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1.
Appl Environ Microbiol ; 86(23)2020 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-32948524

RESUMO

Acetogenic bacteria are a diverse group of anaerobes that use the reductive acetyl coenzyme A (acetyl-CoA) (Wood-Ljungdahl) pathway for CO2 fixation and energy conservation. The conversion of 2 mol CO2 into acetyl-CoA by using the Wood-Ljungdahl pathway as the terminal electron accepting process is the most prominent metabolic feature for these microorganisms. However, here, we describe that the fecal acetogen Clostridium bovifaecis strain BXX displayed poor metabolic capabilities of autotrophic acetogenesis, and acetogenic utilization of glucose occurred only with the supplementation of formate. Genome analysis of Clostridium bovifaecis revealed that it contains almost the complete genes of the Wood-Ljungdahl pathway but lacks the gene encoding formate dehydrogenase, which catalyzes the reduction of CO2 to formate as the first step of the methyl branch of the Wood-Ljungdahl pathway. The lack of a gene encoding formate dehydrogenase was verified by PCR, reverse transcription-PCR analysis, enzyme activity assay, and its formate-dependent acetogenic utilization of glucose on DNA, RNA, protein, and phenotype level, respectively. The lack of a formate dehydrogenase gene may be associated with the adaption to a formate-rich intestinal environment, considering the isolating source of strain BXX. The formate-dependent acetogenic growth of Clostridium bovifaecis provides insight into a unique metabolic feature of fecal acetogens.IMPORTANCE The acetyl-CoA pathway is an ancient pathway of CO2 fixation, which converts 2 mol of CO2 into acetyl-CoA. Autotrophic growth with H2 and CO2 via the acetyl-CoA pathway as the terminal electron accepting process is the most unique feature of acetogenic bacteria. However, the fecal acetogen Clostridium bovifaecis strain BXX displayed poor metabolic capabilities of autotrophic acetogenesis, and acetogenic utilization of glucose occurred only with the supplementation of formate. The formate-dependent acetogenic growth of Clostridium bovifaecis was associated with its lack of a gene encoding formate dehydrogenase, which may result from adaption to a formate-rich intestinal environment. This study gave insight into a unique metabolic feature of fecal acetogens. Because of the requirement of formate for the acetogenic growth of certain acetogens, the ecological impact of acetogens could be more complex and important in the formate-rich environment due to their trophic interactions with other microbes.


Assuntos
Ácido Acético/metabolismo , Proteínas de Bactérias , Clostridium/metabolismo , Formiato Desidrogenases/deficiência , Formiatos/metabolismo , Acetilcoenzima A/metabolismo , Clostridium/enzimologia , Clostridium/genética , Redes e Vias Metabólicas
2.
Chemosphere ; 261: 127734, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32771714

RESUMO

CO is one of the toxic components of syngas, which is the major source of air pollution. Syngas fermentation technology has the ability to convert toxic gases into valuable biofuels, such as ethanol. Fermentative ethanol production is an important method that can be used to promote environmental protection. CO can be converted into ethanol, via the Wood-Ljungdahl pathway, using Clostridium ljungdahlii. The components of the growing medium--especially the trace-element solution and yeast extract--are the main reasons for the high costs associated with this process, however, and this especially impacts scaled-up operations. In this study, cheaper substitutes for these components were used in order to determine their effect on ethanol production. The study comprised three main parts--the optimization of CO concentration, and the substitution of corn syrup and whey powder in the process. The optimum volume of CO for ethanol production was found to be 10 mL. Corn syrup can be used instead of trace-element solution, but the use of yeast extract with the corn syrup was determined to be essential. Up to 1.4 g/L ethanol production was observed with the addition of 15 mL corn syrup. Whey powder had the advantage of being usable without yeast extract, with up to 2.5 g/L ethanol being produced from a 30-g/L concentration. The main finding was that either corn syrup or whey powder can be used as substitutes for expensive basal-medium components.


