Takahashi N, Iwami Y, Yamada T
Tohoku University School of Dentistry, Sendai, Japan.
Oral Microbiol Immunol. 1991 Oct;6(5):299-304. doi: 10.1111/j.1399-302x.1991.tb00497.x.
Streptococcus mutans, which had accumulated glycogen-like iodophilic intracellular polysaccharide (IPS), produced large amounts of formate, acetate and ethanol from the IPS by pyruvate formate-lyase (PFL) under strictly anaerobic conditions without exogenous sugar. Under aerobic conditions, the same S. mutans produced exclusively lactate and pyruvate from the IPS because of the inactivation of PFL by oxygen. The total amount of acid produced under anaerobic conditions was larger than that under aerobic conditions. The analysis of intracellular glycolytic intermediates revealed that levels of fructose 1,6-bisphosphate (lactate dehydrogenase (LDH) activator) and glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (PFL inhibitors) were low when IPS was used as a glycolytic substrate, implying that PFL functions more efficiently than LDH in IPS metabolism. These findings suggest that the PFL pathway contributes to the acid production from IPS, and may explain partially why the acids in starved dental plaque are mainly acetate and formate.
变形链球菌积累了糖原样嗜碘细胞内多糖（IPS），在无外源糖的严格厌氧条件下，通过丙酮酸甲酸裂解酶（PFL）从IPS产生大量甲酸、乙酸和乙醇。在有氧条件下，由于氧气使PFL失活，同一株变形链球菌仅从IPS产生乳酸和丙酮酸。厌氧条件下产生的酸总量大于有氧条件下产生的酸总量。细胞内糖酵解中间产物的分析表明，当IPS用作糖酵解底物时，1,6-二磷酸果糖（乳酸脱氢酶（LDH）激活剂）、3-磷酸甘油醛和磷酸二羟丙酮（PFL抑制剂）的水平较低，这意味着在IPS代谢中PFL比LDH更有效地发挥作用。这些发现表明，PFL途径有助于从IPS产生酸，并且可以部分解释为什么饥饿牙菌斑中的酸主要是乙酸和甲酸。
