200 research outputs found
Genetic Basis of Tetracycline Resistance in Bifidobacterium animalis subsp lactis
All strains of Bifidobacterium animalis subsp. lactis described to date show medium level resistance to tetracycline. Screening of 26 strains from a variety of sources revealed the presence of tet(W) in all isolates. A transposase gene upstream of tet(W) was found in all strains, and both genes were cotranscribed in strain IPLAIC4. Mutants with increased tetracycline resistance as well as tetracycline-sensitive mutants of IPLAIC4 were isolated and genetically characterized. The native tet(W) gene was able to restore the resistance phenotype to a mutant with an alteration in tet(W) by functional complementation, indicating that tet(W) is necessary and sufficient for the tetracycline resistance seen in B. animalis subsp. lactis
The infant gut microbiome as a microbial organ influencing host well-being
Initial establishment of the human gut microbiota is generally believed to occur immediately following birth, involving key gut commensals such as bifidobacteria that are acquired from the mother. The subsequent development of this early gut microbiota is driven and modulated by specific dietary compounds present in human milk that support selective colonization. This represents a very intriguing example of host-microbe co-evolution, where both partners are believed to benefit. In recent years, various publications have focused on dissecting microbial infant gut communities and their interaction with their human host, being a determining factor in host physiology and metabolic activities. Such studies have highlighted a reduction of microbial diversity and/or an aberrant microbiota composition, sometimes referred to as dysbiosis, which may manifest itself during the early stage of life, i.e., in infants, or later stages of life. There are growing experimental data that may explain how the early human gut microbiota affects risk factors related to adult health conditions. This concept has fueled the development of various nutritional strategies, many of which are based on probiotics and/or prebiotics, to shape the infant microbiota. In this review, we will present the current state of the art regarding the infant gut microbiota and the role of key commensal microorganisms like bifidobacteria in the establishment of the first microbial communities in the human gut
Decoding the genomic variability among members of the bifidobacterium dentium species
Members of the Bifidobacterium dentium species are usually identified in the oral cavity of humans and associated with the development of plaque and dental caries. Nevertheless, they have also been detected from fecal samples, highlighting a widespread distribution among mammals. To explore the genetic variability of this species, we isolated and sequenced the genomes of 18 different B. dentium strains collected from fecal samples of several primate species and an Ursus arctos. Thus, we investigated the genomic variability and metabolic abilities of the new B. dentium isolates together with 20 public genome sequences. Comparative genomic analyses provided insights into the vast metabolic repertoire of the species, highlighting 19 glycosyl hydrolases families shared between each analyzed strain. Phylogenetic analysis of the B. dentium taxon, involving 1140 conserved genes, revealed a very close phylogenetic relatedness among members of this species. Furthermore, low genomic variability between strains was also confirmed by an average nucleotide identity analysis showing values higher than 98.2%. Investigating the genetic features of each strain, few putative functional mobile elements were identified. Besides, a consistent occurrence of defense mechanisms such as CRISPR–Cas and restriction–modification systems may be responsible for the high genome synteny identified among members of this taxon
Diet: Cause or consequence of the microbial profile of cholelithiasis disease?
Recent dietary habits and lifestyle could explain the shaping of the gut microbiota composition and, in consequence, the increasing prevalence of certain pathologies. However, little attention has been paid to the influence of diet on microbiotas, other than the gut microbiota. This is important in cholelithiasis, given that changes in the production of bile acids may affect gallbladder microbial communities. Our aim was to assess the association between regular dietary intake and gallbladder microbial composition. Fourteen adults with cholelithiasis and 14 controls, sex-age-matched and without gastrointestinal pathology, were included. Diet was assessed through a food frequency questionnaire and quantification of gallbladder microbiota sequences by Illumina 16S rRNA gene-based analysis. The cholelithiasic patients showed greater intake of potatoes and lower consumption of vegetables, non-alcoholic drinks, and sauces, which resulted in a lower intake of energy, lipids, digestible polysaccharides, folate, calcium, magnesium, vitamin C, and some phenolic compounds. Regarding the altered bile microorganisms in cholelithiasic patients, dairy product intake was negatively associated with the proportions of Bacteroidaceae and Bacteroides, and several types of fiber, phenolics, and fatty acids were linked to the abundance of Bacteroidaceae, Chitinophagaceae, Propionibacteraceae, Bacteroides, and Escherichia-Shigella. These results support a link between diet, biliary microbiota, and cholelithiasis.This research was funded by the Spanish “Plan Estatal de I+D+i” Grant number (AGL2013-44761-P) I. GutiĂ©rrez-DĂaz was supported by “Plan Regional de InvestigaciĂłn del Principado de Asturias” Grant number (GRUPIN14-043).Peer reviewe
