Assessing causal relationships between gut microbiota and psoriasis: evidence from two sample Mendelian randomization analysis

Mounting data hints that the gut microbiota's role may be pivotal in understanding the emergence of psoriasis. However, discerning a direct causal link is yet elusive. In this exploration, we adopted a Mendelian randomization (MR) strategy to probe the prospective causal interplay between the gut's microbial landscape and the predisposition to psoriasis. Genetic markers acting as instrumental variables for gut microbiota were extrapolated from a genome-wide association study (GWAS) encompassing 18,340 individuals. A separate GWAS yielded summary data for psoriasis, which covered 337,159 patients and 433,201 control subjects. The primary analysis hinged on inverse variance weighting (IVW). Additional methods like the weighted median approach and MR-Egger regression were employed to validate the integrity of our findings. Intriguing correlations emerged between psoriasis risk and eight specific bacterial traits. To illustrate: Mollicutes presented an odds ratio (OR) of 1.003 with a 95% confidence interval (CI) spanning 1.001-1.005 (p = 0.016), while the family. Victivallaceae revealed an OR of 0.998 with CI values between 0.997 and 0.999 (p = 0.023). Eubacterium (coprostanoligenes group) revealed an OR of 0.997 with CI values between 0.994 and 0.999 (p = 0.027). Eubacterium (fissicatena group) revealed an OR of 0.997 with CI values between 0.996 and 0.999 (p = 0.005). Holdemania revealed an OR of 1.001 with CI values 1-1.003 (p = 0.034). Lachnospiraceae (NK4A136 group) revealed an OR of 0.997 with CI values between 0.995 and 0.999 (p = 0.046). Lactococcus revealed an OR of 0.998 with CI values between 0.996 and 0.999 (p = 0.008). Tenericutes revealed an OR of 1.003 with CI values between 1.001 and 1.006 (p = 0.016). Sensitivity analysis for these bacterial features yielded congruent outcomes, reinforcing statistically significant ties between the eight bacterial entities and psoriasis. This comprehensive probe underscores emerging evidence pointing towards a plausible causal nexus between diverse gut microbiota and the onset of psoriasis. It beckons further research to unravel the intricacies of how the gut's microbial constituents might sway psoriasis's pathogenesis.

Eubacterium rectale is a potential marker of altered gut microbiota in psoriasis and psoriatic arthritis

Previous studies have profiled the gut microbiota among psoriatic patients compared to that among healthy individuals. However, a comprehensive understanding of the magnitude, direction, and detailed compositional and functional profiles remains limited. Additionally, research exploring the gut microbiota in the context of both plaque psoriasis (PsO) and psoriatic arthritis (PsA) is lacking. To assess the taxonomic and functional characteristics of the gut microbiota in PsO and PsA patients and investigate potential links between the gut microbiota and disease pathogenesis. We collected fecal samples from 70 psoriatic patients (44 PsO and 26 PsA) and 25 age- and gender-matched healthy controls (HC) and employed deep metagenomic sequencing to characterize their gut microbiota. We noted significant alternations in the gut microbiota compositions of both PsO and PsA patients compared to those of HC. Despite limited effect sizes in alpha diversity (12.3% reduction of microbial richness but unchanged evenness in psoriatic patients) and beta diversity (disease accounts for 3.5% of total variations), we consistently observed substantial reductions of Eubacterium rectale in both PsO and PsA patients, with PsA patients exhibiting even lower levels of E. rectale than PsO patients. Additionally, two Alistipes species were also depleted in psoriatic patients. These microorganisms are known to play crucial roles in carbohydrate metabolism pathways, mainly producing short-chain fatty acids with anti-inflammatory effects. Overall, our observations supplemented the profiling of altered gut microbiota in patients with PsO and PsA at the species level and described a link between the dominant short-chain fatty acid-producing bacterial species and systemic immunity in psoriatic patients.

