Microparticle-enhanced DX-THS3 β-d-glucuronidase production by controlled fungal morphology in submerged fermentation.

Glycyrrhetinic acid monoglucuronide (GAMG) is a novel and low-calorie sweetener that is widely applied in the food industry. This study aimed to enhance the production of fungal β-d-glucuronidase (GUS) via a novel fermentation technique by evaluating the effects of the various microparticles on DX-THS3 GUS production. Results showed that the silica microparticle greatly affected the morphology of DX-THS3 strain relative to the other microparticles. Microbial structure imaging results showed that the smallest average diameter of fungal pellets was achieved (0.7 ± 0.1 mm) by adding 10 g/L (600 mesh) of silica. The diameter of the control was 3.0 ± 0.5 mm in shake flask fermentation. The GUS activity and biomass of DX-THS3 reached 680 U/mL and 4.2 g/L, respectively, with the use of 10 g/L of silica microparticles, whereas those of the control were 210 U/mL and 2.8 g/L via shake flask fermentation. The findings in this study may provide a potential strategy for designing the morphology of filamentous fungi using microparticles in the industrial production of GAMG.