Differential Metabolism of Exopolysaccharides from Probiotic Lactobacilli by the Human Gut Symbiont Bacteroides thetaiotaomicron

ABSTRACTProbiotic microorganisms are ingested as food or supplements and impart positive health benefits to consumers. Previous studies have indicated that probiotics transiently reside in the gastrointestinal tract and, in addition to modulating commensal species diversity, increase the expression of genes for carbohydrate metabolism in resident commensal bacterial species. In this study, it is demonstrated that the human gut commensal speciesBacteroides thetaiotaomicronefficiently metabolizes fructan exopolysaccharide (EPS) synthesized by probioticLactobacillus reuteristrain 121 while only partially degrading reuteran and isomalto/malto-polysaccharide (IMMP) α-glucan EPS polymers.B. thetaiotaomicronmetabolized these EPS molecules via the activation of enzymes and transport systems encoded by dedicated polysaccharide utilization loci specific for β-fructans and α-glucans. Reduced metabolism of reuteran and IMMP α-glucan EPS molecules may be due to reduced substrate binding by components of the starch utilization system (sus). This study reveals that microbial EPS substrates activate genes for carbohydrate metabolism inB. thetaiotaomicronand suggests that microbially derived carbohydrates provide a carbohydrate-rich reservoir forB. thetaiotaomicronnutrient acquisition in the gastrointestinal tract.

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The Glycine Lipids ofBacteroides thetaiotaomicronAre Important for Fitness during GrowthIn VivoandIn Vitro

Applied and Environmental Microbiology ◽

10.1128/aem.02157-18 ◽

2018 ◽

Vol 85 (10) ◽

Cited By ~ 2

Author(s):

Alli Lynch ◽

Seshu R. Tammireddy ◽

Mary K. Doherty ◽

Phillip D. Whitfield ◽

David J. Clarke

Keyword(s):

Amino Acid ◽

Gut Microbiome ◽

Molecular Mechanisms ◽

Cellular Membrane ◽

Bacteroides Thetaiotaomicron ◽

Human Gut ◽

Acyltransferase Activity ◽

Content Type ◽

Health And Disease ◽

And Function

ABSTRACTAcylated amino acids function as important components of the cellular membrane in some bacteria. Biosynthesis is initiated by theN-acylation of the amino acid, and this is followed by subsequentO-acylation of the acylated molecule, resulting in the production of the mature diacylated amino acid lipid. In this study, we use both genetics and liquid chromatography-mass spectrometry (LC-MS) to characterize the biosynthesis and function of a diacylated glycine lipid (GL) species produced inBacteroides thetaiotaomicron. We, and others, have previously reported the identification of a gene, namedglsBin this study, that encodes anN-acyltransferase activity responsible for the production of a monoacylated glycine calledN-acyl-3-hydroxy-palmitoyl glycine (or commendamide). In all of theBacteroidalesgenomes sequenced so far, theglsBgene is located immediately downstream from a gene, namedglsA, that is also predicted to encode a protein with acyltransferase activity. We use LC-MS to show that the coexpression ofglsBandglsAresults in the production of GL inEscherichia coli. We constructed a deletion mutant of theglsBgene inB. thetaiotaomicron, and we confirm thatglsBis required for the production of GL inB. thetaiotaomicron. Moreover, we show thatglsBis important for the ability ofB. thetaiotaomicronto adapt to stress and colonize the mammalian gut. Therefore, this report describes the genetic requirements for the biosynthesis of GL, a diacylated amino acid species that contributes to fitness in the human gut bacteriumB. thetaiotaomicron.IMPORTANCEThe gut microbiome has an important role in both health and disease of the host. The mammalian gut microbiome is often dominated by bacteria from theBacteroidales, an order that includesBacteroidesandPrevotella. In this study, we have identified an acylated amino acid, called glycine lipid, produced byBacteroides thetaiotaomicron, a beneficial bacterium originally isolated from the human gut. In addition to identifying the genes required for the production of glycine lipids, we show that glycine lipids have an important role during the adaptation ofB. thetaiotaomicronto a number of environmental stresses, including exposure to either bile or air. We also show that glycine lipids are important for the normal colonization of the murine gut byB. thetaiotaomicron. This work identifies glycine lipids as an important fitness determinant inB. thetaiotaomicronand therefore increases our understanding of the molecular mechanisms underpinning colonization of the mammalian gut by beneficial bacteria.