IMPORTANCE

In this observational clinical study with sufficient sample size and metagenomic sequencing to profile the gut microbiota, we identified consistent signals of the depleted abundance of Eubacterium rectale and related functional genes among psoriatic patients, including those with psoriatic arthritis. E. rectale may serve as an ecologically important functional unit in the gut microbiota, holding potential as a diagnostic marker and target for therapeutic interventions to achieve lasting effects. Our findings provide comprehensive gut microbiota profiling in psoriasis, resolving previous contradictions and generating new hypotheses for further investigation. These insights may significantly impact psoriasis management and related conditions.

Eubacterium bacteremia - a retrospective observational study of a seldom found anaerobic pathogen

BACKGROUND

Human infections due to Eubacterium are rare and knowledge of the condition is limited. This study aimed to describe clinical characteristics and outcome in patients with Eubacterium bacteremia.

METHODS

Episodes of Eubacterium bacteremia were identified through the clinical microbiology laboratory in Lund, Sweden. Medical records were retrospectively reviewed. Blood isolates of Eubacterium were collected and antibiotic susceptibility testing was performed with agar dilution.

RESULTS

Seventeen patients with Eubacterium bacteremia were identified of whom six had monomicrobial bacteremia. The incidence was 1.7 cases of Eubacterium bacteremia per million inhabitants and year. The median age was 67 years (interquartile range 63-79 years), and six patients had some form of malignancy. Most of the patients an abdominal focus of infection and the 30-day mortality was low (n = 1).

CONCLUSIONS

Invasive infections with Eubacterium have a low incidence. The condition has a low mortality and an abdominal focus of infection, and malignancy, is common.

Robust demarcation of the family Peptostreptococcaceae and its main genera based on phylogenomic studies and taxon-specific molecular markers

The family Peptostreptococcaceae, which contains 15 genera including Clostridioides, presently lacks proper circumscription. Using 52 available genomes for Peptostreptococcaceae species, we report comprehensive phylogenomic and comparative analyses to reliably discern their evolutionary relationships. In phylogenetic trees based on core genome proteins and 16S rRNA gene sequences, the examined species formed a strongly supported clade designated as Peptostreptococcaceae sensu stricto. This clade encompassed the genera Peptostreptococcus (type genus), Asaccharospora, Clostridioides, Intestinibacter, Paeniclostridium, Paraclostridium, Peptacetobacter, Romboutsia and Terrisporobacter, and two misclassified species (viz. Eubacterium tenue and 'Clostridium dakarense'). The distinctness of this clade is strongly supported by eight identified conserved signature indels (CSIs), which are specific for the species from this clade. Based on the robust evidence provided by presented studies, we are proposing the emendment of family Peptostreptococcaceae to only the genera within the Peptostreptococcaceae sensu stricto clade. We also report 67 other novel CSIs, which reliably demarcate different Peptostreptococcaceae species clades and clarify the classification of some misclassified species. Based on the consistent evidence obtained from different presented studies, we are making the following proposals to clarify the classification of Peptostreptococcaceae species: (i) transfer of Eubacterium tenue, Paeniclostridium ghonii and Paeniclostridium sordellii as comb. nov. into the genus Paraclostridium; (ii) transfer of Clostridioides mangenotii as a comb. nov. into Metaclostridioides gen. nov.; (iii) classification of 'Clostridium dakarense' as a novel species Faecalimicrobium dakarense gen. nov., sp. nov. (type strain FF1T; genome and 16S rRNA accession numbers GCA_000499525.1 and KC517358, respectively); (iv) transfer of two misclassified species, Clostridium paradoxum and Clostridium thermoalcaliphilum, into Alkalithermobacter gen. nov.; and (v) proposals for two novel families, Peptoclostridiaceae fam. nov. and Tepidibacteraceae fam. nov., to accommodate remaining unclassified Peptostreptococcaceae genera. The described CSIs specific for different families and genera provide novel and reliable means for the identification, diagnostics and biochemical studies on these bacteria.

