He Zhi-Yan, Zhou Wei, Huang Zheng-Wei, Liang Jing-Ping, Jiang Wei
Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology. Shanghai 200011, China. E-mail:
Shanghai Kou Qiang Yi Xue. 2019;28(2):113-117.
To evaluate the effect of S.mutans luxS gene on mixed-species biofilms communities.
Biofilms were formed by S. mutans (wild type strain, its luxS overexpression strain and luxS knockout strain) and Lactobacillus acidophilus (ATCC4356) with a ratio of 1:1 at 37℃ for 4 h, 14 h and 24 h. MTT assay was used to detect the quantification of the biofilms formed. The structures of biofilms were observed under confocal laser scanning microscopy after 24 h, and expression of biofilm-related genes (ftf, smu630, brpA, gbpB, gtfB, vicR, comDE and relA) was investigated by real-time PCR. Statistical analysis was performed with SPSS17.0 software package.
The results showed that biofilm formed by S. mutans(wild type strain, its luxS overexpression strain and luxS knockout strain) and L.acidophilus after 14 h were 0.481±0.024, 0.591±0.023 and 0.279±0.019, respectively. The same findings were present after 24 h, the biofilm formed by S.mutans overexpression strain with L.acidophilus was higher than wild type strain, and the biofilm formed by knockout strain significantly decreased; but there was no significant difference at 4 h time points. CLSM images revealed that both S.mutans overexpression strain and its wild type strain tended to aggregate into distinct clusters and dense structures, whereas the luxS knockout strain appeared relatively sparse. Compared with wild type strain, all of the genes examined were upregulated in the biofilms formed by the overexpression strain, and were downregulated in the biofilms formed by the luxS mutant strain in mixed-species biofilm.
S.mutans luxS gene can affect mixed-species biofilm formation with L.acidophilus, which provides evidences for further study.
评估变形链球菌luxS基因对混合菌生物膜群落的影响。
变形链球菌（野生型菌株、luxS过表达菌株和luxS基因敲除菌株）与嗜酸乳杆菌（ATCC4356）按1:1比例在37℃分别培养4小时、14小时和24小时形成生物膜。采用MTT法检测生物膜形成量。24小时后利用共聚焦激光扫描显微镜观察生物膜结构，并通过实时PCR研究生物膜相关基因（ftf、smu630、brpA、gbpB、gtfB、vicR、comDE和relA）的表达。使用SPSS17.0软件包进行统计分析。
结果显示，变形链球菌（野生型菌株、luxS过表达菌株和luxS基因敲除菌株）与嗜酸乳杆菌在14小时形成的生物膜量分别为0.481±0.024、0.591±0.023和0.279±0.019。24小时后结果相同，变形链球菌过表达菌株与嗜酸乳杆菌形成的生物膜高于野生型菌株，基因敲除菌株形成的生物膜显著减少；但在4小时时间点无显著差异。共聚焦激光扫描显微镜图像显示，变形链球菌过表达菌株及其野生型菌株均倾向于聚集成明显的簇和致密结构，而luxS基因敲除菌株显得相对稀疏。与野生型菌株相比，在混合菌生物膜中，过表达菌株形成的生物膜中所有检测基因均上调，luxS突变菌株形成的生物膜中所有检测基因均下调。
变形链球菌luxS基因可影响与嗜酸乳杆菌混合菌生物膜的形成，为进一步研究提供了依据。