Assuntos
Biocombustíveis/análise , Monóxido de Carbono/química , Etanol/análise , Xarope de Milho Rico em Frutose/química , Soro do Leite/química , Monóxido de Carbono/metabolismo , Clostridium/metabolismo , Meios de Cultura/metabolismo , Etanol/metabolismo , Fermentação , Xarope de Milho Rico em Frutose/metabolismo , Pós , Soro do Leite/metabolismo
4.
Nature ; 582(7813): 566-570, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32555455

RESUMO

The gut microbiota synthesize hundreds of molecules, many of which influence host physiology. Among the most abundant metabolites are the secondary bile acids deoxycholic acid (DCA) and lithocholic acid (LCA), which accumulate at concentrations of around 500 µM and are known to block the growth of Clostridium difficile1, promote hepatocellular carcinoma2 and modulate host metabolism via the G-protein-coupled receptor TGR5 (ref. 3). More broadly, DCA, LCA and their derivatives are major components of the recirculating pool of bile acids4; the size and composition of this pool are a target of therapies for primary biliary cholangitis and nonalcoholic steatohepatitis. Nonetheless, despite the clear impact of DCA and LCA on host physiology, an incomplete knowledge of their biosynthetic genes and a lack of genetic tools to enable modification of their native microbial producers limit our ability to modulate secondary bile acid levels in the host. Here we complete the pathway to DCA and LCA by assigning and characterizing enzymes for each of the steps in its reductive arm, revealing a strategy in which the A-B rings of the steroid core are transiently converted into an electron acceptor for two reductive steps carried out by Fe-S flavoenzymes. Using anaerobic in vitro reconstitution, we establish that a set of six enzymes is necessary and sufficient for the eight-step conversion of cholic acid to DCA. We then engineer the pathway into Clostridium sporogenes, conferring production of DCA and LCA on a nonproducing commensal and demonstrating that a microbiome-derived pathway can be expressed and controlled heterologously. These data establish a complete pathway to two central components of the bile acid pool.


Assuntos
Ácidos e Sais Biliares/química , Ácidos e Sais Biliares/metabolismo , Microbioma Gastrointestinal/genética , Microbioma Gastrointestinal/fisiologia , Hidroxilação/genética , Redes e Vias Metabólicas/genética , Animais , Clostridium/enzimologia , Clostridium/genética , Clostridium/metabolismo , Ácido Desoxicólico/química , Ácido Desoxicólico/metabolismo , Ácido Litocólico/química , Ácido Litocólico/metabolismo , Masculino , Engenharia Metabólica , Camundongos , Óperon/genética , Simbiose
5.
Appl Environ Microbiol ; 86(14)2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32414802

RESUMO

Bioethanol production from syngas using acetogenic bacteria has attracted considerable attention in recent years. However, low ethanol yield is the biggest challenge that prevents the commercialization of syngas fermentation into biofuels using microbial catalysts. The present study demonstrated that ethanol metabolism plays an important role in recycling NADH/NAD+ during autotrophic growth. Deletion of bifunctional aldehyde/alcohol dehydrogenase (adhE) genes leads to significant growth deficiencies in gas fermentation. Using specific fermentation technology in which the gas pressure and pH were constantly controlled at 0.1 MPa and 6.0, respectively, we revealed that ethanol was formed during the exponential phase, closely accompanied by biomass production. Then, ethanol was oxidized to acetate via the aldehyde ferredoxin oxidoreductase pathway in Clostridium ljungdahlii A metabolic experiment using 13C-labeled ethanol and acetate, redox balance analysis, and comparative transcriptomic analysis demonstrated that ethanol production and reuse shared the metabolic pathway but occurred at different growth phases.IMPORTANCE Ethanol production from carbon monoxide (CO) as a carbon and energy source by Clostridium ljungdahlii and "Clostridium autoethanogenum" is currently being commercialized. During gas fermentation, ethanol synthesis is NADH-dependent. However, ethanol oxidation and its regulatory mechanism remain incompletely understood. Energy metabolism analysis demonstrated that reduced ferredoxin is the sole source of NADH formation by the Rnf-ATPase system, which provides ATP for cell growth during CO fermentation. Therefore, ethanol production is tightly linked to biomass production (ATP production). Clarification of the mechanism of ethanol oxidation and biosynthesis can provide an important reference for generating high-ethanol-yield strains of C. ljungdahlii in the future.


