Faculty & Staff

  • Image of Federico E. Rey

    Federico E. Rey

    Assistant Professor of Bacteriology

    5157 Microbial Sciences Building
    Office: 608-890-2046
    Lab: 608-890-2366
    Google Scholar

Start and Promotion Dates

  • Assistant Professor: 2013


1998 Licenciado en Bioquimica (equivalent to B.S. and M.S. in Clinical Chemistry). Facultad de Ciencias Quimicas. Universidad Nacional de Cordoba, Cordoba, Argentina. 2006 Ph.D. Microbiology.

University of Iowa Postdoctoral Research: Center for Genome Sciences and Systems Biology, Washington University

Areas of Study

Gut bacterial metabolism and human health
microbial cross-feeding

Research Overview

Humans harbor large microbial communities in the gastrointestinal tract. This collection of microbes (microbiota) and their associated genes (microbiome) affect many aspects of our physiology. Host diet determines gut microbial metabolism, which in turn modifies the nutritional impact of many dietary components. Thus, in principle, the gut microbiota can be targeted through diet to promote health. However, to successfully manipulate this microbial bioreactor, we need to understand how microbes metabolize nutrients, how they interact with each other as a function of diet, and their impact on the host. The overall goal of our research is to dissect diet by microbiota interactions that impact human health, so that therapeutic/preventive dietary recommendations can be made based on the metabolic potential of a subject’s microbiome.

Gut microbial metabolism of specific dietary components (e.g., choline, flavonoids) generates compounds that can impact cardiovascular diseases. The microbes responsible for such transformations, and their representation in humans remain poorly characterized. Projects in my lab aim at identifying human gut bacterial species that transform some of these compounds, the genes involved in these processes, their regulation and their impact in the development of cardiovascular disease. Towards this end, we are using gnotobiotic mouse models of cardiovascular disease, bacterial genetics, transcriptional profiling and metabolomics.

Lab Personnel

Picture of Cross
Tzu-Wen Cross
Picture of Kasahara
Kazu Kasahara
Picture of Kemis
Julia Kemis
Grad Student
Picture of Kerby
Bob Kerby
Senior Scientist
Picture of Traeger
Lindsay Traeger
Picture of Vivas
Nacho Vivas
Sr Research Specialist
Lab Manager
Picture of Zarbock
Katie Zarbock
Grad Student
Picture of Zhang
Qijun Zhang
Grad Student

Research Papers

  • Cross TL, Kasahara K, Rey FE (2018) Sexual dimorphism of cardiometabolic dysfunction: Gut microbiome in the play? Mol Metab : 10.1016/j.molmet.2018.05.016 · Pubmed

    Sex is one of the most powerful modifiers of disease development. Clear sexual dimorphism exists in cardiometabolic health susceptibility, likely due to differences in sex steroid hormones. Changes in the gut microbiome have been linked with the development of obesity, type 2 diabetes, and atherosclerosis; however, the impact of microbes in sex-biased cardiometabolic disorders remains unclear. The gut microbiome is critical for maintaining a normal estrous cycle, testosterone levels, and reproductive function. Gut microbes modulate the enterohepatic recirculation of estrogens and androgens, affecting local and systemic levels of sex steroid hormones. Gut bacteria can also generate androgens from glucocorticoids. This review summarizes current knowledge of the complex interplay between sexual dimorphism in cardiometabolic disease and the gut microbiome. Emerging evidence suggests the role of gut microbiome as a modifier of disease susceptibility due to sex; however, the impact on cardiometabolic disease in this complex interplay is lacking. Elucidating the role of gut microbiome on sex-biased susceptibility in cardiometabolic disease is of high relevance to public health given its high prevalence and significant financial burden.

  • Yang H, Wang W, Romano KA, Gu M, Sanidad KZ, Kim D, Yang J, Schmidt B, Panigrahy D, Pei R, Martin DA, Ozay EI, Wang Y, Song M, Bolling BW, Xiao H, Minter LM, Yang GY, Liu Z, Rey FE, Zhang G (2018) A common antimicrobial additive increases colonic inflammation and colitis-associated colon tumorigenesis in mice. Sci Transl Med 10(443): 10.1126/scitranslmed.aan4116 · Pubmed

    Triclosan (TCS) is a high-volume chemical used as an antimicrobial ingredient in more than 2000 consumer products, such as toothpaste, cosmetics, kitchenware, and toys. We report that brief exposure to TCS, at relatively low doses, causes low-grade colonic inflammation, increases colitis, and exacerbates colitis-associated colon cancer in mice. Exposure to TCS alters gut microbiota in mice, and its proinflammatory effect is attenuated in germ-free mice. In addition, TCS treatment increases activation of Toll-like receptor 4 (TLR4) signaling in vivo and fails to promote colitis in mice. Together, our results demonstrate that this widely used antimicrobial ingredient could have adverse effects on colonic inflammation and associated colon tumorigenesis through modulation of the gut microbiota and TLR4 signaling. Together, these results highlight the need to reassess the effects of TCS on human health and potentially update policies regulating the use of this widely used antimicrobial.

