Screening Of Monacolin K-high-yielding Monascus Strain By Combinative Mutation Treatment And Study Of Solid-state Fermentation

Red yeast rice is a traditional fermented product in China and other countries，itis thought they are medicine homologous food since the ancient times．Throughout itsdevelopment，the research of monascus，monascus pigment that are used for brewinghas been more mature．In the1970s，researchers found a cholesterol synthesisinhibitors which is called Monacolin K in the fermented red aspergillus prodect．It andlovastatin found in the soil aspergillus are the same material，which have the role ofinhibiting the liveness of the key enzymes HMG-CoA reductase in the process oforganisms cholesterol synthetic，so that it can regulates organisms abnormal bloodfat．In view of the huge research value and commercial value of Monacolin K，how toimprove content of Monacolin K in the red aspergillus products becomes the focus ofresearch.．This topic research purpose is to raise the Monacolin K product of functionalMonascus，the results of the study are as follows：Separate four strains of monascus，and identify the pure culture，detect theMonacolin K of each strains monascus soild fermentation by the method of TLC(thinlayer chromatography)，then screen out four trains that can produce Monacolin Kpreliminarily，number M-H1、M-H2、M-H3and M-H4respectively，then detect thecontent of Monacolin K by the means of HPLC(High Performance LiquidChromatography)，thus screen out M-H2that has the highest content of Monacolin K，which is2.12mg/g．It can be identified that the strain is M. rubber by common mouldappraisal method，such as morphologic observation．Take the germinated brown rice which have more protein and sugar and containγ-characteristics as the fermentation substrate，add extra different carbon sources，nitrogen source and metal ions，study the effect of these three factors on the metabolicaccumulation of Monacolin K in its fermentation process．The results shows thatwhen we choose glycerin as carbon source、choose peptone as nitrogen source andchoose ZnSO4as inorganic salt，it is good for Monacolin K synthesis．Throughorthogonal experiment，we find the best Proportion，glycerin concentration is0.2%，peptone concentration is0.15%，ZnSO4addition is0.0005g/g．Take the Monascus M-H2as start trains，give them ultraviolet ray and LiClcomposite mutation processing，combine with antibacterial circle screening，to getstrain M-H4-3which can product more Monacolin K，then test its genetic stability，inoculate it in the malt juice to get the fifth generation．All generations areinoculated in the rice to conduct solid fermentation cultivation and detected the fermentation samples by the means of HPLC．The result shows that strains M-H4-3have stable performance，its yield reaches to4.02mg/g，which is2times higher thanthe start trains．Use the response surface method to analyse the M-H2solid fermentationconditions．The result shows that under the condition of earlier stage temperature is30℃，later temperature is24℃，initial water content is60%，the highest output ofMonacolin K can reach5.33mg/g．...