Reference genomes are essential for metagenomic analyses and functional characterization of the human gut microbiota. We present the Culturable Genome Reference (CGR), a collection of 1,520 nonredundant, high-quality draft genomes generated from >6,000 bacteria cultivated from fecal samples of healthy humans. Of the 1,520 genomes, which were chosen to cover all major bacterial phyla and genera in the human gut, 264 are not represented in existing reference genome catalogs. We show that this increase in the number of reference bacterial genomes improves the rate of mapping metagenomic sequencing reads from 50% to >70%, enabling higher-resolution descriptions of the human gut microbiome. We use the CGR genomes to annotate functions of 338 bacterial species, showing the utility of this resource for functional studies. We also carry out a pan-genome analysis of 38 important human gut species, which reveals the diversity and specificity of functional enrichment between their core and dispensable genomes.

Butyrate-producing bacteria can biosynthesize butyrate and alleviate inflammatory diseases. However, few studies have reported that the genus Collinsella has the ability to produce butyric acid. Here, our study depicts a Collinsella strain, which is a rod-shaped obligate anaerobe that is able to produce butyric acid. This microorganism was isolated from a human gut, and the optimal growth conditions were found to be 37 °C on PYG medium with pH 6.5. The 16S rRNA gene sequence demonstrated that this microorganism shared 99.93% similarity with C. aerofaciens ATCC 25986^T, which was higher than the threshold (98.65%) for differentiating two species. Digital DNA–DNA hybridization and average nucleotide identity values also supported that this microorganism belonged to the species C. aerofaciens. Distinct phenotypic characteristics between TF06-26 and the type strain of C. aerofaciens, such as the fermentation of D-lactose, D-fructose and D-maltose, positive growth under pH 5 and 0.2% (w/v) cholate, suggested this strain was a novel subspecies. Comparative genome analysis revealed that butyric acid kinase and phosphate butyryltransferase enzymes were coded exclusively by this strain, indicating a specific butyric acid-producing function of this C. aerofaciens subspecies within the genus Collinsella. Thus, Collinsella aerofaciens subsp. shenzhenensis subsp. nov. was proposed, with set strain TF06-26^T (=CGMCC 1.5216^T = DSM 105138^T) as the type strain.

Intestinal microbiota is closely associated with various metabolic diseases such as type 2 diabetes (T2D), and microbiota is definitely affected by diet. However, more work is required to gain detailed information about gut metagenome and their associated impact with diet in T2D patients. We used a streptozotocin-high-fat diet (HFD) to induce a T2D mouse model and investigated the effect of standard chow diet and HFD on the composition and function of gut microbiota. We found that a HFD could worsen the diabetes status compared with a standard diet. 16S rRNA gene sequencing revealed that a HFD caused a large disturbance to the microbial structure and was linked to an increased ratio of Firmicutes to Bacteroidetes. A HFD increased the bacteria of the Ruminococcaceae and Erysipelotrichaceae family and decreased the bacteria of S24-7 and Rikenellaceae. Meanwhile, a HFD decreased the abundance of Parabacteroides distasonis and Eubacterium dolichum, both of which have previously been reported to alleviate obesity and metabolic dysfunctions. Moreover, PICRUSt-predicted KEGG pathways related to membrane transport, lipid metabolism, and xenobiotics biodegradation and metabolism were significantly elevated in HFD-fed T2D mice. Our results provide insights into dietary and nutritional approaches for improving host metabolism and ameliorating T2D.

Objective: Fecal microbiota transplantation (FMT) holds promises as a beneficial supplement to methotrexate in patients with psoriatic arthritis (PsA). We therefore investigated how gut bacterial signatures in patients and donor strain engraftment were associated with long‐term response to FMT. Methods: This exploratory study is based on the FLORA trial cohort, encompassing 31 patients with moderate‐to‐high PsA disease activity and four FMT donors. Of the 15 patients receiving one single‐donor FMT, 13 were included in the per‐protocol (PP) population. Stool samples were collected before and after FMT (week 4, 12, and 26). We performed shotgun metagenomics to characterize gut microbiota features. Results: At baseline, 17 patients (55%) had a gut microbiota community type dominated by the Bacteroides genus (B‐type), whereas 14 (45%) had a Prevotella ‐driven community type (P‐type). The B‐ and P‐type patients did not differ in disease activity or demographics, but the B‐type had a significantly higher species diversity compared to the P‐type ( P = 0.005). In the PP population, five of seven B‐type patients versus none of six P‐type patients ( P = 0.021) achieved a long‐term clinical beneficial response at week 26. Bacterial strain richness increased significantly from baseline to week 4 and week 26 in B‐type ( P = 0.016), but not in P‐type, patients. Eighteen engrafted strains persisted only in B‐type recipients by week 26, including a Bacteroides clarus strain, which demonstrated a negative effect size regarding arthritis pain and the patients’ global assessment of disease. Conclusion: Recipients with a Bacteroides ‐dominated community structure were more likely to achieve long‐term beneficial response following one FMT.

Background: Evidence is accumulating that gut bacterial communities modulate the outcome of dietary interventions. Objective: To assess how gut microbial enterotypes correlate with obesity-related outcomes during one month of whole milk consumption. Methods: This post hoc analysis used data from a previously published trial, which included a lead-in phase during which men with abdominal adiposity replaced habitual dairy product consumption with 400 g/day of whole milk for one month. We compared body weight, urinary metabolites, fecal metabolites, and gut microbiome composition and function based on shotgun metagenomic sequencing at the beginning and at the end of the lead-in phase between individuals with the two most prevalent enterotypes, the Bacteroides1 (B1) enterotype (n = 24) and the Ruminococcaceae (R) enterotype (n = 38). Results: Individuals with the B1 enterotype, but not those with the R enterotype, exhibited decreases in body weight and the relative abundance of Streptococcus thermophilus. Multiple linear regression analysis identified enterotype as a strong predictor of body weight change (p = 0.0034). In addition, urinary taurine level change was positively associated with body weight change in B1 individuals, not in R individuals. Conclusions: Our findings reveal an enterotype-specific response to an identical dietary modification, underscoring the value of integrating enterotype information into nutrition-intervention design and personalized nutrition strategies.