Yeasts in cacti and tropical fruit

Abstract

Yeast communities associated with necrotic tissues of cacti and ripe tropical fruits are excellent models for studying the ecology and evolution of these fungi. The availability of carbon sources, chemistry of the substrate, presence of antimicrobial compounds, mutualisms with insect vectors, competition, predation, and habitat heterogeneity in space and time all influence cactophilic yeast occurrence. Four yeast species are prevalent in necrotic cactus tissues: Pichia cactophila, Candida (Ogataea) sonorensis, Clavispora opuntiae, and Sporopachydermia cereana species complex. Other species are limited to determined geographic areas or host plants. Species isolated only from necrotic cactus tissues are considered as cactophilic and are vectored by insects that feed and breed in these substrates, mainly Drosophila spp. Ripe fruit yeast communities are composed mainly of species with a limited physiological nutritional profile during the early stages of fruit deterioration. Ascomycetous yeast species are most frequently associated with ripe fruits, such as Hanseniaspora uvarum, Pichia kudriavzevii, Meyerozyma guilliermondii, Aureobasidium pullulans, Wickerhamiella spp., and others. Basidiomycetous species occur mainly in the later stages of fruit deterioration. Necrotic cactus tissues and ripe tropical fruits also represent rich sources for the discovery of new yeast species.