变异链球菌LuxS基因突变株生物被膜结构的电镜观察

Observation on biofilm formation of Streptococcus mutans LuxS mutant with scanning electron microscope

目的:探讨变异链球菌IngbrittC(血清C型)国际标准株与LuxS基因缺失的变异链球菌突变株之间生物被膜的形成差异。方法:分别将变异链球菌标准株和LuxS基因突变株接种于含有2%葡萄糖、2%蔗糖的乳酪消化胨酵母(TPY)液体培养基中,以牙釉质磨片为载体,于扫描电镜下观察形成24h的上述两菌株生物被膜。结果:(1)当以葡萄糖作为补充糖源时,变异链球菌标准株和LuxS基因突变株所形成的生物被膜表现型未见明显差异;(2)当以蔗糖作为补充糖源时,两菌株所形成的生物被膜有明显的不同,标准株生物被膜相对平滑均质,而LuxS基因突变株的生物被膜呈松散的蜂房状,基质间有较大的间隙,形成较大的团簇状菌落;(3)加入标准株的无菌体上清液可以使LuxS基因突变株的生物被膜表型部分恢复正常,提高LuxS基因突变株形成生物被膜的能力。结论:变异链球菌标准株和LuxS基因突变株均能形成生物被膜,但LuxS基因突变株的生物被膜结构发生改变;依赖于LuxS的群体感应系统会影响变异链球菌生物被膜的形成。

Objective： To study the difference of biofilm formation between Streptococcus mutans Ingbritt C international standard strain and LuxS mutant strain. Methods： Both Streptococcus mutans standard strain and LuxS mutant strain were cultured in TPY liquid medium containing glucose or sucrose in 2% concentration by enamel slabs,and then Twenty-four-hour biofilms of the two strains were observed using scanning electron microscope. Results： （ 1）The LuxS mutant showed no significant qualitative difference in the biofilm phenotypes compared to the Streptococcus mutans standard strain in the medium supplemented with 2%glucose; （2）In contrast,the LuxS mutant formed bilfilms that markedly differed from the standard strain when grown with 2% sucrose.The biofilms of standard strain appeared smooth and more evenly distributed,whereas the biofilms formed by the LuxS mutant were loose,hive-like,and had large gaps between the biofilm matrix,and the cell aggregates appeared muth larger;, （3）The mutant phenotypes were Complemented partly by exposure to supernatants with no cells from standard strain cultures,and the capacity of mutant strain to form bilfilms was enhanced. Conclusion： Both Streptococcus mutans standard strain and LuxS mutant strain can form the biofilms,but the architecture of biofilms formed by the LuxS mutant appears to be altered; LuxS-Based quorum sensing could affect Streptococcus mutans biofilm formation.