低聚木糖对变异链球菌生长和产酸影响的体外研究

目的　比较低聚木糖与蔗糖对变异链球菌生长和产酸的影响,为低聚木糖在牙齿保健中的应用提供理论依据。方法　分别采用质量浓度为0、1%、2%、8%、16%和20%的低聚木糖和蔗糖培养基培养变异链球菌24 h,通过Bioscreen C全自动微生物生长曲线分析仪每间隔30 min测定各组培养基的吸光度值（A值）;采用pH计分别于0、5.5、10、24 h测定各组培养基的pH值,运用Origin 2017描绘其变化曲线图。比较变异链球菌培养和发酵前后各组A值及pH值的变化量（ΔA和ΔpH）。结果　（1）低聚木糖组和蔗糖组细菌培养基的ΔA均随着培养时间的延长而增大（F值分别为467.165、3207.610,P < 0.05）;低聚木糖组和蔗糖组不同质量浓度培养基的ΔA比较,差异均有统计学意义（F值分别为11682.528、5483.421,P < 0.05）;且这种差异随着培养时间的延长而增大（F值分别为88.140、41.171,P < 0.05）。（2）变异链球菌培养和发酵24 h后,低质量浓度（1%、2%）低聚木糖在略微或不提高变异链球菌生长水平的同时（P > 0.05）,明显抑制了变异链球菌的产酸能力（P < 0.05）;高质量浓度（16%、20%）低聚木糖在明显抑制变异链球菌生长的同时,变异链球菌的产酸水平略有提升（均P < 0.05）。（3）变异链球菌培养和发酵24 h后,与同质量浓度的蔗糖相比,16%、20%的低聚木糖可明显降低变异链球菌的生长水平（P < 0.05）;1%、2%的低聚木糖细菌培养基的ΔA略高,但差异无统计学意义（P > 0.05）;8%的低聚木糖可提高变异链球菌的生长水平（P < 0.05）;各质量浓度低聚木糖细菌培养基的ΔpH均高于相同质量浓度的蔗糖（均P < 0.05）。（4）与同甜度的蔗糖（质量浓度为8%）比较,低聚木糖（质量浓度为20%）抑制变异链球菌的生长及产酸作用更显著。结论　低质量浓度低聚木糖可抑制变异链球菌产酸,高质量浓度低聚木糖可抑制变异链球菌生长;相较于蔗糖,高质量浓度低聚木糖可降低变异链球菌的生长及产酸水平,提示低聚木糖作为龋病易感人群的食品甜味剂具有良好的应用前景。     

赤藓糖醇对变异链球菌产酸作用影响的研究

目的研究赤藓糖醇对变异链球菌产酸作用的影响,为赤藓糖醇的防龋应用提供依据。方法观察变异链球菌分别在质量分数1%、2%、4%、8%的赤藓糖醇、木糖醇和蔗糖胰蛋白胨-多价蛋白-酵母提取物（tryptone-polypeptone-yeast extract,TPY）液体培养基中培养24 h后pH值的变化;测定在以上浓度条件下,体外菌斑糖酵解模型产酸液的pH值变化。结果浓度为2%（q=5.63）、4%（q=4.12）、8%（q=5.77）时,变异链球菌在赤藓糖醇中pH值变化均小于蔗糖组,且差异均有统计学意义（P〈0.05）;浓度为8%时,赤藓糖醇组的pH值变化较木糖醇组小,具有统计学意义（q=6.53,P〈0.05）;浓度为2%（q=6.73）、4%（q=6.11）、8%（q=6.98）时,赤藓糖醇对体外菌斑糖酵解模型的产酸pH值大于蔗糖组,具有统计学意义（P〈0.05）;浓度为2%（q=5.46）、4%（q=6.49）、8%（q=6.01）时,赤藓糖醇对体外菌斑糖酵解模型的产酸pH值小于木糖醇组,差异有统计学意义（P〈0.05）。结论一定浓度的赤藓糖醇对变异链球菌产酸代谢和体外菌斑糖酵解模型产酸代谢具有较明显的抑制作用。     