Assuntos
Biocombustíveis/microbiologia , Monóxido de Carbono/metabolismo , Clostridium/metabolismo , Etanol/metabolismo , Processos Autotróficos , Clostridium/crescimento & desenvolvimento , Fermentação
6.
PLoS One ; 15(5): e0229889, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32396555

RESUMO

The purpose of the study involves the development of an anaerobic, thermophilic microbial consortium TERIK from the high temperature reservoir of Gujarat for enhance oil recovery. To isolate indigenous microbial consortia, anaerobic baltch media were prepared and inoculated with the formation water; incubated at 65°C for 10 days. Further, the microbial metabolites were analyzed by gas chromatography, FTIR and surface tension. The efficiency of isolated consortia towards enhancing oil recovery was analyzed through core flood assay. The novelty of studied consortia was that, it produces biomass (600 mg/l), bio-surfactant (325 mg/l), and volatile fatty acids (250 mg/l) at 65°C in the span of 10 days, that are adequate to alter the surface tension (70 to 34 mNm -1) and sweep efficiency of zones facilitating the displacement of oil. TERIK was identified as Clostridium sp. The FTIR spectra of biosurfactant indicate the presence of N-H stretch, amides and polysaccharide. A core flooding assay was designed to explore the potential of TERIK towards enhancing oil recovery. The results showed an effective reduction in permeability at residual oil saturation from 2.14 ± 0.1 to 1.39 ± 0.05 mD and 19% incremental oil recovery.


Assuntos
Archaea/metabolismo , Microbiologia Industrial , Consórcios Microbianos , Campos de Petróleo e Gás/microbiologia , Clostridium/metabolismo , Temperatura Alta , Humanos , Petróleo/microbiologia , Tensão Superficial , Tensoativos/farmacologia
7.
Proc Natl Acad Sci U S A ; 117(23): 13168-13175, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32471945

RESUMO

Living biological systems display a fascinating ability to self-organize their metabolism. This ability ultimately determines the metabolic robustness that is fundamental to controlling cellular behavior. However, fluctuations in metabolism can affect cellular homeostasis through transient oscillations. For example, yeast cultures exhibit rhythmic oscillatory behavior in high cell-density continuous cultures. Oscillatory behavior provides a unique opportunity for quantitating the robustness of metabolism, as cells respond to changes by inherently compromising metabolic efficiency. Here, we quantify the limits of metabolic robustness in self-oscillating autotrophic continuous cultures of the gas-fermenting acetogen Clostridium autoethanogenum Online gas analysis and high-resolution temporal metabolomics showed oscillations in gas uptake rates and extracellular byproducts synchronized with biomass levels. The data show initial growth on CO, followed by growth on CO and H2 Growth on CO and H2 results in an accelerated growth phase, after which a downcycle is observed in synchrony with a loss in H2 uptake. Intriguingly, oscillations are not linked to translational control, as no differences were observed in protein expression during oscillations. Intracellular metabolomics analysis revealed decreasing levels of redox ratios in synchrony with the cycles. We then developed a thermodynamic metabolic flux analysis model to investigate whether regulation in acetogens is controlled at the thermodynamic level. We used endo- and exo-metabolomics data to show that the thermodynamic driving force of critical reactions collapsed as H2 uptake is lost. The oscillations are coordinated with redox. The data indicate that metabolic oscillations in acetogen gas fermentation are controlled at the thermodynamic level.


