Comparison of 16S rRNA Sequences of Segmented Filamentous Bacteria Isolated from Mice, Rats, and Chickens and Proposal of "Candidatus Arthromitus"

Abstract

Segmented filamentous bacteria (SFB) are nonpathogenic bacteria that are commonly found attached to the intestinal walls of many animals. Until now, these bacteria have not been cultured in vitro. Recently, a 16s rRNA sequence analysis revealed that SFB isolated from mice represent a distinct subline within the Cfostridium subphylum of the gram-positive bacteria. Since SFB isolated from mice, rats, and chickens are known to be host specific, we investigated the phylogenetic relationships among SFB obtained from these three hosts.Total DNAs from the intestinal floras of chickens and rats were used as templates for PCR amplification of 16s rRNA genes. PCR products were cloned and screened by a dot blot hybridization procedure to identify homologous sequences that cross-reacted with mouse SFB-specific oligonucleotide probes. A phylogenetic analysis of these 16s ribosomal DNA sequences revealed that SFB isolated from these three hosts form a natural group, which is peripherally related to the genus Cfostridiurn sensu strict0 (group I Cfostridiurn). The SFB obtained from chickens, rats, and mice had closely related, albeit different, 16s rRNA gene sequences. The observed levels of 16s rRNA sequence divergence, ca. 1.5 to 3%, together with host specificity, suggest that SFB isolated from mice, rats, and chickens represent different species and that coevolution of the SFB and their hosts occurred. "Candidatus Arthromitus" is proposed as the provisional generic name for this group of organisms.The small intestines of many animals (e.g., mice, rats, pigs, and other mammals, as well as chickens, amphibians, and insects) are inhabited by segmented filamentous bacteria (SFB), which are also referred to as long segmented filamentous organisms (reviewed in reference 10). These bacteria cannot be cultured in vitro and do not have official taxonomic names. Until recently, SFB could be recognized only on the basis of their morphology and their ecological niches. In intestines, these gram-positive, endospore-forming organisms are attached via holdfasts to the epithelial walls. In rodents, colonization by SFB is restricted to the ileum (4). In birds, SFB are also found in the ceca (9). No pathologic effects of SFB have been found, even in immunodeficient animals. SFB found in different animal species are morphologically very similar. However, attempts to transfer bacteria from one host species to another have revealed that SFB found in mice, rats, and chickens exhibit host specificity (1, 13, 21). It is not known if SFB that inhabit different hosts are taxonomically closely related or whether they belong to different species.In a recent study, the 16s rRNA-encoding gene sequence of SFB obtained from mice was determined (19). This study was greatly facilitated by the use of a monoculture of these organisms in formerly germfree mice (12). A comparative 16s rRNA * Corresponding author. Mailing address: Central Animal Laboratory, University of Nijmegen, P.O. Box 9101, NL-6500 HB Nijmegen, 'The Netherlands. analysis revealed that th...

Uncultivated Tannerella BU045 and BU063 are slim segmented filamentous rods of high prevalence but low abundance in inflammatory disease-associated dental plaques

“…They are considered to be noncultivable, species-specific, non-pathogenic, and potent activators of the mucosal immune system. However, based on the available 16S rRNA gene sequence data, the Tannerella phylotypes and the SFB belong to quite distinct phylogenetic groups (Snel et al, 1995;Tanner & Izard, 2006) and labelling of any SFB by our FISH probes can be excluded. The length of cells from the uncultivable Single-cell analysis of oral Tannerella populations Tannerella phylotypes was quite variable.…”

Absence of Microbiota (Germ-Free Conditions) Accelerates the Atherosclerosis in ApoE-Deficient Mice Fed Standard Low Cholesterol Diet

“…We used oligonucleotide probes for 16S rRNA, universal probe EUB 338 (5´-GCTGCCTCCCG-TAGGAGT-3´) FITC − , which detects all bacteria 13) , Bac 303 (5´-CCAATGTGGGGGACCTT-3´) FITC − for detection of Bacteroides spp. and Prevotella 14) , ECO 1531 (5´-CACCGTAGTGCCTCGTCA-3´) CY 3 − Escherichia coli 15) , E rectale 482 (5´-GCTTCTTAGT-CARGTACCG-3´) FITC − for detection of Eubacterium rectale and Clostridium coccoides 16) , and SFB 1008 (5´-GCGAGCTTCCCTCATTACAAGG-3´)FITC − for SFB 17) . All samples were counterstained using 4, 6-diamidino-2-phenylindole (DAPI; Sigma-Aldrich, St. Louis, USA).…”

Comparative analysis of the distribution of segmented filamentous bacteria in humans, mice and chickens

“…Two primer pairs of 779 F (5 0 -TGTGGGTTGTGAATAACAAT-3 0 ) with 1008 R (5 0 -GCGGGCTTCCCTCATTACAAGG-3 0 ) and 779 F with 1380 R (5 0 -GGTTAGCCCACAGGCTTCGG-3 0 ) were used in the current study (Snel et al, 1995;Urdaci et al, 2001). A standard PCR was performed in a total volume of 25 ml containing 2.5 ml dNTP (2.5 mmol), 2.5 ml 10 Â EX Taq buffer, 1 ml of each primer (10 mmol), Amplification products were separated using TAEagarose gel electrophoresis (1.0%) and purified using a Biospin Gel Extraction Kit (Bioer Technology Co., Ltd, Hangzhou, China).…”

“…Phylogenetic analysis based on 16S rRNA sequences show that SFB are most closely related to the genus Clostridium, and they were previously designated 'Candidatus Arthromitus' (Snel et al, 1995). The whole SFB genome was recently determined using DNA isolated from the feces of SFB mono-associated mice and single cell sequencing of five individual mouse isolates.…”