Environmental Uncultivable Bacteria Model for Understanding Human Periodontitis

描述（由申请人提供）：I025是一种新的不可培养的细菌群，与牙周病有关，影响了工业化世界18%的成年人。无论是天然储层还是这个群体的完整多样性都不为人所知。I025属于候选门TM7，该门首次在海水、土壤、活性污泥等多种自然环境中被发现，完全由不可培养的物种组成。最近的独立调查已经在健康和患病人群的口腔微生物群落中检测到TM7核糖体DNA （rDNA）基因序列，而I025主要在患病人群中检测到。环境和人类TM7菌株的rDNA序列比较表明，有些菌株几乎相同，表明它们是近亲，如果不是同一物种。我们假设环境中的I025样细菌可以作为更好地理解I025在人类牙周炎中的作用的模型。我们的目标是建立这样一个I025模型。然而，对培养的抗性使得TM7物种的描述超出了它们的rDNA序列和很少的形态特征，尽管它们在人类口腔菌斑中有长达70米的明显细丝。上海外国语大学的本科生和硕士生将运用现代和高度敏感的非培养分子技术来研究i025样细菌在其自然栖息地的功能。

DESCRIPTION (provided by applicant): I025, a novel uncultivable bacteria group, has been associated with periodontal disease, which affects 18% of the adult population in the industrialized world. Neither the natural reservoir nor the complete diversity of this group is known. I025 belongs to the candidate phylum TM7, which was first discovered in diverse natural environments including seawater, soil, and activated sludge, and is made entirely of uncultivable species. Recent independent investigations have detected TM7 ribosomal DNA (rDNA) gene sequences in the human oral microbial community of both healthy and diseased individuals, whereas I025 was detected primarily in diseased individuals. rDNA sequence comparison between environmental and human TM7 strains indicate some are nearly identical, suggesting they are close relatives, if not the same species. We hypothesize that an environmental I025-like bacteria can serve as model for better understanding the I025 role in human periodontitis. Our goal is to establish such an I025 model. Resistance to cultivation, however, has kept TM7 species undescribed beyond their rDNA sequence and few morphological features, despite their conspicuous filaments of up to 70 ¿m in length in the human oral plaque. Undergraduate and Master's students at SJSU will apply modern and highly sensitive culture-independent molecular techniques to investigate the function of I025-like bacteria in their natural habitat. The specific aims of this project are: Aim 1: Identify ecological sites with TM7 and then characterize the diversity of TM7 in those environmental samples related to human periodontal-associated TM7 species through PCR amplification of 16S rDNA gene and sequence analysis. Aim 2: Quantify environmental TM7 closely related to the periodontitis-associated TM7 (I025) through real-time quantitative PCR and fluorescence in situ hybridization. Aim 3: Characterize the metabolic function of TM7 cells in their natural environment through innovative methods that combine microautoradiography and in situ hybridization to measure nutrient uptake by single cells, without the need of cultivation. Ecological environments serve as the reservoir for many human pathogens. I025 is a potential emerging human pathogen, and once its environmental source is defined and the nutrient requirements understood, we can proceed to establish a model for better understanding its role in humans.