Historic and charming <italic>Monascus</italic> spp.

Abstract

<p indent="0mm"><italic>Monascus</italic> species are well-known as fermentation strains in food and pharmaceutical industries in China. <italic>Monascus</italic> spp. have a long application history for more than <sc>2000 years.</sc> Red mold rice (RMR), also known as anka and Hongqu in China, is the fermented product of steamed rice inoculated with certain <italic>Monascus</italic> strains. Nowadays, RMR and its related products have been extensively applied in food and medicine industries. In these RMR products, <italic>Monascus</italic> strains produce two kinds of the most well-known secondary metabolites (SMs) <italic>Monascus</italic> pigments (MPs) and monacolin K (MK). MPs have been employed as natural food colorant in Southeast Asia over one thousand years. MK (also known as lovastatin), an anticholesterol compound, has been developed to be a hypolipidemic drug and food supplements. Today, RMR and its relative products mainly yielded in China are not only applied in Southeast Asia, but also exported to Europe and America. It is estimated that more than one billion people, around the world, eat RMR and other relative products in their daily life. Therefore, <italic>Monascus</italic> species are considered as one of the historic and charming fermentation strains in China. Theoretical researches and product development of <italic>Monascus</italic> strains have attracted wide attention and made fruitful scientific achievements, especially in recent <sc>30 years.</sc> In-depth studies regarding RMR have revealed that <italic>Monascus</italic> spp. not only produce beneficial SMs, MPs and MK, but also a mycotoxin citrinin (CIT). A substantial amount of researches has been successfully made to elucidate the biosynthetic pathways of these SMs and their regulation mechanism. These achievements not only serve as models of fungal SMs biosynthesis, but also provide a roadmap for metabolic engineering and synthetic biology towards the selective production of the more valuable components. Furthermore, <italic>Monascus</italic> spp. also are unique objects for researching fungal reproduction regulation and magnetic and/or light responses because <italic>Monascus</italic> spp. are found to be significantly different from the known filamentous fungi in these two fields. The progress on reproduction regulation of <italic>Monascus</italic> spp. revealed that the well-established conidiation central regulation in <italic>Aspergillus</italic> species is not applicable in their <italic>Monascus</italic> relatives. On the other hand, <italic>M</italic>.<italic> ruber</italic> M7 genome contains one red-light and two green-light receptors, but not any blue-light receptor ortholog is present in<italic> M</italic>.<italic> ruber </italic>M7 and other <italic>Monascus</italic> species, indicating a biologically significant difference between <italic>Monascus</italic> species and other filamentous fungi. Because of the unique reproduction mechanism, light and magnetic response and abundant SMs biosynthesis of <italic>Monascus</italic> spp., it is expected to enrich the theoretical understanding of filamentous fungi and even the biological world through further research on <italic>Monascus</italic> spp. Therefore, it demonstrates a great potential for developing <italic>Monascus</italic> spp. into a model microorganism. The key discussions and future prospects are also proposed from the aspects of faced challenge on <italic>Monascus</italic> spp. investigation and their products development.