Mutation Breeding Of Itaconic Acid-Hign-Yielding Strain Of Aspergillus Terreus And Studies Of Its Fermentation Conditions Of The Strain

Itaconic acid（IA,methylene butanedioic acid.common synonyms: methylene succinic acid,3-carboxy-3-butanoic acid,propylenedicarboxylic acid） is one of the promising substances within the group of organic acids. It is a white crystalline unsaturated dicarbonic acid with conjugated double bonds and two carboxyl groups.Due to its unique structure and characteristics,itaconic acid and its ester are useful materials in much domain.It is used for the synthesis of fiber,resin,plastic,rubber,paints, surfactant,ion-exchange resins,lubricant,and so on.It has broad prospects of development and utilization.Althoufh the chemical synthesis route to itaconic acid production have also been examined,none of these ways can really compete with fermentation by Aspergillus terreus,producing and is practiced commercially.A strain,designated Aspergillus terreus,producing IA with a high yield was successfully obtained by selecting at will and directive selection after A.terreus ZJB-04173 was mutagenized by UV-irradiation,ion implantation and with LiCl combining UV.linear tendency of strain death rate was observed when the strain was mutagenized with UV.And an increase-decline-increase tendency of strain death rate was found when it was implanted by N⁺ ion with dose from 30×2.6×10¹³ions/cm² to 180×2.6×10¹³ions/cm² under implantation energy 20keV.The tendency of strain death rate was apparently appeared"saddle shape".It was very efficacious in selection the high-producing IA strains by using 2-deoxy-D-glucose agar plate and the high concentration acid agar plate containing with itaconic acid.Under fermentation conditions,A.terreus YIA2090 could accumulate 78g/L from 140g/L glucose in shaking flask, IA producing increasing by 39.2%.Characters of the A.terreus YIA2090 were studied.The effects of fermentation conditions on the production of IA by A.terreus YIA2090 were studied in considerable detail.The results indicated that it could produce most production when glucose as carbon source,NH₄NO₃ as nitrogen source and corn steep liquor as auxiliary nitrogen source.It also found the addition of Mg²⁺ could stimulate the growth of mycelia and IA production.Zn²⁺（ZnSO₄·7H₂O） could promote the sprout of spores of A.terreus YIA2090 and IA production.The effects of other conditions such as temperature,pH,inoculation,broth volume,et al. Then the Box-Behnken design and response surface analysis were applied to optimize the medium components.The optimal constitutes of medium and culture conditions determined were as follows（%）:Glucose 14,NH₄NO₃ 2,NaCl 0.4,KH₂PO₄ 0.1,MgSO₄·7H₂O 8,FeSO₄·7H₂O 0.01,corn steep liquor 0.6,ZnSO₄·7H₂O 0.1.The process of batch fermentation was investigated by culturing A.terreus YIA2090 in 500L stirred tank reactor.The kinetics had been studied about batch fermentation of IA production by A.terreus YIA2090.