Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Chin Med J (Engl). 2011 Nov;124(21):3499-503.
Streptococcus (S.) oligofermentans is a newly identified bacteria with a yet to be defined mechanism of sucrose metabolism that results in acid production. This study aimed to investigate the biochemical mechanisms of S. oligoferm-entans glucose metaolism.
The S. oligofermentans LMG21532, Lactobacillus (L.) fermentum 38 and the S. mutans UA140 were used to characterize sucrose metabolism by measuring lactate dehydrogenase (LDH) activity and lactic acid production. Continuous dynamics and high performance capillary electrophoresis were used to determine LDH activity and lactic acid production, respectively, from bacteria collected at 0, 10 and 30 minutes after cultured in 10% sucrose.
These analyses demonstrated that LDH activity of the three bacterial strains examined remained stable but significantly different throughout the sucrose fermentation process. The S. oligofermentans LDH activity ((0.61 ± 0.05) U/mg) was significantly lower than that of L. fermentum ((52.91 ± 8.97) U/mg). In addition, the S. oligofermentans total lactate production ((0.048 ± 0.021) mmol/L) was also significantly lower than that of L. fermentum ((0.958 ± 0.201) mmol/L). Although the S. oligofermentans LDH production was almost double of that produced by S. mutans ((0.32 ± 0.07) U/mg), lactic acid production was approximately one sixth that of S. mutans ((0.296 ± 0.058) mmol/L). Additional tests examining pyruvic acid production (the LDH substrate) demonstrated that lactic acid concentrations correlated with pyruvic acid production. That is, pyruvic acid production by S. oligofermentans was undetectable following sucrose incubation, however, (0.074 ± 0.024) and (0.175 ± 0.098) mmol/L pyruvic acid were produced by S. mutans and L. fermentum, respectively.
S. oligofermentans is incapable of fermenting carbohydrates to produce enough pyruvic acid, which results in reduced lactic acid production.
寡养单胞菌（S.）是一种新发现的细菌，其蔗糖代谢机制尚未确定，会导致酸的产生。本研究旨在探讨寡养单胞菌葡萄糖代谢的生化机制。
使用寡养单胞菌 LMG21532、发酵乳杆菌 38 和变异链球菌 UA140 来通过测量乳酸脱氢酶（LDH）活性和乳酸产生来表征蔗糖代谢。使用连续动力学和高效毛细管电泳分别在培养于 10%蔗糖 0、10 和 30 分钟后从细菌中测定 LDH 活性和乳酸产生。
这些分析表明，在所检查的三种细菌菌株的 LDH 活性在蔗糖发酵过程中保持稳定，但差异显著。寡养单胞菌的 LDH 活性（（0.61 ± 0.05）U/mg）显著低于发酵乳杆菌的（（52.91 ± 8.97）U/mg）。此外，寡养单胞菌的总乳酸产量（（0.048 ± 0.021）mmol/L）也显著低于发酵乳杆菌的（（0.958 ± 0.201）mmol/L）。尽管寡养单胞菌的 LDH 产量几乎是变异链球菌的两倍（（0.32 ± 0.07）U/mg），但乳酸产量约为变异链球菌的六分之一（（0.296 ± 0.058）mmol/L）。进一步测试丙酮酸（LDH 底物）的产生表明，乳酸浓度与丙酮酸的产生相关。也就是说，在蔗糖孵育后，寡养单胞菌的丙酮酸产生无法检测到，然而，变异链球菌和发酵乳杆菌分别产生了（0.074 ± 0.024）和（0.175 ± 0.098）mmol/L 的丙酮酸。
寡养单胞菌不能发酵碳水化合物产生足够的丙酮酸，这导致乳酸产量减少。
