Bacteroides faecalis sp. nov., isolated from human faeces

Bacteroides rhinocerotis sp. nov., isolated from the fresh feces of rhinoceros in Beijing Zoo

A Gram-negative strain, anaerobic, non-motile, non-spore-forming, rod-shaped bacterial strain named as NGMCC 1.200684 ^T was isolated from the fresh feces of rhinoceros in Beijing Zoo. Based on 16S rRNA gene sequences, phylogenetic analysis indicated that strain NGMCC 1.200684 ^T belonged to the genus Bacteroides and was most strongly related to the type strain of Bacteroides uniformis ATCC 8492 ^T (96.88%). The G + C content of the genomic DNA was determined to be 46.62%. Between strains NGMCC 1.200684 ^T and B. uniformis ATCC 8492 ^T, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) were 93.89 and 67.60%, respectively. Strain NGMCC 1.200684 ^T can produce acid from fermentation of several substrates, including glucose, mannitol, lactose, saccharose, maltose, salicin, xylose, cellobiose, mannose, raffinose, sorbitol, trehalose, D-galactose, and maltotriose. The major cellular fatty acids (> 10%) were identified as anteiso-C_15:0, iso-C_15:0, iso-C_14:0, and iso-C_17:0 3-OH. The polar lipid profiles of strain NGMCC 1.200684 ^T were determined to contain diphosphatidyl glycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, and two unknown amino-phospholipids. Based on phenotypic, phylogenetic, and chemotaxonomic characteristics, a novel species of the genus Bacteroides, Bacteroides rhinocerotis sp. nov. is proposed. The type strain is NGMCC 1.200684 ^T (= CGMCC 1.18013 ^T = JCM 35702 ^T).

Bacteroides faecium sp. nov. isolated from human faeces

A novel bacterial strain, CBA7301^T, was isolated from human faeces and was characterised using a polyphasic taxonomic approach. A phylogenetic analysis based on 16S rRNA gene sequences revealed that CBA7301^T represented a member of the genus Bacteroides, in the family Bacteroidaceae. The similarity between the 16S rRNA gene sequence of CBA7301^T and that of its most closely related species, Bacteroides faecichinchillae JCM 17102^T, was 96.2 %, and the average nucleotide identity between these two strains was 77.9 %. The genome size was 6 782 182 bp, and the DNA G+C content was 42.5 mol%. Cells of CBA7301^T were Gram-stain-negative, strictly anaerobic and rod-shaped. The optimal growth of this organism occurred at 30-35 °C, pH 7.0 and 0.5 % (w/v) NaCl. The respiratory quinone was menaquinone 10. The predominant polar lipids were phosphatidylethanolamine, phospholipids and aminophospholipids. The major cellular fatty acid was anteiso-C_15 : 0. According to the results of the polyphasic taxonomic analysis, CBA7301^T represents a novel species of the genus Bacteroides, which we named Bacteroides faecium sp. nov. The type strain is CBA7301^T (=KCCM 43355^T=ATCC TSD-227^T).

Bacteroides propionicigenes sp. nov., isolated from human faeces

An anaerobic bacterial strain, designated as NSJ-90T, was isolated from the faeces of a healthy adult in China. Cells of strain NSJ-90T were Gram-stain-negative, non-motile, non-spore-forming and rod-shaped. Based on 16S rRNA gene sequence analysis, strain NSJ-90T belonged to the genus Bacteroides and was phylogenetically closely related to Bacteroides clarus YIT 12056T (16S rRNA gene identity was 97.04 %). The DNA G+C content of strain NSJ-90T was 44.85 mol% (calculated from the genome). The average nucleotide identity between strain NSJ-90T and B. clarus YIT 12056T was 87.60 %. The major cellular fatty acids (>10 %) of strain NSJ-90T were iso-C15 : 0, anteiso-C15 : 0 and iso-C17 : 0 3-OH. Menaquinone-10 was detected as the respiratory quinone. The major products of glucose fermentation were acetic, propionic and isovaleric acids. Based on its phylogenetic, phenotypic and chemotaxonomic characteristics, we propose that strain NSJ-90T represents a novel species of the genus Bacteroides , for which the name Bacteroides propionicigenes sp. nov. is proposed. The type strain is NSJ-90T (=CGMCC 1.17886T=KCTC 25305T).

