Quivey R G, Kuhnert W L, Hahn K
Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
Adv Microb Physiol. 2000;42:239-74. doi: 10.1016/s0065-2911(00)42004-7.
The strategies employed by oral streptococci to resist the inimical influences of acidification reflect the diverse and dynamic niches of the human mouth. All of the oral streptococci are capable of rapid degradation of sugar to acidic end-products. As a result, the pH value of their immediate environment can plummet to levels where glycolysis and growth cease. At this point, the approaches for survival in acid separate the organisms. Streptococcus mutans, for example, relies on its F-ATPase, to protect itself from acidification by pumping protons out of the cells. S. salivarius responds by degrading urea to ammonia and S. sanguis produces ammonia by arginolysis. The mechanisms by which these organisms regulate their particular escape route are now being explored experimentally. The picture that emerges is that the acid-adaptive regulatory mechanisms of the oral streptococci differ markedly from those employed by Gram-negative bacteria. What remains to be elucidated are the breadth of the acid-response systems in these organisms and how they permit the microbes to sustain themselves in the face of low pH and the bacterial competition present in their respective niches. In this article, we summarize reports concerning the means by which oral streptococci either utilize acidification to subdue their competitors or protect themselves until pH values return to a more favorable level.
口腔链球菌用来抵抗酸化有害影响的策略反映了人类口腔多样且动态的生态位。所有口腔链球菌都能够将糖快速降解为酸性终产物。因此，它们周围环境的pH值会骤降至糖酵解和生长停止的水平。此时，在酸性环境中的生存方式使这些微生物出现分化。例如，变形链球菌依靠其F - ATP酶，通过将质子泵出细胞来保护自身免受酸化影响。唾液链球菌通过将尿素降解为氨来应对，而 sanguis 链球菌通过精氨酸分解产生氨。目前正在通过实验探索这些微生物调节其特定逃逸途径的机制。出现的情况是，口腔链球菌的酸适应性调节机制与革兰氏阴性菌所采用的机制明显不同。这些微生物中酸反应系统的广度以及它们如何使微生物在低pH值和各自生态位中存在的细菌竞争面前维持自身生存，仍有待阐明。在本文中，我们总结了有关口腔链球菌利用酸化来制服其竞争者或保护自身直至pH值恢复到更有利水平的方式的报告。
