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Gastroenterology Sep 2020Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects gastrointestinal tissues, little is known about the roles of gut commensal microbes in...
BACKGROUND & AIMS
Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects gastrointestinal tissues, little is known about the roles of gut commensal microbes in susceptibility to and severity of infection. We investigated changes in fecal microbiomes of patients with SARS-CoV-2 infection during hospitalization and associations with severity and fecal shedding of virus.
METHODS
We performed shotgun metagenomic sequencing analyses of fecal samples from 15 patients with Coronavirus Disease 2019 (COVID-19) in Hong Kong, from February 5 through March 17, 2020. Fecal samples were collected 2 or 3 times per week from time of hospitalization until discharge; disease was categorized as mild (no radiographic evidence of pneumonia), moderate (pneumonia was present), severe (respiratory rate ≥30/min, or oxygen saturation ≤93% when breathing ambient air), or critical (respiratory failure requiring mechanical ventilation, shock, or organ failure requiring intensive care). We compared microbiome data with those from 6 subjects with community-acquired pneumonia and 15 healthy individuals (controls). We assessed gut microbiome profiles in association with disease severity and changes in fecal shedding of SARS-CoV-2.
RESULTS
Patients with COVID-19 had significant alterations in fecal microbiomes compared with controls, characterized by enrichment of opportunistic pathogens and depletion of beneficial commensals, at time of hospitalization and at all timepoints during hospitalization. Depleted symbionts and gut dysbiosis persisted even after clearance of SARS-CoV-2 (determined from throat swabs) and resolution of respiratory symptoms. The baseline abundance of Coprobacillus, Clostridium ramosum, and Clostridium hathewayi correlated with COVID-19 severity; there was an inverse correlation between abundance of Faecalibacterium prausnitzii (an anti-inflammatory bacterium) and disease severity. Over the course of hospitalization, Bacteroides dorei, Bacteroides thetaiotaomicron, Bacteroides massiliensis, and Bacteroides ovatus, which downregulate expression of angiotensin-converting enzyme 2 (ACE2) in murine gut, correlated inversely with SARS-CoV-2 load in fecal samples from patients.
CONCLUSIONS
In a pilot study of 15 patients with COVID-19, we found persistent alterations in the fecal microbiome during the time of hospitalization, compared with controls. Fecal microbiota alterations were associated with fecal levels of SARS-CoV-2 and COVID-19 severity. Strategies to alter the intestinal microbiota might reduce disease severity.
Topics: Adult; Aged; Betacoronavirus; COVID-19; Coronavirus Infections; Dysbiosis; Feces; Female; Gastrointestinal Microbiome; Gastrointestinal Tract; Hong Kong; Hospitalization; Humans; Male; Middle Aged; Pandemics; Pilot Projects; Pneumonia, Viral; SARS-CoV-2
PubMed: 32442562
DOI: 10.1053/j.gastro.2020.05.048 -
Frontiers in Microbiology 2021Bacteroidetes are the most common bacterial phylum in the mammalian intestine and the effects of several spp. on multiple facets of host physiology have been...
Bacteroidetes are the most common bacterial phylum in the mammalian intestine and the effects of several spp. on multiple facets of host physiology have been previously described. Of the spp., has recently garnered attention due to its beneficial effects in the context of intestinal inflammation. In this study, we aimed to examine model host intestinal physiological conditions and dietary modifications to characterize their effects on growth. Using Biolog phenotypic microarrays, we evaluated 62 primary carbon sources and determined that ATCC 8384 can use the following carbohydrates as primary carbon sources: 10 disaccharides, 4 trisaccharides, 4 polysaccharides, 4 polymers, 3 L-linked sugars, 6 D-linked sugars, 5 amino-sugars, 6 alcohol sugars, and 15 organic acids. Proteomic profiling of bacteria revealed that a significant portion of the proteome contains proteins important for metabolism. Among the proteins, we found glycosyl hydrolase (GH) familes GH2, GH5, GH20, GH 43, GH88, GH92, and GH95. We also identified multiple proteins with antioxidant properties and reasoned that these proteins may support growth in the GI tract. Upon further testing, we showed that grew robustly in various pH, osmolarity, bile, ethanol, and HO concentrations; indicating that is a well-adapted gut microbe. Taken together, we have demonstrated that key host and diet-derived changes in the intestinal environment influence growth. These data provide the framework for future work toward understanding how diet and lifestyle interventions may promote a beneficial environment for growth.