Molecular Basis and Genome Editing Applications of a Compact Eubacterium ventriosum CRISPR-Cas9 System

CRISPR-Cas9 systems have been widely harnessed for diverse genome editing applications because of their ease of use and high efficiency. However, the large molecular sizes and strict PAM requirements of commonly used CRISPR-Cas9 systems restrict their broad applications in therapeutics. Here, we report the molecular basis and genome editing applications of a novel compact type II-A Eubacterium ventriosum CRISPR-Cas9 system (EvCas9) with 1107 residues and distinct 5'-NNGDGN-3' (where D represents A, T, or G) PAM specificity. We determine the cryo-EM structure of EvCas9 in a complex with an sgRNA and a target DNA, revealing the detailed PAM recognition and sgRNA and target DNA association mechanisms. Additionally, we demonstrate the robust genome editing capacity of EvCas9 in bacteria and human cells with superior fidelity compared to SaCas9 and SpCas9, and we engineer it to be efficient base editors by fusing a cytidine or adenosine deaminase. Collectively, our results facilitate further understanding of CRISPR-Cas9 working mechanisms and expand the compact CRISPR-Cas9 toolbox.

Collinsella aerofaciens as a predictive marker of response to probiotic treatment in non-constipated irritable bowel syndrome

Probiotics are exploited for adjuvant treatment in IBS, but reliable guidance for selecting the appropriate probiotic to adopt for different forms of IBS is lacking. We aimed to identify markers for recognizing non-constipated (NC) IBS patients that may show significant clinical improvements upon treatment with the probiotic strain Lacticaseibacillus paracasei DG (LDG). To this purpose, we performed a post-hoc analysis of samples collected during a multicenter, double-blind, parallel-group, placebo-controlled trial in which NC-IBS patients were randomized to receive at least 24 billion CFU LDG or placebo capsules b.i.d. for 12 weeks. The primary clinical endpoint was the composite response based on improved abdominal pain and fecal type. The fecal microbiome and serum markers of intestinal (PV1 and zonulin), liver, and kidney functions were investigated. We found that responders (R) in the probiotic arm (25%) differed from non-responders (NR) based on the abundance of 18 bacterial taxa, including the families Coriobacteriaceae, Dorea spp. and Collinsella aerofaciens, which were overrepresented in R patients. These taxa also distinguished R (but not NR) patients from healthy controls. Probiotic intervention significantly reduced the abundance of these bacteria in R, but not in NR. Analogous results emerged for C. aerofaciens from the analysis of data from a previous trial on IBS with the same probiotic. Finally, C. aerofaciens was positively correlated with the plasmalemmal vesicle associated protein-1 (PV-1) and the markers of liver function. In conclusion, LDG is effective on NC-IBS patients with NC-IBS with a greater abundance of potential pathobionts. Among these, C. aerofaciens has emerged as a potential predictor of probiotic efficacy.

Brain abscess caused by Porphyromonas gingivalis and Eubacterium nodatum mimicking acute stroke

We described a case of a 65-year-old man with a brain abscess caused by Porphyromonas gingivalis and Eubacterium nodatum. The patient presented right central facial nerve palsy, mutism and right hemiparesis at the examination. The patient underwent a left frontal craniotomy with evacuation of the brain abscess. Specimens were collected for microbiological analysis and intravenous treatment was started with levetiracetam, dexamethasone, meropenem (1 g/8 h) and linezolid (600 mg/12 h). After identification of anaerobic bacteria the antibiotic treatment was changed to piperacillin/tazobactam (4 g/0,5 g/8 h), fulfilling 8 weeks of antibiotic with good clinical and radiological evolution.

