O'Brien R W
J Bacteriol. 1975 May;122(2):468-73. doi: 10.1128/jb.122.2.468-473.1975.
Anaerobic growth of Klebsiella aerogenes NCDO 711 (NCTC 418) on citrate was dependent on the presence of Na+ in the medium, and fermentation of citrate was mediated via the fermentation pathway enzymes, citrate lyase and a Na+-dependent oxalacetate decarboxylase. This confirms the previous findings on strain NCTC 418. Growth under aerobic conditions was independent of Na+. The mean generation time for cells grown aerobically on either Na+ or K+ citrate medium was about 60 min, with a molar growth yield of about 40 g (dry weight) of cells per mol of citrate utilized. Citrate was apparently metabolized aerobically in both the Na+ and K+ citrate cells via the citric acid cycle, since cell extracts contained alpha-ketoglutarate dehydrogenase but not the citrate fermentation enzymes. The presence of theother enzymes of the citric acid cycle in K. aerogenes was shown in earlier studies. Under aerated conditions (no detectable oxygen tension in the culture), growth was faster on the Na+ citrate medium (mean generation time, 85 min) than on the K+ citrate medium (mean generation time, 120 min). Both cultures grew slower than under aerobic conditions, presumably because of oxygen limitation. Despite the faster growth rate, the molar growth yield of the aerated Na+ citrate culture was one-half that observed for the aerated K+ citrate culture. Citrate was metabolized via the citric acid cycle in cells grown in the K+ citrate medium under aerated conditions since alpha-ketoglutarate dehydrogenase, but not the fermentation enzymes, was detected in extracts prepared from these cells. Metabolism of citrate in the Na+ citrate medium under aerated conditions occurred via both the fermentation pathway (approximately 75 percent) and the citric acid cycle (about 25 percent), as evidenced by (i) the presence of the fermentation enzymes and alpha-ketoglutarate dehydrogenase in extracts of cells grown under these conditions, (ii) a molar growth yield which was intermediate between that obtained for anaerobic and aerated K+ citrate cultures, and (iii) the excretion of acetate, which also occurred in anaerobic cultures but not in aerated K+ citrate or aerobic cultures.
产气克雷伯氏菌NCDO 711（NCTC 418）在柠檬酸盐上的厌氧生长依赖于培养基中Na+的存在，柠檬酸盐的发酵是通过发酵途径的酶——柠檬酸裂合酶和一种依赖Na+的草酰乙酸脱羧酶介导的。这证实了之前关于菌株NCTC 418的研究结果。在有氧条件下的生长不依赖于Na+。在以Na+或K+柠檬酸盐为培养基进行有氧培养时，细胞的平均代时约为60分钟，每利用1摩尔柠檬酸盐，细胞的摩尔生长产量约为40克（干重）。在Na+和K+柠檬酸盐培养的细胞中，柠檬酸盐显然都是通过柠檬酸循环进行有氧代谢的，因为细胞提取物中含有α-酮戊二酸脱氢酶，但不含有柠檬酸盐发酵酶。早期研究表明产气克雷伯氏菌中存在柠檬酸循环的其他酶。在通气条件下（培养物中无可检测到的氧张力），在Na+柠檬酸盐培养基上的生长速度比在K+柠檬酸盐培养基上快（平均代时分别为85分钟和120分钟）。两种培养物的生长速度都比有氧条件下慢，推测是由于氧气限制。尽管生长速度较快，但通气的Na+柠檬酸盐培养物的摩尔生长产量仅为通气的K+柠檬酸盐培养物的一半。在通气条件下，K+柠檬酸盐培养基中生长的细胞通过柠檬酸循环代谢柠檬酸盐，因为从这些细胞制备的提取物中检测到了α-酮戊二酸脱氢酶，但没有检测到发酵酶。在通气条件下，Na+柠檬酸盐培养基中柠檬酸盐的代谢通过发酵途径（约75%）和柠檬酸循环（约25%）进行，证据如下：（i）在这些条件下生长的细胞提取物中存在发酵酶和α-酮戊二酸脱氢酶；（ii）摩尔生长产量介于厌氧和通气的K+柠檬酸盐培养物之间；（iii）乙酸盐的排泄，这在厌氧培养物中也会发生，但在通气的K+柠檬酸盐或有氧培养物中不会发生。