颊纤毛菌对变异链球菌产酸及黏附作用的影响

目的:研究分别使用颊纤毛菌(L.buccalis)及其上清液与变异链球菌(S.m)共培养,观察S.m的产酸、黏附变化及乳酸脱氢酶(ldh)、葡糖基转移酶(gtfb、gtfc、gtfd)基因表达变化.方法:首先从龈上菌斑中分离口腔L.buccalis,采用生化鉴定和测序鉴定;将L.buccalis单独培养组、S.m单独培养组、L.buccalis与S.m共培养组和S.m加入L.buccalis上清液培养组均培养9 h,比较每小时各组细菌产酸能力的变化;再将L.buccalis单独培养组、S.m单独培养组、分别加入1、2、3 mL L.buccalis菌液的S.m共培养组和分别加入1、2、3 mL L.buccalis上清液的S.m菌液培养组,用实时定量RT?PCR法测定各组ldh、gtfb、gtfc和gtfd的基因表达;在S.m中分别加入50、100、150μL L.buccalis上清液培养,在激光共聚焦显微镜下观察S.m黏附数量变化.结果:本实验成功分离L.buccalis,S.m中加入L.buccalis或L.buccalis上清液培养后pH下降速率增快,细菌的黏附数量增多,且随L.buccalis或L.buccalis上清液体积的增加ldh、gtfb、gtfc和gtfd的基因表达增高.结论:L.buccalis及其上清液对S.m的产酸及黏附能力具有促进作用.     

氟化钠对变形链球菌的生长,产酸和葡糖基转移酶的影响

本实验就氟化钠对我国儿童龋病流行相关的5株不同血清型变形链球菌,在生长、产酸和葡糖基转移酶等诸方面的影响进行了研究,结果表明乳酸是细菌主要糖发酵终末产物,氟化钠抑制细菌产乳酸和抑制细菌生长的强度与其浓度成正比,且抑制前者远强于后者。240ppm氟离子能完全抑制细菌生长。对葡糖基转移酶,氟离子似乎要达一定浓度阈值才见明显影响作用,在不同菌株间该阈值有所不同。     

甘草酸对酸性环境中变异链球菌生长影响的体外研究

目的研究酸性环境中甘草酸对体外培养变异链球菌生长的影响。方法在pH 7.0、pH 5.5和pH 4.0环境中培养变异链球菌,同时在培养基中加入3种浓度（0.78、1.57、3.13 mg·mL-1）的甘草酸,37 ℃下厌氧培养24 h后,测定各组的菌落计数和菌悬液吸光度值,分别以阴性对照组和pH 7.0组细菌生存率为对照,计算各组细菌的生存率。结果以阴性对照组为对照,0.78、1.57和3.13 mg·mL-1甘草酸组在pH 5.5环境时细菌生存率为60.96%、60.27%和45.58%,在pH 4.0时细菌生存率为68.75%、53.12%和45.83%。以pH 7.0组为对照,0.78、1.57和3.13 mg·mL-1甘草酸组在pH 5.5和pH 4.0时细菌生存率分别为52.25%和39.05%、74.39%和43.11%、86.38%和55.30%。结论在酸性环境中,甘草酸能够抑制体外变异链球菌的生长,环境酸度降低可使甘草酸的抑菌作用增强。     

两种糖对变异链球菌产酸能力影响的比较研究

目的:通过测量变异链菌代谢高果糖玉米糖浆(high-fructose corn syrup,HFCS)和蔗糖后△pH值的变化,比较两种糖对变异链球菌产酸能力的影响。方法:配制质量浓度为0.25%、0.5%、1%、3%和5%的高果糖玉米糖浆和蔗糖培养基,将变异链球菌UA159于上述各培养基37℃微需氧培养,分别于培养1、4、8、24、48 h各个时间点,用酸度计测量培养前后的pH值,计算ΔpH值,代表变异链球菌的产酸能力。结果:在本研究设定的糖浓度范围和培养时间段内,高果糖玉米糖浆(HFCS)和蔗糖培养基中的ΔpH值均随时间的延长而增大,在培养4～8 h内,HFCS培养基内pH值下降速度快于蔗糖培养基。在培养4、8、24 h时,5种浓度的HFCS培养基中ΔpH值均明显大于蔗糖培养基,差异均有统计学意义(P<0.05),而在培养1 h和48 h时,两种糖培养基中ΔpH值的变化无统计学意义(P>0.05)。结论:在培养4～8 h内,HFCS利于变异链球菌代谢产酸,而在24～48 h内,蔗糖则显示出较强的持续产酸能力。     