Assuntos
Reatores Biológicos/microbiologia , Clostridium/metabolismo , Metabolismo Energético , Fermentação , Processos Autotróficos , Biomassa , Monóxido de Carbono/metabolismo , Hidrogênio/metabolismo , Metabolômica , Oxirredução , Proteômica , Termodinâmica
8.
Sci Rep ; 10(1): 7705, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32382092

RESUMO

Uncontrolled oxidative stress, reported in Salmonella and HIV infections, colorectal cancer or severe acute malnutrition, has been associated with anaerobic gut microbiome alteration, impaired butyrate production, mucosal immunity dysregulation and disruption of host-bacterial mutualism. However, the role of major antioxidant molecules in the human body, such as glutathione, ascorbic acid and uric acid, has been neglected in this context. Here, we performed an in vitro metabolomics study of the 3 most odorous anaerobic microbes isolated from the human gut in our laboratory (Clostridium sporogenes, Clostridium subterminale and Romboutsia lituseburensis) when grown in anaerobiosis or in aerobiosis with these 3 antioxidant molecules via gas and liquid chromatography-mass spectrometry (GC/MS and LC/MS). There was no growth or volatile organic compound production in aerobic cultures without the 3 antioxidant molecules. In anaerobiosis, the major metabolic products of the bacteria were thiols, alcohols and short-chain fatty acid esters. The production of alkanes, cycloheptatriene and, paradoxically, increased butyrate production, was observed in the cultures grown in aerobiosis with the 3 antioxidant molecules. The qualitative shift suggests specific molecular mechanisms that remain to be elucidated. The increased production of butyrate, but also isobutyrate and isovalerate in vitro suggests that these 3 antioxidant molecules contributed to the maintenance and active resilience of host-bacterial mutualism against mucosal oxygen and uncontrolled oxidative stress in vivo.


Assuntos
Antioxidantes/metabolismo , Microbioma Gastrointestinal/genética , Metabolômica , Estresse Oxidativo/genética , Aerobiose/genética , Anaerobiose/genética , Ácido Ascórbico/metabolismo , Butiratos/metabolismo , Cromatografia Líquida , Clostridiales/metabolismo , Clostridium/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Glutationa/metabolismo , Humanos , Oxigênio/metabolismo , Ácido Úrico/metabolismo
9.
Proc Natl Acad Sci U S A ; 117(13): 7516-7523, 2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-32170009

RESUMO

Among CO2-fixing metabolic pathways in nature, the linear Wood-Ljungdahl pathway (WLP) in phylogenetically diverse acetate-forming acetogens comprises the most energetically efficient pathway, requires the least number of reactions, and converts CO2 to formate and then into acetyl-CoA. Despite two genes encoding glycine synthase being well-conserved in WLP gene clusters, the functional role of glycine synthase under autotrophic growth conditions has remained uncertain. Here, using the reconstructed genome-scale metabolic model iSL771 based on the completed genome sequence, transcriptomics, 13C isotope-based metabolite-tracing experiments, biochemical assays, and heterologous expression of the pathway in another acetogen, we discovered that the WLP and the glycine synthase pathway are functionally interconnected to fix CO2, subsequently converting CO2 into acetyl-CoA, acetyl-phosphate, and serine. Moreover, the functional cooperation of the pathways enhances CO2 consumption and cellular growth rates via bypassing reducing power required reactions for cellular metabolism during autotrophic growth of acetogens.


Assuntos
Aminoácido Oxirredutases/metabolismo , Aminometiltransferase/metabolismo , Processos Autotróficos/fisiologia , Complexos Multienzimáticos/metabolismo , Acetilcoenzima A/metabolismo , Aminoácido Oxirredutases/genética , Aminometiltransferase/genética , Proteínas de Bactérias/metabolismo , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Monóxido de Carbono/metabolismo , Clostridium/metabolismo , Redes e Vias Metabólicas , Complexos Multienzimáticos/genética , Família Multigênica , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo
10.
Enzyme Microb Technol ; 135: 109490, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32146936