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Metabolic Feedback Inhibition Influences Metabolite Secretion by the Human Gut Symbiont Bacteroides thetaiotaomicron

mSystems ◽

10.1128/msystems.00252-20 ◽

2020 ◽

Vol 5 (5) ◽

Author(s):

Jennie L. Catlett ◽

Jonathan Catazaro ◽

Mikaela Cashman ◽

Sean Carr ◽

Robert Powers ◽

...

Keyword(s):

Amino Acids ◽

Phenotypic Plasticity ◽

Energy Conservation ◽

Organic Acids ◽

Feedback Inhibition ◽

Bacteroides Thetaiotaomicron ◽

Human Gut ◽

Content Type ◽

Abundant Taxon ◽

Metabolic Interactions

Bacteroides is a highly abundant taxon in the human gut, and Bacteroides thetaiotaomicron (B. theta) is a ubiquitous human symbiont that colonizes the host early in development and persists throughout its life span. The phenotypic plasticity of keystone organisms such as B. theta is important to understand in order to predict phenotype(s) and metabolic interactions under changing nutrient conditions such as those that occur in complex gut communities. Our study shows B. theta prioritizes energy conservation and suppresses secretion of “overflow metabolites” such as organic acids and amino acids when concentrations of acetate are high. Secreted metabolites, especially amino acids, can be a source of nutrients or signals for the host or other microbes in the community. Our study suggests that when metabolically stressed by acetate, B. theta stops sharing with its ecological partners.

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Decreased Ecological Resistance of the Gut Microbiota in Response to Clindamycin Challenge in Mice Colonized with the Fungus Candida albicans

mSphere ◽

10.1128/msphere.00982-20 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Laura Markey ◽

Antonia Pugliese ◽

Theresa Tian ◽

Farrah Roy ◽

Kyongbum Lee ◽

...

Keyword(s):

Candida Albicans ◽

Gut Microbiota ◽

Bacterial Species ◽

Species Abundance ◽

Alpha Diversity ◽

Human Gut ◽

Content Type ◽

Ecological Resistance ◽

Bacterial Microbiota ◽

Host Health

ABSTRACT The mammalian gut microbiota is a complex community of microorganisms which typically exhibits remarkable stability. As the gut microbiota has been shown to affect many aspects of host health, the molecular keys to developing and maintaining a “healthy” gut microbiota are highly sought after. Yet, the qualities that define a microbiota as healthy remain elusive. We used the ability to resist change in response to antibiotic disruption, a quality we refer to as ecological resistance, as a metric for the health of the bacterial microbiota. Using a mouse model, we found that colonization with the commensal fungus Candida albicans decreased the ecological resistance of the bacterial microbiota in response to the antibiotic clindamycin such that increased microbiota disruption was observed in C. albicans-colonized mice compared to that in uncolonized mice. C. albicans colonization resulted in decreased alpha diversity and small changes in abundance of bacterial genera prior to clindamycin challenge. Strikingly, co-occurrence network analysis demonstrated that C. albicans colonization resulted in sweeping changes to the co-occurrence network structure, including decreased modularity and centrality and increased density. Thus, C. albicans colonization resulted in changes to the bacterial microbiota community and reduced its ecological resistance. IMPORTANCE Candida albicans is the most common fungal member of the human gut microbiota, yet its ability to interact with and affect the bacterial gut microbiota is largely uncharacterized. Previous reports showed limited changes in microbiota composition as defined by bacterial species abundance as a consequence of C. albicans colonization. We also observed only a few bacterial genera that were significantly altered in abundance in C. albicans-colonized mice; however, C. albicans colonization significantly changed the structure of the bacterial microbiota co-occurrence network. Additionally, C. albicans colonization changed the response of the bacterial microbiota ecosystem to a clinically relevant perturbation, challenge with the antibiotic clindamycin.

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Substrate Use Prioritization by a Coculture of Five Species of Gut Bacteria Fed Mixtures of Arabinoxylan, Xyloglucan, β-Glucan, and Pectin

Applied and Environmental Microbiology ◽

10.1128/aem.01905-19 ◽

2019 ◽

Vol 86 (2) ◽

Cited By ~ 4

Author(s):

Yafei Liu ◽

Anne-Louise Heath ◽

Barbara Galland ◽

Nancy Rehrer ◽

Lynley Drummond ◽

...

