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

Marília Gomes da Silva Santos, Marília de Holanda Cavalcanti Maciel, Minelli Albuquerque Sousa, Aline Gleyce Julião Bomfim, Jadson Diogo Pereira Bezerra, Adalberto Pessoa Júnior & Cristina Maria de Souza-Motta

Sydowia 74: 303-313

Published online on January 21st, 2022

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.

Keywords: aqueous two-phase systems, asparagine, Aspergillus flavus, endophytic fungus, leukaemia.

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