The effect of medium composition on enzyme and β-glucan production by Aspergillus oryzae KCCM 12698 was investigated. Brown rice, rice bran, nitrogen, and ascorbic acid are key components of the synthetic medium used in liquid-state fermentation. To determine the optimal concentrations of these components for enzyme and β-glucan production, we conducted one factor at a time experiments, which showed that the optimal concentrations were 30 g/l brown rice, 30 g/l rice bran, 10 g/l soytone, and 3 g/l ascorbic acid. Pretreatment of brown rice for 60 min prior to inoculation enhanced fungal biomass, while increasing the production of enzymes and β-glucan using solidstate fermentation. Maximum fungal biomass of 0.76 mg/g, amylase (26,551.03 U/g), protease (1,340.50 U/g), and β-glucan at 9.34% (w/w) were obtained during fermentation. Therefore, solidstate fermentation of brown rice is a process that could enhance yield and overall production of enzymes and β-glucan for use in various applications.

Aspergillus oryzae KCCM 11372 was used to enhance the production of β-glucan using humidity control strategies. Under conditions of 60% humidity, solid-state fermentation (SSF) increased the yields of enzymes (amylase and protease), fungal biomass (ergosterol), and β-glucan. The maximum concentrations obtained were 14800.58 U/g at 72 h, 1068.14 U/g at 120 h, 1.42 mg/g at 72 h, and 12.0% (w/w) at 72 h, respectively. Moreover, the β-glucan containing fermented brown rice (β-glucan-FBR) extracts at concentrations of 25–300 μg/ml was considered noncytotoxic to 3T3-L1 preadipocytes. We then studied the inhibitory effects of the extracts on fat droplet formation in 3T3-L1 cells. As a result, 300 μg/ml of β-glucan-FBR extracts showed a high inhibition of 38.88% in lipid accumulation. Further, these extracts inhibited adipogenesis in the 3T3-L1 adipocytes by decreasing the expression of C/EBPα, PPARγ, aP2, and GLUT4 genes.

Liquid-state fermentation (LSF) and solid-state fermentation (SSF) were carried out to produce enzymes and β-glucan. The modified synthetic medium composition in liquid-state fermentation (LSF) was determined to be 5% (w/v) whole oat flour, 2% (w/v) tryptone, and 2% (w/v) rice bran. The different humidity conditions of oat by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 0.23 mg/g, 7,157.38 U/g, 413.67 U/g, and 8.26% (w/w), respectively, at 60% of humidity condition. Moreover, α-glucosidase inhibition activities of fermented oat with 60% humidity at 48 h were shown to be high 49.08% (w/w). Therefore, liquid-and solid-state fermentation processes were found to enhance the overall fermentation yields of oat to produce enzymes and β-glucan.