Metabolic network analysis of Streptomyces tenebratius, a Streptomyces species with an active Entner-Doudoroff pathway
Metabolic network analysis of Streptomyces tenebratius, a Streptomyces species with an active Entner-Doudoroff pathway
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DOI：
10.1128/aem.71.5.2294-2302.2005
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发表时间：
2005-05-01
影响因子：
4.4
通讯作者：
Nielsen, J
中科院分区：
文献类型：
--
作者：
Borodina, I;Schöller, C;Nielsen, J
黑暗链霉菌是一种重要的工业微生物，其产生的抗生素复合物主要由氨基糖苷类抗生素安普霉素、妥布霉素氨基甲酸酯和卡那霉素氨基甲酸酯B组成。当S.尽管拟暗孢菌用于妥布霉素的工业生产，但卡那霉素B氨基甲酸酯是不需要的副产物。这两种化合物仅相差一个羟基，该羟基存在于卡那霉素氨基甲酸酯中，但在妥布霉素生物合成过程中被减少。C-13代谢通量分析用于阐明初级碳代谢和抗生素复合物的组成之间的联系。代谢通量图构建的细胞生长在基本培养基上与葡萄糖或葡萄糖-甘油混合物作为碳源。添加甘油，其比葡萄糖还原得更多，导致抗生素复合物的卡那霉素部分的三倍还原。该标记指示活性的Entner-Doudoroff（艾德）途径，其先前被认为在链霉菌中是无功能的。戊糖磷酸（PP）途径的活性较低（葡萄糖摄取率的10 - 20%）。在葡萄糖指数生长过程中，通过Embden-Meyerhof-Parnas（EMP）和艾德途径的通量几乎均匀分布。在从生长阶段到生产阶段的过渡期间，观察到代谢转变，其特征在于通过艾德途径的通量减少和通过EMP和PP途径的通量增加。在葡萄糖-甘油培养基中计算出较高的特定NADH和NADPH产生速率，这与较低百分比的非还原抗生素卡那霉素B氨基甲酸酯有关。
Streptomyces tenebrarius is an industrially important microorganism, producing an antibiotic complex that mainly consists of the aminoglycosides apramycin, tobramycin carbamate, and kanamycin B carbamate. When S. tenebrarius is used for industrial tobramycin production, kanamycin B carbamate is an unwanted by-product. The two compounds differ only by one hydroxyl group, which is present in kanamycin carbamate but is reduced during biosynthesis of tobramycin. C-13 metabolic flux analysis was used for elucidating connections between the primary carbon metabolism and the composition of the antibiotic complex. Metabolic flux maps were constructed for the cells grown on minimal medium with glucose or with a glucose-glycerol mixture as the carbon source. The addition of glycerol, which is more reduced than glucose, led to a three-times-greater reduction of the kanamycin portion of the antibiotic complex. The labeling indicated an active Entner-Doudoroff (ED) pathway, which was previously considered to be nonfunctional in Streptomyces. The activity of the pentose phosphate (PP) pathway was low (10 to 20% of the glucose uptake rate). The fluxes through Embden-Meyerhof-Parnas (EMP) and ED pathways were almost evenly distributed during the exponential growth on glucose. During the transition from growth phase to production phase, a metabolic shift was observed, characterized by a decreased flux through the ED pathway and increased fluxes through the EMP and PP pathways. Higher specific NADH and NADPH production rates were calculated in the cultivation on glucose-glycerol, which was associated with a lower percentage of nonreduced antibiotic kanamycin B carbamate.