磷脂酶D发酵菌株的自然筛选及条件优化本科毕业论文精选.doc

成绩 本科毕业论文（设计） 题目：磷脂酶D发酵菌株的自然筛选及条件优化 诚信声明 本人郑重声明：本人所呈交的毕业论文（设计），是在导师的指导下独立进行研究所取得的成果。毕业论文（设计）中凡引用他人已经发表或未发表的成果、数据、观点等，均已明确注明出处。除文中已经注明引用的内容外，不包含任何其他个人或集体已经发表或在网上发表的论文。 特此声明。 论文作者签名： 日 期： 年 月 日 摘 要 磷脂酶D(PLD)能催化水解卵磷脂(PLs)释放出磷脂酸和胆碱,在乙醇等物质存在的条件下,PLD能进行碱基交换反应,将具有羟基的乙醇等物质与胆碱的极性头部进行酯交换反应,连接到磷脂受体上。因此,具有碱基交换功能的PLD通过对磷脂极性头部特异性基团的改变,可以生成许多稀有或半合成磷脂,满足保健品、医药等方面的需要。PLD广泛存在于细菌、真菌、植物、脊椎动物中,特别是来源于链霉菌的PLD,表现出较好的水解及转酯活性。 本文以实验室初步筛选的产PLD菌株为出发菌株,首先根据PLD反应的特点,采用薄板层析(TLC)法,实现酶活力的快速测定。然后在此基础上对菌种进行自然选育,摇瓶复筛,建立了一套PLD生产菌株的筛选方法。通过摇瓶培养,对发酵培养基组分进行优化,确定了碳源、氮源和无机盐的最佳用量和对实验的影响。 关键词：磷脂;磷脂酶D;链霉菌;筛选;发酵 Abstract PhospholipaseD(PLD) is an enzyme that catalyzes PLs hydrolysis to release a phosphatidic acid(PA) and a choline.While in the presence of an additional alcohol,PLD preferentially catalyzes the transphosphatidylation reaction,in which a polar-head modified phosphatidyl alcohol is synthesized by the substrate PLs that act as the phosphatidyl-moiety donors.The transphosphatidylation reaction carried out by the PLD enzyme should be,therefore,a powerful tool for achieving PL modifications economically.As a fairly abiquitous enzyme,PLD is widely distributed in bacteria,fungi,plant and vertebrate species.Particularly,the PLD enzymes produced by Streptomyces species appear to much high activity. However,the wild strain of Streptomyces produces lower unit PLD,limiting its industrial production greatly.In this paper,a rapid determination of PLD enzyme based on the mechanism of the PLD reaction was firstly built with the Thin Layer Chromatography(TLC)method. Then on this basis to natural selection of species, shake flask after screen, established a set of PLD production strain screening method. Through shake flask culture, optimize the fermentation medium components, determine the amount of carbon source, nitrogen source and inorganic salts has a great influence on experiment. Keywords: phospholipids;phospholipase D; Streptomyces; s