壳寡聚糖对变形链球菌表面疏水性的影响

目的:研究壳寡聚糖对变形链球菌细胞表面疏水性的影响,从而进一步了解壳寡聚糖影响细菌黏附的机制。方法:使用不同浓度(10-2、10-1、1g/L)的壳寡聚糖溶液处理变形链球菌,并采用微生物黏着碳氢化合物法测试细胞表面疏水性。结果:随壳寡聚糖浓度增加,变形链球菌ATCC25175细胞表面疏水性有显著性降低。结论:壳寡聚糖可能通过降低细菌表面疏水作用而抑制变形链球菌的黏附。     

3种植物提取物联用对变形链球菌致龋力的影响

目的:探究绿茶、野菊花、薄荷提取物及其混合物对变形链球菌增殖、产酸及粘附能力的影响。方法:变形链球菌在含有不同浓度植物提取物的MS培养基中培养24 h后,进行离心,清洗,将菌细胞混悬于一定体积蒸馏水中,分光光度计测出A值。使用pH仪测定离心后上清液pH值。玻片粘附法观察提取物对变形链球菌粘附能力的影响。结果:各浓度的提取物及其混合物对变形链球菌增殖、产酸、粘附均有抑制作用(P＜0.05)。浓度为24 g/L时,绿茶较其他提取物抑制变形链球菌增殖能力强(P＜0.01)。浓度为0.75 g/L、1.5 g/L、3 g/L时,混合物抑制变形链球菌粘附能力较同浓度其他提取物强(P＜0.05)。结论:3种植物提取物均具有一定防龋能力,在抑制变形链球菌粘附能力方面三者可协同发挥作用。     

对氨基苯甲酸对牙龈卟啉单胞菌生长代谢影响的研究

目的 通过对氨基苯甲酸（para-aminobenzoic acid,PABA)对牙龈卟啉单胞菌生长代谢的影响，研究血链球菌在龈下菌斑生态平衡中的作用。方法 在培养基中加入不同浓度的PABA，对牙龈卟啉单胞菌行常规厌氧培养，测定培养后的细菌浓度吸光度（A）值和胰酶样蛋白酶活性，并用扫描电镜观察菌细胞形态。结果 PABA能促进牙龈卟啉单胞菌的生长和胰酶样蛋白酶的活性，当PABA浓度为1mg/L时，其促进作用最强，随着PABA浓度的升高，促进作用降低，当PABA浓度为100mg/L时，无明显的促进作用。PABA还能对菌细胞的形态和粘附产生影响。结论 PABA能影响牙龈卟啉单胞菌的生长代谢，提示血链球菌可能对龈下菌班的微生态平衡具有调节作用。     

壳寡聚糖抑制变形链球菌的致龋能力

目的研究壳寡聚糖(chitooligosaccharide,COS)对变形链球菌生长、产酸及粘附能力的影响。方法选用变形链球菌标准株ATCC 25175,采用对倍稀释法测定COS对变形链球菌的最低抑菌浓度(minimum inhibitory concentration,MIC)和最低杀菌浓度(minimum bactericidal concentration,MBC);采用菌落计数法,通过时间—杀菌曲线的变化,分析COS对细菌生长速度的影响;将COS及变形链球菌菌悬液各1 m L接种于无菌试管内厌氧培养,使COS的终浓度分别达到1/2 MIC、1/4 MIC、1/8MIC,测定上清液p H变化并绘制p H曲线;采用液体闪烁计数法测定壳寡聚糖对变形链球菌粘附羟磷灰石能力的影响。结果 COS对变形链球菌的MIC和MBC分别为2.00 g/L和4.00 g/L;COS能有效抑制变形链球菌的生长,较高浓度时对细菌还具有杀菌作用。亚抑菌浓度的COS可显著影响变形链球菌的产酸性和粘附能力,并且这种抑制作用呈浓度依赖性。结论 COS对变形链球菌的生长、产酸和粘附能力均有抑制作用。     

