烟酰胺抑制变异链球菌生长及生物膜形成的研究

Inhibitory Effects of Nicotinamide on Streptococcus mutans Growth and Biofilm Formation

目的研究烟酰胺(nicotinamide,NAM)对变异链球菌(Streptococcus mutans,S.mutans)生长、形成生物膜及合成胞外多糖的影响。方法通过药敏试验测定NAM对S.mutans的最低抑菌浓度(minimum inhibitory concentration,MIC)。NAM处理组设置1/2 MIC、1/4 MIC和1/8 MIC三个质量浓度组;设置阴性对照组为不含NAM的培养基;设置阳性对照组为含0.1 mg/mL NaF的培养基(扫描电镜检测除外)。绘制S.mutans在不同浓度NAM作用下的生长曲线;结晶紫定量法和蒽酮-硫酸法分别探究NAM对S.mutans形成生物膜及合成水不溶性胞外多糖的影响;在扫描电镜下观察NAM对S.mutans浮游菌及生物膜的形态和结构的影响。结果NAM对S.mutans的MIC值为32μg/μL。经过16μg/μL(1/2 MIC)、8μg/μL(1/4 MIC)、4μg/μL(1/8 MIC)NAM处理后,S.mutans的生长和生物膜的形成均受到抑制,其中16μg/μL NAM组的抑制效果最显著。16μg/μL NAM组、8μg/μL NAM组胞外多糖的合成均下降,与阴性对照组相比差异有统计学意义(P<0.05)。扫描电镜观察发现,经NAM处理后,S.mutans的细胞长度缩短,宽度延长,长宽比例下降,16μg/μL和8μg/μL的NAM组与阴性对照组相比差异有统计学意义(P<0.05)。结论在一定浓度的NAM作用下,S.mutans的生长、生物膜形成及胞外多糖合成均受到抑制。

Objective To explore the effects of nicotinamide(NAM)on the growth,biofilm formation and exopolysaccharides(EPS)production of Streptococcus mutans.Methods The minimum inhibitory concentration(MIC)of NAM on S.mutans was determined by the planktonic bacterial susceptibility assay.The NAM mass concentrations were set as 1/2 MIC,1/4 MIC and 1/8 MIC for hree separate treatment groups.Culture medium without NAM was used in the negative control group and culture medium containing 0.1 mg/mL NaF was used for the positive control group(except for the scanning electron microscopy).The growth curves of S.mutans under different NAM concentrations were drawn.Crystal violet assay and anthrone-sulfuric acid method were used to explore the effects of NAM on S.mutans biofilm formation and water-insoluble EPS production,respectively.The morphology and structure of S.mutans planktons and biofilms after NAM treatment were observed by scanning electron microscopy.Results The MIC of NAM on S.mutans was 32μg/μL.After 16μg/μL(1/2 MIC),8μg/μL(1/4 MIC)and 4μg/μL(1/8 MIC)NAM treatments,S.mutans growth and biofilm formation were inhibited,with the 16μg/μL NAM group displaying the most significant inhibitory effects.The synthesis of EPS decreased significantly in the 16μg/μL and 8μg/μL NAM groups in comparison with that of the negative control group(P<0.05).Under scanning electron microscope,the cell length of S.mutans was shortened,the cell width was extended,and the length/width ratio was decreased,showing significant difference when comparing the 16μg/μL and 8μg/μL NAM groups with the negative control group(P<0.05).Conclusion Under the influence of NAM at certain concenrations,the growth,biofilm formation,and EPS synthesis of S.mutans were inhibited.