Keyword(s):

Gut Microbiota ◽

Dietary Fiber ◽

Bacterial Species ◽

Short Chain ◽

Emergent Properties ◽

Human Gut ◽

Fermentation Products ◽

Plant Polysaccharides ◽

Content Type ◽

Human Gut Microbiota

ABSTRACT Dietary fiber provides growth substrates for bacterial species that belong to the colonic microbiota of humans. The microbiota degrades and ferments substrates, producing characteristic short-chain fatty acid profiles. Dietary fiber contains plant cell wall-associated polysaccharides (hemicelluloses and pectins) that are chemically diverse in composition and structure. Thus, depending on plant sources, dietary fiber daily presents the microbiota with mixtures of plant polysaccharides of various types and complexity. We studied the extent and preferential order in which mixtures of plant polysaccharides (arabinoxylan, xyloglucan, β-glucan, and pectin) were utilized by a coculture of five bacterial species (Bacteroides ovatus, Bifidobacterium longum subspecies longum, Megasphaera elsdenii, Ruminococcus gnavus, and Veillonella parvula). These species are members of the human gut microbiota and have the biochemical capacity, collectively, to degrade and ferment the polysaccharides and produce short-chain fatty acids (SCFAs). B. ovatus utilized glycans in the order β-glucan, pectin, xyloglucan, and arabinoxylan, whereas B. longum subsp. longum utilization was in the order arabinoxylan, arabinan, pectin, and β-glucan. Propionate, as a proportion of total SCFAs, was augmented when polysaccharide mixtures contained galactan, resulting in greater succinate production by B. ovatus and conversion of succinate to propionate by V. parvula. Overall, we derived a synthetic ecological community that carries out SCFA production by the common pathways used by bacterial species for this purpose. Systems like this might be used to predict changes to the emergent properties of the gut ecosystem when diet is altered, with the aim of beneficially affecting human physiology. IMPORTANCE This study addresses the question as to how bacterial species, characteristic of the human gut microbiota, collectively utilize mixtures of plant polysaccharides such as are found in dietary fiber. Five bacterial species with the capacity to degrade polymers and/or produce acidic fermentation products detectable in human feces were used in the experiments. The bacteria showed preferential use of certain polysaccharides over others for growth, and this influenced their fermentation output qualitatively. These kinds of studies are essential in developing concepts of how the gut microbial community shares habitat resources, directly and indirectly, when presented with mixtures of polysaccharides that are found in human diets. The concepts are required in planning dietary interventions that might correct imbalances in the functioning of the human microbiota so as to support measures to reduce metabolic conditions such as obesity.

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Zinc Competition among the Intestinal Microbiota

mBio ◽

10.1128/mbio.00171-12 ◽

2012 ◽

Vol 3 (4) ◽

Cited By ~ 61

Author(s):

Lindsay M. Gielda ◽

Victor J. DiRita

Keyword(s):

Gastrointestinal Tract ◽

Campylobacter Jejuni ◽

Pathogenic Bacteria ◽

Zinc Transporter ◽

Zinc Uptake ◽

Zinc Binding ◽

Transport Systems ◽

Content Type ◽

High Affinity ◽

Wide Range

ABSTRACT Bioavailable levels of trace metals, such as iron and zinc, for bacterial growth in nature are sufficiently low that most microbes have evolved high-affinity binding and transport systems. The microbe Campylobacter jejuni lives in the gastrointestinal tract of chickens, the principal source of human infection. A high-affinity ABC transporter for zinc uptake is required for Campylobacter survival in chicken intestines in the presence of a normal microbiota but not when chickens are raised with a limited microbiota. Mass spectrometric analysis of cecal contents revealed the presence of numerous zinc-binding proteins in conventional chicks compared to the number in limited-microbiota chicks. The presence of a microbiota results in the production of host zinc-binding enzymes, causing a growth restriction for bacteria that lack the high-affinity zinc transporter. Such transporters in a wide range of pathogenic bacteria make them good targets for the development of broad-spectrum antimicrobials. IMPORTANCE Zinc is an essential trace element for the growth of most organisms. Quantities of zinc inside cells are highly regulated, as too little zinc does not support growth, while too much zinc is toxic. Numerous bacterial cells require zinc uptake systems for growth and virulence. The work presented here demonstrates that the microbiota in the gastrointestinal tract reduces the quantity of zinc. Without a high-affinity zinc transporter, Campylobacter jejuni, a commensal organism of chickens, is unable to replicate or colonize the gastrointestinal tract. This is the first demonstration of zinc competition between microbiota in the gastrointestinal tract of a host. These results could have profound implications in the field of microbial pathogenesis and in our understanding of host metabolism and the microbiota.

