Pigment Formation by <i>Monascus pilosus</i> DBM 4361 in Submerged Liquid Culture

<i>Monascus pilosus</i> is usually cultivated on rice because of monacolin K. We focused on pigment production in submerged liquid culture (SLC) where <i>M. pilosus</i> produced different pigments compared to <i>M. purpureus</i> and <i>M. ruber</i>. From the group of classic <i>Monascus</i> pigments, there were formed mostly compounds with a five-carbon side chain, and the dominant pigment was monascuspiloin, a yellow pigment structurally similar to monascin. In SLC, previously undescribed patterns affecting pigment formation were observed, such as the Crabtree effect, carbon catabolite repression of pigments caused by glucose and other mono-/disaccharides, as well as nitrogen regulation, particularly repression of pigment formation by ammonium sulfate. The highest pigment concentration in the extract was obtained using an organic nitrogen source, specifically 340 mg/L for yellow pigments utilizing a combination of sucrose and tryptone, 346 mg/L for orange pigments using starch and tryptone, and 75 mg/L for red pigments using lactose and tryptone.