Th17 responses and natural IgM antibodies are related to gut microbiota composition in systemic lupus erythematosus patients
Intestinal dysbiosis, characterized by a reduced Firmicutes/Bacteroidetes ratio, has been reported in systemic lupus erythematosus (SLE) patients. In this study, in vitro cultures revealed that microbiota isolated from SLE patient stool samples (SLE-M) promoted lymphocyte activation and Th17 differentiation from naĂŻve CD4+ lymphocytes to a greater extent than healthy control-microbiota. Enrichment of SLE-M with Treg-inducing bacteria showed that a mixture of two Clostridia strains significantly reduced the Th17/Th1 balance, whereas Bifidobacterium bifidum supplementation prevented CD4+ lymphocyte over-activation, thus supporting a possible therapeutic benefit of probiotics containing Treg-inducer strains in order to restore the Treg/Th17/Th1 imbalance present in SLE. In fact, ex vivo analyses of patient samples showed enlarged Th17 and Foxp3+ IL-17+ populations, suggesting a possible Treg-Th17 trans-differentiation. Moreover, analyses of fecal microbiota revealed a negative correlation between IL-17+ populations and Firmicutes in healthy controls, whereas in SLE this phylum correlated directly with serum levels of IFNÎł, a Th1 cytokine slightly reduced in patients. Finally, the frequency of Synergistetes, positively correlated with the Firmicutes/Bacteroidetes ratio in healthy controls, tended to be reduced in patients when anti-dsDNA titers were increased and showed a strong negative correlation with IL-6 serum levels and correlated positively with protective natural IgM antibodies against phosphorylcholine.This work was supported by European Union FEDER funds, Fondo de InvestigaciĂłn Sanitaria (PI12/00523), Spanish Plan Nacional de I+D (AGL2010-14952 and AGL2013-44039-R) and FundaciĂłn para el Fomento en Asturias de la InvestigaciĂłn CientĂfica Aplicada y la TecnologĂa (EQUIP09-19). J.R.-C. is a recipient of a FPU grant from the Spanish Ministerio de EducaciĂłn, Cultura y Deporte. B.J. and A.H. are recipients of a RamĂłn y Cajal postdoctoral contract and a FPI grant, respectively, both from the Spanish Ministerio deEconomĂa y Competitividad. We thank SLE patients and ALAS (AsociaciĂłn LĂşpicos de Asturias) for their continuous encouragement.Peer reviewe
Impact of prematurity and perinatal antibiotics on the developing intestinal microbiota: A functional inference study
The microbial colonization of the neonatal gut provides a critical stimulus for normal maturation and development. This process of early microbiota establishment, known to be affected by several factors, constitutes an important determinant for later health. Methods: We studied the establishment of the microbiota in preterm and full-term infants and the impact of perinatal antibiotics upon this process in premature babies. To this end, 16S rRNA gene sequence-based microbiota assessment was performed at phylum level and functional inference analyses were conducted. Moreover, the levels of the main intestinal microbial metabolites, the short-chain fatty acids (SCFA) acetate, propionate and butyrate, were measured by Gas-Chromatography Flame ionization/Mass spectrometry detection. Results: Prematurity affects microbiota composition at phylum level, leading to increases of Proteobacteria and reduction of other intestinal microorganisms. Perinatal antibiotic use further affected the microbiota of the preterm infant. These changes involved a concomitant alteration in the levels of intestinal SCFA. Moreover, functional inference analyses allowed for identifying metabolic pathways potentially affected by prematurity and perinatal antibiotics use. Conclusion: A deficiency or delay in the establishment of normal microbiota function seems to be present in preterm infants. Perinatal antibiotic use, such as intrapartum prophylaxis, affected the early life microbiota establishment in preterm newborns, which may have consequences for later healt
Evolutionary development and co-phylogeny of primate-associated bifidobacteria
In recent years, bifidobacterial populations in the gut of various monkey species have been assessed in several ecological surveys, unveiling a diverse, yet unexplored ecosystem harbouring novel species. In the current study, we investigated the species distribution of bifidobacteria present in 23 different species of primates, including human samples, by means of 16S rRNA microbial profiling and internal transcribed spacer bifidobacterial profiling. Based on the observed bifidobacterial-host co-phylogeny, we found a statistically significant correlation between the Hominidae family and particular bifidobacterial species isolated from humans, indicating phylosymbiosis between these lineages. Furthermore, phylogenetic and glycobiome analyses, based on 40 bifidobacterial species isolated from primates, revealed that members of the Bifidobacterium tissieri phylogenetic group, which are typical gut inhabitants of members of the Cebidae family, descend from an ancient ancestor with respect to other bifidobacterial taxa isolated from primates
Inside the adaptation process of Lactobacillus delbrueckii subsp. lactis to bile
