Abstract
The yeast species found in necrotic stems of three columnar cacti (Pilosocereus machrisii, Pilosocereus vilaboensis, and Praecereus euchlorus) at eight localities in Brazil were described and a similarity analysis using Sorensen distances was used to compare the composition of yeast species at these localities. Of 56 necrotic cactus stems sampled, 32 produced yeast colonies. Ten species of yeast or yeast-like microorganisms were identified from 53 isolates, with Pichia cactophila, Candida sonorensis, Geotrichum sp., and Sporopachydermia cereana being the most common. The remaining species occurred in low proportions in the cacti surveyed. The similarity analysis provided a dendogram (UPGMA) that clustered the yeast communities from different cactus species and indicated that host cactus species was unimportant in this clustering.
Highlights
The cactus-yeast-Drosophila system represents a three-way ecological association in which necrotic cactus tissue serves as a substrate for a diverse and often highly specific yeast flora
Pichia heedii is specific to only one cactus species in the North American Sonoran desert (Phaff et al, 1978), Candida deserticola is restricted to several species of the genus Stenocereus (Phaff et al, 1985), and Pichia cactophila and Candida sonorensis are found in almost all cactus species from which yeasts have been collected (Lachance et al, 1988; Starmer et al, 1990)
In this work we describe the yeast species found in the necrotic stems of three columnar cactus species at eight localities in Brazil and report a similarity analysis for these localities based on the species composition
Summary
The cactus-yeast-Drosophila system represents a three-way ecological association in which necrotic cactus tissue serves as a substrate for a diverse and often highly specific yeast flora. Studies on the spatial heterogeneity in species composition and relative abundance in yeast communities associated with necrotic cacti have shown differences within and among geographic areas (Starmer et al, 1990; Barker et al, 1983). Studies of the cactus-yeast-Drosophila system in Brazil have used mainly the Drosophila buzzatii species cluster and the cactus genera Opuntia, Cereus, and Pilosocereus (Sene et al, 1988; Rosa et al, 1994, 1995).
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