PubMed: 34899632
DOI: 10.3389/fmicb.2021.745469 -
Nature Protocols Feb 2023Interest in the communication between the gastrointestinal tract and central nervous system, known as the gut-brain axis, has prompted the development of quantitative... (Review)
Review
Interrogation of the mammalian gut-brain axis using LC-MS/MS-based targeted metabolomics with in vitro bacterial and organoid cultures and in vivo gnotobiotic mouse models.
Interest in the communication between the gastrointestinal tract and central nervous system, known as the gut-brain axis, has prompted the development of quantitative analytical platforms to analyze microbe- and host-derived signals. This protocol enables investigations into connections between microbial colonization and intestinal and brain neurotransmitters and contains strategies for the comprehensive evaluation of metabolites in in vitro (organoids) and in vivo mouse model systems. Here we present an optimized workflow that includes procedures for preparing these gut-brain axis model systems: (stage 1) growth of microbes in defined media; (stage 2) microinjection of intestinal organoids; and (stage 3) generation of animal models including germ-free (no microbes), specific-pathogen-free (complete gut microbiota) and specific-pathogen-free re-conventionalized (germ-free mice associated with a complete gut microbiota from a specific-pathogen-free mouse), and Bifidobacterium dentium and Bacteroides ovatus mono-associated mice (germ-free mice colonized with a single gut microbe). We describe targeted liquid chromatography-tandem mass spectrometry-based metabolomics methods for analyzing microbially derived short-chain fatty acids and neurotransmitters from these samples. Unlike other protocols that commonly examine only stool samples, this protocol includes bacterial cultures, organoid cultures and in vivo samples, in addition to monitoring the metabolite content of stool samples. The incorporation of three experimental models (microbes, organoids and animals) enhances the impact of this protocol. The protocol requires 3 weeks of murine colonization with microbes and ~1-2 weeks for liquid chromatography-tandem mass spectrometry-based instrumental and quantitative analysis, and sample post-processing and normalization.
Topics: Animals; Mice; Brain-Gut Axis; Tandem Mass Spectrometry; Chromatography, Liquid; Germ-Free Life; Metabolomics; Bacteria; Mammals; Organoids
PubMed: 36352124
DOI: 10.1038/s41596-022-00767-7 -
Nutrients Dec 2022Fecal microbiota transplantation (FMT) is a promising therapeutic modality for the treatment and prevention of metabolic disease. We previously conducted a double-blind,... (Randomized Controlled Trial)
Randomized Controlled Trial
Fecal microbiota transplantation (FMT) is a promising therapeutic modality for the treatment and prevention of metabolic disease. We previously conducted a double-blind, randomized, placebo-controlled pilot trial of FMT in obese metabolically healthy patients in which we found that FMT enhanced gut bacterial bile acid metabolism and delayed the development of impaired glucose tolerance relative to the placebo control group. Therefore, we conducted a secondary analysis of fecal samples collected from these patients to assess the potential gut microbial species contributing to the effect of FMT to improve metabolic health and increase gut bacterial bile acid metabolism. Fecal samples collected at baseline and after 4 weeks of FMT or placebo treatment underwent shotgun metagenomic analysis. Ultra-high-performance liquid chromatography-mass spectrometry was used to profile fecal bile acids. FMT-enriched bacteria that have been implicated in gut bile acid metabolism included and . To identify candidate bacteria involved in gut microbial bile acid metabolism, we assessed correlations between bacterial species abundance and bile acid profile, with a focus on bile acid products of gut bacterial metabolism. and were positively correlated with unconjugated bile acids. , , and were positively correlated with secondary bile acids. Together, these data identify several candidate bacteria that may contribute to the metabolic benefits of FMT and gut bacterial bile acid metabolism that requires further functional validation.
Topics: Humans; Fecal Microbiota Transplantation; Gastrointestinal Microbiome; Feces; Bacteria; Bile Acids and Salts
PubMed: 36558359
DOI: 10.3390/nu14245200 -
Applied Microbiology and Biotechnology Mar 2019Lipopolysaccharide (LPS) can promote the expression of pro-inflammatory cytokines, damage the tight junction of epithelial walls, and thereby lead to chronic low-grade...
