Study On The Optimization Of The Production Process Of Monascus Yellow Pigment By Submurged Fermentation

Monascus pigments are secondary metabolites produced by Monascus.As a natural harmless food coloring agent,it is widely used in the food industry.Monascus yellow pigment has become a research hotspot of Monascus pigments because of its high economic benefits and wide application range.Based on this,this article mainly focuses on the breeding of high-yellow pigment monascus,optimization of liquid fermentation conditions,immobilized continuous fermentation and extractive fermentation to improve the yield and production of yellow pigment.The main contents areas follow:1.Breeding of high-yield Monascus yellow pigment strain.A yellow pigment-producing strain H14 was obtained by heavy ion mutagenesis and atmospheric and room temperature plasma(ARTP).The total and extracellular yellow pigment production of strain H14 were 21.41 U/mL and 18.98 U/mL,respectively,and the proportion of extracellular pigment was 88.65%.Compared with the parent strain H1,the production of extracellular pigment and total pigment increased by 437.67%and 247.00%respectively.Then the pigment produced by mutant H14 was determined to be water soluble pigment by the identification of pigments with ethyl acetate.2.Response surface methodology(RSM)was used to optimize the production of yellow pigment.Single factor experiments and Box-Behnken RSM were designed to optimize the liquid fermentation medium.The results showed that when the pH was 4.8,the glucose was 20 g/L,and the vitamin B5 concentration was 0.4 g/L,the Monascus pigment production reached the maximum.When the malt extract was used as the nitrogen source,the yellow pigment production increased by 61.8 U/mL.When Zn2+and Mn2+were added,the yellow pigment production increased by 51.23 U/mL and 41.16 U/mL,respectively.According to the results of singlefactor experiment,four factors of ZnSO4.7H2O,MnSO4·H2O,malt extract and vitamin B5 were finally selected,and the Box-Behnken four-factor three-level orthogonal experimental design was performed using Design expert 8.0 software.Fermentation conditions were optimized to determine the optimal medium:25 g/L KH2PO4,0.4 g/L vitamin Bs,12.29 g/L malt extract,1.5 g/L FeSO4.7H2O,1.5 g/L L CaCl2,15 g/L peptone,0.2 g/L MgSO4.7H2O,5 g/L sodium nitrate,0.32 g/L ZnSO4.7H2O,0.1 g/L MnSO4.H2O,20 g/L glucose,pH=4.8.Under the optimal condition,the production of yellow pigment was 104.67 U/mL,which was 98.26%of the predicted value.Compared with the control group,the production of extracellular yellow pigment and total yellow pigment of mutant H14 increased by 65.66 U/mL and 71.32 U/mL,respectively,and the proportion of extracellular yellow pigment increased from 68.04%to 84.39%.3.Improvement of yellow pigment productivity by coupling immobilized cell fermentation with extraction fermentation.The results showed that when the concentration ratio of sodium alginate:polyvinyl alcohol was(2.5%:0.5%),the immobilized cells had the best effect,and the production of extracellular yellow pigment by continuous fermentation of Monascus strain H14 reached the maximum.Using batch free fermentation and immobilized fermentation,the Monascus yellow pigment production of Monascus H14 was 120.58 U/mL and 139.75 U/mL,respectively.The results of multi-batch immobilized fermentation and multi-batch immobilized extraction fermentation of Monascus H14 showed that the average productivity of yellow pigment was 6.13 U/mL/d and 9.75 AU370nm/day,and the total yellow pigment production was 42.31 AU370nm,57.89 AU370nm.