Morphological and cultural characteristics and sporulation in microorganisms isolated from spontaneously fermented wines

¹ Agricultural academy, Institute of Viticulture and Enology – Pleven, Bulgaria
² University of Food Technologies – Plovdiv, Bulgaria

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The morphological and cultural characteristics of newly isolated yeast and bacterial strains and the process of sporulation in yeasts, were studied. As a result of spontaneous alcoholic fermentation of grape pomace from 10 samples of grapes from autochthonous white and red vine varieties, a total of 38 morphological types were isolated. A morphological and cultural characterization of the isolated pure cultures of microorganisms was made, of which 26 yeast and 12 bacterial strains. For the investigation, 72-hour liquid cultures grown in sterile grape juice medium and colonies formed on grape juice–agar medium were used. In shape, the yeast cells were spherical to slightly elliptical, located singly in the medium. They multiplied by budding, most often unilateral, polar. Cell sizes ranged from 3-6 µm to 4-10 µm in length. The growth of the different strains of yeast and bacteria in liquid and on solid nutrient media was similar. Their propagation started around 18-24 hours. The flocculation of individual yeast strains varied, with no definite trend. A sporulation process was observed in yeast. Almost all isolated strains produced spores without prior copulation. Sporulation was most often quite abundant to abundant, about 50-60% and 70-80% of the cells formed spores.