A mathematical model of Bacteroides thetaiotaomicron, Methanobrevibacter smithii, and Eubacterium rectale interactions in the human gut

The human gut microbiota is a complex ecosystem that affects a range of human physiology. In order to explore the dynamics of the human gut microbiota, we used a system of ordinary differential equations to model mathematically the biomass of three microorganism populations: Bacteroides thetaiotaomicron, Eubacterium rectale, and Methanobrevibacter smithii. Additionally, we modeled the concentrations of relevant nutrients necessary to sustain these populations over time. Our model highlights the interactions and the competition among these three species. These three microorganisms were specifically chosen due to the system's end product, butyrate, which is a short chain fatty acid that aids in developing and maintaining the intestinal barrier in the human gut. The basis of our mathematical model assumes the gut is structured such that bacteria and nutrients exit the gut at a rate proportional to its volume, the rate of volumetric flow, and the biomass or concentration of the particular population or nutrient. We performed global sensitivity analyses using Sobol' sensitivities to estimate the relative importance of model parameters on simulation results.

New putative periodontopathogens and periodontal health-associated species: A systematic review and meta-analysis

To investigate the existence of any association between new putative periodontal pathogens and periodontitis. Two independent reviewers conducted electronic literature searches in the MEDLINE (PubMed), EMBASE, DOSS and Google Scholar databases as well as a manual search to identify eligible clinical studies prior to November 2022. Studies comparing the prevalence of microorganisms other than the already-known periodontal pathogens in subgingival plaque and/or saliva samples between subjects with periodontitis and subject with periodontal health were included. Meta-analyses were performed on data provided by the included studies. Fifty studies including a total of 2739 periodontitis subjects and 1747 subjects with periodontal health were included. The Archaea domain and 25 bacterial species (Anaeroglobus geminatus, Bacteroidales [G-2] bacterium HMT 274, Desulfobulbus sp. HMT 041, Dialister invisus, Dialister pneumosintes, Eubacterium brachy, Enterococcus faecalis, Eubacterium nodatum, Eubacterium saphenum, Filifactor alocis, Fretibacterium sp. HMT 360, Fretibacterium sp. HMT 362, Mogibacterium timidum, Peptoniphilaceae sp. HMT 113, Peptostreptococcus stomatis, Porphyromonas endodontalis, Slackia exigua, Streptococcus gordonii, Selenomonas sputigena, Treponema amylovorum, Treponema lecithinolyticum, Treponema maltophilum, Treponema medium, Treponema parvum and Treponema socranskii) were found to be statistically significantly associated with periodontitis. Network studies should be conducted to investigate the role of these newly identified periodontitis-associated microorganisms through interspecies interaction and host-microbe crosstalk analyses.

Lower gut abundance of Eubacterium rectale is linked to COVID-19 mortality

Introduction

Emerging preclinical and clinical studies suggest that altered gut microbiome composition and functions are associated with coronavirus 2019 (COVID- 19) severity and its long-term complications. We hypothesize that COVID-19 outcome is associated with gut microbiome status in population-based settings.

Methods

Gut metagenomic data of the adult population consisting of 2871 subjects from 16 countries were obtained from ExperimentHub through R, while the dynamic death data of COVID-19 patients between January 22, 2020 and December 8, 2020 in each country was acquired from Johns Hopkins Coronavirus Resource Center. An adjusted stable mortality rate (SMR) was used to represent these countries' mortality and correlated with the mean relative abundance (mRA) of healthy adult gut microbiome species.

Results

After excluding bacterial species with low prevalence (prevalence <0.2 in the included countries), the β-diversity was significantly higher in the countries with high SMR when compared with those with median or low SMR (p <0.001). We then identified the mRA of two butyrate producers, Eubacterium rectale and Roseburia intestinalis, that were negatively correlated with SMR during the study period. And the reduction of these species was associated with severer COVID-19 manifestation.

Conclusion

Population-based microbiome signatures with the stable mortality rate of COVID-19 in different countries suggest that altered gut microbiome composition and functions are associated with mortality of COVID-19.