  • Romano KA, Dill-McFarland KA, Kasahara K, Kerby RL, Vivas EI, Amador-Noguez D, Herd P, Rey FE (2018) Fecal Aliquot Straw Technique (FAST) allows for easy and reproducible subsampling: assessing interpersonal variation in trimethylamine-N-oxide (TMAO) accumulation. Microbiome 6(1):91 (PMC5960144) 10.1186/s40168-018-0458-8 · Pubmed

    Convenient, reproducible, and rapid preservation of unique biological specimens is pivotal to their use in microbiome analyses. As an increasing number of human studies incorporate the gut microbiome in their design, there is a high demand for streamlined sample collection and storage methods that are amenable to different settings and experimental needs. While several commercial kits address collection/shipping needs for sequence-based studies, these methods do not preserve samples properly for studies that require viable microbes. We describe the Fecal Aliquot Straw Technique (FAST) of fecal sample processing for storage and subsampling. This method uses a straw to collect fecal material from samples recently voided or preserved at low temperature but not frozen (i.e., 4 °C). Different straw aliquots collected from the same sample yielded highly reproducible communities as disclosed by 16S rRNA gene sequencing; operational taxonomic units that were lost, or gained, between the two aliquots represented very low-abundance taxa (i.e., < 0.3% of the community). FAST-processed samples inoculated into germ-free animals resulted in gut communities that retained on average ~ 80% of the donor's bacterial community. Assessment of choline metabolism and trimethylamine-N-oxide accumulation in transplanted mice suggests large interpersonal variation. Overall, FAST allows for repetitive subsampling without thawing of the specimens and requires minimal supplies and storage space, making it convenient to utilize both in the lab and in the field. FAST has the potential to advance microbiome research through easy, reproducible sample processing.

  • Li XS, Wang Z, Cajka T, Buffa JA, Nemet I, Hurd AG, Gu X, Skye SM, Roberts AB, Wu Y, Li L, Shahen CJ, Wagner MA, Hartiala JA, Kerby RL, Romano KA, Han Y, Obeid S, Lüscher TF, Allayee H, Rey FE, DiDonato JA, Fiehn O, Tang WHW, Hazen SL (2018) Untargeted metabolomics identifies trimethyllysine, a TMAO-producing nutrient precursor, as a predictor of incident cardiovascular disease risk. JCI Insight 3(6): (PMC5926943) 10.1172/jci.insight.99096 · Pubmed

    Using an untargeted metabolomics approach in initial (N = 99 subjects) and replication cohorts (N = 1,162), we discovered and structurally identified a plasma metabolite associated with cardiovascular disease (CVD) risks, N6,N6,N6-trimethyl-L-lysine (trimethyllysine, TML). Stable-isotope-dilution tandem mass spectrometry analyses of an independent validation cohort (N = 2,140) confirmed TML levels are independently associated with incident (3-year) major adverse cardiovascular event risks (hazards ratio [HR], 2.4; 95% CI, 1.7-3.4) and incident (5-year) mortality risk (HR, 2.9; 95% CI, 2.0-4.2). Genome-wide association studies identified several suggestive loci for TML levels, but none reached genome-wide significance; and d9(trimethyl)-TML isotope tracer studies confirmed TML can serve as a nutrient precursor for gut microbiota-dependent generation of trimethylamine (TMA) and the atherogenic metabolite trimethylamine N-oxide (TMAO). Although TML was shown to be abundant in both plant- and animal-derived foods, mouse and human fecal cultures (omnivores and vegans) showed slow conversion of TML to TMA. Furthermore, unlike chronic dietary choline, TML supplementation in mice failed to elevate plasma TMAO or heighten thrombosis potential in vivo. Thus, TML is identified as a strong predictor of incident CVD risks in subjects and to serve as a dietary precursor for gut microbiota-dependent generation of TMAO; however, TML does not appear to be a major microbial source for TMAO generation in vivo.

  • Vogt NM, Kerby RL, Dill-McFarland KA, Harding SJ, Merluzzi AP, Johnson SC, Carlsson CM, Asthana S, Zetterberg H, Blennow K, Bendlin BB, Rey FE (2017) Gut microbiome alterations in Alzheimer's disease. Sci Rep 7(1):13537 (PMC5648830) 10.1038/s41598-017-13601-y · Pubmed

    Alzheimer's disease (AD) is the most common form of dementia. However, the etiopathogenesis of this devastating disease is not fully understood. Recent studies in rodents suggest that alterations in the gut microbiome may contribute to amyloid deposition, yet the microbial communities associated with AD have not been characterized in humans. Towards this end, we characterized the bacterial taxonomic composition of fecal samples from participants with and without a diagnosis of dementia due to AD. Our analyses revealed that the gut microbiome of AD participants has decreased microbial diversity and is compositionally distinct from control age- and sex-matched individuals. We identified phylum- through genus-wide differences in bacterial abundance including decreased Firmicutes, increased Bacteroidetes, and decreased Bifidobacterium in the microbiome of AD participants. Furthermore, we observed correlations between levels of differentially abundant genera and cerebrospinal fluid (CSF) biomarkers of AD. These findings add AD to the growing list of diseases associated with gut microbial alterations, as well as suggest that gut bacterial communities may be a target for therapeutic intervention.

