Ethanol catabolism in Corynebacterium glutamicum
Ethanol catabolism in Corynebacterium glutamicum
复制标题
DOI：
10.1159/000107370
复制
发表时间：
2008-01-01
影响因子：
1.2
通讯作者：
Eikmanns, Bernhard J.
中科院分区：
文献类型：
--
作者：
Arndt, Annette;Auchter, Marc;Eikmanns, Bernhard J.
谷氨酸棒杆菌生长在各种碳水化合物和有机酸作为单一或组合的碳源和能源。在这里我们展示了C.谷氨酸菌在乙醇上生长，生长速率高达0.24 h（-1），生物量产量高达0.47 g干重（g乙醇）（-1）。突变体C.缺乏磷酸转乙酰酶（PTA）、异柠檬酸裂解酶（ICL）和苹果酸合酶（MS）的谷氨酸杆菌不能在乙醇上生长，表明乙酸活化和乙醛酸循环对于利用该底物是必需的。因此，乙醇培养的C.与葡萄糖培养的细胞相比，谷氨酸细胞中编码乙酸激酶（AK）、PTA、ICL和MS的基因的表达增加。此外，发现这四种酶以及乙醇脱氢酶（ADH）和乙醛脱氢酶（ALDH）的比活性在乙醇培养的细胞中高，而在葡萄糖培养的细胞中低。C.生长谷氨酸杆菌在葡萄糖和乙醇的混合物上导致双相生长行为，这是由于在乙醇之前顺序利用葡萄糖。因此，ADH，ALDH，AK，PTA，ICL和MS在含有两种底物的培养基中生长的细胞中的比活性在第一生长期与葡萄糖生长的细胞中一样低，但在第二生长期期间增加5至100倍。结果表明，乙醇在C.谷氨酸受到碳源依赖性调节，即，到碳分解代谢物对照。版权所有（c）2007 S. Karger AG，巴塞尔。
Corynebacterium glutamicum grows on a variety of carbohydrates and organic acids as single or combined sources of carbon and energy. Here we show the ability of C. glutamicum to grow on ethanol with growth rates up to 0.24 h(-1) and biomass yields up to 0.47 g dry weight (g ethanol)(-1). Mutants of C. glutamicum deficient in phosphotransacetylase (PTA), isocitrate lyase (ICL) and malate synthase (MS) were unable to grow on ethanol, indicating that acetate activation and the glyoxylate cycle are essential for utilization of this substrate. In accordance, the expression profile of ethanol-grown C. glutamicum cells compared to that of glucosegrown cells revealed an increased expression of genes encoding acetate kinase (AK), PTA, ICL and MS. Furthermore, the specific activities of these four enzymes as well as those of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) were found to be high in ethanol-grown and low in glucose-grown cells. Growth of C. glutamicum on a mixture of glucose and ethanol led to a biphasic growth behavior, which was due to the sequential utilization of glucose before ethanol. Accordingly, the specific activities of ADH, ALDH, AK, PTA, ICL and MS in cells grown in medium containing both substrates were as low as in glucose-grown cells in the first growth phase, but increased 5- to 100-fold during the second growth phase. The results indicate that ethanol catabolism in C. glutamicum is subject to carbon source-dependent regulation, i.e., to a carbon catabolite control. Copyright (c) 2007 S. Karger AG, Basel.