Structural Basis for (2R,3R)-Taxifolin Binding and Reaction Products to the Bacterial Chalcone Isomerase of Eubacterium ramulus

The bacterial chalcone isomerase (CHI) from Eubacterium ramulus catalyses the first step in a flavanone-degradation pathway by a reverse Michael addition. The overall fold and the constitution of the active site of the enzyme completely differ from the well-characterised chalcone isomerase of plants. For (+)-taxifolin, CHI catalyses the intramolecular ring contraction to alphitonin. In this study, Fwe perform crystal structure analyses of CHI and its active site mutant His33Ala in the presence of the substrate taxifolin at 2.15 and 2.8 Å resolution, respectively. The inactive enzyme binds the substrate (+)-taxifolin as well defined, whereas the electron density maps of the native CHI show a superposition of substrate, product alphitonin, and most probably also the reaction intermediate taxifolin chalcone. Evidently, His33 mediates the stereospecific acid-base reaction by abstracting a proton from the flavonoid scaffold. The stereospecificity of the product is discussed.

A Preliminary Study on the Value of Intestinal Flora in Predicting Major Adverse Cardiovascular and Cerebrovascular Events in Patients with Refractory Hypertension

Objective

To investigate the value of intestinal flora in predicting major adverse cardiovascular and cerebrovascular events (MACCE) in patients with refractory hypertension (RH).

Methods

359 patients with RH hospitalized in our hospital from April 2020 to March 2021 were followed up for 1 year and selected for the study. These patients were divided into a MACCE group and no-MACCE group. Results were analyzed by comparing general information, the abundance of intestinal flora at the phylum level, and the abundance of intestinal flora at the species level between the two groups. The influence factors related to MACCE were evaluated using multifactor logistic regression analysis, and the value of intestinal flora in predicting MACCE was determined using receiver operating characteristic (ROC) and the area under ROC (AUC).

Results

Systolic blood pressure was higher in the MACCE group than in the no-MACCE group (P < 0.05). The abundances of Actinomycetes and Verrucomicrobia were higher in the MACCE group than in the no-MACCE group, while unnamed viruses were the opposite (P < 0.05). The abundances of Eubacterium eligens, Akkermansia muciniphila, Prevotella stercorea, and Eubacterium rectale were lower in the MACCE group than in the no-MACCE group, while Escherichia coli, Clostridium hathewayi, and Ruminococcus gnavus were opposite (P < 0.05). Systolic blood pressure, Actinomycetes, unnamed viruses, Verrucomicrobia, Eubacterium eligens, Akkermansia muciniphila, Prevotella stercorea, Eubacterium rectale, Escherichia coli, Clostridium hathewayi, and Ruminococcus gnavus were closely associated with MACCE in RH patients (P < 0.05). In addition, Akkermansia muciniphila had the highest AUC among the single indicator but was still lower than the AUC of the combined detection.

Conclusion

The increases of Actinomycetes, Verrucomicrobia, Escherichia coli, Clostridium hathewayi, and Ruminococcus gnavus and the decreases of unnamed viruses, Eubacterium eligens, Akkermansia muciniphila, Prevotella stercorea, and Eubacterium rectale were associated with MACCE in RH patients, and the combined detection may provide a method and idea for predicting and preventing MACCE.

Comparison of gut microbiota in male MAFLD patients with varying liver stiffness

Purpose

In this study, we examined the changes to the composition and function of the gut microbiota from patients with metabolic dysfunction-associated fatty liver disease (MAFLD).We compared patients in a case group (liver stiffness (LSM) ≥ 7.4 kPa) with a matched control group (LSM < 7.4 kPa) and investigated the correlation between characteristics of the microbiota and other biochemical indicators.

Methods

The study looked at a total of 85 men with MAFLD, 17 of whom were in the case group and 68 of whom were in the control group. We measured waist circumference, blood pressure, and body mass index, as well as clinical parameters including liver stiffness, enzyme levels, cholesterol levels, and fat attenuation. Whole-genome shotgun sequencing technology and the MetaCyc database were then used to detect the composition and major pathways of the gut microbiota for each patient. Statistical analyses were performed, including the chi-square test, the student’s t-test, the Wilcoxon rank-sum test, and the Mann–Whitney test.

