Filamentous fungi producing l-asparaginase with low glutaminase activity isolated from Brazilian savanna soil

L-asparaginase is an enzyme used as treatment for acute lymphoblastic leukemia (ALL) due to its ability to hydrolyze L-asparagine, an essential amino acid synthesized by normal cells unlike neo-plastic cells. The adverse effects of L-asparaginase formulations are associated with its glutaminase activity and bacterial origin; therefore, it is important to find new sources of L-asparaginase-producing eukaryotic microorganisms with low glutaminase activity. This work evaluated the biotechnological potential of filamentous fungi isolated from Brazilian Savanna soil and plants for L-asparaginase production. Thirty-nine isolates were screened for enzyme production using the plate assay, followed by measuring enzymatic activity in cells after submerged fermentation. The variables influencing L-asparaginase production were evaluated using Plackett–Burman design. Cell disruption methods were evaluated for L-asparaginase release. Penicillium sizovae 2DSST1 and Fusarium proliferatum DCFS10 showed the highest L-asparaginase activity levels and the lowest glutaminase activity levels. Penicillium sizovae L-asparaginase was repressed by carbon sources, whereas higher carbon concentrations enhanced L-asparaginase by F. proliferatum. Maximum enzyme productivity, specific enzyme yield and the biomass conversion factor in the enzyme increased after Plackett–Burman design. Freeze-grinding released 5-fold more L-asparaginase from cells than sonication. This study shows two species, which have not yet been reported, as sources of L-asparaginase with possible reduced immunogenicity for ALL therapy.