Basidiomycetous Yeast, Glaciozyma antarctica, Forming Frost-Columnar Colonies on Frozen Medium

• Published in: Microorganisms
• Main Authors: Seiichi Fujiu, Masanobu Ito, Eriko Kobayashi, Yuichi Hanada, Midori Yoshida, Sakae Kudoh, Tamotsu Hoshino
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2021
• Subjects: cold adaptation; ecological strategy; frost resistance; ice-binding proteins (IBPs); polysaccharide; unfrozen water; East Antarctica; Sôya Coast; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/microorganisms9081679

The basidiomycetous yeast, Glaciozyma antarctica, was isolated from various terrestrial materials collected from the Sôya coast, East Antarctica, and formed frost-columnar colonies on agar plates frozen at −1 °C. Thawed colonies were highly viscous, indicating that the yeast produced a large number of extracellular polysaccharides (EPS). G. antarctica was then cultured on frozen media containing red food coloring to observe the dynamics of solutes in unfrozen water; pigments accumulated in frozen yeast colonies, indicating that solutes were concentrated in unfrozen water of yeast colonies. Moreover, the yeast produced a small quantity of ice-binding proteins (IBPs) which inhibited ice crystal growth. Solutes in unfrozen water were considered to accumulate in the pore of frozen colonies. The extracellular IBPs may have held an unfrozen state of medium water after accumulation in the frost-columnar colony.