Results

Whole-genome sequencing showed that the composition of the gut microbiota in patients with an LSM of above 7.4 kPa was significantly different to that of the control group. There were seven bacterial species that were different between the two groups. Prevotella copri, Phascolarctobacterium succinatutens, Eubacterium biforme, and Collinsella aerofaciens were enriched in the case group (P < 0.05). Conversely, Bacteroides coprocola, Bacteroides stercoris and Clostridiales bacterium 1_7_47FAA were decreased in the case group (P < 0.05). Furthermore, after removing low abundance pathways, a total of 32 microbial pathways were found to be significantly different between the two groups. Most pathways enriched in the case group over the control were related to biosynthesis of metabolites including amino acids, vitamins, nucleosides, and nucleotides. Conclusion. The composition and function of the gut microbiota in patients with increased liver stiffness are significantly altered. This observation may provide new avenues to better understand the mechanism of liver fibrosis.

Expanding the genetic engineering toolbox for the metabolically flexible acetogen Eubacterium limosum

Acetogenic bacteria are an increasingly popular choice for producing fuels and chemicals from single carbon (C1) substrates. Eubacterium limosum is a promising acetogen with several native advantages, including the ability to catabolize a wide repertoire of C1 feedstocks and the ability to grow well on agar plates. However, despite its promise as a strain for synthetic biology and metabolic engineering, there are insufficient engineering tools and molecular biology knowledge to leverage its native strengths for these applications. To capitalize on the natural advantages of this organism, here we extended its limited engineering toolbox. We evaluated the copy number of three common plasmid origins of replication and devised a method of controlling copy number and heterologous gene expression level by modulating antibiotic concentration. We further quantitatively assessed the strength and regulatory tightness of a panel of promoters, developing a series of well-characterized vectors for gene expression at varying levels. In addition, we developed a black/white colorimetric genetic reporter assay and leveraged the high oxygen tolerance of E. limosum to develop a simple and rapid transformation protocol that enables benchtop transformation. Finally, we developed two new antibiotic selection markers—doubling the number available for this organism. These developments will enable enhanced metabolic engineering and synthetic biology work with E. limosum.

Vascular Calcification and the Gut and Blood Microbiome in Chronic Kidney Disease Patients on Peritoneal Dialysis: A Pilot Study

Vascular calcification (VC) is a frequent condition in chronic kidney disease (CKD) and a well-established risk factor for the development of cardiovascular disease (CVD). Gut dysbiosis may contribute to CVD and inflammation in CKD patients. Nonetheless, the role of gut and blood microbiomes in CKD-associated VC remains unknown. Therefore, this pilot study aimed to explore the link between gut and blood microbiomes and VC in CKD patients on peritoneal dialysis (CKD-PD). Our results showed relative changes in specific taxa between CKD-PD patients with and without VC, namely Coprobacter, Coprococcus 3, Lactobacillus, and Eubacterium eligens group in the gut, and Cutibacterium, Pajaroellobacter, Devosia, Hyphomicrobium, and Pelomonas in the blood. An association between VC and all-cause mortality risk in CKD-PD patients was also observed, and patients with higher mortality risk corroborate the changes of Eubacterium eligens in the gut and Devosia genus in the blood. Although we did not find differences in uremic toxins, intestinal translocation markers, and inflammatory parameters among CKD-PD patients with and without VC, soluble CD14 (sCD14), a nonspecific marker of monocyte activation, positively correlated with VC severity. Therefore, gut Eubacterium eligens group, blood Devosia, and circulating sCD14 should be further explored as biomarkers for VC, CVD, and mortality risk in CKD.