RESUMO

Bioproducts production using monomeric sugars derived from lignocellulosic biomass presents several challenges, such as to require a physicochemical pretreatment to improve its conversion yields. Hydrothermal lignocellulose pretreatment has several advantages and results in solid and liquid streams. The former is called hemicellulosic hydrolysate (HH), which contains inhibitory phenolic compounds and sugar degradation products that hinder microbial fermentation products from pentose sugars. Here, we developed and applied a novel enzyme process to detoxify HH. Initially, the design of experiments with different redox activities enzymes was carried out. The enzyme mixture containing the peroxidase (from Armoracia rusticana) together with superoxide dismutase (from Coptotermes gestroi) are the most effective to detoxify HH derived from sugarcane bagasse. Butanol fermentation by the bacteria Clostridium saccharoperbutylacetonicum and ethanol production by the yeast Scheffersomyces stipitis increased by 24.0× and 2.4×, respectively, relative to the untreated hemicellulosic hydrolysates. Detoxified HH was analyzed by chromatographic and spectrometric methods elucidating the mechanisms of phenolic compound modifications by enzymatic treatment. The enzyme mixture degraded and reduced the hydroxyphenyl- and feruloyl-derived units and polymerized the lignin fragments. This strategy uses biocatalysts under environmentally friendly conditions and could be applied in the fuel, food, and chemical industries.


Assuntos
Clostridium/metabolismo , Peroxidase/química , Polissacarídeos/química , Saccharum/química , Superóxido Dismutase/química , Leveduras/metabolismo , Biocatálise , Butanóis/metabolismo , Celulose/química , Celulose/metabolismo , Fermentação , Microbiologia Industrial , Peroxidase/metabolismo , Polissacarídeos/metabolismo , Saccharum/microbiologia , Superóxido Dismutase/metabolismo
11.
World J Microbiol Biotechnol ; 36(3): 48, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152786

RESUMO

The search for gasoline substitutes has grown in recent decades, leading to the increased production of ethanol as viable alternative. However, research in recent years has shown that butanol exhibits various advantages over ethanol as a biofuel. Furthermore, butanol can also be used as a chemical platform, serving as an intermediate product and as a solvent in industrial reactions. This alcohol is naturally produced by some Clostridium species; however, Clostridial fermentation processes still have inherent problems, which focuses the interest on Saccharomyces cerevisiae for butanol production, as an alternative organism for the production of this alcohol. S. cerevisiae exhibits great adaptability to industrial conditions and can be modified with a wide range of genetic tools. Although S. cerevisiae is known to naturally produce isobutanol, the n-butanol synthesis pathway has not been well established in wild S. cerevisiae strains. Two strategies are most commonly used for of S. cerevisiae butanol production: the heterologous expression of the Clostridium pathway or the amino acid uptake pathways. However, butanol yields produced from S. cerevisiae are lower than ethanol yield. Thus, there are still many challenges needed to be overcome, which can be minimized through genetic and evolutive engineering, for butanol production by yeast to become a reality.


Assuntos
1-Butanol/metabolismo , Biocombustíveis , Proteínas Fúngicas/metabolismo , Saccharomyces cerevisiae/metabolismo , Vias Biossintéticas , Butanóis/metabolismo , Clostridium/metabolismo , Tolerância a Medicamentos , Etanol/metabolismo , Fermentação , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Microbiologia Industrial , Engenharia Metabólica , Saccharomyces cerevisiae/genética , Solventes
12.
J Ind Microbiol Biotechnol ; 47(3): 319-328, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32103460

RESUMO

Clostridium saccharoperbutylacetonicum N1-4 (Csa) is a historically significant anaerobic bacterium which can perform saccharolytic fermentations to produce acetone, butanol, and ethanol (ABE). Recent genomic analyses have highlighted this organism's potential to produce polyketide and nonribosomal peptide secondary metabolites, but little is known regarding the identity and function of these metabolites. This study provides a detailed bioinformatic analysis of seven biosynthetic gene clusters (BGCs) present in the Csa genome that are predicted to produce polyketides/nonribosomal peptides. An RNA-seq-based untargeted transcriptomic approach revealed that five of seven BGCs were expressed during ABE fermentation. Additional characterization of a highly expressed nonribosomal peptide synthetase gene led to the discovery of its associated metabolite and its biosynthetic pathway. Transcriptomic analysis suggested an association of this nonribosomal peptide synthetase gene with butanol tolerance, which was supported by butanol challenge assays.