变异链球菌蛋白质组研究进展

变异链球菌是口腔龋病的重要的病原菌之一。随着实验新技术的不断涌现,对于变异链球菌的研究,也从形态学、生化鉴定、基因等的水平,上升到蛋白质组水平。变异链球菌的蛋白组随着生长环境、生长状态和菌珠的变化而变化。本文综述了近年来变异链球菌蛋白质组的研究状况。     

赤藓糖醇和木糖醇对变异链球菌生长和产酸作用的对比研究

目的对比相同浓度下赤藓糖醇和木糖醇对变异链球菌生长和产酸的影响。方法分别用含0.5%、1%、2%、4%、8%、12%、16%赤藓糖醇和木糖醇的TPY培养基在厌氧条件下培养变异链球菌,分别于0、2、4、6、8、10、12、18、24 h测量液体培养基的光密度值（A值）和pH值,运用SPSS描绘其变化曲线图。结果在0.5%、1%、2%浓度下,赤藓糖醇培养基的A值较木糖醇培养基高,pH值较木糖醇培养基低,说明变异链球菌在含0.5%、1%、2%赤藓糖醇的培养基内的生长和产酸能力明显较相同浓度木糖醇培养基高。在8%、12%、16%浓度下,赤藓糖醇培养基的A值较木糖醇培养基低,pH值较木糖醇培养基高,说明变异链球菌在含8%、12%、16%赤藓糖醇的培养基内的生长和产酸能力明显较相同浓度木糖醇培养基低。结论对比木糖醇,低浓度下赤藓糖醇对变异链球菌生长和产酸的抑制作用较弱,高浓度下赤藓糖醇的抑菌效果更强。     

变异链球菌防治药物的研究现状

变异链球菌是人类主要的致龋微生物,其在口腔中的定植与龋病的发生密切相关。国内外学者多年来一直致力于寻找和研究抑制或杀灭变异链球菌的药物,曾运用抗生素、消毒剂、氟化物和免疫制剂等抗变异链球菌感染。本文就抗变异链球菌化学合成药物和抗变异链球菌植物提取物等研究进展作一综述。     

不同浓度的葡萄糖对变形链球菌初始粘附能力的影响

目的 研究不同浓度的葡萄糖对变形链球菌初始粘附能力的影响,同时观察高龋组、无龋组变形链球菌初始粘附能力的差别。方法 选取高龋组、无龋组变形链球菌（血清 c型）临床分离株各10株及1株参考株UA159,用唾液包被的羟基磷灰石（SHA）模拟口腔中牙面情况。各菌株分别在含3H的0.2%、1.0%、5.0%葡萄糖的液体培养基中培养,配成菌悬液。菌液与SHA作用90 min,清洗、吸干,液体闪烁计数测量各样本中粘附于SHA的细菌的量。各变形链球菌菌株在不同浓度葡萄糖条件下对SHA的粘附能力以粘附量CPM值表示。结果 变形链球菌高龋组分离株初始粘附能力明显高于无龋组分离株（P<0.05）;同时变形链球菌在不同浓度的葡萄糖营养条件下其初始
粘附能力也有统计学上的差别（P<0.05）,5.0%葡萄糖组粘附力最强,0.2%葡萄糖组粘附力最低,1.0%葡萄糖组粘附力界于两者之间。结论 ①变形链球菌的初始粘附能力可能与龋病的发生有关;②葡萄糖可能与变形链球菌的初始粘附相关,在一定范围内,葡萄糖可能会促进变形链球菌的 初始粘附。     