Unveiling the Pathogenic Bacteria Causing Descending Necrotizing Mediastinitis

The combination of maxillofacial infections (MI) with descending necrotizing mediastinitis (DNM) is a complex disease characterized by rapid development and high mortality. Here, we performed metagenomic next-generation sequencing (mNGS) using samples from 21 patients with MI and eight patients with DNM. In this study, we found that the species richness of the DNM group was higher than that of the MI group, and the species diversity of the DNM group was higher than that of the MI group, with no statistically significant differences between groups (P > 0.05). LefSE analysis revealed that the main species differing between groups were Bacillus, Lactobacillus, Streptococcaceae, and Streptococcus (S. constellatus and S. anginosus). In addition, the PLS-DA analysis revealed that the dominant groups in the DNM group at the species level were S. constellatus, S. anginosus, Streptococcus intermedius, Prevotella oris, Mogibacterium timidum, and Eubacterium nodatum. Next, we correlated the clinical characteristics of the patients with the relative abundance of the pathogens identified in the LefSe and PLS-DA analyses. The relative abundance of S. anginosus was positively correlated with C-reactive protein (CRP) and calcitoninogen (PCT) but negatively correlated with the percentage of lymphocytes (Lymph%) (P < 0.05). On the other hand, M. timidum was positively correlated with the percentage of neutrophils (Neut%) and glycated hemoglobin (GLU) (P < 0.05), and Parvimonas micra was positively correlated with CRP (P < 0.05).

Not a 'they' but a 'we': the microbiome helps promote our well-being

Anaerobic microbes in the human gut produce beneficial and harmful compounds, as well as neutral compounds like trimethylamine (TMA), which undergoes microbial metabolism or host-catalyzed transformation into proatherogenic trimethylamine-N-oxide (TMAO). Ellenbogen et al. identified a microbiome-associated demethylase that short-circuits the production of TMAO from the metabolite γ-butyrobetaine and instead produces methyltetrahydrofolate, a key intermediate in the microbial production of beneficial small chain fatty acids. This paper highlights an example of how the microbiome is integrally involved in producing metabolites that support our health and in preventing the formation of compounds that promote disease.

Metabolism perturbation Causedby the overexpression of carbon monoxide dehydrogenase/Acetyl-CoA synthase gene complex accelerated gas to acetate conversion rate ofEubacterium limosumKIST612

Microbial conversion of carbon monoxide (CO) to acetate is a promising upcycling strategy for carbon sequestration. Herein, we demonstrate that CO conversion and acetate production rates of Eubacterium limosum KIST612 strain can be improved by in silico prediction and in vivo assessment. The mimicked CO metabolic model of KIST612 predicted that overexpressing the CO dehydrogenase (CODH) increases CO conversion and acetate production rates. To validate the prediction, we constructed mutant strains overexpressing CODH gene cluster and measured their CO conversion and acetate production rates. A mutant strain (ELM031) co-overexpressing CODH, coenzyme CooC2 and ACS showed a 3.1 × increased specific CO oxidation rate as well as 1.4 × increased specific acetate production rate, compared to the wild type strain. The transcriptional and translational data with redox balance analysis showed that ELM031 has enhanced reducing potential from up-regulation of ferredoxin and related metabolism directly linked to energy conservation.

Butyrate production in the acetogen Eubacterium limosum is dependent on the carbon and energy source

Eubacterium limosum KIST612 is one of the few acetogenic bacteria that has the genes encoding for butyrate synthesis from acetyl-CoA, and indeed, E. limosum KIST612 is known to produce butyrate from CO but not from H2  + CO2 . Butyrate production from CO was only seen in bioreactors with cell recycling or in batch cultures with addition of acetate. Here, we present detailed study on growth of E. limosum KIST612 on different carbon and energy sources with the goal, to find other substrates that lead to butyrate formation. Batch fermentations in serum bottles revealed that acetate was the major product under all conditions investigated. Butyrate formation from the C1 compounds carbon dioxide and hydrogen, carbon monoxide or formate was not observed. However, growth on glucose led to butyrate formation, but only in the stationary growth phase. A maximum of 4.3 mM butyrate was observed, corresponding to a butyrate:glucose ratio of 0.21:1 and a butyrate:acetate ratio of 0.14:1. Interestingly, growth on the C1 substrate methanol also led to butyrate formation in the stationary growth phase with a butyrate:methanol ratio of 0.17:1 and a butyrate:acetate ratio of 0.33:1. Since methanol can be produced chemically from carbon dioxide, this offers the possibility for a combined chemical-biochemical production of butyrate from H2 + CO2 using this acetogenic biocatalyst. With the advent of genetic methods in acetogens, butanol production from methanol maybe possible as well.

