Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon, USA.
The State Key Laboratory of Oral Diseases and the National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Appl Environ Microbiol. 2018 Jan 2;84(2). doi: 10.1128/AEM.01697-17. Print 2018 Jan 15.
Commensal and are pioneer oral biofilm colonizers. Characteristic for both is the SpxB-dependent production of HO, which is crucial for inhibiting competing biofilm members, especially the cariogenic species HO production is strongly affected by environmental conditions, but few mechanisms are known. Dental plaque pH is one of the key parameters dictating dental plaque ecology and ultimately oral health status. Therefore, the objective of the current study was to characterize the effects of environmental pH on HO production by and HO production was not found to be affected by moderate changes in environmental pH, whereas HO production declined markedly in response to lower pH. Further investigation into the pyruvate node, the central metabolic switch modulating HO or lactic acid production, revealed increased lactic acid levels for at pH 6. The bias for lactic acid production at pH 6 resulted in concomitant improvement in the survival of at low pH and seems to constitute part of the acid tolerance response of Differential responses to pH similarly affect other oral streptococcal species, suggesting that the observed results are part of a larger phenomenon linking environmental pH, central metabolism, and the capacity to produce antagonistic amounts of HO Oral biofilms are subject to frequent and dramatic changes in pH. and can compete with caries- and periodontitis-associated pathogens by generating HO Therefore, it is crucial to understand how and adapt to low pH and maintain their competitiveness under acid stress. The present study provides evidence that certain oral bacteria respond to environmental pH changes by tuning their metabolic output in favor of lactic acid production, to increase their acid survival, while others maintain their HO production at a constant level. The differential control of HO production provides important insights into the role of environmental conditions for growth competition of the oral flora.
共生菌和是先驱口腔生物膜定植者。两者的特征都是依赖 SpxB 产生 HO，这对于抑制竞争生物膜成员，特别是致龋物种，至关重要。HO 的产生强烈受到环境条件的影响，但已知的机制很少。牙菌斑 pH 值是决定牙菌斑生态和最终口腔健康状况的关键参数之一。因此，本研究的目的是表征环境 pH 值对和 HO 产生的影响。HO 的产生未发现受到环境 pH 值适度变化的影响，而在较低 pH 值下，HO 的产生明显下降。对调节 HO 或乳酸产生的中心代谢开关丙酮酸节点的进一步研究表明，在 pH 值为 6 时，产生的乳酸水平增加。在 pH 值为 6 时偏向产生乳酸导致在低 pH 值下共生菌的生存能力显著提高，并且似乎构成共生菌酸耐受反应的一部分。对 pH 值的不同响应同样影响其他口腔链球菌种，表明观察到的结果是将环境 pH 值、中心代谢和产生拮抗量 HO 的能力联系起来的更大现象的一部分。口腔生物膜经常受到 pH 值的频繁和剧烈变化的影响。和可以通过产生 HO 来与龋齿和牙周炎相关病原体竞争。因此，了解和如何适应低 pH 值并在酸应激下保持竞争力至关重要。本研究提供的证据表明，某些口腔细菌通过调整其代谢产物以有利于产生乳酸来响应环境 pH 值变化，从而增加其酸生存能力，而其他细菌则保持其 HO 产生水平不变。HO 产生的差异控制为环境条件对口腔菌群生长竞争的作用提供了重要的见解。
