Pigment Formation by Monascus pilosus DBM 4361 in Submerged Liquid Culture

Monascus pilosus is usually
cultivated
on rice because of monacolin K. We focused on pigment production in
submerged liquid culture (SLC) where M. pilosus produced different pigments compared to M. purpureus and M. ruber. From the group of classic Monascus 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.

毛红曲霉（Monascus pilosus）通常因莫纳可林K（monacolin K）的生产需求而在大米基质上培养。本研究聚焦于深层液体培养（submerged liquid culture, SLC）体系下的色素合成：相较于紫红曲霉（M. purpureus）与红色红曲霉（M. ruber），毛红曲霉在此培养条件下可产生差异化的色素组分。经典红曲霉色素类群中，多数化合物带有五碳侧链，其中优势色素为毛红曲素（monascuspiloin）——一种结构与红曲素（monascin）相似的黄色色素。在深层液体培养体系中，研究团队观测到此前未见报道的色素形成调控模式，包括克拉布特里效应（Crabtree effect）、葡萄糖及其他单/双糖介导的色素碳分解代谢物阻遏，以及氮代谢调节，其中硫酸铵对色素形成的阻遏作用尤为显著。采用有机氮源时，发酵提取物的色素浓度可达峰值：当以蔗糖与胰蛋白胨复配为培养基时，黄色色素产量达340 mg/L；以淀粉与胰蛋白胨复配时，橙色色素产量达346 mg/L；而以乳糖与胰蛋白胨复配时，红色色素产量为75 mg/L。