Optimizing culture medium for debittering constitutive enzyme naringinase production by <i>Aspergillus oryzae</i> JMU316

Abstract

The objective of this study was to investigate nutrient requirements for extracellular constitutive naringinase production by Aspergillus oryzae JMU316. The one-factor-at-a-time method was used to determine the impact of different carbon and nitrogen sources on naringinase production. Naringin exhibited the highest naringinase activity compared to all other carbon sources and pomelo pericarp powder produced comparable naringinase activity. Pomelo pericarp powder was selected as carbon source because it is a waste of fruit process, which means that it is a cheap resource and has additional environmental benefits. Peptone proved to be the most suitable nitrogen source for naringinase production. Subsequently, the orthogonal matrix method was used to further optimize the concentration of pomelo pericarp powder, peptone, and minerals. The optimal concentration of the components were15 g pomelo pericarp powder, 12 g peptone, 0.2 g CaCl₂, 0.4 g NaCl, 2 g MgSO₄·7H₂O and 1 g K₂HPO₄ in 1 L distilled water for producing 408.28 IU/mL naringinase activity. The effects of medium components on naringinase were in the order of pomelo pericarp powder, K₂HPO₄, NaCl, peptone, CaCl₂, MgSO₄·7H₂O. This two-step optimization strategy used in this study can be widely applied to other microbial fermentation processes.

Key words: Pomelo pericarp powder, orthogonal matrix method, naringinase, culture medium optimization, Aspergillus oryzae JMU316.