Department of Operative Dentistry, Periodontology, and Preventive Dentistry, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany.
Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Bern, Switzerland.
Clin Oral Investig. 2019 Mar;23(3):1225-1235. doi: 10.1007/s00784-018-2547-2. Epub 2018 Jul 6.
The present study aims at correlating the relative bacterial activity with the H concentration and the ldh expression of caries-associated bacteria in co-cultures.
Well plates were prepared with BHI medium and cultures of Lactobacillus paracasei and Fusobacterium nucleatum. Bacterial growth at 37 °C was measured using a microplate-photometer before and after adding sucrose to the samples. Samples of co-cultures (n = 12) and single-species cultures (n = 3) were taken and pH was assessed. Real-time quantitative PCRs were applied targeting the 16S-gene, the 16S-rRNA, the ldh-gene, and the ldh-mRNA.
For L. paracasei with sucrose, an increase in relative bacterial activity (62.8% ± 23.5% [mean, SE]) was observed, while F. nucleatum showed a clear decrease in relative bacterial activity (- 35.0% ± 9.6%). Simultaneously, the H concentration increased (1.15E-05 moll-1 ± 4.61E-07 moll-1). Consequently, a significant positive correlation was found between L. paracasei's relative bacterial activity and H concentration (Spearman rank correlation, r = 0.638; p = 0.002), while F. nucleatum exhibited a negative correlation (r = - 0.741; p ≤ 0.001). Furthermore L. paracasei with sucrose showed a moderate, but significant positive correlation between relative bacterial activity and ldh-expression (r = 0.307; p = 0.024).
The relative bacterial activity after sucrose pulse showed a significant correlation not only to the acid production (H concentration) but also to ldh expression of L. paracasei. However, further research is required to confirm these findings in a mature biofilm in vivo.
本研究旨在将相对细菌活性与龋病相关细菌的 H 浓度和 ldh 表达相关联。
在 BHl 培养基中制备微孔板，并培养副干酪乳杆菌和核梭杆菌。在向样品中添加蔗糖之前和之后，使用微孔板光度计测量 37°C 下的细菌生长。从共培养物（n=12）和单种培养物（n=3）中取样并评估 pH 值。应用针对 16S-基因、16S-rRNA、ldh-基因和 ldh-mRNA 的实时定量 PCR。
对于有蔗糖的副干酪乳杆菌，观察到相对细菌活性（62.8%±23.5%[均值，SE]）增加，而核梭杆菌的相对细菌活性明显下降（-35.0%±9.6%）。同时，H 浓度增加（1.15E-05 moll-1±4.61E-07 moll-1）。因此，发现副干酪乳杆菌的相对细菌活性与 H 浓度之间存在显著正相关（Spearman 等级相关，r=0.638；p=0.002），而核梭杆菌则呈负相关（r=-0.741；p≤0.001）。此外，有蔗糖的副干酪乳杆菌的相对细菌活性与 ldh 表达之间呈中度但显著正相关（r=0.307；p=0.024）。
蔗糖脉冲后的相对细菌活性不仅与产酸（H 浓度）显著相关，而且与副干酪乳杆菌的 ldh 表达显著相关。然而，需要进一步的研究来确认这些发现是否适用于体内成熟的生物膜。
