Selection and Optimization of Medium Components for the Efficient Production of L-Asparaginase by Leucosporidium scottii L115-A Psychrotolerant Yeast

This study reports the production of L-asparaginase (ASNase), an enzyme mainly used for the treatment of acute lymphoblastic leukemia, by Leucosporidium scottii L115, a psychrotolerant yeast isolated from the Antarctic ecosystem. Focus was given to select the most appropriate medium components able to maximize the enzyme production by this yeast, as a first step for the development of a new process to produce ASNase. By combining knowledge in bioprocesses, statistical analysis and modeling, the medium composition that most favored enzyme production was established, which consisted of using a mixture of sucrose (28.34 g L-1) and glycerol (15.61 g L-1) as carbon sources, supplemented with proline (6.15 g L-1) and the following salts (g L-1): KCl, 0.52; MgSO4 center dot 7H(2)O, 0.52; CuNO3 center dot 3H(2)O, 0.001; ZnSO4 center dot 7H(2)O, 0.001; and FeSO4 center dot 7H(2)O, 0.001. By using this medium, enzyme production of 2850 U L-1 (productivity of 23.75 U L-1 h(-1)) was obtained, which represented a 28-fold increase in enzyme production per gram of cells (178 U gdcw(-1)) when compared to the control (non-optimized medium), and a 50-fold increase when compared to a reference medium used for ASNase production.