Breeding Of Hugh-yield Strain Of Itaconic Acid And Optimization Of Fermentation Condition

Itaconic acid can be polymerized,esterified,and added.It is an important industrial raw material for chemical synthesis and chemical production.At present,the main production methods of itaconic acid are chemical synthesis method and biological fermentation method.The fermentation method is widely used because it is non-toxic,and the use of cheap biomass instead of starch-based fermentation to produce itaconic acid has become a new research hotspot.In this paper,mutagenesis and pressure sieving were used to obtain the Aspergillus terreus fermented with xylose,and the fermentation prcess conditions were optimized.Finally,the fermentation broth was fermented with distiller's hydrolysate as carbon source.The specific research contents and achievements are as follows:Firstly,Aspergillus terreus CICC 40205-2-67 was obtained by pressure and mutagenesis screening,which can simultaneously produce glucose and xylose to produce itaconic acid.The fermentation yield of glucose as carbon source can reach 48.84 g/L,and the acid yield is higher.The original bacteria increased by 36.42%;the yield of xylose as carbon source reached 30.96 g/L,and the acid yield increased by 69.03%compared with the original bacteria.The strains obtained by the screening have strong growth ability,good spore-producing ability and good stability of strains.Secondly,the orthogonal optimization of Aspergillus terreus seed culture medium,the optimized seeds contain dense core zone and loose zone,and the dissolved oxygen transfer is good,and the metabolic acid production ability is strong.The fermentation medium was optimized by response surface methodology,and the fermentation conditions were optimized by single factor.Finally,the mixed sugar of xylose:glucose=3:7 was used as the substrate for fermentation.The yield of itaconic acid reached 56.94 g/L.Increased by 85.35%.Finally,the tartar hydrolysate is used as a carbon source to produce itaconic acid.The treated distiller's hydrolysate containing 25.16 g/L of reducing sugar was fermented as a carbon source,and the yield of itaconic acid was up to 7.9 g/L.In order to increase the acid yield,the hydrolyzate was concentrated 4 times,and the production of itaconic acid reached 34.27 g/L;the reducing sugar was added to the fermentation broth to ferment,and the experiment was supplemented with sugar(xylose:glucose=3:7)The yields of itaconic acid,which was fermented with glucose as a substrate,were 23.76 g/L and 34.98 g/L,respectively.It is indicated that the hydrolyzate can replace the reducing sugar as the fermenting carbon source of the microorganism.