with the recovery of yeasts per sample decreasing from 100% to approximately 70% with lowered organic content, increasing salinity and remoteness from land. Average cell population densities, variety of species, and particularly the number of sexual yeasts, decreased in saline samples. The isolation media used were evaluated and have been discussed in terms of yeast densities obtained. Stritly oxidative species of Candida, Cryptococcus, and Rhodotorula and the sexual yeast, Debaryomyces hansenii, were the most widespread in all the habitas studied and the predominant forms in water of relatively low organic content. Selective survival of certain yeasts in the various aquatic environments was suggested. Definite distributional patterns were exhibited by various taxa and the possible existence of indicator species wa suggested. The systematics of the fungi have been reviewed at length and the significance of strain differences considered and discussed as related to the unique characteristics of the various ecological habitats.