Assuntos
Butanóis/metabolismo , Clostridium/metabolismo , Metabolismo Secundário , Acetona/metabolismo , Clostridium/genética , Etanol/metabolismo , Fermentação
13.
Biotechnol J ; 15(1): e1900284, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31475782

RESUMO

Clostridium has great potential in industrial application and medical research. But low DNA repair capacity and plasmids transformation efficiency severely delay development and application of genetic tools based on homologous recombination (HR). TargeTron is a gene editing technique dependent on the mobility of group II introns, rather than homologous recombination, which makes it very suitable for gene disruption of Clostridium. The application of TargeTron technology in solventogenic Clostridium is academically reported in 2007 and this tool has been introduced in various clostridia as it is easy to operate, time saving, and reliable. TargeTron has made great progress in solventogenic Clostridium in the aspects of acetone-butanol-ethanol (ABE) fermentation pathway modification, important functional genes identification, and xylose metabolic pathway analysis and reconstruction. In the review, 12 years' advances of TargeTron technology applicable in solventogenic Clostridium, including its principle, technical characteristics, application, and efforts to expand its capabilities, or to avoid potential drawbacks, are revisisted. Some other technologies as putative competitors or collaborators are also discussed. It is believed that TargeTron combined with CRISPR/Cas-assisted gene/base editing and gene-expression regulation system will make a better future for clostridial genetic modification.


Assuntos
Clostridium , Edição de Genes , Engenharia Metabólica/métodos , Solventes/metabolismo , Acetona/metabolismo , Butanóis/metabolismo , Sistemas CRISPR-Cas , Clostridium/genética , Clostridium/metabolismo , Fermentação/fisiologia
14.
N Biotechnol ; 55: 118-126, 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-31626983

RESUMO

A kinetic model of acetone-butanol-ethanol (ABE) fermentation taking into account butyric acid effects was developed and implemented in COPASI. The model was validated by comparing the simulation results with experimental data in batch cultures of Clostridium saccharoperbutylacetonicum under various concentrations of initial glucose (97.1 to 152.6 mM) and butyric acid (90.7 to 153.2 mM). The modeling results suggested that increasing the conversion rates from butyryl-CoA (BCoA) to butanol, from butyrate to BCoA, or from pyruvate to lactate would increase butanol synthesis. Similarly, reducing glucose uptake rate or the reaction rates from pyruvate to acetyl CoA (ACoA), from acetoacetyl CoA (AACoA) to BCoA, or from BCoA to butyrate would improve butanol production. Overall, the kinetic model developed can accurately predict the dynamic behavior of metabolites in ABE fermentation with butyric acid addition, which may subsequently be used to identify genetic manipulation strategies for higher bio-butanol production.


Assuntos
Butanóis/metabolismo , Ácido Butírico/metabolismo , Clostridium/metabolismo , Fermentação , Técnicas de Cultura Celular por Lotes , Simulação por Computador , Glucose/metabolismo , Cinética , Redes e Vias Metabólicas , Modelos Teóricos , Reprodutibilidade dos Testes , Fatores de Tempo
15.
Microb Pathog ; 139: 103805, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31790791

