液态发酵条件对红曲菌菌体形态及产物Monacolin K的影响

Effects of the fermentation conditions on mycelial morphology of Monascus ruber 9901 and production of Monacolin K through its submerged fermentation

红曲菌是一种重要的食药双用丝状真菌,红曲菌9901种子扩大培养及液态发酵过程中,发酵条件、菌体形态与代谢产物Monacolin K（MK）之间有着紧密的联系。研究发现,斜面菌种的种龄和孢子接种量对红曲菌种子液的菌球直径、菌球外菌丝长度和菌体量等有明显的影响;在30 L机械搅拌发酵罐培养过程中,搅拌转速对红曲菌菌体形态、生物量和代谢产物MK的产量有较明显的影响。当搅拌转速较低时（150~350 r/min）,红曲菌菌球直径和菌球比例随着转速的加大而逐渐增加,当搅拌转速为350 r/min时,发酵液的中菌体为均匀的、较大的、表面光滑的菌丝球,其液态发酵合成MK产量较高;当搅拌转速为400 r/min,初始直径为1 500μm的菌球减小至最终大小稳定为900μm的菌丝球,这些分散的、较小的、表面有较长菌丝的菌丝球,液态发酵合成MK产量较低。最后选择种子液初始菌球大小为1 500μm,设搅拌转速为350 r/min时,30 L发酵罐分批发酵384 h时MK的产量为1 308 mg/L,进而为更大规模的发酵罐以至工业化生产的实现奠定基础。

Monascus species are important medicinal and edible fungi,the effects of the fermentation conditions on its mycelial morphology and the production of MK through submerged fermentation of Monascus ruber 9901 were investigated in30 L stirred bioreactors. The results indicated that the average diameter of pellet,the length of filamentous and the biomass of seed culture were significantly influenced by the spore age and the concentration of spore suspension. Moreover,the pellet diameter of the mycelia and the ratio of pellet were affected by the rotation speed in 30 L stirred bioreactors. The rotation speed could significantly affect the mycelial morphology,the biomass and the production of MK in submerged fermentation of M. ruber 9901 in 30 L stirred bioreactors. The pellet diameter and the ratio of pellet were gradually increased along with the increase of rotation speed of the bioreactor. When rotation speed was 350 r / min,the pellets were uniform,larger and smoother,and MK yield of fermentation broth was higher. When rotation speed was 400 r / min,the pellets were scattered,smaller and rougher,and MK yield of fermentation broth was lower. Finally,the production of MK reached 1 308 mg / L after 384 h of fermentation when the mycelial pellet diameter was 1 500 μm,rotation speed was 350 r / min in 30 L stirred bioreactors. This study laid a good foundation for the subsequent large scale production of MK.