Investigation Of Biosynthetic Mechanisms Of Monacolink And Pigments In Monascus Purpureus Based On Transcriptomic Analysis

At present,Monascus.spp has been widely used in the food and pharmaceutical industries.The secondary metabolites of Monascus have also received more and more attention.monacolin K is a cholesterol-lowering drug that specifically inhibits HMG-CoA reductase.monacolin K-rich red mold rice(RMR)can be used as a dietary supplement to regulate blood lipids.Monascus can produce different pigments,and many have been shown to have beneficial functions such as anti-inflammatory,anti-atherosclerotic,anti-diabetic and anti-cancer activities.However,the discovery of citrinin has led to controversy over the safety of RMR,which has nephrotoxicity and potential genotoxicity,but studies have shown that not all Monascus produces citrinin,so choosing the right strain is currently The best way is also the most economical way to save capital.Many strains have good ability to produce monacolin K and monascus pigment,so it is very important for the study of such strains.Therefore,this study screened monacolin K and red yeast pigment,which did not produce citrinin,from the commercially available red yeast products in Xinjiang,and mutagenized and optimized the experiment,using transcriptomics technology.The molecular mechanism of monacolin K and Monascus pigment was studied.The main research contents of this paper are as follows:Through the isolation and identification of the commercially available red yeast products in Xinjiang,a total of 67 strains of Monascus were obtained.After genetic comparison,they were divided into four different genera,namely M.pilosus,M.purpureus,M.ruber and M.sanguineus.After screening,a total of 18 good strains of Monascus were obtained,belonging to M.pilosus,M.purpureus,M.ruber and M.sanguineus.M.purpureus which was subjected to liquid fermentation,tested for red pigment,monacolin K yield,citrinin yield,obtained a good strain of M.purpureus HQ32,and identified HQ32 strain as M.purpureus.In order to further optimize the yield of monacolin K,a mutant strain purple red yeast XX-1 with a significantly higher yield than HQ32 was screened by compound mutagenesis,and the M.purpureus XX-1was tested by single factor test and Plackett-Burman test.The medium and fermentation conditions of XX-1 pigment and monacolin K were optimized.The results showed that the optimal fermentation conditions were 6 % glycerol addition,8 % inoculum,and fermentation temperature 28 ?.Monacolin K yield was as high as 210.95±16.35 ?g / mL,20.58 times higher than the wild strain.A transcriptome analysis of the lag phase,log phase and stationary phase(2 d,8 d,12 d)of M.purpureus XX-1 was screened for the participation of M.purpureus XX-1 pigment and monacolin K.The key genes of monacolin K,the metabolic pathways of Monascus pigment and monacolin K and their regulatory networks.The results showed that the key gene mok A synthesized by monacolin K was highly expressed in the log phase and stationary phase of M.purpureus XX-1,indicating that it is a key gene involved in the synthesis of pigment and monacolin K.