变异链球菌alr缺失突变株的构建及初步观察  

Construction and Preliminary Observation of Streptococcus mutans alr Deletion Mutant

作　　者：陆慧[1] 李永亮[1] 孙育杰[2] 魏世成[1] 

机构地区：[1]北京大学口腔医学院/口腔医院口腔颌面外科,北京100081 [2]北京大学生物动态光学成像中心,北京100871

出　　处：《微生物学杂志》2013年第4期9-13,共5页Journal of Microbiology

基　　金：国家自然科学基金面上项目(30973317)

摘　　要：已知右旋氨基酸参与了细菌细胞壁肽聚糖的形成,但尚未有实验对其如何影响致龋菌变异链球菌进行研究。本实验成功构建了变异链球菌丙氨酸消旋酶alr缺失型突变菌IFD140Δalr。表型观察突变株菌落外观和生长情况与野生株无明显差异,但生长曲线提示对数生长期之后比野生株生长快,且饱和浓度较高。扫描电镜显示突变株相较野生株形成了更厚更致密的生物膜。通过变异链球菌alr缺失突变菌株的构建成功,提示右旋氨基酸可能对维持变异链球菌的正常生长和形成生物膜有重要作用。It is known that D-amino acids （D-aa） involve in the formation of bacterial cell wall peptidoglycan, but there have been no reports about how D-aa affects the cariogenic Streptococcus mutans. A ,S. mutans alr （ alanine racemase） deletion mutant IFD140△alr was successfully constructed. There was no significant difference between the mutant strains and wild strain on their phenotype of colony morphology and their growth, however, the growth curve showed that after logarithmic phase the mutant strain grew faster than wild strain, and in addition the saturated concentration was fairly high. Scanning electron microscopy showed that thicker and denser biofilms were formed by alr mu- tant strain as compared with wild-type. The successful construction of alr deletion S. mutans indicated that D-aa may have an important role on the maintenance of normal growth and biofilm formation of S. mutans.

关 键 词：变异链球菌 丙氨酸消旋酶 右旋氨基酸 缺失突变 

分 类 号：Q784[生物学—分子生物学]