  • Romano KA, Martinez-Del Campo A, Kasahara K, Chittim CL, Vivas EI, Amador-Noguez D, Balskus EP, Rey FE (2017) Metabolic, Epigenetic, and Transgenerational Effects of Gut Bacterial Choline Consumption. Cell Host Microbe 22(3):279-290.e7 (PMC5599363) 10.1016/j.chom.2017.07.021 · Pubmed

    Choline is an essential nutrient and methyl donor required for epigenetic regulation. Here, we assessed the impact of gut microbial choline metabolism on bacterial fitness and host biology by engineering a microbial community that lacks a single choline-utilizing enzyme. Our results indicate that choline-utilizing bacteria compete with the host for this nutrient, significantly impacting plasma and hepatic levels of methyl-donor metabolites and recapitulating biochemical signatures of choline deficiency. Mice harboring high levels of choline-consuming bacteria showed increased susceptibility to metabolic disease in the context of a high-fat diet. Furthermore, bacterially induced reduction of methyl-donor availability influenced global DNA methylation patterns in both adult mice and their offspring and engendered behavioral alterations. Our results reveal an underappreciated effect of bacterial choline metabolism on host metabolism, epigenetics, and behavior. This work suggests that interpersonal differences in microbial metabolism should be considered when determining optimal nutrient intake requirements.

  • Krautkramer KA, Rey FE, Denu JM (2017) Chemical signaling between gut microbiota and host chromatin: What is your gut really saying? J. Biol. Chem. 292(21):8582-8593 (PMC5448088) 10.1074/jbc.R116.761577 · Pubmed

    Mammals and their gut microbial communities share extensive and tightly coordinated co-metabolism of dietary substrates. A large number of microbial metabolites have been detected in host circulation and tissues and, in many cases, are linked to host metabolic, developmental, and immunological states. The presence of these metabolites in host tissues intersects with regulation of the host's epigenetic machinery. Although it is established that the host's epigenetic machinery is sensitive to levels of endogenous metabolites, the roles for microbial metabolites in epigenetic regulation are just beginning to be elucidated. This review focuses on eukaryotic chromatin regulation by endogenous and gut microbial metabolites and how these regulatory events may impact host developmental and metabolic phenotypes.

  • Kreznar JH, Keller MP, Traeger LL, Rabaglia ME, Schueler KL, Stapleton DS, Zhao W, Vivas EI, Yandell BS, Broman AT, Hagenbuch B, Attie AD, Rey FE (2017) Host Genotype and Gut Microbiome Modulate Insulin Secretion and Diet-Induced Metabolic Phenotypes. Cell Rep 18(7):1739-1750 (PMC5325228) 10.1016/j.celrep.2017.01.062 · Pubmed

    Genetic variation drives phenotypic diversity and influences the predisposition to metabolic disease. Here, we characterize the metabolic phenotypes of eight genetically distinct inbred mouse strains in response to a high-fat/high-sucrose diet. We found significant variation in diabetes-related phenotypes and gut microbiota composition among the different mouse strains in response to the dietary challenge and identified taxa associated with these traits. Follow-up microbiota transplant experiments showed that altering the composition of the gut microbiota modifies strain-specific susceptibility to diet-induced metabolic disease. Animals harboring microbial communities with enhanced capacity for processing dietary sugars and for generating hydrophobic bile acids showed increased susceptibility to metabolic disease. Notably, differences in glucose-stimulated insulin secretion between different mouse strains were partially recapitulated via gut microbiota transfer. Our results suggest that the gut microbiome contributes to the genetic and phenotypic diversity observed among mouse strains and provide a link between the gut microbiome and insulin secretion.

  • Krautkramer KA, Kreznar JH, Romano KA, Vivas EI, Barrett-Wilt GA, Rabaglia ME, Keller MP, Attie AD, Rey FE, Denu JM (2016) Diet-Microbiota Interactions Mediate Global Epigenetic Programming in Multiple Host Tissues. Mol. Cell 64(5):982-992 (PMC5227652) · Pubmed

    Histone-modifying enzymes regulate transcription and are sensitive to availability of endogenous small-molecule metabolites, allowing chromatin to respond to changes in environment. The gut microbiota produces a myriad of metabolites that affect host physiology and susceptibility to disease; however, the underlying molecular events remain largely unknown. Here we demonstrate that microbial colonization regulates global histone acetylation and methylation in multiple host tissues in a diet-dependent manner: consumption of a "Western-type" diet prevents many of the microbiota-dependent chromatin changes that occur in a polysaccharide-rich diet. Finally, we demonstrate that supplementation of germ-free mice with short-chain fatty acids, major products of gut bacterial fermentation, is sufficient to recapitulate chromatin modification states and transcriptional responses associated with colonization. These findings have profound implications for understanding the complex functional interactions between diet, gut microbiota, and host health.

  • Martínez-Del Campo A, Romano KA, Rey FE, Balskus EP (2016) The Plot Thickens: Diet Microbe Interactions May Modulate Thrombosis Risk. Cell Metab. 23(4):573-5 · Pubmed

    Thrombosis plays an important role in cardiovascular disease (CVD). Platelet activation is an essential step in the genesis and propagation of atherothrombotic complications. In a recent publication, Zhu and colleagues report that gut microbe-derived TMAO enhances platelet responsiveness and thrombosis, providing a novel mechanistic connection between microbes and CVD (Zhu et al., 2016).

