【作者】 李业英；

【导师】 阚振荣； 朱宝成；

【作者基本信息】 河北大学 ， 微生物学， 2004， 硕士

【摘要】 本论文研究了碳源、氮源、温度、pH等因素对维生素B₁₂产生菌发酵的影响，并进行了补糖、补氨、以及丙酸对发酵影响的研究。其主要研究内容有以下几个方面： 1．碳源的筛选 实验结果表明碳源A是VB₁₂发酵的最佳碳源。 2．培养基中起始A浓度对发酵产素的影响 实验结果表明，培养基中A的含量对菌体的生长有较大的影响。在不同水平的A加量实验中，随着培养基中起始A浓度的增加，对数生长期的菌体生长速率逐渐下降；随着A浓度的增加，生物量经过了一个由低到高再到低的变化过程；发酵单位也经过了一个类似的过程，但与生物量的变化规律有所不同。同时，当培养基中A起始浓度达到7％以上时，会对菌体的生物量和发酵单位产生抑制作用。 3．发酵过程中补加A对发酵的影响 实验结果表明，补加A对发酵单位上升有促进作用，这种促进作用可能有两方面的原因1)可能是由于生物量的增加而产生的。2)可能是过程中较低的A浓度解除了其对VB₁₂合成的代谢反馈抑制，从而使发酵单位上升。 当A浓度维持在4％左右时并维持20—30小时，对发酵单位提高最为有利。 4．氮源的筛选 通过对氮源进行筛选得出氮源B是VB₁₂发酵的最佳氮源。 5．发酵过程中补加氨水对发酵的影响 实验结果表明，在一定的时期内补加氨水对发酵单位的上升有促进作用；补加时间过长会导致发酵单位的下降。 6．对氮源B的成分进行初步分析 氮源B对VB₁₂的发酵单位有很大影响，不同来源的B对发酵的影响也不一致，我们对其造成这种影响的原因进行了初步分析。 7．氨基氮变化规律 对发酵过程种氨基氮的变化规律进行了研究。表明初始A浓度和接种量的不同对氨基氮的变化有较大的影响。 摘要巴里里皿三里里里巴里口里里口里里里里里巴里里孚里里里巴里里里里里8.温度及pH对VB:2发酵的影响 研究了温度及pH对菌体生长和A代谢的影响。9.前体添加时间和添加量对VB12发酵的影响及其它添加物对VB，2发酵的影响10.丙酸对VB12发酵的影响 丙酸作为VB12合成中的代谢产物，其产生对菌体的生长和A代谢有不利的影响。更多还原

【Abstract】 In this work, we studied the effect of carbon resource, nitrogen resource, temperature, pH and other factors on fermentation and researched the influence of supplemented A, ammonia and propionic acid on VB12 production.1. Screening of carbon resourceThe result showed that carbon resource A was the best for VB12 fermentation.2. The effect of initial concentration of A on fermentationThe results showed that initial concentration of A drastically influenced the biomass and biosynthesis of VB12. Wjth the increase of initial concentration of A, the growth rate decreased during exponent phase, and the biomass changed from lower to higher and to lower again. And the same change to the biosynthesis of VB12. ’When initial concentration of A was 7% or beyond, the biomass and VBn production was repressed.3. The influence of supplemented A on VB12 productionThe experiment results showed that supplemented A could promote VB12 production, and the promotion effect may be caused by the increase of biomass or the elimination of feedback inhibition to VB12 biosynthesis. When concentration of A was sustained about 4% and was maintained about 20-30h, fermentation titer was improved largely.4. Screening of nitrogen resourceThe results showed that nitrogen resource B was the best for VB12 fermentation.5. The influence of supplemented ammonia on VB12 productionThe result showed that supplemented ammonia was beneficial to improve the biomass and fermentation titer of VB12. But if the feeding time was beyond 90h and last the whole period of fermentation, the fermentation titer fell.6. Analysis of the components of nitrogen resource BNitrogen resource B from different firm had different effect on VB12 fermentation. We analyzed the content of protein and the kinds and the content of amino acids of B in order to find the cause that led to the difference. But the resultsdid not tell the difference.7. The change of amino nitrogen vs. timeWe studied the change of amino nitrogen vs. time. The results showed that initial concentration of A and inoculums quantity both had influence on the change of amino nitrogen.8. We also researched the influence of temperature and pH on the growth and the change of A. And the effect of VBn precursor on the VB12 fermentation9. Other additional components on the VB12 fermentation was studied too.10. propionic acid on the VB12 fermentationThe results showed that propionic acid had bad effect on VB12 fermentation.更多还原