Breeding Of Monascus Purpureus Strain For High Yield Water-Soluble Red Pigments And Regulation Of Lanthanum (?) Ion Fermentation And Application Characteristics

Monascus pigments is a kind of natural and green edible pigment which only one produced by microbial fermentation at present,have gained widespread application due to thier beneficial properties,including antioxidant,antitumor,antibacterial,antiinflammatory and hypoglycemic functions.Red pigments is one of the most widely used.With the deepening of the research on Monascus red pigments,how to improve the yield and application quality of extracellular water-soluble red pigments is a difficult problem.Rare earth elements have been widely applied as efficient elicitors to improve production of secondary metabolites in plants and microorganisms.However,there are less reports on the effects of rare earth elements on Monascus metabolites.In this study,screening and breeding of Monascus strains with high yield of water-soluble red pigments,the regulation of Lanthanum(?)ion on fermentation metabolism of high yield strain and the characteristics and application of water-soluble red pigments were investigated,which provided guidance for theoretical research,industrial production and practical application of Monascus red pigments.The main conclusions are as follows:According to the problem of submerged fermenation to produce Monascus red pigments in industrial application,starting from screening and breeding of strains,Monascus purpureus M-3(GDMCC NO.61166)with high yield of water-soluble red pigments was screened from commercially available red yeast rice in Gutian,Fujian.The carbon,nitrogen sources and important culture conditions were optimized by single factor experiments.The experiment results showed that:carbon and nitrogen sources could significantly affect the production of Monascus red pigments by submerged fermenation.The combination of glycerinum as the only carbon source with yeast extract was conducive to synthtic to extracellular water-soluble red pigments,and added 4 g/L gultamic acid,seed inoculum was 9%(v/v),after fermentation8 d,the production of red pigment reached 104.72 U/m L,extracellular water-soluble red pigment andintracellular red pigment were reached 73.87 U/m L and 30.85 U/m L,respectively.This results indicated that M-3 could effectively convert glycerol into Monascus red pigments,which provided a healthy and environmentally friendly pathway for the efficient utilization of glycerinum.In order to further improve the ability of M-3 to produce extracellular water-soluble red pigments,the fermentation metabilic regulation of La Cl₃.7H₂O on red pigments production by M-3 was investigated.When 0.4 g/L La³⁺was added to the fermentation medium on the 2nd day and fermenting for another 6 days,reactive oxygen species levels were obviously improved to facilitate Monascus pigments biosynthesis via the oxidative stress response.The Monascus cell membrance was more inclined to synthesize unsaturated fatty acids,enhance permeability and fluidity of the cell membrane,the hydrophobic red pigments in mycelia were secreted into the fermentation broth and then removed the feedback inhibition effect of intracellualr red pigment biosynthesis.La³⁺regulated the expression of genes associated with secondary metabolite of M-3,resulted in genes related to red pigment synthesis were upregulated,while genes related to citrinin synthesis were downregulated.Finally,the yield of extracellular red pigment and biomass were reached 124.10 U/m L and 33.10 g/L,respectively,which were 70.23%and 88.45%higher than those of the control;simultaneously,citrinin was decreased by 59.93%and 38.14%in the extracellular and intracellular fractions.Finally,the physical,chemical properties and biological activities of the extracellular water-soluble red pigments were evaluated,demonstrated that it possess good thermal stability,poor light stability and good antioxidant capacity.In addition,a new color stabilization-honeysuckle water extract was developed,which could effectively improve the light stability of the extracellular water-soluble red pigments.The red pigments degradation rate after 24 h UV irradiation was reduced by 3.14 times with 0.7%honeysuckle water extract.When it was applied to apple juice drinks and candies,found that it could effectively improve the antioxidant capacity and preservation stability of apple juice drinks and candies.This study provided a reference for the application of extracellular red pigment in the field of food.