Isolation and characterization of yeasts present in the mountain apple Syzygium malaccense (l.) Merr. & L.M Perry in commune 1 of Neiva- Huila

Abstract

The city of Neiva (Colombia), hosts a diversity of tropical fruit, including the rose apple (Syzygium malaccense), which is one of the most abundant, but rarely consumed. In this study, the yeasts in the rose apple were isolated and characterized after samples were taken from different areas of the city’s Comuna 1, taking into account that they are most abundant in June and December. In order to calculate the CFU/g of the fruit, serial dilutions were undertaken that were subsequently cultivated in Potato Dextrose Agar (PDA) with gentamicin. The characterization of the different morphotypes is carried out through using the plate count method and analyzing the cells through a microscope. Moreover, physiological and biochemical tests were undertaken, such as the evaluation of bacterial growth at a temperature of 37 °C and at room temperature, and the assimilation of some simple sugars. The calculations of the isolated yeasts from the different samples were found to be between 10x102 and 54x102 CFU/g. Twenty different morphotypes were identified, which were understood to belong to six different genera of yeast: Rhodotorula spp.; Hanseniaspora spp; Brettanomyces spp; Candida spp; Kloeckera; Torulopsis, as well as a Dimorphic fungus. The evaluation of the artisanal cultivation method for the same fruit allowed for the optimum increase of the different yeast morphotypes that were previously isolated in the PDA. The isolated yeasts kept their viability for six months conserved under a mineral-oil overlay. The results obtained in this study can be used for the selection of important yeasts in the bio-technic industry. Furthermore, it is shown that the fruit is free of pathogenic yeast