The composition of the oral microbiota from 10 individuals with healthy oral tissues was determined using culture-independent techniques. From each individual, 26 specimens, each from different oral ...sites at a single point in time, were collected and pooled. An eleventh pool was constructed using portions of the subgingival specimens from all 10 individuals. The 16S rRNA gene was amplified using broad-range bacterial primers, and clone libraries from the individual and subgingival pools were constructed. From a total of 11 368 high-quality, non-chimeric, near full-length sequences, 247 species-level phylotypes (using a 99% sequence identity threshold) and 9 bacteria phyla were identified. At least 15 bacterial genera were conserved among all 10 individuals, with significant interindividual differences at the species and strain level. Comparisons of these oral bacterial sequences to near full-length sequences found previously in the large intestines and feces of other healthy individuals suggest that the mouth and intestinal tract harbor distinct sets of bacteria. Co-occurrence analysis demonstrated significant segregation of taxa when community membership was examined at the level of genus, but not at the level of species, suggesting that ecologically-significant, competitive interactions are more apparent at a broader taxonomic level than species. This study is one of the more comprehensive, high-resolution analyses of bacterial diversity within the healthy human mouth to date, and highlights the value of tools from macroecology for enhancing our understanding of bacterial ecology in human health.
Members of the genus Campylobacter are defined as fastidious, microaerophilic, oxidase positive, nonfermentative, gram‐negative bacteria. All predicted proteins from the five Campylobacter genomes ...were compared with data from other published microbial genomes by BLASTP. The chromosomes of all five Campylobacter strains in this comparative study were examined for the presence or absence of clustered regularly interspaced short palindromic repeats (CRISPR) elements in intergenic regions. In this study, a strain is considered CRISPR positive when it contains two or more direct repeats of a 21‐bp or larger DNA segment separated by unique spacer sequences of a similar size. The Campylobacter species strains analyzed in this study have the Sec‐dependent and Sec‐independent protein export pathways for the secretion of proteins across the inner or periplasmic membrane. Of the 580 open reading frames (ORFs) conserved between the Campylobacter and Helicobacter species included in this study, 27 ORFs involved in flagellar biosynthesis and function were conserved between Campylobacter and Helicobacter. A research group applied in vitro mariner‐based transposition system to identify genes involved in motility in C. jejuni 81‐176. They followed up this work to show that flagellar genes were regulated by σ
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, but not σ
28
. Although some proteomic studies have been conducted for C. jejuni, these were limited to differential analysis of specific mutations, planktonic versus biofilm growth, and on NCTC 11168 stocks with different amounts of passaging.
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