RESUMO

Studies on understanding the human microbiome continue to grow rapidly; nonetheless, reports on alterations in the microbiome post HIV infection are limited. Human microbiome is an aggregate of bacteria, fungi, viruses and archaea that have co-evolved with humans. These microbes have important roles in immune modulation, vitamin synthesis, metabolism etc. The human pharyngeal microbiome, which resides in the junction between digestive and respiratory tracts, might have a key role in the prevention of respiratory tract infections, akin to the actions of the intestinal microbiome against enteric infections. The respiratory tract is constantly exposed to various environmental and endogenous microbes; however, unlike other similar mucosal surfaces, there has been limited investigation of the microbiome of the respiratory tract. HIV infection is associated with alterations in the respiratory microbiome. The aim of this study was to use next-generation sequencing to determine the composition of the oropharyngeal microbiome in a HIV-positive individual. The bacterial composition was determined by illumina sequencing using MiSeq of partial 16S rRNA genes (V3-V4). A total of 3, 57,926 reads were analyzed. Overall, the genera Proteus, Enterococcus, Bacteroides, Prevotella and Clostridium were most prevalent bacterial populations in the oropharynx of an HIV positive patient.


Assuntos
Infecções por HIV/microbiologia , Microbiota , Orofaringe/microbiologia , Bacteroides/isolamento & purificação , Bacteroides/metabolismo , Clostridium/isolamento & purificação , Clostridium/metabolismo , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Enterococcus/isolamento & purificação , Enterococcus/metabolismo , Microbioma Gastrointestinal , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Micrococcus/isolamento & purificação , Micrococcus/metabolismo , Faringe/microbiologia , Filogenia , Prevotella/isolamento & purificação , Prevotella/metabolismo , Proteus/isolamento & purificação , Proteus/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Sistema Respiratório/metabolismo , Sistema Respiratório/microbiologia , Infecções Respiratórias/microbiologia , Análise de Sequência de DNA
16.
J Clin Invest ; 130(1): 438-450, 2020 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-31815740

RESUMO

An excess of fecal bile acids (BAs) is thought to be one of the mechanisms for diarrhea-predominant irritable bowel syndrome (IBS-D). However, the factors causing excessive BA excretion remain incompletely studied. Given the importance of gut microbiota in BA metabolism, we hypothesized that gut dysbiosis might contribute to excessive BA excretion in IBS-D. By performing BA-related metabolic and metagenomic analyses in 290 IBS-D patients and 89 healthy volunteers, we found that 24.5% of IBS-D patients exhibited excessive excretion of total BAs and alteration of BA-transforming bacteria in feces. Notably, the increase in Clostridia bacteria (e.g., C. scindens) was positively associated with the levels of fecal BAs and serum 7α-hydroxy-4-cholesten-3-one (C4), but negatively correlated with serum fibroblast growth factor 19 (FGF19) concentration. Furthermore, colonization with Clostridia-rich IBS-D fecal microbiota or C. scindens individually enhanced serum C4 and hepatic conjugated BAs but reduced ileal FGF19 expression in mice. Inhibition of Clostridium species with vancomycin yielded opposite results. Clostridia-derived BAs suppressed the intestinal FGF19 expression in vitro and in vivo. In conclusion, this study demonstrates that the Clostridia-rich microbiota contributes to excessive BA excretion in IBS-D patients, which provides a mechanistic hypothesis with testable clinical implications.


Assuntos
Ácidos e Sais Biliares/metabolismo , Clostridium/metabolismo , Diarreia , Microbioma Gastrointestinal , Síndrome do Intestino Irritável , Adolescente , Adulto , Idoso , Diarreia/metabolismo , Diarreia/microbiologia , Diarreia/patologia , Feminino , Humanos , Síndrome do Intestino Irritável/metabolismo , Síndrome do Intestino Irritável/microbiologia , Síndrome do Intestino Irritável/patologia , Masculino , Pessoa de Meia-Idade
17.
Science ; 366(6471)2019 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-31831639

RESUMO

The gut microbiota produce hundreds of molecules that are present at high concentrations in the host circulation. Unraveling the contribution of each molecule to host biology remains difficult. We developed a system for constructing clean deletions in Clostridium spp., the source of many molecules from the gut microbiome. By applying this method to the model commensal organism Clostridium sporogenes, we knocked out genes for 10 C. sporogenes-derived molecules that accumulate in host tissues. In mice colonized by a C. sporogenes for which the production of branched short-chain fatty acids was knocked out, we discovered that these microbial products have immunoglobulin A-modulatory activity.


