Lopar Markan, Špoljarić Ivna Vrana, Cepanec Nikolina, Koller Martin, Braunegg Gerhart, Horvat Predrag
Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6/IV, 10000, Zagreb, Croatia.
J Ind Microbiol Biotechnol. 2014 Jun;41(6):913-30. doi: 10.1007/s10295-014-1439-y. Epub 2014 Apr 9.
A metabolic network consisting of 48 reactions was established to describe intracellular processes during growth and poly-3-hydroxybutyrate (PHB) production for Cupriavidus necator DSM 545. Glycerol acted as the sole carbon source during exponential, steady-state cultivation conditions. Elementary flux modes were obtained by the program Metatool and analyzed by using yield space analysis. Four sets of elementary modes were obtained, depending on whether the pair NAD/NADH or FAD/FADH2 contributes to the reaction of glycerol-3-phosphate dehydrogenase (GLY-3-P DH), and whether 6-phosphogluconate dehydrogenase (6-PG DH) is present or not. Established metabolic network and the related system of equations provide multiple solutions for the simultaneous synthesis of PHB and biomass; this number of solutions can be further increased if NAD/NADH or FAD/FADH2 were assumed to contribute in the reaction of GLY-3-P DH. As a major outcome, it was demonstrated that experimentally determined yields for biomass and PHB with respect to glycerol fit well to the values obtained in silico when the Entner-Doudoroff pathway (ED) dominates over the glycolytic pathway; this is also the case if the Embden-Meyerhof-Parnas pathway dominates over the ED.
构建了一个由48个反应组成的代谢网络，以描述食酸铜绿假单胞菌DSM 545生长和聚3-羟基丁酸酯（PHB）生产过程中的细胞内过程。在指数生长、稳态培养条件下，甘油作为唯一碳源。通过Metatool程序获得基本通量模式，并使用产率空间分析进行分析。根据烟酰胺腺嘌呤二核苷酸/还原型烟酰胺腺嘌呤二核苷酸（NAD/NADH）或黄素腺嘌呤二核苷酸/还原型黄素腺嘌呤二核苷酸（FAD/FADH2）是否参与3-磷酸甘油脱氢酶（GLY-3-P DH）反应，以及是否存在6-磷酸葡萄糖酸脱氢酶（6-PG DH），获得了四组基本模式。所建立的代谢网络和相关方程组为同时合成PHB和生物质提供了多种解决方案；如果假设NAD/NADH或FAD/FADH2参与GLY-3-P DH反应，解决方案的数量可以进一步增加。作为主要结果，结果表明，当恩特纳-杜德洛夫途径（ED）比糖酵解途径占主导时，实验测定的生物质和PHB相对于甘油的产率与计算机模拟得到的值非常吻合；当糖酵解途径比ED占主导时，情况也是如此。
