枯草芽孢杆菌和红曲菌共培养诱导天然黄色素合成的分子机制

红曲菌（传统称为红曲霉）是广泛应用于食品行业的丝状真菌，然而市场上现有的红曲黄色素产品是经过化学转化制得，其安全性存在争议，因此通过发酵法直接生产红曲黄色素具有重要意义。针对其发酵过程缺乏高效调控手段的瓶颈问题，申请人利用枯草芽孢杆菌和红曲菌共培养诱导黄色素的大量合成，但是其调控过程及内在分子机制仍不清晰。基于此，本项目首先通过研究枯草芽孢杆菌的添加比例和时机等重要因素对红曲黄色素产量的影响规律，建立合适的共培养诱导体系；接着通过初筛分离、色谱纯化和质谱解析等手段，明确共培养体系中枯草芽孢杆菌所分泌的信号因子的物质信息；进而探究信号因子对红曲菌体形态，膜通透性及胞内第二信使的影响，并通过多组学分析黄色素合成途径关键基因/酶的变化，结合分子生物学验证，阐明共培养诱导红曲黄色素合成的分子机制。本研究成果可为红曲天然黄色素的高效生产奠定理论基础，也可为微生物共培养的机理研究提供有益的参考。

Monascus spp. (traditionally known as red yeast/mold) are filamentous fungi which have been widely used in the food industry. However, the safety of existing Monascus yellow pigments on the market is still controversial because they are produced by chemical transformation. Hence, it is of great importance to produce yellow pigments directly from Monascus fermentation. Until now, the lack of efficient regulation method is the bottleneck in the fermentation process. To solve this problem, co-culture of Bacillus subtilis and Monascus purpureus has been applied to markedly induce the biosynthesis of yellow pigments. However, the regulatory process and the underlying mechanisms are still unclear. Hence, in this project, firstly the effect of the critical factors such as the addition proportion and time of Bacillus subtilis on the yield of Monascus yellow pigments will be studied and then a co-culture induced system will be established. Secondly, the accurate information of the signal factor secreted by Bacillus subtilis will be revealed by primary screening, chromatography purification and mass spectrometry analysis, etc. Thirdly, the effects of signal factor on the cell morphology, membrane permeability and intracellular second messenger of Monascus purpureus will be investigated. Finally, the molecular mechanism of co-culture induction on the Monascus yellow pigment biosynthesis will be elucidated by multiple omics analysis, and further verified by the molecular biology experiments. This study will not only offer a theoretical support for the industrial production of Monascus natural yellow pigment, but also provide useful reference for understanding the mechanism of microbial interaction in the co-culture induction process.