The gut microbial metabolite formate exacerbates colorectal cancer progression

The gut microbiome is a key player in the immunomodulatory and protumorigenic microenvironment during colorectal cancer (CRC), as different gut-derived bacteria can induce tumour growth. However, the crosstalk between the gut microbiome and the host in relation to tumour cell metabolism remains largely unexplored. Here we show that formate, a metabolite produced by the CRC-associated bacterium Fusobacterium nucleatum, promotes CRC development. We describe molecular signatures linking CRC phenotypes with Fusobacterium abundance. Cocultures of F. nucleatum with patient-derived CRC cells display protumorigenic effects, along with a metabolic shift towards increased formate secretion and cancer glutamine metabolism. We further show that microbiome-derived formate drives CRC tumour invasion by triggering AhR signalling, while increasing cancer stemness. Finally, F. nucleatum or formate treatment in mice leads to increased tumour incidence or size, and Th17 cell expansion, which can favour proinflammatory profiles. Moving beyond observational studies, we identify formate as a gut-derived oncometabolite that is relevant for CRC progression.

Establishment and evaluation of a specific antibiotic-induced inflammatory bowel disease model in rats

Physical and chemical methods for generating rat models of enteritis have been established; however, antibiotic induction has rarely been used for this purpose. The present study aimed to establish and evaluate a rat model of inflammatory bowel disease (IBD) using antibiotics. A total of 84 Sprague-Dawley (SD) rats were divided into the following groups, according to the dosage and method of administration of the antibiotics: A, control; B, low-dose clindamycin; C, medium-dose clindamycin; D, high-dose clindamycin; E, low-dose clindamycin, ampicillin and streptomycin; F, medium-dose clindamycin, ampicillin and streptomycin; and G, high-dose clindamycin, ampicillin and streptomycin. Antibiotic administration was stopped on day 7; the modeling period covered days 1-7, and the recovery period covered days 8-15. Half of the animals were dissected on day 11, with the remaining animals dissected on day 15. Food and water intake, body weight and fecal weight were recorded. Intestinal flora was analyzed via microbial culture and quantitative PCR. The content of TNF-α, IL1-β, IL-6 and C-reactive protein (CRP) was assessed in abdominal aorta blood. Colonic and rectal tissues were examined pathologically via hematoxylin-eosin staining to assess leukocyte infiltration and intestinal mucosal changes as indicators of inflammation. Rat weight, food intake, water intake and 2-h fecal weight were significantly different across the experimental groups (P = 0.040, P = 0.016, P<0.001 and P = 0.009, respectively). Microbial cultures revealed no significant differences between group A and B,C (P = 0.546,0.872) but significant differences betwenn group A and the other experimental groups (all P<0.001). Furthermore, significant differences in the levels of Bacteroides, Faecalibacterium prausnitzii and Dialister invisus on day 4 between groups A, C and F (P = 0.033, P = 0.025 and P = 0.034, respectively). Significant differences were detected in the levels of TNF-α, IL1-β, IL-6 and CRP between the groups (all P<0.001). The colonic and rectal pathological inflammation scores of the experimental groups were significantly different compared with group A (B vs. A, P = 0.002; others, all P<0.001). These findings indicated that an antibiotic-induced IBD model was successfully established in SD rats; this animal model may serve as a useful model for clinical IBD research.

Bacteroides luhongzhouii sp. nov. and Bacteroides zhangwenhongii sp. nov., isolated from human faeces

