The production, purification, and characterization of an extracellular protease released by
Rhodotorula mucilaginosa L7 were evaluated in this study. This strain was isolated from an
Antarctic marine alga and previously selected among others based on the capacity to produce
the highest extracellular proteolytic activity in preliminary tests. R. mucilaginosa L7
was grown in Saboraud-dextrose medium at 25 C, and the cell growth, pH of the medium,
extracellular protease production and the glucose and protein consumption were determined
as a function of time. The protease was then purified, and the effects of pH, temperature,
and salt concentration on the catalytic activity and enzyme stability were
determined. Enzyme production started at the beginning of the exponential phase of
growth and reached a maximum after 48 h, which was accompanied by a decrease in
the pH as well as reductions of the protein and glucose concentrations in the medium.
The purified protease presented optimal catalytic activity at pH 5.0 and 50 C. Finally, the
enzyme was stable in the presence of high concentrations of NaCl. These characteristics
are of interest for future studies and may lead to potential biotechnological applications
that require enzyme activity and stability under acidic conditions and/or high salt
concentrations.