  • Romano KA, Vivas EI, Amador-Noguez D, Rey FE (2015) Intestinal microbiota composition modulates choline bioavailability from diet and accumulation of the proatherogenic metabolite trimethylamine-N-oxide. MBio 6(2):e02481 (PMC4453578) · Pubmed

    Choline is a water-soluble nutrient essential for human life. Gut microbial metabolism of choline results in the production of trimethylamine (TMA), which upon absorption by the host is converted in the liver to trimethylamine-N-oxide (TMAO). Recent studies revealed that TMAO exacerbates atherosclerosis in mice and positively correlates with the severity of this disease in humans. However, which microbes contribute to TMA production in the human gut, the extent to which host factors (e.g., genotype) and diet affect TMA production and colonization of these microbes, and the effects TMA-producing microbes have on the bioavailability of dietary choline remain largely unknown. We screened a collection of 79 sequenced human intestinal isolates encompassing the major phyla found in the human gut and identified nine strains capable of producing TMA from choline in vitro. Gnotobiotic mouse studies showed that TMAO accumulates in the serum of animals colonized with TMA-producing species, but not in the serum of animals colonized with intestinal isolates that do not generate TMA from choline in vitro. Remarkably, low levels of colonization by TMA-producing bacteria significantly reduced choline levels available to the host. This effect was more pronounced as the abundance of TMA-producing bacteria increased. Our findings provide a framework for designing strategies aimed at changing the representation or activity of TMA-producing bacteria in the human gut and suggest that the TMA-producing status of the gut microbiota should be considered when making recommendations about choline intake requirements for humans. Cardiovascular disease (CVD) is the leading cause of death and disability worldwide, and increased trimethylamine N-oxide (TMAO) levels have been causally linked with CVD development. This work identifies members of the human gut microbiota responsible for both the accumulation of trimethylamine (TMA), the precursor of the proatherogenic compound TMAO, and subsequent decreased choline bioavailability to the host. Understanding how to manipulate the representation and function of choline-consuming, TMA-producing species in the intestinal microbiota could potentially lead to novel means for preventing or treating atherosclerosis and choline deficiency-associated diseases.

  • Seedorf H, Griffin NW, Ridaura VK, Reyes A, Cheng J, Rey FE, Smith MI, Simon GM, Scheffrahn RH, Woebken D, Spormann AM, Van Treuren W, Ursell LK, Pirrung M, Robbins-Pianka A, Cantarel BL, Lombard V, Henrissat B, Knight R, Gordon JI (2014) Bacteria from diverse habitats colonize and compete in the mouse gut. Cell 159(2):253-66 (PMC4194163) · Pubmed

    To study how microbes establish themselves in a mammalian gut environment, we colonized germ-free mice with microbial communities from human, zebrafish, and termite guts, human skin and tongue, soil, and estuarine microbial mats. Bacteria from these foreign environments colonized and persisted in the mouse gut; their capacity to metabolize dietary and host carbohydrates and bile acids correlated with colonization success. Cohousing mice harboring these xenomicrobiota or a mouse cecal microbiota, along with germ-free "bystanders," revealed the success of particular bacterial taxa in invading guts with established communities and empty gut habitats. Unanticipated patterns of ecological succession were observed; for example, a soil-derived bacterium dominated even in the presence of bacteria from other gut communities (zebrafish and termite), and human-derived bacteria colonized germ-free bystander mice before mouse-derived organisms. This approach can be generalized to address a variety of mechanistic questions about succession, including succession in the context of microbiota-directed therapeutics.

  • Ridaura VK, Faith JJ, Rey FE, Cheng J, Duncan AE, Kau AL, Griffin NW, Lombard V, Henrissat B, Bain JR, Muehlbauer MJ, Ilkayeva O, Semenkovich CF, Funai K, Hayashi DK, Lyle BJ, Martini MC, Ursell LK, Clemente JC, Van Treuren W, Walters WA, Knight R, Newgard CB, Heath AC, Gordon JI (2013) Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science 341(6150):1241214 (PMC3829625) · Pubmed

    The role of specific gut microbes in shaping body composition remains unclear. We transplanted fecal microbiota from adult female twin pairs discordant for obesity into germ-free mice fed low-fat mouse chow, as well as diets representing different levels of saturated fat and fruit and vegetable consumption typical of the U.S. diet. Increased total body and fat mass, as well as obesity-associated metabolic phenotypes, were transmissible with uncultured fecal communities and with their corresponding fecal bacterial culture collections. Cohousing mice harboring an obese twin's microbiota (Ob) with mice containing the lean co-twin's microbiota (Ln) prevented the development of increased body mass and obesity-associated metabolic phenotypes in Ob cage mates. Rescue correlated with invasion of specific members of Bacteroidetes from the Ln microbiota into Ob microbiota and was diet-dependent. These findings reveal transmissible, rapid, and modifiable effects of diet-by-microbiota interactions.