对氨基苯甲酸对变形链球菌生长影响的体外实验

目的:探讨不同浓度的对氨基苯甲酸(PABA)对变链菌生长的影响。方法:将变形链球菌ATCC25175(血清c 型)在改良Carlsson培养基中厌氧培养,实验组在其中加入不同浓度(10-10~10-3gPL)的PABA液厌氧培养48 h后采用紫外可见分光光度仪测定细菌浓度OD值(K=550 nm),并在琼脂平板上培养观察细菌生长情况,进行菌落计数。结果:菌液比浊及菌落计数结果均表明PABA确有促进变链菌生长的能力,当PABA的浓度从10-10~10-4gPL增大时,其促进变链菌生长的能力增强,但当PABA浓度增大到10-3gPL,则促进变链菌生长的能力开始下降。当PABA 浓度为10-9~10-3gPL时,实验组的细菌生长明显高于对照组(P<0105)。结论:当PABA的浓度为10-4gPL时,其促进变链菌生长的能力达最强,高于或低于此浓度,这种促生长作用均下降。     

赤芍粗提物对变形链球菌影响的实验研究

目的研究赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖的影响。方法采用倍比稀释法测定不同浓度赤芍粗提物抑制变形链球菌生长的情况,通过统计学方法确定最低抑菌浓度（minimal inhibitory concentration,MIC）;再以MIC及低于MIC的4个倍比稀释浓度配制含药的胰酶解酪蛋白-植物蛋白胨-酵母提取物（trypticase-phytone-yeast extract medium,TPY）液体培养基,测定赤芍粗提物对变形链球菌产酸、粘附及合成胞外多糖能力的影响。结果赤芍粗提物抑制变形链球菌体外生长的MIC为12.5g/L;当赤芍粗提物浓度≥3.13g/L时有较明显地抑制变形链球菌产酸、粘附、合成水溶性胞外多糖的作用;当赤芍粗提物浓度≥6.25g/L时能明显抑制变形链球菌合成水不溶性胞外多糖。结论达到一定浓度的赤芍粗提物对变形链球菌的生长、产酸、粘附及合成胞外多糖均有一定的抑制作用。     

唾液富酷蛋白对致龋细菌粘附的影响

目的：探讨唾液富酪蛋白（statherin）对致龋细菌变形链球菌和血链球菌粘附的影响。方法：用高效疏水色谱分离提纯30名个体唾液富酪蛋白并观察不同浓度唾液富酪蛋白与变开链球菌和血链球菌粘附的关系。结果：唾液富酪蛋白明显促进变形链球菌对羟磷灰石的粘附且其促进作用的大小与其浓度有关（P＜0．05）;而对血链球菌的粘附无明显影响（P＞0．05）。结论：唾液富酪蛋白可促进变形链球粘附于羟磷灰石上。     

氟对纯钛表面变形链球菌和血链球菌黏附的影响

目的研究氟对纯钛表面变形链球菌和血链球菌黏附的影响。方法采用四唑盐比色法检测经不同浓度氟化钠人工唾液浸泡24 h后变形链球菌和血链球菌在纯钛表面的黏附情况,并用原子力显微镜分析变形链球菌和血链球菌黏附后纯钛表面的粗糙度及表面形貌。采用SPSS 11.0软件包对数据进行统计学分析。结果经不同浓度氟化钠人工唾液浸泡后,变形链球菌和血链球菌在纯钛表面黏附的OD值随着氟化钠浓度的升高越来越大：0 g/L < 0.5 g/L < 1.0 g/L < 2.0g/L (P<0.05)。此外,变形链球菌和血链球菌黏附后,纯钛表面的粗糙度Ra值随着氟化钠浓度的升高也越来越大：0 g/L < 0.5 g/L < 1.0 g/L < 2.0g/L (P<0.05);纯钛的表面形貌有明显差异,无论是经变形链球菌还是经血链球菌黏附后,随着氟化钠浓度的升高,纯钛表面均变得越来越粗糙、不平整。结论经不同浓度氟化钠人工唾液浸泡后,变形链球菌和血链球菌在纯钛表面的黏附、黏附后粗糙度及表面形貌结果一致,提示氟化钠加剧了纯钛的腐蚀,使得纯钛表面的粗糙度增加,进而促进了变形链球菌和血链球菌在纯钛表面的黏附。     

