OXYGEN AND GROWTH AND METABOLISM OF CLOSTRIDIUM-ACETOBUTYLICUM
OXYGEN AND GROWTH AND METABOLISM OF CLOSTRIDIUM-ACETOBUTYLICUM
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DOI：
10.1099/00221287-68-3-307
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发表时间：
1971-01-01
期刊：
影响因子：
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通讯作者：
MORRIS, JG
中科院分区：
文献类型：
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作者：
OBRIEN, RW;MORRIS, JG
在葡萄糖+酪蛋白水解物+维生素和盐培养基中，在pH 7和35°下分批培养丙酮丁醇梭菌，保持（i）厌氧（Eh，−400至−370 mV），（ii）通气（Eh，−50至0 mV;溶解O2，< 1μm）和（iii）好氧（Eh，+ 100 mV;溶解O2，40至50μm）。短期（4至6小时）暴露在氧气中并不致命，尽管在足够高的浓度下，氧气降低了葡萄糖消耗的速率，停止了生长，并阻止了DNA、RNA和蛋白质的净合成。在这些有氧条件下，生物体的“还原力”被耗尽，能量匮乏-这可以通过丁酸盐形成的停止（但不是乙酸盐的产生）和细胞内ATP的显着下降来证明。当厌氧条件重新建立时，这些氧合的后果迅速逆转;然后恢复“正常”生长和葡萄糖代谢。没有H2 O2产生的证据，也不能仅仅归因于其升高的培养Eh的氧化作用。因此，氧气（40μm）即使在-50 mV下与二硫苏糖醇平衡的培养基中也会抑制生长，而当厌氧培养物的Eh通过添加铁氰化钾保持在+370 mV时，生长和葡萄糖代谢继续不受抑制。
Clostridium acetobutylicumhas been studied during batch cultivation at pH 7 and 35° in a glucose + casein hydrolysate + vitamins and salts medium kept (i) anaerobic (Eh, −400 to −370 mV), (ii) aerated (Eh, −50 to o mV; dissolved 02, < 1μm), and (iii) aerobic (Eh, + 100 mV; dissolved O2, 40 to 50μm). Shortterm (4 to 6 h.) exposure to oxygen was not lethal, though at sufficiently high concentrations oxygen decreased the rate of glucose consumption, halted growth and prevented net synthesis of DNA, RNA and protein. Under these aerobic conditions the organism was drained of‘reducing power’ and starved of energy - as evidenced by cessation of butyrate formation (but not of acetate production), and by a marked fall in intracellular ATP. These consequences of oxygenation were swiftly reversed when anaerobic conditions were re-established; ‘ normal ’ growth and glucose metabolism then resumed. There was no evidence of H202production, nor could the effects of oxygenation be attributed merely to its elevation of the cultureEh. Thus oxygen (40μm) inhibited growth even in a medium poised with dithiothreitol at − 50 mV, while growth and glucose metabolism continued unchecked when theEhof an anaerobic culture was maintained at + 370 mV by addition of potassium ferricyanide.