低频磁场对红曲菌次生代谢的调控效应及机理研究

Low-frequency magnetic field (LFMF) can significantly affect the growth and metabolism of microorganisms. Monascus spp. are important resource microorganisms that can produce many beneficial secondary metabolites,such as natural edible pigments, lipid lowering drugs-monacolin K, etc.,and that also can produce mycotoxin called citrinin. In previous studies, LFMF were explored as a means to increase biomass and metabolic production of four types of fungi. Based on this research, the current study will investigate variation of typical secondary metabolites such as pigments, monacolin K, and citrinin from the Monascus spp. exposed to low frequency magnetic field. A multiple regression model of the magnetic treatment conditions and quantity of secondary metabolites will be established. Simultaneously, morphological changes of the colonies and structure will be evaluated after LFMF treatment, and the relationships between the secondary metabolites and thalli growth and activity will be constructed. The regulation mechanism of LFMF effecting on secondary metabolism of Monascus spp. will be illustrated with the law of gene expression and protein secretion related to secondary metabolites (pksCT (citrinin synthesis related PKS gene) and mokA (monacolin K synthesis related PKS gene)) , the composition of secondary metabolites and the physiological characteristics such as cell membrane permeability and soluble protein, which affected by LFMF. The study will provide necessary theoretical basis and breakthrough to regulate selectively secondary metabolites of Monascus spp by LFMF.

低频磁场对微生物有明显的磁致效应，能影响微生物的生长和代谢。红曲菌是我国重要的微生物资源，能产生天然食用色素、降脂药物莫那可林K和真菌毒素桔霉素等次生代谢产物。 课题组在前期研究中已发现了低频磁场对4 种真菌生长和代谢的影响规律。本项目将在此基础上，进一步探寻低频磁场作用下红曲菌代谢红曲色素、莫那可林K和桔霉素等3种次生代谢产物的变化规律，回归磁场处理条件与这3种代谢产物生成量之间的关系模型；分析低频磁场处理后，红曲菌菌丝形态的变化，建立菌体生长和菌体活性与次生代谢物生产之间的关系；再结合低频磁场对次生代谢产物的相关基因（如pksCT（桔霉素合成相关PKS基因）和mokA（莫那可林K合成相关PKS基因））转录水平和蛋白质水平的影响，及对次生代谢产物组分和细胞膜通透性、可溶性蛋白质含量等生理特性的影响规律，阐明低频磁场对红曲菌次生代谢的调控机理。为选择性地调控红曲菌次生代谢产物找到新的方法。

采用18SrDNA鉴定了试验用的紫红曲菌菌种，建立了磁场处理条件与莫那可林K、红曲色素和桔霉素等3种次生代谢产物生成量之间的关系，得出了这3种代谢物产量的磁场条件，分别从形态学和生理生化层面上得出了经低频磁场处理后，紫红曲菌的菌落直径、细胞内糖化酶酶活和细胞内蛋白质含量等生理生化特性的变化规律；利用qPCR和Hiseq2000高通量测序以及iTRAQ技术，分别从基因组学和蛋白质组学揭示了在高产莫纳可林K和低产桔霉素的磁场处理条件下，相关基因和蛋白的变化规律。在此基础上，推测得到了低频磁场影响红曲菌次生代谢物的生物合成机制。