Characterization and partial purification of L-asparaginase produced by endophytic fungi from cactus Cereus jamacaru

Abstract

L-asparaginase (L-ASNase) is used in the treatment of acute lymphoblastic leukaemia and in food processing. This paper evaluates the production, purification, and characterisation of L-ASNase from five endophytic fungi isolated from the cactus Cereus jamacaru. All five filamentous fungi showed the ability to produce L-ASNase; however, Aspergillus flavus URM 6886 showed the highest enzymatic activity (0.12 U/ml). The L-ASNase produced by this fungus exhibited highest enzymatic activity at pH 4.0 and 50 °C, and showed enzymatic activity over a wide range of pH values (4.0–9.2) at temperatures of 20 °C and 30 °C. The activity of L-ASNase showed lower values in the presence of Co2+, Zn2+, Mn2+, and Ca2+ ions and was completely inactivated in the presence of Mg2+ and Cu2+. Phenylmethanesulfonyl fluoride and iodoacetic acid caused significant increases of 122.9 % and 168.7 %, respectively, in enzyme activity. The optimal conditions for the purification of L-ASNase using a two-phase aqueous system were 24.0 % (w/w) of 6000 g/mol PEG and 20.0 % (w/w) of citrate. Aspergillus flavus URM 6886 is indicated for future studies to optimize the production of L-ASNase and its biotechnological applications, be it in the food or medicine industry