Response surface modeling for y-aminobutyric acid production by Monascus pilosus GM100 under solid-state fermentation

Abstract

Monascus, a traditional Chinese fermentation fungus, is used as a natural dietary supplement. As a metabolite of Monascus, g-aminobutyric acid (GABA) had been proven to be a hypotensive agent. In this study, the ability of Monascus pilosus to produce GABA was investigated under solid-state fermentation. Plackett-Burman design (PBD) was applied to seek for the crucial parameters that affect the production of GABA. In addition, central composite design (CCD) was used to optimize each crucial variable. As a result, the maximum GABA production predicted by the CCD was 937.61 mg/kg using 60 g sterilized rice and 0.5% ethanol; optimum values of those crucial coefficients were determined to be monosodium glutamate (MSG) 0.714 (37.14 gkg-1), CaCl22H2O -0.025 (4.4625 gkg-1), and time of anaerobic treatment with CO2 (CO2 Time) -0.1947 (43.327 h). Under the theoretical optimal conditions, the actual GABA production was 884.32 mg/kg, approximately 4.9 times than that before optimization.