Study On The Performance Of Monascus Pigments Produced By Liquid Fermentation Of A Strain Of Monascus Purpurea

Monascus microorganism can synthesize useful secondary metabolite Monascus pigment?MPs?,which is widely used as food pigment in the food industry.MPs also have good market prospects in the pharmaceutical,cosmetic and textile industries.The traditional production of MPs is mainly by solid-state fermentation,but it has some limitations in large-scale production.Compared with solid-state fermentation,the production of MPs by liquid fermentation technology has more advantages and competitiveness on an industrial scale.In this thesis,a strain of Monascus purpureus isolated from commercial red yeast rice was used in fermentation to determine the effects of different nutrients such as carbon and nitrogen source and its concentration,organic acid metabolism regulator on production MPs.Different illumination conditions on the production of MPs were also investigated,the culture medium and fermentation conditions were optimized preliminarily,which provided a reference for the production MPs with submerged fermentation.The main research results are as follows:?1?The results of single factor experiment of different nutrients show that:Higher mycelium concentration and MPs production could be obtained when glucose was the sole carbon source,and MPs synthesis could be promoted when glycerol was the sole carbon source,but the influence on the biomass was not significant.The appropriate concentrations of glucose and glycerol were 120 g/L and 60 g/L,respectively.The appropriate nitrogen sources were KNO₃ and peptone,and the appropriate concentrations were 2 g/L and 10 g/L,respectively.Suitable concentrations of inorganic salts such as KH₂PO₄,MgSO₄,CaCl₂ and trisodium citrate were 4.0 g/L,0.5 g/L,1.5 g/L and 0.5 g/L,respectively.The addition of pyruvate?1.5 g/L?to the medium promoted MPs synthesis,but citric and malic acids had significant inhibitory effects.?2?On the basis of the single factor experiment,an orthogonal experiment was used to optimize the composition of the medium for producing MPs with glycerol as the main carbon source and promoter.The optimized medium composition was:glycerol 80 g/L,KNO₃ 1.0 g/L,KH₂PO₄ 6.0 g/L,MgSO₄ 0.5 g/L,and CaCl₂ 1.5 g/L.In the optimized culture medium?30?,200 rpm,6 days?,the highest pigment content?yellow:3.86 AU/ml,red:3.88 AU/ml?and biomass?3.1 g/L?were obtained.?3?Medium pH,culture temperature,fluid volume and shake flask speed have significant effects on the synthesis of MPs,the suitable culture condition respectively:pH 5.5,25 ml/250 ml,25?and 150 rpm.?4?Different illumination conditions significantly affect the biomass and MPs synthesis and accumulation of M.purpureus.Compared with the dark treatment,when the light intensity increased from 200 lux to 600 lux,the synthesis quantity of MPs was significantly increased.Blue light significantly promoted the synthesis of MPs,while red light promoted the accumulation of both biomass and MPs.Under optimized conditions,the contents of yellow and red pigment were up to 25.68 AU/ml and 23.33 AU/ml respectively.