  • Rey FE, Gonzalez MD, Cheng J, Wu M, Ahern PP, Gordon JI (2013) Metabolic niche of a prominent sulfate-reducing human gut bacterium. Proc. Natl. Acad. Sci. U.S.A. 110(33):13582-7 (PMC3746858) · Pubmed

    Sulfate-reducing bacteria (SRB) colonize the guts of ∼50% of humans. We used genome-wide transposon mutagenesis and insertion-site sequencing, RNA-Seq, plus mass spectrometry to characterize genetic and environmental factors that impact the niche of Desulfovibrio piger, the most common SRB in a surveyed cohort of healthy US adults. Gnotobiotic mice were colonized with an assemblage of sequenced human gut bacterial species with or without D. piger and fed diets with different levels and types of carbohydrates and sulfur sources. Diet was a major determinant of functions expressed by this artificial nine-member community and of the genes that impact D. piger fitness; the latter includes high- and low-affinity systems for using ammonia, a limiting resource for D. piger in mice consuming a polysaccharide-rich diet. Although genes involved in hydrogen consumption and sulfate reduction are necessary for its colonization, varying dietary-free sulfate levels did not significantly alter levels of D. piger, which can obtain sulfate from the host in part via cross-feeding mediated by Bacteroides-encoded sulfatases. Chondroitin sulfate, a common dietary supplement, increased D. piger and H2S levels without compromising gut barrier integrity. A chondroitin sulfate-supplemented diet together with D. piger impacted the assemblage's substrate utilization preferences, allowing consumption of more reduced carbon sources and increasing the abundance of the H2-producing Actinobacterium, Collinsella aerofaciens. Our findings provide genetic and metabolic details of how this H2-consuming SRB shapes the responses of a microbiota to diet ingredients and a framework for examining how individuals lacking D. piger differ from those who harbor it.

  • Yatsunenko T, Rey FE, Manary MJ, Trehan I, Dominguez-Bello MG, Contreras M, Magris M, Hidalgo G, Baldassano RN, Anokhin AP, Heath AC, Warner B, Reeder J, Kuczynski J, Caporaso JG, Lozupone CA, Lauber C, Clemente JC, Knights D, Knight R, Gordon JI (2012) Human gut microbiome viewed across age and geography. Nature 486(7402):222-7 (PMC3376388) · Pubmed

    Gut microbial communities represent one source of human genetic and metabolic diversity. To examine how gut microbiomes differ among human populations, here we characterize bacterial species in fecal samples from 531 individuals, plus the gene content of 110 of them. The cohort encompassed healthy children and adults from the Amazonas of Venezuela, rural Malawi and US metropolitan areas and included mono- and dizygotic twins. Shared features of the functional maturation of the gut microbiome were identified during the first three years of life in all three populations, including age-associated changes in the genes involved in vitamin biosynthesis and metabolism. Pronounced differences in bacterial assemblages and functional gene repertoires were noted between US residents and those in the other two countries. These distinctive features are evident in early infancy as well as adulthood. Our findings underscore the need to consider the microbiome when evaluating human development, nutritional needs, physiological variations and the impact of westernization.

  • Wei X, Yang Z, Rey FE, Ridaura VK, Davidson NO, Gordon JI, Semenkovich CF (2012) Fatty acid synthase modulates intestinal barrier function through palmitoylation of mucin 2. Cell Host Microbe 11(2):140-52 (PMC3285413) · Pubmed

    No abstract available.

  • Faith JJ, McNulty NP, Rey FE, Gordon JI (2011) Predicting a human gut microbiota's response to diet in gnotobiotic mice. Science 333(6038):101-4 (PMC3303606) · Pubmed

    The interrelationships between our diets and the structure and operations of our gut microbial communities are poorly understood. A model community of 10 sequenced human gut bacteria was introduced into gnotobiotic mice, and changes in species abundance and microbial gene expression were measured in response to randomized perturbations of four defined ingredients in the host diet. From the responses, we developed a statistical model that predicted over 60% of the variation in species abundance evoked by diet perturbations, and we were able to identify which factors in the diet best explained changes seen for each community member. The approach is generally applicable, as shown by a follow-up study involving diets containing various mixtures of pureed human baby foods.

  • Hansen EE, Lozupone CA, Rey FE, Wu M, Guruge JL, Narra A, Goodfellow J, Zaneveld JR, McDonald DT, Goodrich JA, Heath AC, Knight R, Gordon JI (2011) Pan-genome of the dominant human gut-associated archaeon, Methanobrevibacter smithii, studied in twins. Proc. Natl. Acad. Sci. U.S.A. 108 Suppl :4599-606 (PMC3063581) · Pubmed

    The human gut microbiota harbors three main groups of H(2)-consuming microbes: methanogens including the dominant archaeon, Methanobrevibacter smithii, a polyphyletic group of acetogens, and sulfate-reducing bacteria. Defining their roles in the gut is important for understanding how hydrogen metabolism affects the efficiency of fermentation of dietary components. We quantified methanogens in fecal samples from 40 healthy adult female monozygotic (MZ) and 28 dizygotic (DZ) twin pairs, analyzed bacterial 16S rRNA datasets generated from their fecal samples to identify taxa that co-occur with methanogens, sequenced the genomes of 20 M. smithii strains isolated from families of MZ and DZ twins, and performed RNA-Seq of a subset of strains to identify their responses to varied formate concentrations. The concordance rate for methanogen carriage was significantly higher for MZ versus DZ twin pairs. Co-occurrence analysis revealed 22 bacterial species-level taxa positively correlated with methanogens: all but two were members of the Clostridiales, with several being, or related to, known hydrogen-producing and -consuming bacteria. The M. smithii pan-genome contains 987 genes conserved in all strains, and 1,860 variably represented genes. Strains from MZ and DZ twin pairs had a similar degree of shared genes and SNPs, and were significantly more similar than strains isolated from mothers or members of other families. The 101 adhesin-like proteins (ALPs) in the pan-genome (45 ± 6 per strain) exhibit strain-specific differences in expression and responsiveness to formate. We hypothesize that M. smithii strains use their different repertoires of ALPs to create diversity in their metabolic niches, by allowing them to establish syntrophic relationships with bacterial partners with differing metabolic capabilities and patterns of co-occurrence.

