Optimization of L-Asparaginase Production from Aspergillus caespitosus: Solid-State and Submerged Fermentation Using Low-Cost Substrates and Partial Purification
Natana Gontijo Rabelo, Luara Aparecida Simões, Natalia Andrade Teixeira Fernandes, Angélica Cristina de Souza, Maysa Lima Parente Fernandes, Lizzy Ayra Alcântara Veríssimo, Rosane Freitas Schwan, Disney Ribeiro Dias
Abstract
This work aimed to optimize the production of L-asparaginase (L-ASNase) from Aspergillus caespitosus CCDCA 11593 using Pereskia aculeata (Ora-pro-nóbis) leaf fiber as a substrate for solid-state fermentation (SSF), along with powdered whey protein as a substrate in submerged fermentation (SmF) processes. A centered face design was applied to evaluate the effect of the different parameters. Additionally, L-ASNase was partially purified on an ion-exchange cryogel column. For SSF, the experimental condition, inoculum concentration 105 spores/mL, 120 h at 25 °C, 14% of substrate, and 1% of asparagine, corresponded to the highest enzymatic activity (2.75 U/mL) of L-ASNase. For SmF, the experimental condition of greater enzymatic activity (1.49 U/mL) was obtained in the medium containing 16% to 24% asparagine, 3.3% to 4.7% substrate, spore concentration of 7 × 106 to 107 spores/mL, temperature range of 29.8 to 34.8 °C, pH range of 5.7 to 6.3, and 87 to 105 h of fermentation. The L-ASNase obtained from SmF was subjected to adsorption tests, resulting in 4.4 U/mg of partially purified enzyme. This study suggested that whey protein and Ora-pro-nóbis leaf fiber could be a low-cost substrate for L-ASNase production. Additionally, using an ion-exchange cryogel column for enzyme purification holds promise for sustainable applications in the clinical and food industries.