Phylogeny of the Defined Murine Microbiota: Altered Schaedler Flora

Abstract

The “altered Schaedler flora” (ASF) was developed for colonizing germfree rodents with a standardized microbiota. The purpose of this study was to identify each of the eight ASF strains by 16S rRNA sequence analysis. Three strains were previously identified asLactobacillus acidophilus (strain ASF 360),Lactobacillus salivarius (strain ASF 361), andBacteroides distasonis (strain ASF 519) based on phenotypic criteria. 16S rRNA analysis indicated that each of the strains differed from its presumptive identity. The 16S rRNA sequence of strain ASF 361 is essentially identical to the 16S rRNA sequences of the type strains of Lactobacillus murinis and Lactobacillus animalis (both isolated from mice), and all of these strains probably belong to a single species. Strain ASF 360 is a novel lactobacillus that clusters with L. acidophilus andLactobacillus lactis. Strain ASF 519 falls into an unnamed genus containing [Bacteroides] distasonis, [Bacteroides] merdae, [Bacteroides] forsythus, and CDC group DF-3. This unnamed genus is in theCytophaga-Flavobacterium-Bacteroides phylum and is most closely related to the genus Porphyromonas. The spiral-shaped strain, strain ASF 457, is in the Flexistipesphylum and exhibits sequence identity with rodent isolates of Robertson. The remaining four ASF strains, which are extremely oxygen-sensitive fusiform bacteria, group phylogenetically with the low-G+C-content gram-positive bacteria (Firmicutes,Bacillus-Clostridium group). ASF 356, ASF 492, and ASF 502 fall into Clostridium cluster XIV of Collins et al. Morphologically, ASF 492 resembles members of this cluster,Roseburia cecicola, and Eubacterium plexicaudatum. The 16S rRNA sequence of ASF 492 is identical to that of E. plexicaudatum. Since the type strain and other viable original isolates of E. plexicaudatum have been lost, strain ASF 492 is a candidate for a neotype strain. Strain ASF 500 branches deeply in the low-G+C-content gram-positive phylogenetic tree but is not closely related to any organisms whose 16S rRNA sequences are currently in the GenBank database. The 16S rRNA sequence information determined in the present study should allow rapid identification of ASF strains and should permit detailed analysis of the interactions of ASF organisms during development of intestinal disease in mice that are coinfected with a variety of pathogenic microorganisms.

Shuttling of information between the mucosal and luminal environment drives intestinal homeostasis

“…PSA directly induces Foxp3-expressing T-reg cell differentiation and anti-inflammatory activity through TLR2-dependent mechanisms, and reduces 2,4,6-trinitrobenzenesulfonic acid-mediated colitis symptoms [82]. Intestinal colonization with diverse bacterial species, namely altered Schaedler flora (ASF) [83] -in contrast to Clostridia colonization -leads to TLR-dependent expansion and activation of T-reg cells, as determined by disrupted T-reg cell activation in colonized mice without the TLR adaptor molecule Myd88 [84]. Again, T-reg cell activation requires IL-10 production.…”

Removal of cadmium ions during stationary growth phase by an extremely cadmium‐resistant strain of Stenotrophomonas sp.

“…The DNA was extracted from cell pellets by Triton-Prep method. The 16S rDNA was amplified with bacterial universal primers F24 and F25 as described [22]. Purified DNA obtained from the polymerase chain reaction (PCR) then was sequenced using a LICOR IR 2 4200 DNA sequencer (LI-COR, Lincoln, NE, USA) according to manufacturer's instructions.…”

The Role of Mucosal Microbiota in the Development, Maintenance, and Pathologies of the Mucosal Immune System

“…These early studies have led to the development of mice with a defined intestinal flora-"altered Schaedler's flora"and these represent oligo-associated, gnotobiotic mice carrying eight benign commensal enteric bacteria (Dewhirst et al, 1999). Further definition of the normal intestinal microbiota of mice has led to discovery of a major colonizer, segmented filamentous bacteria (SFB) (Davis and Savage, 1974).…”

“…We have sought to extend the analyses by Moreau et al (1978) to include seven innocuous enteric organisms as monoassociates of formerly GF mice as well as the eight commensal microbes in the altered Schaedler's flora (ASF) (Dewhirst et al, 1999). We compared their ability to stimulate the expression of "natural" IgA in the gut as well as specific antibodies reactive with sonicates of the organisms.…”