【作者】 丁满生；

【导师】 肖冬光；

【作者基本信息】 天津科技大学 ， 发酵工程， 2001， 硕士

【摘要】 本论文针对营养酵母出发菌株的筛选，高核黄素含量菌株的诱变育种及营养酵母摇瓶培养条件、生产工艺进行了研究。 通过对面包酵母（Saccharomyces cerevisiae）（BY-1～8），假丝酵母（Candida utilis）（CY-1～11），啤酒酵母（Saccharomyces carlsbergensis）（SY-1～10），奶酒酵母（Saccharomyces uvarum）（MY-1）等四种酵母的核黄素、自溶浸出物比率进行研究，选定了核黄素含量及自溶浸出物比率较高的奶酒酵母（MY-1）作为出发菌株。 将MY-1经连续3次EMS诱变，依次选育富含核黄素的腺嘌呤营养缺陷型菌株（M1-3）和腺嘌呤缺陷型的回复突变株（M2-8）。对所得的菌株进一步进行抗铵突变株的选育，最终得到富含核黄素的营养酵母突变株（M3-20），其核黄素含量达到245.56mg／kg，与出发菌株核黄素含量相比提高了约150％。 在优化培养基成分时，用两水平析因试验及快速登高法等方法设计实验方案，并结合SAS，Origin等统计软件对实验数据进行析因分析和响应曲面分析。得出生产富含核黄素酵母的优化结果如下： （1）种子培养基：硫酸铵0.86g／L，酵母粉10g／L，葡萄糖40g／L，磷酸二氢钾0.6g／L，硫酸镁0.5g／L，pH自然。 （2）发酵培养基：葡萄糖35.6g／L，酵母粉67g／L，（NH₄）₂SO₄ 1g／L，KH₂PO₄0.2g／L，MgSO₄.7H₂O 0.5g／L，NaCl 1g／L，ZnSO₄ 0.4mg／L，FeSO₄ 4mg／L，COSO₄11.5mg／L，甘氨酸6g／L，豆油10g／L，pH6.0。 （3）发酵条件：种龄7小时，装液量（80／500mlΔ），接种量10％，培养温度30℃，200r／min，16小时。 对得到的富含核黄素菌株进行了生产工艺研究，内容包括克雷布特效应试验、补糖发酵试验及确定流加培养工艺试验等。结果表明，对于分批发酵，糖浓度5％时，酵母得率最高，且此糖浓度对于发酵前期酵母生长没有抑制作用。在周期为16小时的流加培养中，研究表明在培养过程中流加豆油和甘氨酸效果比较好，细胞生物量和核黄素含量分别达到33.2g／L和237mg／kg，为工业化生产富含核黄素的营养酵母奠定了基础。更多还原

【Abstract】 In the paper, screening of nutritional yeast parent strains, mutation of rich riboflavin strain, shake-flashing culture conditions as well as fermentation technology of nutritional yeast were studied.Baker yeast(Saccharomyces cerevisiae) BY-1-8, Candida yeast(Candida utilis) CY-1-11, beer yeast( Saccharomyces carlsbergensis) SY-1-10 and milk brewer yeast (Saccharomyces uvarum) MY-1 were used for a group of tests. Through the tests, the yeast strain (MY-1), which had the maximum riboflavin and extraction, was selected. Through three-step continual EMS mutation, the adenine autotrophy strain(Ml-3) and the adenine-requiring revertant strain(M2-8) were screened successively, and the resistant strain(M3-20) to ammonium ion variant was further screened. Then the strain (M3-20), which has 245. 56mg/kg riboflavin, was got. Compared with parent strain, the riboflavin content of the mutation strain was increased by 150%.Shake-flash culture conditions of nutritional yeast were studied with mutant M3-20.Two-lever-factor tests and climb-quickly methods were used to design experiment. At the same time, according to factor analysis and the response surface analysis, data were analyzed with statistical software, such as SAS, Origin. In the end we got an optimal culture conditions as follows.(1) Seed medium: yeastponder10g/L, glucose 40g/L, (NH4)2SO4 0.86g/L, KH2PO40.6g/L,MgSO4.7H2O0.5g/L ,pH spontaneous combustion.(2) Fermentation medium: glucose 35.6g/L, yeastponder 67g/L, bean oil 10g/L, glycine 6g/L,(NH4)2SO4lg/L,KH2PO40.2g/L,MgSO4.7H2O0.5g/L, NaCl lg/L,ZnSO40.4mg/L,FeSO44mg/L,CoSO411.5mg/L,pH6.0.(3)Fermentation conditions: breed cultivation time 7h,loading size (80/500ml A ),inoculation size10%,cultivation temperature 30 C ,200r/min,the optimum culture time was 16h.The high-riboflavin containing strain was used to study the fermentation process, including the experiment of Crabtree effect and the technology of feeding culture, etc. The results showed that during the batch fermentation, when the glucose concentration was 5%, yeast cell concentration is sovereign, and the glucose concentration has no remarkable inhibition to the initial stage of fermentation. During the flow-plus culture of 16 hour, the results showed that effects of feeding oil and glycine were good, the biomass and content of riboflavinwas 33.2g/L and 237mg/kg respectively. The feet laid solid foundation for production of nutritional yeast full of riboflavin.更多还原