DIFFERENTIAL METABOLISM OF CELLOBIOSE AND GLUCOSE BY CLOSTRIDIUM-THERMOCELLUM AND CLOSTRIDIUM-THERMOHYDROSULFURICUM
DIFFERENTIAL METABOLISM OF CELLOBIOSE AND GLUCOSE BY CLOSTRIDIUM-THERMOCELLUM AND CLOSTRIDIUM-THERMOHYDROSULFURICUM
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DOI：
10.1128/jb.150.3.1391-1399.1982
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发表时间：
1982-01-01
影响因子：
3.2
通讯作者：
ZEIKUS, JG
中科院分区：
文献类型：
--
作者：
NG, TK;ZEIKUS, JG
热硫化梭菌优先消耗葡萄糖而不是纤维二糖作为生长的能源。在65℃下，葡萄糖和纤维二糖培养的细胞悬浮液的底物摄取率分别为每毫克(干重)45和24nmol/min。在纤维二糖和葡萄糖上的摩尔生长产量(即每摩尔葡萄糖当量的细胞克数)相似(分别为19和16)。葡萄糖和纤维二糖培养的细胞都含有葡萄糖渗透酶活性和高水平的己糖激酶(在40摄氏度时每毫克蛋白质大于0.34摩尔/分钟)。在纤维二糖上的生长与纤维二糖渗透酶活性的诱导有关。相反，热梭状芽孢杆菌优先代谢纤维二糖而不是葡萄糖作为能源，并且在两种底物上的生长速度都较低。在纤维二糖和葡萄糖培养的细胞悬浮液中，底物摄取率分别为每毫克(干重)18和17nmol/min。纤维二糖的摩尔产率为38，葡萄糖的摩尔产率为20。葡萄糖和纤维二糖培养细胞的提取物都含有纤维二糖磷酸化酶和磷酸葡萄糖变位酶活性，而只有葡萄糖培养细胞含有可检测到的葡萄糖渗透酶和己糖激酶活性。描述了这两个物种中葡萄糖和纤维二糖分解酶的一般催化和动力学性质，并提出了用这两种嗜热乙醇菌区分不同糖代谢的模型。
Clostridium thermohydrosulfuricum consumed glucose in preference to cellobiose as an energy source for growth. The rates of substrate uptake in glucose- and cellobiose-grown cell suspensions were 45 and 24 nmol/min per mg (dry weight), respectively, at 65 degrees C. The molar growth yields (i.e., grams of cells per mole of glucose equivalents) were similar on cellobiose and glucose (19 and 16, respectively). Both glucose- and cellobiose-grown cells contained a glucose permease activity and high levels of hexokinase (greater 0.34 mumol/min per mg of protein at 40 degrees C). Growth on cellobiose was associated with induction of a cellobiose permease activity. In contrast, Clostridium thermocellum metabolized cellobiose in preference to glucose as an energy source and displayed lower growth rates on both substrates. The substrate uptake rates in cellobiose- and glucose-grown cell suspensions were 18 and 17 nmol/min per mg (dry weight), respectively. The molar yields were 38 on cellobiose and 20 on glucose. Extracts of glucose- and cellobiose-grown cells both contained cellobiose phosphorylase and phosphoglucomutase activities, whereas only glucose-grown cells contained detectable levels of glucose permease and hexokinase activities. The general catalytic and kinetic properties of the glucose- and cellobiose-catabolizing enzymes in the two species are described, and a model is proposed to distinguish differential saccharide metabolism by these thermophilic ethanologens.