| The study aimed at the industrialization of ?-carotene from Blakeslea trispora,mutagenesis and screening for high yield strain B.trispora was studied and high-performance liquid chromatography(HPLC)method for ?-carotene detection was developed.Based on the high yield strain,metabolomics and on-line monitoring technology was developed and scaled up to 12 m3 fermenter.Researches on the extraction and microcapsule technology of ?-carotene were completed,and high-quality products were obtained:?-carotene biomass,oil suspension,crystal and microcapsule products,which represents that the industrialization of ?-carotene was successfully completed.Firstly,high yield strains for ?-carotene production were attained by ion beam implantation and high through put screening.The strains were used for studies on 50 L bioreactors.Influence of different fermentation control strategies for ?-carotene production in 50 L bioreactors was studied.Results showed ?-carotene production and BC content in dry cell weight(BC/DCW)decreased with the increasement of the medium volume.Improving aeration rate combined with the glucose limitedly fed,the dissolved oxygen was controlled around 20%,P-carotene production was increased from 2.28 g/L to 3.2 g/L,BC/DCW increased from 61.7 to 78.1 mg/g DCW,which increased by 40.4%and 26.6%than the control,respectively.Based on the optimal process,a novel seed pretreatment method(SPH)combined with feeding strategy was developed to optimize BC production in B.trispora.Results indicated that ?-carotene production and BC/DCW were improved by 29.9%and 24.1%,respectively in SPH than Control.Comparative metabolomics study showed that metabolites associated with glycolysis pathway(phosphoric acid and glycerol)and fatty acids(oleic acid and linoleic acid)differentiated SPH from Control significantly.Using online shearing machine for seed inoculums pretreatment combined with sunflower oil and citric acid feeding strategy,BC titer attained 4.48 g/L,other than this,addition of phosphorylated distarch phosphate and the pH regulation by phytic acid combined with the method of semi-continuous culture,further increase the production of ?-carotene to 4.8g/L which was the highest in B.trispora reported on the pilot scale fermenter.On the highly efficient extraction technology research,a wide range of extraction ways was tried,it was found that the extraction yield of ?-carotene was 28.8%higher than that of conventional extraction after pretreatment with compound enzyme method,followed by conventional dry granulation and solvent extraction.In the hot solvent extraction section,the use of butylated hydroxytoluene(BHT)can reduce the oxidation of ?-carotene,and the extraction rate further increased 12%.The method of low temperature crystallization was applied in the crystallization process,which showed more energy saving than evaporation crystallization and higher yield of ?-carotene crystal.The comprehensive yield attained more than 80%.?-carotene was microencapsulated by various drying processes such as spray drying,spray freeze drying,coating and spray granulation.Scanning electron microcopy measurement suggested that microencapsulated powder using coating process has the smallest bulk density and the best compressibility.The chemical stability of microcapsules was evaluated during 6 months storage under different temperatures.It was found that coating-treated powder possessed the highest content of ?-carotene,which indicated that coating process was superior to the other three drying processes. |
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