Production of monascus pigments by a solid-liquid state culture method

Abstract

In a simple batch culture of Monascus growing on 50 g/l tapioca starch as the carbon substrate, the biomass dry weight reached a maximum value of 8 g/l. The red and yellow polyketide pigments continued to be produced after cell growth had leveled off at 40 h, and reached the concentrations of 31 and 26.5 optical density (OD) units, respectively. When a 200 g/l starch medium was continuously fed into a Monascus culture after being grown in batch mode for 60 h, the biomass dry weight reached a concentration of 16 g/l at 140 h. At this point in time, the red and yellow pigment concentrations were 70 and 60 OD units, respectively. A two-state (solid-liquid) batch culture system was constructed using a solid state of 400 g/l gelatinized starch cake and a liquid state which contained all the culture substrates except starch, in which the mycelia were cultured. The starch block was digested gradually through the amylolytic activity of enzymes produced by the Monascus culture. The growth rate of the culture was almost linear up to 170 h, and a cell concentration of 37.5 g/l and pigment concentrations of about 145 OD units for both the red and yellow pigments were achieved.