白屈菜红碱对变形链球菌表面疏水性及黏附作用的影响

目的：测定白屈菜红碱对变形链球菌表面疏水性及黏附作用的影响,研究其对变形链球菌黏附的作用机制。方法：将白屈菜红碱对倍稀释为不同浓度的溶液,浓度范围为24．4～781．3μg／ml。采用微生物黏着碳氢化合物法（MATH）测定白屈菜红碱对变形链球菌的细胞表面疏水性,并测定不同浓度的白屈菜红碱溶液对变形链球菌在玻璃表面黏附作用的影响。使用SPSS13．0统计软件包对结果进行处理,各浓度组总体均数之间比较采用单因素方差分析。结果：变形链球菌表面疏水性随白屈菜红碱溶液浓度的升高而逐渐下降,各浓度实验组与对照组均数之间均具有高度显著性差异（P〈0．01）,24．4—195．3μg／ml4个浓度组之间均无显著性差异（P〉0．05）;变形链球菌对玻璃表面的黏附抑制率随白屈菜红碱浓度的升高逐渐增高。195．3μml和390．6μg／ml2个浓度组与对照组和其余浓度组之间均有高度显著性差异（P〈0．01）。结论：白屈菜红碱对变形链球菌细胞表面疏水性和黏附具有抑制作用,提示其具有良好的防龋应用前景。     

复方五倍子煎剂对变形链球菌抑菌作用的实验研究

目的:观察复方五倍子制剂对变形链球菌的抑制作用。方法:将五倍子、大黄、甘草等10味中草药制成煎剂(GER) ,测量其不同浓度对变形链球菌生长、产酸、粘附等作用的抑制效果。结果:当GRE浓度为10 0 %时(最终浓度2 0 %W /V) ,细菌生长量仅为对照组的3 5 .6% ;粘附率下降12 .7% ;pH值升高1.5 4。药物浓度为5 0 %时(最终浓度10 %W /V) ,与对照组比较,细菌生长和粘附作用分别下降43 .8%和10 .6% ,pH值升高1.18。结论:GRE对变形链球菌有一定的抑制作用。     

对氨基苯甲酸对乳杆菌生长影响的体外实验

目的:探讨对氨基苯甲酸菌株(PABA)对牙本质龋、根面龋致病菌之一的乳杆菌生长的影响。方法:10倍系列稀释法配制浓度为10-3~10-10gPL的PABA液,将其分别加入改良的Carlsson培养基中,再将乳杆菌ATCC4356放入该培养基厌氧培养48 h(80%N2、10%H2、10%CO2),用紫外可见分光光度仪测定细菌浓度OD值(K=540 nm);并在琼脂平板培养观察细菌生长的情况,进行菌落计数。结果:PABA也有促进乳杆菌生长的能力,当PABA的浓度从 10-10~10-4gPL增加时,其促进乳杆菌生长的能力增强(P<0.05),且当浓度为10-5gPL时,促进乳杆菌生长的能力达最强,随着PABA的浓度增加到10-4gPL时,此促进作用开始下降,PABA的浓度再增加至10-3gPL时,对乳杆菌的生长无明显的促进作用。结论:PABA的浓度为10-5gPL时,促进乳杆菌生长的能力达最强,高于或低于此浓度,这种促生长的作用均下降。     

Comparative studies on the effect of crude aqueous (CA) and solvent (CM) extracts of clove on the cariogenic properties of Streptococcus mutans

A study was conducted to compare the efficiency of crude aqueous (CA) and solvent extracts (CM) of clove on the caries-inducing properties of Streptococcus mutans. The cariogenic properties investigated included the cell adhesion, cell-surface hydrophobicity and glucan synthesis activities of S. mutans. There was a significant difference between the effect of the CA and CM extracts on the adhesion of S. mutans (P < 0.05) within a concentration range of 5-15 mg/ml, the CM extract demonstrating a slightly higher inhibitory effect. However, the effect of the CM extract on the cell-surface hydrophobicity of S. mutans was weaker than that of the CA extract. The two extracts were found to reduce the synthesis of water-insoluble glucan (WIG) by almost 50% at a concentration as low as 0.5 mg/ml and the CM extract exhibited a significantly higher inhibitory effect than the CA extract (P < 0.05). The present findings indicate that both the CA and CM extracts exert inhibitory effects on the cariogenic properties of S. mutans and that the CA extract is as equally effective as the CM extract.     