  • Faith JJ, Rey FE, O'Donnell D, Karlsson M, McNulty NP, Kallstrom G, Goodman AL, Gordon JI (2010) Creating and characterizing communities of human gut microbes in gnotobiotic mice. ISME J 4(9):1094-8 (PMC2927777) · Pubmed

    No abstract available.

  • Rey FE, Faith JJ, Bain J, Muehlbauer MJ, Stevens RD, Newgard CB, Gordon JI (2010) Dissecting the in vivo metabolic potential of two human gut acetogens. J. Biol. Chem. 285(29):22082-90 (PMC2903421) · Pubmed

    Fermenting microbial communities generate hydrogen; its removal through the production of acetate, methane, or hydrogen sulfide modulates the efficiency of energy extraction from available nutrients in many ecosystems. We noted that pathway components for acetogenesis are more abundantly and consistently represented in the gut microbiomes of monozygotic twins and their mothers than components for methanogenesis or sulfate reduction and subsequently analyzed the metabolic potential of two sequenced human gut acetogens, Blautia hydrogenotrophica and Marvinbryantia formatexigens in vitro and in the intestines of gnotobiotic mice harboring a prominent saccharolytic bacterium. To do so, we developed a generally applicable method for multiplex sequencing of expressed microbial mRNAs (microbial RNA-Seq) and, together with mass spectrometry of metabolites, showed that these organisms have distinct patterns of substrate utilization. B. hydrogenotrophica targets aliphatic and aromatic amino acids. It increases the efficiency of fermentation by consuming reducing equivalents, thereby maintaining a high NAD(+)/NADH ratio and boosting acetate production. In contrast, M. formatexigens consumes oligosaccharides, does not impact the redox state of the gut, and boosts the yield of succinate. These findings have strategic implications for those who wish to manipulate the hydrogen economy of gut microbial communities in ways that modulate energy harvest.

  • Rey FE, Harwood CS (2010) FixK, a global regulator of microaerobic growth, controls photosynthesis in Rhodopseudomonas palustris. Mol. Microbiol. 75(4):1007-20 · Pubmed

    Purple non-sulphur phototrophic bacteria (PNSB) are excellent models for analysing the co-ordination of major metabolisms, including oxidative phosphorylation, photophosphorylation, carbon dioxide fixation and nitrogen fixation. In species studied to date, a two-component system called RegBA controls these functions and it has been thought that this redox sensing regulatory system is essential for co-ordinating electron flow and cannot be easily replaced. Here we show that this is not the case for all PNSB and that the oxygen-sensing FixLJ-K system, initially described in rhizobia, controls microaerobic respiration, photophosphorylation and other major metabolic traits in Rhodopseudomonas palustris. A R. palustris fixK mutant grew normally aerobically but was impaired in microaerobic growth. It was also severely impaired in photosynthetic growth. Transcriptome analyses indicated that FixK positively regulates haem and bacteriochlorophyll biosynthesis, cbb3 oxidase and NADH dehydrogenase genes, as well as genes for autotrophy and aromatic compound degradation. Purified FixK interacted with the promoters of a bacteriochlorophyll biosynthesis operon, a bacteriophytochrome-histidine kinase gene and the fnr-type regulatory gene, aadR. A FixK-AadR hierarchy mediates the transition from microaerobic to anaerobic growth. These results underscore that physiologically similar bacteria can use very different regulatory strategies to control common major metabolisms.

  • Rey FE, Harwood CS (2010) FixK, a global regulator of microaerobic growth, controls photosynthesis in Rhodopseudomonas palustris. Mol. Microbiol. : · Pubmed

    No abstract available.

  • Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI (2009) The effect of diet on the human gut microbiome: a metagenomic analysis in humanized gnotobiotic mice. Sci Transl Med 1(6):6ra14 (PMC2894525) · Pubmed

