The effect of different nitrogen sources on pigment production and sporulation of Monascus species in submerged, shaken culture

Abstract

Thirty-nine strains from the genus Monascus [M. albidus, M. albidus var. glaber, M. anka, M. araneous, M. barkeri, M. fuliginosus, M. major, M. paxii, M. pilosus, M. purpureus, M. pubigerus, M. ruber, M. rubiginosus, M. rubropunctatus, M. vitreus, M. serorubescens] were cultivated aerobically to study the relation between N nutrition and sporulation and pigment production. The effects of yeast extract, nitrate, ammonium and ammonium nitrate were compared. During cultivation the pH of the different media are not the same, resulting in the formation of different colored pigments. When the source of N is yeast extract or nitrate the pH is around 6.5 and red pigments are formed, whereas with ammonium or ammonium nitrate the pH is around 2.5 and the pigments are orange. Probably only the orange pigments, monascorubrin and rubropunctatin, are produced biosynthetically and the other pigments are formed from these by chemical transformations depending on the cultural conditions. The presence of organic N is optimal for growth and unfavorable for pigment production. Reduced growth and best pigment formation occurs with the 3 other N sources. Nitrate stimulates conidiation and sexual reproduction, while ammonium is inhibitory. Pigment production is better when conidiation is reduced. A mechanism is proposed for the control of sporulation and pigment production.