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Cross-Feeding among Probiotic Bacterial Strains on Prebiotic Inulin Involves the Extracellularexo-Inulinase ofLactobacillus paracaseiStrain W20

Applied and Environmental Microbiology ◽

10.1128/aem.01539-18 ◽

2018 ◽

Vol 84 (21) ◽

Cited By ~ 11

Author(s):

Markus C. L. Boger ◽

Alicia Lammerts van Bueren ◽

Lubbert Dijkhuizen

Keyword(s):

Degradation Products ◽

Lactobacillus Paracasei ◽

Transport Systems ◽

Glycoside Hydrolase Family ◽

Bacterial Strains ◽

Human Gut ◽

Content Type ◽

Beneficial Effects ◽

Probiotic Lactobacilli

ABSTRACTProbiotic gut bacteria employ specific metabolic pathways to degrade dietary carbohydrates beyond the capabilities of their human host. Here, we report how individual commercial probiotic strains degrade prebiotic (inulin type) fructans. First, a structural analysis of commercial fructose oligosaccharide-inulin samples was performed. These β-(2-1)-fructans differ in termination by either glucose (GF) or fructose (FF) residues, with a broad variation in the degrees of polymerization (DPs). The growth of individual probiotic bacteria on short-chain inulin (sc-inulin) (Frutafit CLR), a β-(2-1)-fructan (DP 2 to DP 40), was studied.Lactobacillus salivariusW57 and other bacteria grew relatively poorly on sc-inulin, with only fractions of DP 3 and DP 5 utilized, reflecting uptake via specific transport systems followed by intracellular metabolism.Lactobacillus paracaseisubsp.paracaseiW20 completely used all sc-inulin components, employing an extracellularexo-inulinase enzyme (glycoside hydrolase family GH32 [LpGH32], also found in other strains of this species); the purified enzyme converted high-DP compounds into fructose, sucrose, 1-kestose, and F2 (inulobiose). The cocultivation ofL. salivariusW57 andL. paracaseiW20 on sc-inulin resulted in cross-feeding of the former by the latter, supported by this extracellularexo-inulinase. The extent of cross-feeding depended on the type of fructan, i.e., the GF type (clearly stimulating) versus the FF type (relatively low stimulus), and on fructan chain length, since relatively low-DP β-(2-1)-fructans contain a relatively high content of GF-type molecules, thus resulting in higher concentrations of GF-type DP 2 to DP 3 degradation products. The results provide an example of howin vivocross-feeding on prebiotic β-(2-1)-fructans may occur among probiotic lactobacilli.IMPORTANCEThe human gut microbial community is associated strongly with host physiology and human diseases. This observation has prompted research on pre- and probiotics, two concepts enabling specific changes in the composition of the human gut microbiome that result in beneficial effects for the host. Here, we show how fructooligosaccharide-inulin prebiotics are fermented by commercial probiotic bacterial strains involving specific sets of enzymes and transporters. Cross-feeding strains such asLactobacillus paracaseiW20 may thus act as keystone strains in the degradation of prebiotic inulin in the human gut, and this strain–exo-inulinase combination may be used in commercialLactobacillus-inulin synbiotics.

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Genome Sequence of Christensenella minuta DSM 22607T

Genome Announcements ◽

10.1128/genomea.01451-16 ◽

2017 ◽

Vol 5 (2) ◽

Cited By ~ 7

Author(s):

Bruce A. Rosa ◽

Kymberlie Hallsworth-Pepin ◽

John Martin ◽

Aye Wollam ◽

Makedonka Mitreva

Keyword(s):

Genome Sequence ◽

Gut Microbiome ◽

Bacterial Species ◽

Biological Mechanism ◽

Valuable Resource ◽

Human Gut ◽

Content Type ◽

Human Gut Microbiome

ABSTRACT Obesity influences and is influenced by the human gut microbiome. Here, we present the genome of Christensenella minuta, a highly heritable bacterial species which has been found to be strongly associated with obesity through an unknown biological mechanism. This novel genome provides a valuable resource for future obesity therapeutic studies.