    Diet and nutritional status are among the most important modifiable determinants of human health. The nutritional value of food is influenced in part by a person's gut microbial community (microbiota) and its component genes (microbiome). Unraveling the interrelations among diet, the structure and operations of the gut microbiota, and nutrient and energy harvest is confounded by variations in human environmental exposures, microbial ecology, and genotype. To help overcome these problems, we created a well-defined, representative animal model of the human gut ecosystem by transplanting fresh or frozen adult human fecal microbial communities into germ-free C57BL/6J mice. Culture-independent metagenomic analysis of the temporal, spatial, and intergenerational patterns of bacterial colonization showed that these humanized mice were stably and heritably colonized and reproduced much of the bacterial diversity of the donor's microbiota. Switching from a low-fat, plant polysaccharide-rich diet to a high-fat, high-sugar "Western" diet shifted the structure of the microbiota within a single day, changed the representation of metabolic pathways in the microbiome, and altered microbiome gene expression. Reciprocal transplants involving various combinations of donor and recipient diets revealed that colonization history influences the initial structure of the microbial community but that these effects can be rapidly altered by diet. Humanized mice fed the Western diet have increased adiposity; this trait is transmissible via microbiota transplantation. Humanized gnotobiotic mice will be useful for conducting proof-of-principle "clinical trials" that test the effects of environmental and genetic factors on the gut microbiota and host physiology. Nearly full-length 16S rRNA gene sequences are deposited in GenBank under the accession numbers GQ491120 to GQ493997.

  • Mahowald MA, Rey FE, Seedorf H, Turnbaugh PJ, Fulton RS, Wollam A, Shah N, Wang C, Magrini V, Wilson RK, Cantarel BL, Coutinho PM, Henrissat B, Crock LW, Russell A, Verberkmoes NC, Hettich RL, Gordon JI (2009) Characterizing a model human gut microbiota composed of members of its two dominant bacterial phyla. Proc. Natl. Acad. Sci. U.S.A. 106(14):5859-64 (PMC2660063) · Pubmed

    The adult human distal gut microbial community is typically dominated by 2 bacterial phyla (divisions), the Firmicutes and the Bacteroidetes. Little is known about the factors that govern the interactions between their members. Here, we examine the niches of representatives of both phyla in vivo. Finished genome sequences were generated from Eubacterium rectale and E. eligens, which belong to Clostridium Cluster XIVa, one of the most common gut Firmicute clades. Comparison of these and 25 other gut Firmicutes and Bacteroidetes indicated that the Firmicutes possess smaller genomes and a disproportionately smaller number of glycan-degrading enzymes. Germ-free mice were then colonized with E. rectale and/or a prominent human gut Bacteroidetes, Bacteroides thetaiotaomicron, followed by whole-genome transcriptional profiling, high-resolution proteomic analysis, and biochemical assays of microbial-microbial and microbial-host interactions. B. thetaiotaomicron adapts to E. rectale by up-regulating expression of a variety of polysaccharide utilization loci encoding numerous glycoside hydrolases, and by signaling the host to produce mucosal glycans that it, but not E. rectale, can access. E. rectale adapts to B. thetaiotaomicron by decreasing production of its glycan-degrading enzymes, increasing expression of selected amino acid and sugar transporters, and facilitating glycolysis by reducing levels of NADH, in part via generation of butyrate from acetate, which in turn is used by the gut epithelium. This simplified model of the human gut microbiota illustrates niche specialization and functional redundancy within members of its major bacterial phyla, and the importance of host glycans as a nutrient foundation that ensures ecosystem stability.

  • Samuel BS, Shaito A, Motoike T, Rey FE, Backhed F, Manchester JK, Hammer RE, Williams SC, Crowley J, Yanagisawa M, Gordon JI (2008) Effects of the gut microbiota on host adiposity are modulated by the short-chain fatty-acid binding G protein-coupled receptor, Gpr41. Proc. Natl. Acad. Sci. U.S.A. 105(43):16767-72 (PMC2569967) · Pubmed

    The distal human intestine harbors trillions of microbes that allow us to extract calories from otherwise indigestible dietary polysaccharides. The products of polysaccharide fermentation include short-chain fatty acids that are ligands for Gpr41, a G protein-coupled receptor expressed by a subset of enteroendocrine cells in the gut epithelium. To examine the contribution of Gpr41 to energy balance, we compared Gpr41-/- and Gpr41+/+ mice that were either conventionally-raised with a complete gut microbiota or were reared germ-free and then cocolonized as young adults with two prominent members of the human distal gut microbial community: the saccharolytic bacterium, Bacteroides thetaiotaomicron and the methanogenic archaeon, Methanobrevibacter smithii. Both conventionally-raised and gnotobiotic Gpr41-/- mice colonized with the model fermentative community are significantly leaner and weigh less than their WT (+/+) littermates, despite similar levels of chow consumption. These differences are not evident when germ-free WT and germ-free Gpr41 knockout animals are compared. Functional genomic, biochemical, and physiologic studies of germ-free and cocolonized Gpr41-/- and +/+ littermates disclosed that Gpr41-deficiency is associated with reduced expression of PYY, an enteroendocrine cell-derived hormone that normally inhibits gut motility, increased intestinal transit rate, and reduced harvest of energy (short-chain fatty acids) from the diet. These results reveal that Gpr41 is a regulator of host energy balance through effects that are dependent upon the gut microbiota.

  • Rey FE, Heiniger EK, Harwood CS (2007) Redirection of metabolism for biological hydrogen production. Appl. Environ. Microbiol. 73(5):1665-71 (PMC1828789) · Pubmed

    No abstract available.

  • Gosse JL, Engel BJ, Rey FE, Harwood CS, Scriven LE, Flickinger MC (2007) Hydrogen production by photoreactive nanoporous latex coatings of nongrowing Rhodopseudomonas palustris CGA009. Biotechnol. Prog. 23(1):124-30 · Pubmed

    No abstract available.