Four unknown strains, characterized as Gram-stain-negative, strictly anaerobic, non-motile and rod-shaped, were isolated from fresh faeces of healthy humans in PR China. Pairwise sequence comparisons of the 16S rRNA genes showed that these isolates were separated into two clusters. Cluster I (strains HF-5141^T and HF-106) was most closely related to Bacteroides xylanisolvens XB1A^T (98.0-98.3 % similarity) and Bacteroides ovatus ATCC 8483^T (97.3-97.5 %), whereas cluster II (strains HF-5287^T and HF-5300) exhibited a similarity range of 96.8-97.0 % to Bacteroides finegoldii JCM 13345^T, 96.7-96.9 % to Bacteroides faecis MAJ27^T and 96.4-96.5 % to Bacteroides xylanisolvens XB1A^T. The DNA G+C contents of type strains HF-5141^T and HF-5287^T were 41.5 and 42.6 mol%, respectively. These strains had anteiso-C_15 : 0 as the major cellular fatty acid, MK-9 and MK-11 as the predominant respiratory quinones, and phosphatidylethanolamine, aminophospholipids and phospholipids as major polar lipids, which is typical for members of the genus Bacteroides. However, the average nucleotide identity and digital DNA-DNA hybridization values, accompanied by different phenotypic and biochemical characteristics, distinguished them from their corresponding closest relatives as well as from other recognized members of the genus Bacteroides. Therefore, strains HF-5141^T and HF-5287^T represent two novel species in the genus Bacteroides, for which the names Bacteroides luhongzhouii sp. nov. and Bacteroides zhangwenhongii sp. nov. are proposed, with HF-5141^T (=CGMCC 1.16787^T=GDMCC 1.1591^T=JCM 33480^T) and HF-5287^T (=CGMCC 1.16724^T=GDMCC 1.1590^T=JCM 33481^T) as type strains.

Summary of Novel Bacterial Isolates Derived from Human Clinical Specimens and Nomenclature Revisions Published in 2018 and 2019

Knowledge of novel prokaryotic taxon discovery and nomenclature revisions is of importance to clinical microbiology laboratory practice, infectious disease epidemiology, and studies of microbial pathogenesis. Relative to bacterial isolates derived from human clinical specimens, we present an in-depth summary of novel taxonomic designations and revisions to prokaryotic taxonomy that were published in 2018 and 2019. Included are several changes pertinent to former designations of or within Propionibacterium spp., Corynebacterium spp., Clostridium spp., Mycoplasma spp., Methylobacterium spp., and Enterobacteriaceae Future efforts to ascertain clinical relevance for many of these changes may be augmented by a document development committee that has been appointed by the Clinical and Laboratory Standards Institute.

Altered diversity and composition of gut microbiota in Wilson's disease

Wilson's disease (WD) is an autosomal recessive inherited disorder of chronic copper toxicosis with high mortality and disability. Recent evidence suggests a correlation between dysbiosis in gut microbiome and multiple diseases such as genetic and metabolic disease. However, the impact of intestinal microbiota polymorphism in WD have not been fully elaborated and need to be explore for seeking some microbiota benefit for WD patients. In this study, the 16S rRNA sequencing was performed on fecal samples from 14 patients with WD and was compared to the results from 16 healthy individuals. The diversity and composition of the gut microbiome in the WD group were significantly lower than those in healthy individuals. The WD group presented unique richness of Gemellaceae, Pseudomonadaceae and Spirochaetaceae at family level, which were hardly detected in healthy controls. The WD group had a markedly lower abundance of Actinobacteria, Firmicutes and Verrucomicrobia, and a higher abundance of Bacteroidetes, Proteobacteria, Cyanobacteria and Fusobacteria than that in healthy individuals. The Firmicutes to Bacteroidetes ratio in the WD group was significantly lower than that of healthy control. In addition, the functional profile of the gut microbiome from WD patients showed a lower abundance of bacterial groups involved in the host immune and metabolism associated systems pathways such as transcription factors and ABC-type transporters, compared to healthy individuals. These results implied dysbiosis of gut microbiota may be influenced by the host metabolic disorders of WD, which may provide a new understanding of the pathogenesis and new possible therapeutic targets for WD.

Roles of intestinal bacteroides in human health and diseases

Bacteroides, an abundant genus in the intestines of mammals, has been recently considered as the next generation probiotics (NGP) candidate due to its potential role in promoting host health. However, the role of Bacteroides in the development of intestinal dysfunctions such as diarrhea, inflammatory bowel disease, and colorectal cancer should not be overlooked. In the present study, we focused on nine most widely occurred and abundant Bacteroides species and discussed their roles in host immunity, glucose and lipid metabolism and the prevention or induction of diseases. Besides, we also discussed the current methods used in the safety evaluation of Bacteroides species and key opinions about the concerns of these strains for the future use.