Diversidade filogenética e caracterização de potencial Killer em leveduras não-Saccharomyces extraídas de frutos do cerrado

Abstract

Yeasts are unicellular fungi that are part of the microbiota of most natural ecosystems and may be cosmopolitan or endemic to specific habitats or regions. They have a sexual state that is not contained in fruiting bodies; grow in habitats rich in sugars, such as fruits, flowers and bark. Killer yeasts are originally defined as producing exotoxins able to killing sensitive cells, and the yeast is immune to own toxin, which gives it competitive advantages. The aim of the present study was to identify, through the analysis of the D1 / D2 domain sequence of the S26 rRNA wild-type non Saccharomyces yeasts that were extracted from fruits of North-Minas GeraisCerrado(araçá, mangaba and panã). Additionally,characterize the occurrence of killer phenotype, to test the tolerance to the different concentrations of ethanol and to evaluate the fermentative efficiency in sugarcane of the tolerants to the 12 % ethanol concentration.Of the total of 60 isolates, three genera and six species were identified: Candida glabrata (2), Kodamaeaohmeri (6), Pichia kluyveri (6), P. kudriavzevii (24), P. manshurica (14) e P. terricola (3);five isolates were not identified. The killer phenotype was positive in four isolates (2.4%), all P. kluyveri. Five isolates were tested for fermentative efficiency and none of them was positive, requiring a second assay.The results indicate that there is a great diversity of yeasts in the North-Minas GeraisCerrado, with great potentials for application in the clinical,biotechnological and agricultural areas. Regarding the killer behavior, these strains are good candidates in the control of fungal pests in fruits, in starter cultures for beverage production, since they can avoid and inhibit the growth of contaminating yeasts in controlled temperature fermentations.