Abstract. Phascolarctobacterium can produce short-chain fatty acids, including acetate and propionate, and can be associated with the metabolic state and mood of the host. The present study investigated the colonization characteristics of Phascolarctobacterium faecium in healthy individuals <1-80 years old in Southern China. A total of 150 fresh fecal samples were collected, and bacterial DNA was isolated from these samples for quantitative polymerase chain reaction analysis. Phascolarctobacterium faecium demonstrated a high colonization rate and abundant colonization in the human gastrointestinal tract. The colonization rate varied between 43.33-93.33%, and the abundance of Phascolarctobacterium faecium ranged between 3.22-5.76 log cells g-1 (<1 years old) and 3.06-9.33 log cells g-1 (>1 year old). The permillage of Phascolarctobacterium faecium in total bacteria ranged between 0.004-1.479. There was presence of Phascolarctobacterium faecium-like bacteria in younger individuals with a gradual increase in the number of bacteria maintained at a high level with increasing ages (between 1 and 60 years old), but with a decrease in elderly individuals (>60 years old). The results of the present study demonstrated that Phascolarctobacterium faecium is abundantly colonized in the human gastrointestinal tract. IntroductionThe human gut microbiota is composed of 400-500 species of microbes. However, the molecular classification of operational taxonomic units (OTUs) indicate the presence of more than 1,000 OTUs (OTUs, equivalent to species) in the gut of each in different societies, and that the number of OTUs increases with age (1,2). The gene pool of the microbial habitants of the gut is extremely diverse and considerably larger than the gene pool of the host, which determines a number of metabolic capacities of the bacteria that are essential for the survival of these organisms in the gut (1,3,4).In recent years, high throughput sequencing technologies have revealed the correlation between gut microbiota and the host. Phascolarctobacterium was found to be a substantial acetate/propionate-producer that could be dramatically increased by berberine and metformin. This in turn may contribute to the beneficial effects of the two drugs on the host (5). Moreover, Phascolarctobacterium was found to be positively correlated to the positive mood of the human (6). An increasing number of studies proposed that Phascolarctobacterium faecium (P. faecium) exerted beneficial effects on the host, including rat model of nonalcoholic fatty liver (7).P. faecium, which utilizes succinate and produces propionate, was first purified from koala feces in 1992. P. faecium are obligate anaerobic, Gram-negative, non-spore-forming, non-motile, asaccharolytic, and belonging to firmicutes (8). Although uncultured colonies closely related to P. faecium were frequently detected in samples from the human gastrointestinal tract, isolation of Phascolarctobacterium from the human gastrointestinal tract and the expansion of the culture are not yet describe...

Background Akkermansia muciniphila is one of the most dominant bacteria that resides on the mucus layer of intestinal tract and plays key role in human health, however, little is known about its genomic content.ResultsHerein, we for the first time characterized the genomic architecture of A. muciniphila based on whole-genome sequencing, assembling, and annotating of 39 isolates derived from human and mouse feces. We revealed a flexible open pangenome of A. muciniphila currently consisting of 5644 unique proteins. Phylogenetic analysis identified three species-level A. muciniphila phylogroups exhibiting distinct metabolic and functional features. Based on the comprehensive genome catalogue, we reconstructed 106 newly A. muciniphila metagenome assembled genomes (MAGs) from available metagenomic datasets of human, mouse and pig gut microbiomes, revealing a transcontinental distribution of A. muciniphila phylogroups across mammalian gut microbiotas. Accurate quantitative analysis of A. muciniphila phylogroups in human subjects further demonstrated its strong correlation with body mass index and anti-diabetic drug usage. Furthermore, we found that, during their mammalian gut evolution history, A. muciniphila acquired extra genes, especially antibiotic resistance genes, from symbiotic microbes via recent lateral gene transfer.ConclusionsThe genome repertoire of A. muciniphila provided insights into population structure, evolutionary and functional specificity of this significant bacterium.Electronic supplementary materialThe online version of this article (10.1186/s12864-017-4195-3) contains supplementary material, which is available to authorized users.

No abstract