古老而充满魅力的红曲菌

Historic and charming Monascus spp.

红曲菌(Monascus spp.)又称红曲霉,是我国传统特色的药食同源发酵微生物.红曲菌可产生天然食品着色剂红曲色素(Monascus pigments,MPs)、降血脂成分莫纳可林K(monacolin K,MK)以及丰富的淀粉酶和酯化酶等酶系,红曲菌的发酵产品红曲在我国有近2000年的应用历史.但是某些红曲菌株也可产生真菌毒素桔霉素(citrinin,CIT),污染红曲产品,导致食品安全问题.研究人员通过不懈努力,目前已经解决了红曲产品中CIT污染的问题,关于MPs、MK和CIT等红曲菌主要次级代谢产物生物合成途径及其调控机理的研究也取得了重大突破.同时,研究还发现,红曲菌具有独特的繁殖调控机制以及对光照和磁场(光磁)的感应机理.本文系统梳理了近30年来所取得的关于红曲菌独特繁殖调控与光磁感应机理,以及MPs、MK和CIT等主要次级代谢产物的生物合成途径及其调控机制的研究进展,并展望了红曲菌的未来研究方向,最后阐述了红曲行业面临的挑战及其应对策略.

Monascus species are well-known as fermentation strains in food and pharmaceutical industries in China.Monascus spp.have a long application history for more than 2000 years.Red mold rice(RMR),also known as anka and Hongqu in China,is the fermented product of steamed rice inoculated with certain Monascus strains.Nowadays,RMR and its related products have been extensively applied in food and medicine industries.In these RMR products,Monascus strains produce two kinds of the most well-known secondary metabolites(SMs)Monascus 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,Monascus species are considered as one of the historic and charming fermentation strains in China.Theoretical researches and product development of Monascus strains have attracted wide attention and made fruitful scientific achievements,especially in recent 30 years.In-depth studies regarding RMR have revealed that Monascus 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,Monascus spp.also are unique objects for researching fungal reproduction regulation and magnetic and/or light responses because Monascus spp.are found to be significantly different from the known filamentous fungi in these two fields.The progress on reproduction regulation of Monascus spp.revealed that the well-established conidiation central regulation in Aspergillus species is not applicable in their Monascus relatives.On the other hand,M.ruber M7 genome contains one red-light and two green-light receptors,but not any blue-light receptor ortholog is present in M.ruber M7 and other Monascus species,indicating a biologically significant difference between Monascus species and other filamentous fungi.Because of the unique reproduction mechanism,light and magnetic response and abundant SMs biosynthesis of Monascus spp.,it is expected to enrich the theoretical understanding of filamentous fungi and even the biological world through further research on Monascus spp.Therefore,it demonstrates a great potential for developing Monascus spp.into a model microorganism.The key discussions and future prospects are also proposed from the aspects of faced challenge on Monascus spp.investigation and their products development.