Effect of pH and nonionic surfactant on profile of intracellular and extracellular Monascus pigments

The uptake of nutrients and export of intracellular products are essential issues of microbial fermentation. Two-stage of Monascus fermentation using monosodium glutamate (MSG) as the sole nitrogen source, i.e., the first stage microbial fermentation in an aqueous solution and the second stage perstractive fermentation in a nonionic surfactant micelle aqueous solution, was carried out under different initial pH conditions. The results revealed that extracellular pH influences on the uptake of MSG and the export of water-soluble red pigment derivates into its extracellular broth. On the other hand, the export of intracellular hydrophobic pigments is affected by perstractive fermentation in nonionic surfactant micelle aqueous solution. All of those factors exhibit strong effect on the profile of Monascus pigments. This information is key to controlling profile of extracellular Monascus pigments by perstractive fermentation in nonionic surfactant micelle aqueous solution. (C) 2013 Elsevier Ltd. All rights reserved.