Caracterização morfológica e fisiológica de leveduras submetidas a preservação prolongada

Abstract

Yeasts of the genus Hanseniaspora are recognized for their aromatic contribution to ciders, fermented fruits and wines. For good preservation of yeast cultures it is essential to maintain the morphological and physiological properties of the strains regardless of the storage method chosen. Freezing at -80°C and lyophilization are widely used methods for the long-term preservation of microorganisms. The objective of the present work was to evaluate the physiological and morphological characteristics of yeasts used in the fermented beverage industry (Hanseniaspora uvarum and Hanseniaspora guilliermondii), preserved by freezing at -80°C and lyophilization. Ecometric test, morphological growth assays in solid and liquid medium, biochemical evaluations involving carbohydrate fermentations and tests of assimilation of several compounds and molecular characterization were performed. The results evidenced the selectivity of the culture medium Malt Agar Extract - YMA for the studied strains. In the biochemical profile the evaluation of the strains showed differences in the capacity to ferment glucose and other sugars as well as in the assimilation of citrate, nitrate and starch hydrolysis, however all other biochemical tests did not change. Therefore, the morphological and physiological characteristics of the strains of yeasts studied, even with small variations, were maintained, guaranteeing the viability of these microorganisms for the production of aromatic compounds in fermented beverages, both by freezing at -80°C and by freeze-drying.