Physiological properties of a new strain of Saccharomyces cerevisiae Dag-1 isolated from the Caspian Sea, Russia

This study reports the isolation of the yeast Saccharomyces cerevisiae Dag-1 (OQ107063.2) from the seawater of the Caspian Sea, specifically from the coastal territory of the Samursky Reserve, Republic of Dagestan, Russia. The strain’s diagnostic and genetic characteristics are provided. Morphological features of the S. cerevisiae Dag-1 include round cells measuring 5.0×5.0 and 1.0×1.0 μkm in size. On Sabouraud’s media, it forms round, convex, opaque, creamy, glossy colonies with a diameter of 3-5 mm. The isolated strain demonstrates the ability to thrive in seawater with a salinity ranging from 12.8-13.0‰, across various temperature ranges (0 –+10, 23- 28, 35-40, 30-37°C), and under different pH conditions (5.6; 8.4-8.5). Additionally, it utilizes monomeric sugars (L-glucose, D-mannose, D-sucrose, D-arabinose, D-cellobiose, and D-xylose) as a source of carbon and energy, also metabolizing alcohols such as D-sorbitol, D-mannitol, and Dinositol (vitamin B8). The strain does not absorb the amino acids lysine and ornithine, and it is catalase-, amylase-, and β-glucosidase-positive while being urease-, oxidase-, and β-galactosidasenegative. Moreover, the strain exhibits high sensitivity to the antibiotics of ketoconazole, nystatin, clotrimazole, fluconazole, and itraconazole. Resistance is observed against the inhibitor potassium tellurite and pathogenic bacteria Escherichia coli, Staphylococcus aurens, and Klebsiella oxitoka. These findings contribute to expanding our understanding of the ecological distribution of marine yeasts and the isolation of an S. cerevisiae strain possessing characteristics of industrial microorganisms.