Belli W A, Marquis R E
Department of Microbiology & Immunology and Caries Research Center, University of Rochester, New York 14642-8672, United States.
Oral Microbiol Immunol. 1994 Feb;9(1):29-34. doi: 10.1111/j.1399-302x.1994.tb00211.x.
The acid tolerance of Streptococcus mutans GS-5 in standard pH-drop assays was found to be affected by the sugar used in the assay and also by the sugar used for growth of the organism. For example, acid tolerance was lower when galactose was used as catabolite than when glucose was used, apparently because galactose/proton symport brought protons extruded by the F-ATPase back into the cell and thus reduced delta pH across the cell membrane. The acid tolerance of glycolysis was related directly to the capacities of the cells to produce acid glycolytically, or probably more correctly, to their capacities to produce adenosine triphosphate but not to acid tolerance of phosphotransferase systems for sugar uptake. Thus, glycolytic acid tolerance of S. mutans depends not only on environmental factors such as potassium or magnesium levels but also on the specific catabolites the organism is metabolizing or to which it has become metabolically adapted.
在标准pH下降试验中，变形链球菌GS-5的耐酸性被发现受到试验中使用的糖以及该生物体生长所用糖的影响。例如，当半乳糖用作分解代谢物时，耐酸性低于使用葡萄糖时，这显然是因为半乳糖/质子同向转运将F-ATP酶挤出的质子带回细胞内，从而降低了细胞膜两侧的ΔpH。糖酵解的耐酸性直接与细胞以糖酵解方式产酸的能力相关，或者可能更准确地说，与它们产生三磷酸腺苷的能力相关，而与糖摄取的磷酸转移酶系统的耐酸性无关。因此，变形链球菌的糖酵解耐酸性不仅取决于钾或镁水平等环境因素，还取决于该生物体正在代谢或已在代谢上适应的特定分解代谢物。
