Abstract
Our previous study shows that an anaerobic intestinal bacterium strain AJ110941P contributes to type 2 diabetes development in mice. Here we phylogenetically and physiologically characterized this unique mouse gut bacterium. The 16S rRNA gene analysis revealed that the strain belongs to the family Lachnospiraceae but shows low sequence similarities ( < 92.5%) to valid species, and rather formed a distinct cluster with uncultured mouse gut bacteria clones. In metagenomic database survey, the 16S sequence of AJ110941P also matched with mouse gut-derived datasets (56% of total datasets) with > 99% similarity, suggesting that AJ110941P-related bacteria mainly reside in mouse digestive tracts. Strain AJ110941P shared common physiological traits (e.g., Gram-positive, anaerobic, mesophilic, and fermentative growth with carbohydrates) with relative species of the Lachnospiraceae. Notably, the biofilm-forming capacity was found in both AJ110941P and relative species. However, AJ110941P possessed far more strong ability to produce biofilm than relative species and formed unique structure of extracellular polymeric substances. Furthermore, AJ110941P cells are markedly long fusiform-shaped rods (9.0–62.5 µm) with multiple flagella that have never been observed in any other Lachnospiraceae members. Based on the phenotypic and phylogenetic features, we propose a new genus and species, Fusimonas intestini gen. nov., sp. nov. for strain AJ110941P (FERM BP-11443).
Highlights
The mammalian digestive tract is one of the largest microbial habitats: more than 1014 cells of microorganisms are present in the entire human gastrointestinal tract[1], and anaerobic bacteria are the main constituents of the ecosystems[2]
Based on metagenomics, Qin et al reported that the abundance of Lachnospiraceae bacteria in the gut was positively correlated with type 2 diabetes, one of the major public health concerns[17], implying that the Lachnospiraceae might be associated with occurrence of the disease
We succeeded in isolating a new member of the family Lachnospiraceae, designated strain AJ110941P, from the feces of hyperglycemic obese mouse[18], and further demonstrated that the new isolate is obviously involved in development of obesity and diabetes in germ-free (GF) ob/ob mice[18]
Summary
Phylogenetic affiliation of strain AJ110941P and its closest relatives. Comparison of 16S rRNA gene sequence of strain AJ110941P with those of validly described species indicated that the strain is moderately related to members of the family Lachnospiraceae with relatively low sequence similarities ( < 92.5%). Strain AJ110941P produced large amounts of EPS, and showed the highest biofilm-forming capacity among Lachnospiraceae species tested in the present study (Fig. 4). By these clear distinctive phenotypic features and low 16S rRNA gene sequence similarities of less than 92.5%, strain AJ110941P can be convincingly distinguished from the related genera within the family Lachonospiraceae. Motility Flagella Spore formation Biofilm formation (48h) (OD595) (96h) DNA G+C (mol%) Growth temperature (°C) Growth pH Major fatty acid Catalase reaction Utilization of: Arabinose Cellobiose Fructose Galactose Glucose Glycerol Inositol Lactose Maltose Mannitol Mannose Melezitose Melibiose Raffinose Rhamnose Ribose Starch Sorbitol Sucrose Trehalose Xylose.
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