Molecular biological analysis of oral bacterial population dynamics

1采用培养非依赖性分子生物学方法分析龋牙本质和牙菌斑细菌群落。16SrDNA的PCR扩增和DNA测序显示，细菌的存在是多种多样的，包括从口腔中分离的较少的细菌或与数据库中登记的细菌没有序列同源性的细菌。此外，细菌种群在龋病初期和进展阶段的差异。浅层龋牙本质中以链球菌、放线菌为代表，与菌斑样品相似，而深度龋牙本质中以乳酸杆菌为主，提示随着龋的进展，细菌种群发生了显著变化。在这项研究中，我们分析了3名不同患者的牙本质龋样。在所有样本中，突变链球菌、sobrinus等强龋病原体的检出率极低或为零，这可能表明多种口腔细菌与龋病的发展有关为了检测污染标本中的特异性细菌，我们尝试对60名年轻健康志愿者牙菌斑样本中的牙周病原菌、放线菌和牙龈卟啉单胞菌进行PCR检测。经过3年的调查，在不同的志愿者群体中，选择性培养基培养无法分离到的放线菌（actionomycetemcomitans）的检出率为20% ~ 30%。如上所述，采用不依赖培养的分子生物学方法进行分析，使人们对口腔细菌群落有了新的认识。

1 Carious dentine and dental plaque bacterial communities were analyzed by the culture-independent molecular biological method. PCR amplification and DNA sequencing of 16SrDNA showed variety of bacterial existence, including organisms less isolated from oral cavity or ones with no sequence homology to the databank registered bacteria. Additionally, bacterial population difference between initial and progressed stage of caries was shown. In the shallow carious dentine bacteria represented Streptococcus, Actinomyces, similar to the plaque sample were detected, but in the deeply progressed carious dentine Lactobacillus was dominant, suggesting that there is a significant change of bacterial population accompanied with the dental caries progression. In this study, we analyzed carious dentine samples from 3 different patients. Of all samples, detection rates of strong carious causative agents such as S.mutant or S.sobrinus are extremely low or zero, which may suggest that various oral bacteria are related to the progression of dental caries.2 In order to detect the specific bacteria from contaminated specimens, we attempted the PCR detection of periodontal pathogens, Actinobacillus actionomycetemcomitans and Porphromonas gingivalis from dental plaque sample of 60 young healthy volunteers. Through 3 years of investigation, against the distinct groups of volunteers, Actinobacillus actionomycetemcomitans, which was not able to be isolated on the selectively media culture, was detected in ratio 20 to 30%.As the above mentioned, analysis using molecular biological culture-independent method brought a new kind of knowledge about the oral bacterial communities.