Invertase and α-glucosidase production by the endemic Antarctic marine yeast Leucosporidium antarcticum

The marine psychrophilic and endemic Antarctic yeast Leucosporidium antarcticum strain 171 synthesizes intracellular β-fructofuranosidase, and intra- and extracellular α-glucosidases. Each enzyme is maximally produced at 5°C, while the strain's optimum growth temperature is 15°C. Invertase biosynthesis appeared regulated by catabolic repression, and induced by sucrose; the enzyme was extremely unstable ex vivo, and only EDTA, Mn²⁺, and BSA stabilized it for up to 12 h after yeast cell lysis. Thermal stability of the invertase was also low (30 min at temperatures up to 12°C). The optimum temperature for invertase activity was 30°C, and optimum pH was 4.55 to 4.75. The extracellular α-glucosidase was maximally active at 35°C and pH 6.70-7.50, and stable for 30 min up to 20°C.