变形链球菌葡糖基转移酶遗传多态性与龋病发生关系的研究

目的:探讨变形链球菌葡糖基转移酶遗传多态性与龋病发生的关系。方法:菌株分别选自本实验室前期工作中分离鉴定的合成水不溶性多糖能力较强和较弱的血清c型变形链球菌临床分离株，提取全菌DNA，经PCR扩增gtfBC(961 - 5574 by)后，分别采用限制性内切酶Hinf工、Mb。工和Taq工进行限制性片段长度多态性分析。结果: 不同龋敏感人群变形链球菌血清。型临床分离株经Hinf工酶切后限制性片段长度多态性分析酶谱出现了差异，有 1.9 kb长片段的菌株在高龋组中的比例高于无龋组(P < 0.05)。结论:萝基因型的不同是导致菌株合成水不溶性多糖能力差异的原因之一。     

Effect of a bacteriocin-producing strain of Streptococcus sobrinus on infection and establishment of Streptococcus mutans on tooth surfaces in rats

The effect of bacteriocin produced by Streptococcus sobrinus MT6223 on infection and establishment of Streptococcus mutans MT6222 was studied in specific pathogen-free rats. These strains were isolated from a carious lesion of a single subject. S. mutans MT6222 was found to be susceptible to the growth inhibitory action of S. sobrinus MT6223. When simultaneously inoculated into the oral cavity of rats, even a small inoculum (10(5) CFU) of S. sobrinus MT6223 completely inhibited colonization of S. mutans MT6222 on the tooth surface. Also, S. sobrinus MT6223 eliminated S. mutans MT6222 when MT6223 (10(8) CFU) was inoculated 2 days after the inoculation of 10(8) CFU cells of MT6222. Similar results were obtained in dental plaque samples from the tooth surface and the fissures of the upper molars at the end of the experiment. However, when S. sobrinus MT6223 (10(8) CFU) was inoculated 2 weeks after the inoculation of S. mutans MT6222 (10(8) CFU), MT6223 coexisted with MT6222. However, the plaque samples showed that MT6223 inhibited the establishment of MT6222 on smooth surfaces, but not in fissures. In addition, MT6223 protected against subsequent infection with MT6222. However, a nonbacteriocinogenic mutant of S. sobrinus MT6223 did not inhibit the infection and establishment of S. mutans MT6222.     

Salivary Streptococcus mutans and caries prevalence in Brazilian schoolchildren

The aim of the present study was to determine the levels of salivary Streptococcus mutans in Brazilian schoolchildren, and its possible correlation with caries prevalence. A positive correlation between different levels of S. mutans and caries prevalence was observed, individuals with high levels of S. mutans (greater than 100 colonies) had a DMFS significantly higher than those with low or no detectable S. mutans (0, 1-20, 21-40 colonies).     

Effect of caries preventive measures on Streptococcus mutans and lactobacilli in selected mothers

Abstract – Mothers of first-born babies were selected on the basis of high salivary counts of Streptococcus mutans. All experimental subjects were given a basic caries preventive program in order to decrease the level of S. Mutans in saliva. the program included dietary counseling, which stressed the role of sucrose in the accumulation of S. Mutans. The treatment was carried out in a public dental office. The effect of the treatment was assessed by microbiological examination of salivary levels of S. mutars and lactobacilli. a stratistically significant reducation in both S. mutans and lactobacilli was found. The basic preventive program was effective in reducing the nuber of S. mutans below a selected threshold value of 3000000 CFU per mlsaliva in 60% of the mothers. In the remaining subjects chlorhexidine treatment was required to suppress the salivary levels of S. mutans below this value.     

