Protamylasse, a residual compound of industrial starch production, provides a suitable medium for large-scale cyanophycin production
Protamylasse, a residual compound of industrial starch production, provides a suitable medium for large-scale cyanophycin production
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DOI：
10.1128/aem.71.12.7759-7767.2005
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发表时间：
2005-12-01
影响因子：
4.4
通讯作者：
Steinbüchel, A
中科院分区：
文献类型：
--
作者：
Elbahloul, Y;Frey, K;Steinbüchel, A
蛋白酶是在从马铃薯工业生产淀粉期间出现的残留化合物。它含有多种营养物质和所有必需的矿物质，可用作细菌生长和蓝藻素（CGP）生物合成的碳，氮和能源。因此，检查仅在水中稀释的含有蛋白酶作为唯一化合物的培养基在CGP生产中的适用性。在本研究中研究的各种细菌菌株中，发现携带质粒pMa/c5-914：：cphA（6803）的大肠杆菌DH 1的重组菌株是最合适的，所述质粒pMa/c5-914：：cphA（6803）携带来自集胞藻属菌株PCC 6803的蓝藻素合成酶结构基因（cphA）。首先在摇瓶培养中优化了用于高CGP含量的各种培养条件。优化的条件，然后成功地应用到30-和500升的发酵规模在搅拌槽反应器。在6%（vol/vol）的蛋白酶培养基中，初始pH为7.0，培养时间仅为24 h，细胞干物质中CGP含量最高可达28%（wt/wt）。采用蛋白酶培养基的重组菌株获得的CGP含量高于在矿物盐培养基或昂贵的商业复合培养基如Luria-Bertani或Terrific肉汤中培养的相同菌株获得的CGP含量。结果表明，在培养过程中，蛋白酶培养基中存在的大多数氨基酸几乎完全被细胞利用。它们是丙氨酸、色氨酸、酪氨酸，最有趣的是精氨酸。此外，CGP很容易从鱼精蛋白酶生长的细胞分离，通过应用酸提取方法。CGP的分子量约为26至30 kDa，由50%（摩尔/摩尔）天冬氨酸、46%（摩尔/摩尔）精氨酸和4%（摩尔/摩尔）赖氨酸组成。使用廉价的残余蛋白酶可以有助于建立一个经济和生态上可行的方法，用于生物技术生产CGP。
Protamylasse is a residual compound occurring during the industrial production of starch from potatoes. It contains a variety of nutrients and all necessary minerals and could be used as a carbon, nitrogen, and energy source for the growth of bacteria and also for cyanophycin (CGP) biosynthesis. Media containing protamylasse as the sole compound diluted only in water were therefore examined for their suitability in CGP production. Among various bacterial strains investigated in this study, a recombinant strain of Escherichia coli DH1 harboring plasmid pMa/c5-914::cphA(6803), which carries the cyanophycin synthetase structural gene (cphA) from Synechocystis sp. strain PCC6803, was found to be most suitable. Various cultivation conditions for high CGP contents were first optimized in shake flask cultures. The optimized conditions were then successfully applied to 30- and 500-liter fermentation scales in stirred tank reactors. A maximum CGP content of 28% (wt/wt) CGP per cell dry matter was obtained in 6% (vol/vol) protamylasse medium at an initial pH of 7.0 within a cultivation period of only 24 h. The CGP contents obtained with this recombinant strain employing protamylasse medium were higher than those obtained with the same strain cultivated in mineral salts medium or in expensive commercial complex media such as Luria-Bertani or Terrific broth. It was shown that most amino acids present in the protamylasse medium were almost completely utilized by the cells during cultivation. Exceptions were alanine, tryptophan, tyrosine, and most interestingly, arginine. Furthermore, CGP was easily isolated from protamylasse-grown cells by applying the acid extraction method. The CGP exhibited a molecular mass of about 26 to 30 kDa and was composed of 50% (mol/mol) aspartate, 46% (mol/mol) arginine, and 4% (mol/mol) lysine. The use of cheap residual protamylasse could contribute in establishing an economically and also ecologically feasible process for the biotechnological production of CGP.