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Limosilactobacillus balticus sp. nov., Limosilactobacillus agrestis sp. nov., Limosilactobacillus albertensis sp. nov., Limosilactobacillus rudii sp. nov. and Limosilactobacillus fastidiosus sp. nov., five novel Limosilactobacillus species isolated from the vertebrate gastrointestinal tract, and proposal of six subspecies of Limosilactobacillus reuteri adapted to the gastrointestinal tract of specific vertebrate hosts

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.004644 ◽

2021 ◽

Vol 71 (2) ◽

Cited By ~ 41

Author(s):

Fuyong Li ◽

Christopher C. Cheng ◽

Jinshui Zheng ◽

Junhong Liu ◽

Rodrigo Margain Quevedo ◽

...

Keyword(s):

Gastrointestinal Tract ◽

Type Strain ◽

Type Species ◽

Bacterial Species ◽

Rrna Gene ◽

16S Rrna Gene Analysis ◽

Content Type ◽

Link Type ◽

Faecal Samples ◽

Genome Phylogeny

Ten strains, BG-AF3-AT, pH52_RY, WF-MT5-AT, BG-MG3-A, Lr3000T, RRLNB_1_1, STM3_1T, STM2_1, WF-MO7-1T and WF-MA3-C, were isolated from intestinal or faecal samples of rodents, pheasant and primate. 16S rRNA gene analysis identified them as Limosilactobacillus reuteri . However, average nucleotide identity and digital DNA–DNA hybridization values based on whole genomes were below 95 and 70 %, respectively, and thus below the threshold levels for bacterial species delineation. Based on genomic, chemotaxonomic and morphological analyses, we propose five novel species with the names Limosilactobacillus balticus sp. nov. (type strain BG-AF3-AT=DSM 110574T=LMG 31633T), Limosilactobacillus agrestis sp. nov. (type strain WF-MT5-AT=DSM 110569T=LMG 31629T), Limosilactobacillus albertensis sp. nov. (type strain Lr3000T=DSM 110573T=LMG 31632T), Limosilactobacillus rudii sp. nov. (type strain STM3_1T=DSM 110572T=LMG 31631T) and Limosilactobacillus fastidiosus sp. nov. (type strain WF-MO7-1T=DSM 110576T=LMG 31630T). Core genome phylogeny and experimental evidence of host adaptation of strains of L. reuteri further provide a strong rationale to consider a number of distinct lineages within this species as subspecies. Here we propose six subspecies of L. reuteri : L. reuteri subsp. kinnaridis subsp. nov. (type strain AP3T=DSM 110703T=LMG 31724T), L. reuteri subsp. porcinus subsp. nov. (type strain 3c6T=DSM 110571T=LMG 31635T), L. reuteri subsp. murium subsp. nov. (type strain lpuph1T=DSM 110570T=LMG 31634T), L. reuteri subsp. reuteri subsp. nov. (type strain F 275T=DSM 20016T=ATCC 23272T), L. reuteri subsp. suis subsp. nov. (type strain 1063T=ATCC 53608T=LMG 31752T) and L. reuteri subsp. rodentium subsp. nov. (type strain 100-23T=DSM 17509T=CIP 109821T).

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Unique Microbial Catabolic Pathway for the Human Core N-Glycan Constituent Fucosyl-α-1,6-N-Acetylglucosamine-Asparagine

mBio ◽

10.1128/mbio.02804-19 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Jimmy E. Becerra ◽

Jesús Rodríguez-Díaz ◽

Roberto Gozalbo-Rovira ◽

Martina Palomino-Schätzlein ◽

Manuel Zúñiga ◽

...

