Optimization of culture conditions and bench-scale production of anticancer enzyme L-asparaginase by submerged fermentation from Aspergillus terreus CCT 7693

Abstract

L-Asparaginase amidohydrolase (EC 3.5.1.1) has received significant attention owing to its clinical use in acute lymphoblastic leukemia treatment and non-clinical applications in the food industry to reduce acrylamide (toxic compound) formation during the frying of starchy foods. In this study, a sequential optimization strategy was used to determine the best culture conditions for L-asparaginase production from filamentous fungus Aspergillus terreus CCT 7693 by submerged fermentation. The cultural conditions were studied using a 3-level, central composite design of response surface methodology, and biomass and enzyme production were optimized separately. The highest amount of biomass (22.0 g·L⁻¹) was obtained with modified Czapek–Dox medium containing glucose (14 g·L⁻¹), L-proline (10 g·L⁻¹), and ammonium nitrate (2 g·L⁻¹) fermented at 37.2 °C and pH 8.56; for maximum enzyme production (13.50 U·g⁻¹), the best condition was modified Czapek–Dox medium containing glucose (2 g·L⁻¹), L-proline (10 g·L⁻¹), and inoculum concentration of 4.8 × 10⁸ espore·mL⁻¹ adjusted to pH 9.49 at 34.6 °C. The L-asparaginase production profile was studied in a 7 L bench-scale bioreactor and a final specific activity of 13.81 U·g⁻¹ was achieved, which represents an increase of 200% in relation to the initial non-optimized conditions.

Keywords:

• Fungal cell culture
• microbial metabolism
• L-asparaginase
• anticancer agent
• submerged fermentation
• bioreactor system

Additional information

Funding

FAPESP – Fundação de Amparo à Pesquisa do Estado de São Paulo: Process numbers: 2013/08617-7 and 2013/19584-2.