Lipopolysaccharide (LPS) can promote the expression of pro-inflammatory cytokines, damage the tight junction of epithelial walls, and thereby lead to chronic low-grade intestinal inflammatory disorders. Evidences of many beneficial functions from Bacteroides strains suggest their intervention capabilities in LPS-induced inflammation. In the present study, both healthy and LPS-treated mice were consistently treated with Bacteroides strains for 5 days. The intestinal microbiota alteration, epithelial permeability, cytokine expression, and autoimmune and innate immune responses were analyzed. B. fragilis HCK-B3 and B. ovatus ELH-B2 from our laboratory collection were demonstrated to assist intestinal equilibrium by maintaining the diversity of gut microbiota and relieve LPS-induced inflammation by either modulating cytokine production or restoring the Treg/Th-17 balance. Our research indicated that the Bacteroides strains with capabilities of alleviating inflammation have the potential as therapeutics to prevent intestinal inflammatory disorders and provided scientific supports for discovering next-generation probiotics.
Topics: Animals; Bacteroides fragilis; Cytokines; Female; Gastrointestinal Microbiome; Inflammation; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Probiotics; T-Lymphocytes, Regulatory; Th17 Cells
PubMed: 30666361
DOI: 10.1007/s00253-019-09617-1 -
Food Research International (Ottawa,... Aug 2023The intestinal microbiome is a community of anaerobic microorganisms whose activities significantly impact human health. Its composition can be modulated by consuming...
The intestinal microbiome is a community of anaerobic microorganisms whose activities significantly impact human health. Its composition can be modulated by consuming foods rich in dietary fiber, such as xylan, a complex polysaccharide that can be considered an emerging prebiotic. In this work, we evaluated how certain gut bacteria acted as primary degraders, fermenting dietary fibers, and releasing metabolites that other bacteria can further use. Different bacterial strains of Lactobacillus, Bifidobacterium, and Bacteroides were evaluated for their ability to consume xylan and interact with one another. Results from unidirectional assays gave indications of possible cross-feeding between bacteria using xylan as a carbon source. Bidirectional assays showed that Bifidobacterium longum PT4 increased its growth in the presence of Bacteroides ovatus HM222. Proteomic analyses indicated that B. ovatus HM222 synthesizes enzymes facilitating xylan degradation, such as β-xylanase, arabinosidase, L-arabinose isomerase, and xylosidase. Interestingly, the relative abundance of these proteins remains largely unaffected in the presence of Bifidobacterium longum PT4. In the presence of B. ovatus, B. longum PT4 increased the production of enzymes such as α-L-arabinosidase, L-arabinose isomerase, xylulose kinase, xylose isomerase, and sugar transporters. These results show an example of positive interaction between bacteria mediated by xylan consumption. Bacteroides degraded this substrate to release xylooligosaccharides, or monosaccharides (xylose, arabinose), which might support the growth of secondary degraders such as B. longum.
Topics: Humans; Sugars; Xylans; Bifidobacterium longum; Proteomics; Bacteroides; Dietary Fiber
PubMed: 37316088
DOI: 10.1016/j.foodres.2023.113025 -
BMC Microbiology Jul 2014Bacteroides ovatus, a member of the genus Bacteroides, is considered for use in molecular-based methods as a general fecal indicator. However, knowledge on its fate and...
BACKGROUND
Bacteroides ovatus, a member of the genus Bacteroides, is considered for use in molecular-based methods as a general fecal indicator. However, knowledge on its fate and persistence after a fecal contamination event remains limited. In this study, the persistence of B. ovatus was evaluated under simulated sunlight exposure and in conditions similar to freshwater and seawater. By combining propidium monoazide (PMA) treatment and quantitative polymerase chain reaction (qPCR) detection, the decay rates of B. ovatus were determined in the presence and absence of exogenous photosensitizers and in salinity up to 39.5 parts per thousand at 27°C.
RESULTS
UVB was found to be important for B. ovatus decay, averaging a 4 log10 of decay over 6 h of exposure without the presence of extracellular photosensitizers. The addition of NaNO2, an exogenous sensitizer producing hydroxyl radicals, did not significantly change the decay rate of B. ovatus in both low and high salinity water, while the exogenous sensitizer algae organic matter (AOM) slowed down the decay of B. ovatus in low salinity water. At seawater salinity, the decay rate of B. ovatus was slower than that in low salinity water, except when both NaNO2 and AOM were present.
CONCLUSION
The results of laboratory experiments suggest that if B. ovatus is released into either freshwater or seawater environment in the evening, 50% of it may be intact by the next morning; if it is released at noon, only 50% may be intact after a mere 5 min of full spectrum irradiation on a clear day. This study provides a mechanistic understanding to some of the important environmental relevant factors that influenced the inactivation kinetics of B. ovatus in the presence of sunlight irradiation, and would facilitate the use of B. ovatus to indicate the occurrence of fecal contamination.