Inhibitory effects of oolong tea extract on caries-inducing properties of mutans streptococci.

The inhibitory effects of oolong tea extract (OTE) on the caries-inducing properties of mutans streptococci were examined in vitro. OTE reduced the rate of acid production by mutans streptococci accompanied with the retardation of growth rate of mutans streptococci, while the action by chromatographically isolated oolong tea polyphenol (OTF6) was weak. On the other hand, both oolong tea products decreased cell surface hydrophobicity of almost all the oral streptococci examined in the present study, and also induced cellular aggregation of Streptococcus mutans, Streptococcus oralis, Streptococcus sanguis or Streptococcus gordonii. In these reactions, OTF6 showed a more pronounced activity than OTE. Furthermore, the oolong tea products inhibited the adherence of mutans streptococci to saliva-coated hydroxyapatite. These results suggest that OTF6 may inhibit bacterial adherence to the tooth surfaces by reducing the hydrophobicity of mutans streptococci, and OTE may inhibit caries-inducing activity of mutans streptococci by reducing the rate of acid production.     

口腔常见致病菌的表面疏水性分析

目的：分析测试几种口腔常见致病菌的细胞表面疏水性，为研究细菌非特异性黏附机制提供科学理论参数。方法：采用碳氢化合物黏着法测试细菌表面疏水性。结果：不同种类的细菌、同种细菌的不同菌株间疏水性均存在差异。每株细菌表面具有其相对稳定的参考值范围。结论：口腔细菌具有强弱不同的疏水作用。     

Characterization of fatty acid composition in the cytoplasmic membrane of Streptococcus mutans

The present study was performed to investigate the role of the fatty acid composition of cytoplasmic membranes in bacterial differentiation and the appearance of cariogenic properties of Streptococcus mutans. Bacterial fatty acid composition was effective for differentiation of Streptococcus mutans from the other oral streptococci. The composition obtained from the reference strains and the clinical isolates involved five groups and was useful as a rapid screening index for Streptococcus mutans. Compositional changes in membrane lipids played important roles in synthesis and secretion of extracellular glucosyltransferase for Streptococcus mutans. A characteristic property of Streptococcus mutans, resistance to 40% sucrose in the medium, is ascribable to compositional changes in membrane lipids, especially the glycolipids, of Streptococcus mutans.     

口腔变异链球菌表面蛋白与转肽酶的关系

口腔变异链球菌表面蛋白P1是变异链球菌的主要黏附素之一,其存在与否影响着变异链球菌的黏附能力、疏水性和致龋性。srtA是变异链球菌转肽酶的编码基因,下面就srtA基因与变异链球菌表面蛋白P1的关系以及srtA基因在变异链球菌中的作用作一综述。     

Protein antigen in serotype k Streptococcus mutans clinical isolates

Streptococcus mutans, a major pathogen of dental caries and infective endocarditis, is classified into serotypes c, e, f, and k, with serotype k strains recently reported to be frequently detected in persons with infective endocarditis. Thus, we hypothesized that common properties associated with infective endocarditis are present in those strains. Fifty-six oral S. mutans strains, including 11 serotype k strains, were analyzed. Western blotting analysis revealed expression of the 3 types of glucosyltransferases in all strains, while expression of the approximately 190-kDa cell-surface protein (PA) was absent in 12 strains, among which the prevalence of serotype k (7/12) was significantly high. Furthermore, cellular hydrophobicity and phagocytosis susceptibility were lower in the group of serotype k strains. These results indicate that the absence of PA expression, low cellular hydrophobicity, and phagocytosis susceptibility are common bacterial properties associated with serotype k strains, which may be associated with virulence for infective endocarditis.