  • Rey FE, Oda Y, Harwood CS (2006) Regulation of uptake hydrogenase and effects of hydrogen utilization on gene expression in Rhodopseudomonas palustris. J. Bacteriol. 188(17):6143-52 (PMC1595397) · Pubmed

    Rhodopseudomonas palustris is a purple, facultatively phototrophic bacterium that uses hydrogen gas as an electron donor for carbon dioxide fixation during photoautotrophic growth or for ammonia synthesis during nitrogen fixation. It also uses hydrogen as an electron supplement to enable the complete assimilation of oxidized carbon compounds, such as malate, into cell material during photoheterotrophic growth. The R. palustris genome predicts a membrane-bound nickel-iron uptake hydrogenase and several regulatory proteins to control hydrogenase synthesis. There is also a novel sensor kinase gene (RPA0981) directly adjacent to the hydrogenase gene cluster. Here we show that the R. palustris regulatory sensor hydrogenase HupUV acts in conjunction with the sensor kinase-response regulator protein pair HoxJ-HoxA to activate hydrogenase expression in response to hydrogen gas. Transcriptome analysis indicated that the HupUV-HoxJA regulatory system also controls the expression of genes encoding a predicted dicarboxylic acid transport system, a putative formate transporter, and a glutamine synthetase. RPA0981 had a small effect in repressing hydrogenase synthesis. We also determined that the two-component system RegS-RegR repressed expression of the uptake hydrogenase, probably in response to changes in intracellular redox status. Transcriptome analysis indicated that about 30 genes were differentially expressed in R. palustris cells that utilized hydrogen when growing photoheterotrophically on malate under nitrogen-fixing conditions compared to a mutant strain that lacked uptake hydrogenase. From this it appears that the recycling of reductant in the form of hydrogen does not have extensive nonspecific effects on gene expression in R. palustris.

  • Oda Y, Samanta SK, Rey FE, Wu L, Liu X, Yan T, Zhou J, Harwood CS (2005) Functional genomic analysis of three nitrogenase isozymes in the photosynthetic bacterium Rhodopseudomonas palustris. J. Bacteriol. 187(22):7784-94 (PMC1280311) · Pubmed

    The photosynthetic bacterium Rhodopseudomonas palustris is one of just a few prokaryotes described so far that has vnf and anf genes for alternative vanadium cofactor (V) and iron cofactor (Fe) nitrogenases in addition to nif genes for a molybdenum cofactor (Mo) nitrogenase. Transcriptome data indicated that the 32 genes in the nif gene cluster, but not the anf or vnf genes, were induced in wild-type and Mo nitrogenase-expressing strains grown under nitrogen-fixing conditions in Mo-containing medium. Strains that were unable to express a functional Mo nitrogenase due to mutations in Mo nitrogenase structural genes synthesized functional V and Fe nitrogenases and expressed vnf and anf genes in nitrogen-fixing growth media that contained Mo and V at concentrations far in excess of those that repress alternative nitrogenase gene expression in other bacteria. Thus, not only does R. palustris have multiple enzymatic options for nitrogen fixation, but in contrast to reports on other nitrogen-fixing bacteria, the expression of its alternative nitrogenases is not repressed by transition metals. Between 95 and 295 genes that are not directly associated with nitrogenase synthesis and assembly were induced under nitrogen-fixing conditions, depending on which nitrogenase was being used by R. palustris. Genes for nitrogen acquisition were expressed at particularly high levels during alternative nitrogenase-dependent growth. This suggests that alternative nitrogenase-expressing cells are relatively starved for nitrogen and raises the possibility that fixed nitrogen availability may be the primary signal that controls the synthesis of the V and Fe nitrogenases.

  • Rey FE, Pagano PJ (2002) The reactive adventitia: fibroblast oxidase in vascular function. Arterioscler. Thromb. Vasc. Biol. 22(12):1962-71 · Pubmed

    No abstract available.

  • Rey FE, Li XC, Carretero OA, Garvin JL, Pagano PJ (2002) Perivascular superoxide anion contributes to impairment of endothelium-dependent relaxation: role of gp91(phox). Circulation 106(19):2497-502 · Pubmed

    No abstract available.

  • Rey FE, Cifuentes ME, Kiarash A, Quinn MT, Pagano PJ (2001) Novel competitive inhibitor of NAD(P)H oxidase assembly attenuates vascular O(2)(-) and systolic blood pressure in mice. Circ. Res. 89(5):408-14 · Pubmed

    No abstract available.

  • Cifuentes ME, Rey FE, Carretero OA, Pagano PJ (2000) Upregulation of p67(phox) and gp91(phox) in aortas from angiotensin II-infused mice. Am. J. Physiol. Heart Circ. Physiol. 279(5):H2234-40 · Pubmed

    No abstract available.

  • Hsich E, Segal BH, Pagano PJ, Rey FE, Paigen B, Deleonardis J, Hoyt RF, Holland SM, Finkel T (2000) Vascular effects following homozygous disruption of p47(phox) : An essential component of NADPH oxidase. Circulation 101(11):1234-6 · Pubmed

    No abstract available.