Comparison of Monascus purpureus growth, pigment production and composition on different cereal substrates with solid state fermentation

Abstract

The growth and pigment production of Monascus purpureus during 14 days solid state fermentation on different cereal substrates i.e. rice, corn, whole sorghum grain (WSG), dehulled sorghum grain (DSG) and sorghum bran (SB); and pigment composition of the fermented-products have been evaluated. Fungal biomass was used as a basis of its growth. Pigment content was measured by using spectrophotometer and thin-layer chromatography, and its composition was analyzed by using liquid chromatography coupled with tandem mass spectrometry. M. purpureus grew faster on rice substrate than did on other substrates. Production of pigments was observed at the end of logarithmic phase on all substrates tested. Similar pigment compounds were found on all substrates and the highest production of pigments was on rice, followed by DSG>WSG>Corn>SB. Twelve pigments, six of which were well-known, were detected on the Monascus-fermented products at different levels. Among those, Monapilol B, found in Monascus-fermented dioscorea, was found. On all cases, the red pigment Rubropunctamine was the major one (57–87%), except on SB substrate which produced Yellow II as the major one. Interestingly, fermented-DSG contained a large amount of Rubropunctatin compared to other fermented products. Among the non-rice substrates, DSG is the most potential substrate, on which the fungus exhibited the highest growth and pigment production. These data suggest that the fermented products are good candidates for development of natural food colorant, food supplement, functional food and or medicine with antiinflammation, anticancer and antimicrobial activities.