In vitro inhibitory effects of Polygonum cuspidatum on bacterial viability and virulence factors of Streptococcus mutans and Streptococcus sobrinus

OBJECTIVES: Polygonum cuspidatum has been used in Korean folk medicine to improve oral hygiene. This study was performed to evaluate the effects of methanol extract from root of P. cuspidatum (MEP) on bacterial viability and the virulence factors of Streptococcus mutans and Streptococcus sobrinus. METHODS: To test the effects of MEP on bacterial viability, we determined the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against 20 bacterial strains, including S. mutans and S. sobrinus, using a micro-dilution assay. In case of S. mutans and S. sobrinus, the assays for time-kill and bacterial growth rate at sub-MIC concentrations were also performed. To determine effects of the extract on the virulence factors of S. mutans and S. sobrinus, the assays for sucrose-dependent adherence, water-insoluble glucan formation, glycolytic acid production, and acid tolerance were performed at sub-MIC levels. Phytochemical analysis for constituents of MEP was carried out. RESULTS: MEP showed a broad antibacterial range (MIC 0.5-4 mg/ml). The MBC was two to four times higher than the MIC. The time-kill curves showed S. mutans and S. sobrinus were significantly killed after 1h of incubation. At sub-MIC levels, doubling times of S. mutans and S. sobrinus dose-dependently increased up to 211% and 123%, respectively. At sub-MIC levels, MEP also showed inhibitory effects on the virulence factors of S. mutans and S. sobrinus in a dose-dependent fashion. Phytochemical analysis revealed the presence of alkaloids, sterol/terpenes, tannins, flavonoids, and carbohydrates. CONCLUSION: These data indicate that MEP has inhibitory effects on bacterial viability at higher concentrations (> or =MIC) and the virulence factors of S. mutans and S. sobrinus at sub-MIC concentrations, suggesting that it might be useful for the control of dental plaque formation and subsequent dental caries formation.     

Effects of nitrite and nitrate on the growth and acidogenicity of Streptococcus mutans

It is hypothesised that exogenous nitrite acidified by metabolic products of acidogenic bacteria in the mouth will be converted to products which inhibit growth of the bacteria in question which contribute to dental caries.

Objectives. The aims of this study were (1) to test the activity of both sodium nitrate and sodium nitrite at differing concentrations on the ability of Streptococcus mutans to lower the pH of its surroundings and hence (2) to determine whether either nitrate or nitrite might be bactericidal or bacteriostatic against S. mutans.

Methods. S. mutans NCTC 10449^T was cultured in a liquid medium to which either sodium nitrate or sodium nitrite was added to a final concentration of 0.0, 0.2, 2.0, 20 or 200 mM, of which the first acted as a test substance negative control. After 24 h, the cultures were streaked onto agar to test for growth and the remaining culture used for pH measurement. The Mann–Whitney U-Test was used for statistical comparison of pH values.

Results. Nitrite at concentrations of 20 and 200 mM had a highly significant inhibitory effect (p<0.001) on the ability of S. mutans NCTC 10449^T to lower pH. Moreover, bacteria that had been subjected to these levels of nitrite were unable to recover on solid medium. Nitrate had no such effect on either the growth of the bacteria or on their ability to lower pH.

Conclusions. It is concluded that nitrite, at final concentrations of either 20 or 200 mM, is both bactericidal and anti-acidogenic with respect to S. mutans, while lower concentrations of nitrite and all concentrations of nitrate are ineffective. Nitrite might be worthy of consideration as a mouth-rinse constituent.     

白屈菜提取物抑制变形链球菌的实验研究

目的:研究白屈菜提取物白屈菜碱和白屈菜红碱对变形链球菌的抑制作用,探讨其防龋机制。方法:用二倍稀释法将白屈菜碱和白屈菜红碱等倍稀释为不同的浓度,用纸片扩散法测定其对变形链球菌的抑制作用,并用液体培养基测定其最低抑菌浓度(MIC),0.16%氯已啶溶液作为阳性对照。采用Spearman相关检验进行两组样本之间的相关分析。结果:白屈菜红碱乙醇溶液出现抑菌圈,而白屈菜碱乙醇溶液的各个浓度则无抑菌圈;100mg/ml的白屈菜红碱抑菌圈(25.8mm)大于对照组氯已啶溶液的抑菌圈(19.4mm);白屈菜红碱溶液浓度与变形链球菌抑菌圈大小之间具有高度相关性(r=0.99,P<0.01)。白屈菜红碱的最低抑菌浓度为0.78mg/ml。结论:白屈菜提取物白屈菜红碱有明显的抗菌作用,提示其可能具有较强的防龋作用。