Keyword(s):

Gastrointestinal Tract ◽

Metabolic Pathway ◽

Lactobacillus Casei ◽

Bacterial Species ◽

Constitutive Expression ◽

Major Facilitator Superfamily ◽

Commensal Bacteria ◽

Content Type ◽

The Core ◽

Major Facilitator

ABSTRACT The survival of commensal bacteria in the human gut partially depends on their ability to metabolize host-derived molecules. The use of the glycosidic moiety of N-glycoproteins by bacteria has been reported, but the role of N-glycopeptides or glycoamino acids as the substrates for bacterial growth has not been evaluated. We have identified in Lactobacillus casei strain BL23 a gene cluster (alf-2) involved in the catabolism of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn (6′FN-Asn), a constituent of the core-fucosylated structures of mammalian N-glycoproteins. The cluster consists of the genes alfHC, encoding a major facilitator superfamily (MFS) permease and the α-l-fucosidase AlfC, and the divergently oriented asdA (aspartate 4-decarboxylase), alfR2 (transcriptional regulator), pepV (peptidase), asnA2 (glycosyl-asparaginase), and sugK (sugar kinase) genes. Knockout mutants showed that alfH, alfC, asdA, asnA2, and sugK are necessary for efficient 6′FN-Asn utilization. The alf-2 genes are induced by 6′FN-Asn, but not by its glycan moiety, via the AlfR2 regulator. The constitutive expression of alf-2 genes in an alfR2 strain allowed the metabolism of a variety of 6′-fucosyl-glycans. However, GlcNAc-Asn did not support growth in this mutant background, indicating that the presence of a 6′-fucose moiety is crucial for substrate transport via AlfH. Within bacteria, 6′FN-Asn is defucosylated by AlfC, generating GlcNAc-Asn. This glycoamino acid is processed by the glycosylasparaginase AsnA2. GlcNAc-Asn hydrolysis generates aspartate and GlcNAc, which is used as a fermentable source by L. casei. These data establish the existence in a commensal bacterial species of an exclusive metabolic pathway likely to scavenge human milk and mucosal fucosylated N-glycopeptides in the gastrointestinal tract. IMPORTANCE The gastrointestinal tract accommodates more than 1014 microorganisms that have an enormous impact on human health. The mechanisms enabling commensal bacteria and administered probiotics to colonize the gut remain largely unknown. The ability to utilize host-derived carbon and energy resources available at the mucosal surfaces may provide these bacteria with a competitive advantage in the gut. Here, we have identified in the commensal species Lactobacillus casei a novel metabolic pathway for the utilization of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn, which is present in the core-fucosylated N-glycoproteins from mammalians. These results give insight into the molecular interactions between the host and commensal/probiotic bacteria and may help to devise new strategies to restore gut microbiota homeostasis in diseases associated with dysbiotic microbiota.

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Defining the Bacteroides Ribosomal Binding Site

Applied and Environmental Microbiology ◽

10.1128/aem.03086-12 ◽

2013 ◽

Vol 79 (6) ◽

pp. 1980-1989 ◽

Cited By ~ 23

Author(s):

Udo Wegmann ◽

Nikki Horn ◽

Simon R. Carding

Keyword(s):

Gastrointestinal Tract ◽

Binding Site ◽

Transcription Initiation ◽

Bacterial Species ◽

Lactobacillus Delbrueckii ◽

Expression Vectors ◽

Human Gastrointestinal Tract ◽

Vast Number ◽

Content Type ◽

Ribosomal Binding Site

ABSTRACTThe human gastrointestinal tract, in particular the colon, hosts a vast number of commensal microorganisms. Representatives of the genusBacteroidesare among the most abundant bacterial species in the human colon.Bacteroidetesdiverged from the common line of eubacterial descent before other eubacterial groups. As a result, they employ unique transcription initiation signals and, because of this uniqueness, they require specific genetic tools. Although some tools exist, they are not optimal for studying the roles and functions of these bacteria in the human gastrointestinal tract. Focusing on translation initiation signals inBacteroides, we created a series of expression vectors allowing for different levels of protein expression in this genus, and we describe the use ofpepIfromLactobacillus delbrueckiisubsp.lactisas a novel reporter gene forBacteroides. Furthermore, we report the identification of the 3′ end of the 16S rRNA ofBacteroides ovatusand analyze in detail its ribosomal binding site, thus defining a core region necessary for efficient translation, which we have incorporated into the design of our expression vectors. Based on the sequence logo information from the 5′ untranslated region of otherBacteroidalesribosomal protein genes, we conclude that our findings are relevant to all members of this order.

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