Assuntos
Clostridium/genética , Clostridium/metabolismo , Microbioma Gastrointestinal/genética , Edição de Genes/métodos , Interações entre Hospedeiro e Microrganismos , Redes e Vias Metabólicas/genética , Animais , Proteína 9 Associada à CRISPR , Sistemas CRISPR-Cas , Deleção de Genes , Camundongos , Camundongos Endogâmicos
18.
Sci Rep ; 9(1): 14339, 2019 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-31586093

RESUMO

The biorecovery of europium (Eu) from primary (mineral deposits) and secondary (mining wastes) resources is of interest due to its remarkable luminescence properties, important for modern technological applications. In this study, we explored the tolerance levels, reduction and intracellular bioaccumulation of Eu by a site-specific bacterium, Clostridium sp. 2611 isolated from Phalaborwa carbonatite complex. Clostridium sp. 2611 was able to grow in minimal medium containing 0.5 mM Eu3+. SEM-EDX analysis confirmed an association between Eu precipitates and the bacterium, while TEM-EDX analysis indicated intracellular accumulation of Eu. According to the HR-XPS analysis, the bacterium was able to reduce Eu3+ to Eu2+ under growth and non-growth conditions. Preliminary protein characterization seems to indicate that a cytoplasmic pyruvate oxidoreductase is responsible for Eu bioreduction. These findings suggest the bioreduction of Eu3+ by Clostridium sp. as a resistance mechanism, can be exploited for the biorecovery of this metal.


Assuntos
Bioacumulação , Clostridium/metabolismo , Európio/metabolismo , Microbiologia do Solo , Anaerobiose , Clostridium/química , Clostridium/isolamento & purificação , Európio/química , Microbiologia Industrial , Mineração , Oxirredução , Solo/química
19.
Molecules ; 24(19)2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31561523

RESUMO

A convenient and effective sucrose transport assay for Clostridium strains is needed. Traditional methods, such as 14C-sucrose isotope labelling, use radioactive materials and are not convenient for many laboratories. Here, a sucrose transporter from potato was introduced into Clostridium, and a fluorescence assay based on esculin was used for the analysis of sucrose transport in Clostridium strains. This showed that the heterologously expressed potato sucrose transporter is functional in Clostridium. Recombinant engineering of high-level sucrose transport would aid sucrose fermentation in Clostridium strains. The assay described herein provides an important technological platform for studying sucrose transporter function following heterologous expression in Clostridium.


Assuntos
Bioensaio , Clostridium/genética , Clostridium/metabolismo , Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Proteínas de Plantas/genética , Solanum tuberosum/metabolismo , Sacarose/metabolismo , Transporte Biológico , Fluorescência , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Plantas/metabolismo
20.
Bioresour Technol ; 291: 121848, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31377513

RESUMO

Butyrate is an important precursor for fine chemicals and biofuels. The aim of this study is to investigate butyrate production as affected by transition metal addition of food waste fermentation including, nickel, Raney nickel and copper particles. Performance of fermentation showed nickel particles achieved the highest butyrate concentration, 7.3 g/L, which was 38.5% higher than that in the control trial. Raney nickel also showed similar effect on the enhancement of butyrate production. However, increased dosage of transition metal particle addition led to decreased butyrate production. The theoretical link between metal-assisted dark fermentation and butyrate production was tentatively explored. Redox potential affected by nickel addition was assumed to be an essential factor for butyrate production. Microbial community analysis found Clostridium sensu stricto 11 may be the dominant functional species for butyrate production. The study demonstrates that development on transition metal catalyst may contribute to waste biorefinery for added value products/energy production.


Assuntos
Butiratos/metabolismo , Fermentação , Alimentos , Elementos de Transição/farmacologia , Clostridium/metabolismo , Fermentação/efeitos dos fármacos , Microbiota
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