MORPHO-PHYSIOLOGICAL FEATURES OF LACTOSE-FERMENTING YEAST ISOLATED FROM FERMENTED MILK PRODUCTS OF MIXED FERMENTATION

Abstract

It is known that long-term storage of cultures with the help of periodic reseeding does not always ensure the stability of morphological, cultural and physiological characteristics. In this regard, the question arises of the need to study the range of variability of individual characters and the influence of the environment on the heterogeneity properties of collection cultures and study their morphophysiological properties. We considered it appropriate to return to the study of the main taxonomically significant phenotypic characters of these yeasts. As a result, it was noted that the culture of Candida sphaerica KM95 does not show natural variability, which would be expressed in the macromorphological heterogeneity of the population: almost all colonies had similar characteristics. The culture of Candida kefyr var. kumis 17 when sieving on a dense medium, a noticeable variability is observed in a number of morphological features. Thus, the population composition is represented by several types of colonies that differ from each other in size, color, shape, structure, etc. In search of cultures that ferment lactose intensively, 25 yeast strains isolated from shubat and assigned to the genus Candida were tested. As a result of a comparative study of enzymatic activity, by examining the ability of different strains to ferment lactose, the most active of them were identified - C. sphaerica 1M and C. sphaerica 3M. According to our observations, the studied cultures are able to ferment maltose after their long-term cultivation on wort agar, however, the ability to grow on a medium with lactose is lost.