The Breeding Of High Productive Strains In Vinegar Fermentation And Continuous Fermentation By Immobilized Cells

Vinegar is a common brewing spice, which is not only rich in nutrients, also has theunique pharmacological effects. Many functions of vinegar have been studied. Therefore,the demand for higher quality of vinegar is increased. The excellent microbial strains arethe basis and key of fermentation industry, breeding excellent strains is a precondition toimprove the yield and quality of fermentation productions. Increasing the yield and qualityof vinegar and improving production efficiency can not be ignored. The strains ofAspergillus niger, Saccharomyces cerevisiae, Acetobacter pasteurianus, were the studyingmaterial in this paper, the strains were mutagenized by the ultraviolet irradiation and theion implantation, high production strains were screened, and mutant strains wereimmobilized with sodium alginate as the carrier to study the stability of performance offermentation. System of continuous fermentation with immobilized cells was constructed,and technology was studied for reform of vinegar fermentation. The main research resultsin this study were showed as following.The strain2244of A. niger was mutagenized by ultraviolet irradiation and ionimplantation technology to get mutant with high activity of glucoamylase. The optimumirradiated time was10min, and the survival of spore was23%. The optimum ionimplantation was70×2.6×10¹³N⁺/cm², and survival was29%. After screening by two times,four mutant strains were obtained, and activities of glucoamylase were174U/mL、188U/mL、222U/mL and232U/mL respectively, and28%、39%、49%and55%higher thanthat of its parent strain. The effects of ion implantation were better than those of ultravioletirradiation. Mutant strains were immobilized with sodium alginate as the carrier. Theresults showed that the performance of fermentation was stable.The strain1001of Saccharomyces cerevisiae was mutagenized. The optimumirradiated time was120seconds, and the survival of spore was27%. The optimum ionimplantation was500×2.6×10¹³N⁺/cm²ï¼Œand survival was27%. After screening by twotimes, four mutant strains were obtained, and ethanol yield were3.20%、3.15%、3.50%and3.53%respectively, and13%、11.7%、23.67%and24.73%higher than that of its parentstrain. The effects of ion implantation were better than those of ultraviolet irradiation.Mutant strains were immobilized with sodium alginate as the carrier. The results showedthat the performance of fermentation was stable.The strain7015of Acetobacter pasteurianus was mutagenized. The optimum irradiatedtime was30seconds, and the survival of spore was26%. The optimum ion implantationwas4×2.6×10¹³N⁺/cm², survival was21%. After screening by two times, five mutant strains were obtained, and acetate acid output were26.7g/L、28.7g/L、27.7g/L、27.8g/L and29g/L respectively, and24%、33%、29%、22%and27%higher than that of its parent strain.The effects of ion implant were better than those of ultraviolet irradiation. Mutant strainswere immobilized with sodium alginate as the carrier. The results showed that theperformance of fermentation was stable.High production strains ASI9、YI18and ACI14were immobilized with sodium alginateas the carrier. A continuous fermentation system was designed with series of fermentorswith immobilized cells. Saccharification pot, alcohol fermentor and acetic acid fermentorwere connected. The fermentation system was run at30℃and with dilution rate of0.025h-1. The concentration of major production of each fermentor was determined. Thehighest activity of glucoamylase of Saccharification pot was72U/mL, ethanol was1.6g/Lin alcohol fermentor and acetate acid output is2.4g/L in final acetic acid fermentor. Thebioreactor is feasible and can be used in the process research of vinegar.