Topics: Bacteroides; Feces; Fresh Water; Microbial Viability; Photosensitizing Agents; Polymerase Chain Reaction; Salinity; Seawater; Sunlight; Temperature
PubMed: 24993443
DOI: 10.1186/1471-2180-14-178 -
Nature Communications Oct 2023Malaria is caused by Plasmodium species and remains a significant cause of morbidity and mortality globally. Gut bacteria can influence the severity of malaria, but the... (Meta-Analysis)
Meta-Analysis
Malaria is caused by Plasmodium species and remains a significant cause of morbidity and mortality globally. Gut bacteria can influence the severity of malaria, but the contribution of specific bacteria to the risk of severe malaria is unknown. Here, multiomics approaches demonstrate that specific species of Bacteroides are causally linked to the risk of severe malaria. Plasmodium yoelii hyperparasitemia-resistant mice gavaged with murine-isolated Bacteroides fragilis develop P. yoelii hyperparasitemia. Moreover, Bacteroides are significantly more abundant in Ugandan children with severe malarial anemia than with asymptomatic P. falciparum infection. Human isolates of Bacteroides caccae, Bacteroides uniformis, and Bacteroides ovatus were able to cause susceptibility to severe malaria in mice. While monocolonization of germ-free mice with Bacteroides alone is insufficient to cause susceptibility to hyperparasitemia, meta-analysis across multiple studies support a main role for Bacteroides in susceptibility to severe malaria. Approaches that target gut Bacteroides present an opportunity to prevent severe malaria and associated deaths.
Topics: Child; Humans; Animals; Mice; Microbial Consortia; Malaria; Bacteroides; Bacteroides fragilis; Anemia; Plasmodium yoelii
PubMed: 37833304
DOI: 10.1038/s41467-023-42235-0 -
Cellular and Molecular Life Sciences :... Jul 2023Members of the Bacteroidetes phylum in the human colon deploy an extensive number of proteins to capture and degrade polysaccharides. Operons devoted to glycan breakdown...
Members of the Bacteroidetes phylum in the human colon deploy an extensive number of proteins to capture and degrade polysaccharides. Operons devoted to glycan breakdown and uptake are termed polysaccharide utilization loci or PUL. The starch utilization system (Sus) is one such PUL and was initially described in Bacteroides thetaiotaomicron (Bt). BtSus is highly conserved across many species, except for its extracellular α-amylase, SusG. In this work, we show that the Bacteroides ovatus (Bo) extracellular α-amylase, BoGH13A, is distinguished from SusG in its evolutionary origin and its domain architecture and by being the most prevalent form in Bacteroidetes Sus. BoGH13A is the founding member of both a novel subfamily in the glycoside hydrolase family 13, GH13_47, and a novel carbohydrate-binding module, CBM98. The BoGH13A CBM98-CBM48-GH13_47 architecture differs from the CBM58 embedded within the GH13_36 of SusG. These domains adopt a distinct spatial orientation and invoke a different association with the outer membrane. The BoCBM98 binding site is required for Bo growth on polysaccharides and optimal enzymatic degradation thereof. Finally, the BoGH13A structure features bound Ca and Mn ions, the latter of which is novel for an α-amylase. Little is known about the impact of Mn on gut bacterial function, much less on polysaccharide consumption, but Mn addition to Bt expressing BoGH13A specifically enhances growth on starch. Further understanding of bacterial starch degradation signatures will enable more tailored prebiotic and pharmaceutical approaches that increase starch flux to the gut.
Topics: Humans; alpha-Amylases; Bacteroides; Starch; Polysaccharides
PubMed: 37500984
DOI: 10.1007/s00018-023-04812-w -
Anaerobe Dec 2020B. ovatus is a member of the human gut microbiota with a broad capability to degrade complex glycans. Here we show that B. ovatus degrades plant polysaccharides in a...
B. ovatus is a member of the human gut microbiota with a broad capability to degrade complex glycans. Here we show that B. ovatus degrades plant polysaccharides in a preferential order, and that glycan structural complexity plays a role in determining the prioritisation of polysaccharide usage.
Topics: Bacteroides; Gastrointestinal Microbiome; Gastrointestinal Tract; Humans; Plants; Polysaccharides
PubMed: 32927049
DOI: 10.1016/j.anaerobe.2020.102276