Crabbendam P M, Neijssel O M, Tempest D W
Arch Microbiol. 1985 Sep;142(4):375-82. doi: 10.1007/BF00491907.
The influence of a number of environmental parameters on the fermentation of glucose, and on the energetics of growth of Clostridium butyricum in chemostat culture, have been studied. With cultures that were continuously sparged with nitrogen gas, glucose was fermented primarily to acetate and butyrate with a fixed stoichiometry. Thus, irrespective of the growth rate, input glucose concentration, specific nutrient limitation and, within limits, the culture pH value, the acetate/butyrate molar ratio in the culture extracellular fluids was uniformly 0.74 +/- 0.07. Thus, the efficiency with which ATP was generated from glucose catabolism also was constant at 3.27 +/- 0.02 mol ATP/mol glucose fermented. However, the rate of glucose fermentation at a fixed growth rate, and hence the rate of ATP generation, varied markedly under some conditions, leading to changes in the Y glucose and YATP values. In general, glucose-sufficient cultures expressed lower yield values than a corresponding glucose-limited culture, and this was particularly marked with a potassium-limited culture. However, with a glucose-limited culture increasing the input glucose concentration above 40 g glucose X 1(-1) also led to a significant decrease in the yield values that could be partially reversed by increasing the sparging rate of the nitrogen gas. Finally glucose-limited cultures immediately expressed an increased rate of glucose fermentation when relieved of their growth limitation. Since the rate of cell synthesis did not increase instantaneously, again the yield values with respect to glucose consumed and ATP generated transiently decreased. Two conditions were found to effect a change in the fermentation pattern with a lowering of the acetate/butyrate molar ratio. First, a significant decrease in this ratio was observed when a glucose-limited culture was not sparged with nitrogen gas; and second, a substantial (and progressive) decrease was observed to follow addition of increasing amounts of mannitol to a glucose-limited culture. In both cases, however, there was no apparent change in the YATP value.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了多种环境参数对葡萄糖发酵以及丁酸梭菌在恒化器培养中生长能量学的影响。对于持续用氮气鼓泡的培养物，葡萄糖主要以固定的化学计量比发酵为乙酸盐和丁酸盐。因此，无论生长速率、输入葡萄糖浓度、特定营养限制以及在一定范围内的培养物pH值如何，培养物细胞外液中的乙酸盐/丁酸盐摩尔比均始终为0.74±0.07。因此，由葡萄糖分解代谢产生ATP的效率也恒定在3.27±0.02 mol ATP/mol发酵葡萄糖。然而，在某些条件下，固定生长速率下的葡萄糖发酵速率以及因此的ATP生成速率会显著变化，导致Y葡萄糖和YATP值发生变化。一般来说，葡萄糖充足的培养物比相应的葡萄糖限制培养物表现出更低的产量值，这在钾限制培养物中尤为明显。然而，对于葡萄糖限制培养物，将输入葡萄糖浓度提高到40 g葡萄糖×1(-1)以上也会导致产量值显著下降，通过提高氮气鼓泡速率可部分逆转。最后，葡萄糖限制培养物在解除生长限制后立即表现出葡萄糖发酵速率增加。由于细胞合成速率没有立即增加，因此相对于消耗的葡萄糖和产生的ATP的产量值也会暂时下降。发现有两种情况会随着乙酸盐/丁酸盐摩尔比的降低而影响发酵模式。首先，当葡萄糖限制培养物不进行氮气鼓泡时，观察到该比例显著下降；其次，向葡萄糖限制培养物中添加越来越多的甘露醇后，观察到该比例大幅（且逐渐）下降。然而，在这两种情况下，YATP值均无明显变化。（摘要截断于250字）
