微生物发酵毕业论文.doc

微生物发酵毕业论文 题 目: 白色链霉菌PL3-6菌株产聚赖氨酸发酵条件研究 专业： 生物工程 摘 要 ε-聚赖氨酸(ε-Poly-L-Lysine)是由微生物发酵合成的一种由赖氨酸单体通过ε-酞胺键形成的多肤。ε-PL 具有优良的抑菌作用，对革兰氏阳性菌和阴性菌、酵母和一些病毒都有抑制作用，而且兼有水溶性好、热稳定性高等特点。采用正交实验对筛选的一株白色链霉菌Streptomyces albulus PL3-6 发酵产ε-聚赖氨酸(ε-PL) 的培养基成分进行了优化。结果表明，该菌株产ε-PL 的优化培养基为:葡萄糖 3.0 g·L-1、酵母粉 0.5 g·L- 1、(N H4)2SO4 1.2 g·L- 1、KH2 PO4 0.20g·L-1、 K2HPO4 0.12 g·L-1、MgSO4·7H2O 0.05 g·L- 1、FeSO4·7H2O 0.003 g·L- 1、ZnSO4·7H2O 0.008 g·L- 1。在优化培养基下，ε-PL 摇瓶产量达到4.05 g·L- 1 ，比优化前提高了25 %。 采用 D152 弱酸性阳离子交换树脂(H型)对发酵法生产的ε-聚赖氨酸进行了分离提取。参考文献设计了合理的工艺流程。离心分离发酵(pH3.2 )，调节滤液的pH值到8.5，过滤除去沉淀。滤液通过D152 离子交换柱(H型)，用水和0.2 N 醋酸洗涤，用0.1N 的盐酸洗脱。用1N的NaOH 调节洗脱液的pH 值到6.5，加入活性炭脱色后浓缩到小体积。加入乙醇和乙醚的混合物(体积比2:1)后，析出白色晶体。 关键词： ε-聚赖氨酸 白色链霉菌 发酵条件 提取 离子交换 Abstract ε-Poly-L-Lysine is comprised of lysine linked by amide bond through microbial fermentation. It has excellent antibacterial activity against Gram-positive and Gram-negative bacteria, yeast and some kinds of viruses. In additional ε-Poly-L-Lysine is soluble and attractive heat stable. The fermentation medium of Streptomyces albulus producing ε-poly-L-Lysine was optimized by orthogonal experiments. The optimal medium consisted of 3.0 g·L- 1 glucose, 0.5 g·L- 1 yeast extract, 1.2 g·L-1 (NH4)2SO4， 0.20 g·L-1 KH2PO4, 0.12 g·L-1 K2HPO4, 0.05 g·L-1 MgSO4·7H2O, 0.003 g·L-1 FeSO4·7H2O and 0.008 g·L-1 ZnSO4·7H2O. The yield of ε-PL reached 4.05 g·L-1with optimal medium, which increased 25% compared to initial medium. The separation and extraction of ε-Poly-L-Lysine from fermentation liquid by using weak acid anion-exchange resin D152 .The culture broth (pH3.2) was filtered and the filtrate was adjusted to pH8.5. Then, the precipitate formed was removed by filtration. The filtrate was applied on a column of weak acid anion-exchange resin D152 (H+-from) and washed with 0.2 N acetic acid and water, successively. The substance was eluted with 0.1N hydrochloric acid. The eluate was neutralized with 1N sodium hydroxide and