Abstract: Monascus pigments are actually mixtures of red, orange and yellow pigments. At present, the mainly industrialized pigments produced by Monascus are the red ones, while the production of yellow pigments are still in the research stage. This work aims to increase the yield of Monascus yellow pigment by optimizing the fermentation conditions. In our previous work, the strain Monascus sjs-6 was screened and proved to be capable of producing high yield of yellow pigments. In this study, the conditions of carbon source, nitrogen source, Mg2+ concentration, initial pH and culture temperature were systematically optimized for further enhancing the yield of yellow pigments. By using liquid chromatography-mass spectrometry and nuclear magnetic resonance, the main component of the Monascus yellow pigment was analyzed. The optimal conditions for producing Monascus yellow pigments were as follows: maltose 80 g/L, ammonium sulfate 10 g/L, magnesium sulfate 1.0 g/L, initial pH of the medium 6.0 and at 30 °C. Under these conditions, the highest Monascus yellow pigments reached 508.61 U/mL, corresponding to 1.52 times over the standard conditions before optimization. After analysis and identification, the Monascus yellow pigment was confirmed to be Monascin with a high purity of 97%. This study provides a theoretical basis for the industrial production of natural Monascus yellow pigments.
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