Cleaver Leanne M, Moazzez Rebecca V, Carpenter Guy H
Centre for Host Microbiome Interactions, King's College London Faculty of Dentistry, Oral and Craniofacial Sciences, London, United Kingdom.
Centre for Oral, Clinical and Translational Science, King's College London Faculty of Dentistry, Oral and Craniofacial Sciences, London, United Kingdom.
Front Microbiol. 2021 Jan 20;11:619968. doi: 10.3389/fmicb.2020.619968. eCollection 2020.
Within the mouth bacteria are starved of saccharides as their main nutrient source between meals and it is unclear what drives their metabolism. Previously oral biofilms grown in saliva have shown proteolytic degradation of salivary proteins and increased extracellular proline. Although arginine and glucose have been shown before to have an effect on oral biofilm growth and activity, there is limited evidence for proline. Nuclear magnetic resonance (NMR) spectroscopy was used to identify extracellular metabolites produced by bacteria in oral biofilms grown on hydroxyapatite discs. Biofilms were inoculated with stimulated whole mouth saliva and then grown for 7 days using sterilized stimulated whole mouth saliva supplemented with proline, arginine or glucose as a growth-medium. Overall proline had a beneficial effect on biofilm growth-with significantly fewer dead bacteria present by biomass and surface area of the biofilms ( < 0.05). Where arginine and glucose significantly increased and decreased pH, respectively, the pH of proline supplemented biofilms remained neutral at pH 7.3-7.5. SDS-polyacrylamide gel electrophoresis of the spent saliva from proline and arginine supplemented biofilms showed inhibition of salivary protein degradation of immature biofilms. NMR analysis of the spent saliva revealed that proline supplemented biofilms were metabolically similar to unsupplemented biofilms, but these biofilms actively metabolized proline to 5-aminopentanoate, butyrate and propionate, and actively utilized glycine. This study shows that in a nutrient limited environment, proline has a beneficial effect on oral biofilms grown from a saliva inoculum.
在口腔内，两餐之间细菌缺乏糖类这一主要营养来源，其代谢的驱动因素尚不清楚。此前，在唾液中生长的口腔生物膜已显示出对唾液蛋白的蛋白水解降解作用以及细胞外脯氨酸增加。尽管之前已证明精氨酸和葡萄糖对口腔生物膜的生长和活性有影响，但关于脯氨酸的证据有限。核磁共振（NMR）光谱用于鉴定在羟基磷灰石圆盘上生长的口腔生物膜中细菌产生的细胞外代谢物。用刺激后的全口唾液接种生物膜，然后使用补充有脯氨酸、精氨酸或葡萄糖的无菌刺激全口唾液作为生长培养基培养7天。总体而言，脯氨酸对生物膜生长有有益影响——通过生物膜的生物量和表面积计算，死细菌数量显著减少（<0.05）。精氨酸和葡萄糖分别显著提高和降低了pH值，而补充脯氨酸的生物膜的pH值在7.3 - 7.5保持中性。对补充脯氨酸和精氨酸的生物膜的用过的唾液进行SDS - 聚丙烯酰胺凝胶电泳显示，未成熟生物膜的唾液蛋白降解受到抑制。对用过的唾液进行NMR分析表明，补充脯氨酸的生物膜在代谢上与未补充的生物膜相似，但这些生物膜将脯氨酸积极代谢为5 - 氨基戊酸、丁酸和丙酸，并积极利用甘氨酸。这项研究表明，在营养有限的环境中，脯氨酸对由唾液接种物生长的口腔生物膜有有益影响。