Progressive adaptation to bile might render some lactobacilli able to withstand physiological bile salt concentrations. In this work, the adaptation to bile was evaluated on previously isolated dairy strains of Lactobacillus delbrueckii subsp. lactis 200 and L. delbrueckii subsp. lactis 200+, a strain derived thereof with stable bile-resistant phenotype. The adaptation to bile was obtained by comparing cytosolic proteomes of both strains grown in the presence or absence of bile. Proteomics were complemented with physiological studies on both strains focusing on glycolytic end-products, the ability to adhere to the human intestinal epithelial cell line HT29-MTX and survival to simulated gastrointestinal conditions. Protein pattern comparison of strains grown with and without bile allowed us to identify 9 different proteins whose production was regulated by bile in both strains, and 17 proteins that showed differences in their levels between the parental and the bile-resistant derivative. These included general stress response chaperones, proteins involved in transcription and translation, in peptidoglycan/exopolysaccharide biosynthesis, in the lipid and nucleotide metabolism and several glycolytic and pyruvate catabolism enzymes. Differences in the level of metabolic end-products of the sugar catabolism were found between the strains 200 and 200+. A decrease in the adhesion of both strains to the intestinal cell line was detected in the presence of bile. In simulated gastric and intestinal juices, a protective effect was exerted by milk improving the survival of both microorganisms. These results indicate that bile tolerance in L. delbrueckii subsp. lactis involves several mechanisms responding to the deleterious impact of bile salts on bacterial physiology. © 2010 Elsevier B.V.This work was supported by the following funds in Argentina: ProgramaciĂłn CAI+D 2006 37-203 (Universidad Nacional del Litoral, Santa Fe, Argentina), Project PICT 2004 No. 09 20358 and PICT JĂłvenes 2005 No. 32118 from the Agencia Nacional de PromociĂłn CientĂfica y TecnolĂłgica (ANPCyT), and Project PIP 5321 from CONICET. The following Spanish funds are acknowledged: projects AGL2006-03336 and AGL2007-62736 from the Ministry of Science and Innovation. Patricia Burns received a 6-month grant from the Agencia Española de CooperaciĂłn Internacional for a research stay at IPLA (CSIC). Lorena Ruiz and Borja Sánchez were the recipients of a predoctoral I3P fellowship from CSIC and a postdoctoral Juan de la Cierva contract from the Spanish Ministry of Science and Innovation, respectively. Spanish and Argentinian groups shared a joint collaboration project CSIC–CONICET (reference 2005AR0047).Peer Reviewe
Proton Motive Force-Dependent Hoechst 33342 Transport by the ABC Transporter LmrA of Lactococcus lactis
The fluorescent compound Hoechst 33342 is a substrate for many multidrug resistance (MDR) transporters and is widely used to characterize their transport activity. We have constructed mutants of the adenosine triphosphate (ATP) binding cassette (ABC)-type MDR transporter LmrA of Lactococcus lactis that are defective in ATP hydrolysis. These mutants and wild-type LmrA exhibited an atypical behavior in the Hoechst 33342 transport assay. In membrane vesicles, Hoechst 33342 transport was shown to be independent of the ATPase activity of LmrA, and it was not inhibited by orthovanadate but sensitive to uncouplers that collapse the proton gradient and to N,N'-dicyclohexylcarbodiimide, an inhibitor of the F0F1-ATPase. In contrast, transport of Hoechst 33342 by the homologous, heterodimeric MDR transporter LmrCD showed a normal ATP dependence and was insensitive to uncouplers of the proton gradient. With intact cells, expression of LmrA resulted in an increased rate of Hoechst 33342 influx while LmrCD caused a decrease in the rate of Hoechst 33342 influx. Cellular toxicity assays using a triple knockout strain, i.e., L. lactis ΔlmrA ΔlmrCD, demonstrate that expression of LmrCD protects cells against the growth inhibitory effects of Hoechst 33342, while in the presence of LmrA, cells are more susceptible to Hoechst 33342. Our data demonstrate that the LmrA-mediated Hoechst 33342 transport in membrane vesicles is influenced by the transmembrane pH gradient due to a pH-dependent partitioning of Hoechst 33342 into the membrane.
Bifidobacterium adolescentis as a key member of the human gut microbiota in the production of GABA
Gamma aminobutyric acid (GABA) is the principal inhibitory neurotransmitter playing a key role in anxiety and depression disorders in mammals. Recent studies revealed that members of the gut microbiota are able to produce GABA modulating the gut–brain axis response. Among members of the human gut microbiota, bifidobacteria are well known to establish many metabolic and physiologic interactions with the host. In this study, we performed genome analyses of more than 1,000 bifidobacterial strains publicly available revealing that Bifidobacterium adolescentis taxon might represent a model GABA producer in human gastrointestinal tract. Moreover, the in silico screening of human/animal metagenomic datasets showed an intriguing association/correlation between B. adolescentis load and mental disorders such as depression and anxiety. Interestingly, in vitro screening of 82 B. adolescentis strains allowed identifying two high GABA producers, i.e. B. adolescentis PRL2019 and B. adolescentis HD17T2H, which were employed in an in vivo trial in rats. Feeding Groningen rats with a supplementation of B. adolescentis strains, confirmed the ability of these microorganisms to stimulate the in vivo production of GABA highlighting their potential implication in gut–brain axis interactions
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