Yamada T, Carlsson J
J Bacteriol. 1975 Oct;124(1):55-61. doi: 10.1128/jb.124.1.55-61.1975.
Streptococcus mutans JC 2 produced mainly lactate as a fermentation product when grown in nitrogen-limited continuous culture in the presence of an excess of glucose and produced formate, acetate, and ethanol, but no lactate, under glucose-limited conditions. The levels of lactate dehydrogenase (LDH) in these cultures were of the same order of magnitude, and the activity of LDH was completely dependent on fructose-1,6-diphosphate (FDP). The intracellular level of FDP was high and the level of phosphoenolpyruvate (PEP) was low under the glucose-excess conditions. In the glucose-limited cultures, all glycolytic intermediates studied, except PEP, were low. S. mutans FIL, which had an FDP-independent LDH and similar levels of glycolytic intermediates as S. mutans JC2, produced mainly lactate under glucose-excess or under glucose-limited conditions. LDH of Streptococcus bovis ATCC 9809 was dependent on FDP for activity at a low concentration of pyruvate but had a significant activity without FDP at a high concentration of pyruvate. This strain also produced mainly lactate both under glucose-excess and glucose-limited conditions. The levels and characteristics of these LDHs were not changed by the culture conditions. These results indicate that changes in the intracellular level of FDP regulate LDH activity, which in turn influences the type of fermentation products produced by streptococci. PEP, adenosine 5'-monophosphate, adenosine 5'-diphosphate, and inorganic phosphate significantly inhibited LDH activity from S. mutans JC 2 and may also participate in the regulation of LDH activity in other streptococci.
变形链球菌JC 2在葡萄糖过量且氮受限的连续培养中生长时，主要产生乳酸作为发酵产物；而在葡萄糖受限条件下，则产生甲酸、乙酸和乙醇，但不产生乳酸。这些培养物中乳酸脱氢酶（LDH）的水平处于相同数量级，且LDH的活性完全依赖于1,6 - 二磷酸果糖（FDP）。在葡萄糖过量条件下，细胞内FDP水平较高，而磷酸烯醇式丙酮酸（PEP）水平较低。在葡萄糖受限的培养物中，除PEP外，所有研究的糖酵解中间产物水平都较低。变形链球菌FIL具有不依赖FDP的LDH，且糖酵解中间产物水平与变形链球菌JC2相似，在葡萄糖过量或葡萄糖受限条件下主要产生乳酸。牛链球菌ATCC 9809的LDH在丙酮酸浓度较低时活性依赖于FDP，但在丙酮酸浓度较高时无FDP也具有显著活性。该菌株在葡萄糖过量和葡萄糖受限条件下也主要产生乳酸。这些LDH的水平和特性不受培养条件的影响。这些结果表明，细胞内FDP水平的变化调节LDH活性，进而影响链球菌产生的发酵产物类型。PEP、5'-单磷酸腺苷、5'-二磷酸腺苷和无机磷酸盐显著抑制变形链球菌JC 2的LDH活性，也可能参与其他链球菌LDH活性的调节。
