Jiang Shan, Chen Shuai, Zhang Chengfei, Zhao Xingfu, Huang Xiaojing, Cai Zhiyu
Department of Endodontics and Operative Dentistry, School and Hospital of Stomatology, Fujian Medical University, 246 Yangqiao Zhong Road, Fuzhou 350002, China.
Department of Endodontics, Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
Int J Mol Sci. 2017 Mar 30;18(4):713. doi: 10.3390/ijms18040713.
() is considered a leading cause of dental caries. The capability of to tolerate low pH is essential for its cariogenicity. Aciduricity of is linked to its adaptation to environmental stress in oral cavity. This study aimed to investigate the effect of biofilm age and starvation condition on acid tolerance of biofilm formed by clinical isolates. clinical strains isolated from caries-active (SM593) and caries-free (SM18) adults and a reference strain (ATCC25175) were used for biofilm formation. (1) Both young and mature biofilms were formed and then exposed to pH 3.0 for 30 min with (acid-adapted group) or without (non-adapted group) pre-exposure to pH 5.5 for three hours. (2) The mature biofilms were cultured with phosphate-buffered saline (PBS) (starved group) or TPY (polypeptone-yeast extract) medium (non-starved group) at pH 7.0 for 24 h and then immersed in medium of pH 3.0 for 30 min. Biofilms were analyzed through viability staining and confocal laser scanning microscopy. In all three strains, mature, acid-adapted and starved biofilms showed significantly less destructive structure and more viable bacteria after acid shock than young, non-adapted and non-starved biofilms, respectively (all < 0.05). Furthermore, in each condition, SM593 biofilm was denser, with a significantly larger number of viable bacteria than that of SM18 and ATCC25175 (all < 0.05). Findings demonstrated that mature, acid-adapted and starvation might protect biofilms of all three strains against acid shock. Additionally, SM593 exhibited greater aciduricity compared to SM18 and ATCC25175, which indicated that the colonization of high cariogenicity of clinical strains may lead to high caries risk in individuals.
（某菌）被认为是龋齿的主要病因之一。该菌耐受低pH值的能力对其致龋性至关重要。该菌的耐酸性与其对口腔环境压力的适应性有关。本研究旨在探讨生物膜年龄和饥饿条件对由该菌临床分离株形成的生物膜耐酸性的影响。从患龋活跃（SM593）和无龋（SM18）成年人中分离出的该菌临床菌株以及一株参考菌株（ATCC25175）用于生物膜形成。（1）形成年轻和成熟生物膜，然后在有（酸适应组）或无（非适应组）预先暴露于pH 5.5三小时的情况下，将其暴露于pH 3.0 30分钟。（2）将成熟生物膜在pH 7.0下用磷酸盐缓冲盐水（PBS）（饥饿组）或TPY（胰蛋白胨 - 酵母提取物）培养基（非饥饿组）培养24小时，然后浸入pH 3.0的培养基中30分钟。通过活菌染色和共聚焦激光扫描显微镜对生物膜进行分析。在所有三种菌株中，成熟、酸适应和饥饿的生物膜在酸冲击后分别比年轻、非适应和非饥饿的生物膜显示出明显更少的破坏结构和更多的活菌（所有P < 0.05）。此外，在每种条件下，SM593生物膜更致密，活菌数量明显多于SM18和ATCC25175（所有P < 0.05）。研究结果表明，成熟、酸适应和饥饿可能保护所有三种该菌菌株的生物膜免受酸冲击。此外，与SM18和ATCC25175相比，SM593表现出更高的耐酸性，这表明临床高致龋性菌株的定植可能导致个体患龋风险增加。