Dietary Eicosapentaenoic Acid and Docosahexaenoic Acid Ethyl Esters Influence the Gut Microbiota and Bacterial Metabolites in Rats

Dietary fish oil containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been reported to affect the diversity and composition of gut microbiota and bacterial metabolites. However, few reports have focused on the effects of EPA and DHA on gut microbiota diversity and bacterial metabolites. This study evaluated the effects of dietary EPA-ethyl ester (EE) and DHA-EE on steroid metabolism, gut microbiota, and bacterial metabolites in Wistar rats. Male rats were fed the experimental diets containing 5% (w/w) soybean oil-EE (SOY diet), EPA-EE (EPA diet), and DHA-EE (DHA diet) for four weeks. The lipid contents in the serum and liver, mRNA expression levels in the liver, and the diversity, composition, and metabolites of the gut microbiota were evaluated. The EPA and DHA diets decreased serum and liver cholesterol contents compared to the SOY diet. In addition, there were no significant changes in gene expression levels related to steroid metabolism in the liver between the EPA and DHA groups. Rats fed the DHA diet had lower microbiota diversity indices, such as Simpson and Shannon indices, than rats fed the SOY and EPA diets. In addition, rats fed EPA and DHA had significant differences in the relative abundance of microbiota at the genus level, such as Phascolarctobacterium, Turicibacter, and [Eubacterium]. Therefore, it was concluded that EPA and DHA have different effects on the diversity and composition of gut microbiota under the experimental conditions employed herein.

Eubacterium rectale Attenuates HSV-1 Induced Systemic Inflammation in Mice by Inhibiting CD83

The purpose of this study was to determine whether administration of the microorganism Eubacterium rectale (E. rectale) could regulate dendritic cell (DC) activation and systemic inflammation in herpes simplex virus type 1-induced Behçet's disease (BD). E. rectale, butyrate-producing bacteria, was administered to BD mice. Peripheral blood leukocytes (PBL) and lymph node cells were isolated and analyzed by flow cytometry. 16S rRNA metagenomic analysis was performed in the feces of mice to determine the differences in the composition of the microbial population between normal and BD mice. Serum cytokine levels were measured by enzyme-linked immunosorbent assay. The frequency of DC activation marker CD83 positive cells was significantly increased in PBL of BD mice. Frequencies of CD83+ cells were also significantly increased in patients with active BD. 16S rRNA metagenomic analysis revealed different gut microbiota composition between normal and BD mice. The administration of E. rectale to BD mice reduced the frequency of CD83+ cells and significantly increased the frequency of NK1.1+ cells with the improvement of symptoms. The co-administration of colchicine and E. rectale also significantly reduced the frequency of CD83+ cells. Differences in gut microbiota were observed between normal mice and BD mice, and the administration of E. rectale downregulated the frequency of CD83, which was associated with BD deterioration. These data indicate that E. rectale could be a new therapeutic adjuvant for BD management.

Methanol supply speeds up synthesis gas fermentation by methylotrophic-acetogenic bacterium, Eubacterium limosum KIST612

This study analyzed the effect of methanol on the metabolism of syngas components (i.e., H₂ and CO) by the syngas fermenting acetogenic strain E. limosum KIST612. The culture characteristics and relevant proteomic expressions (as fold changes) were carefully analyzed under CO/CO₂ and H₂/CO₂ conditions with and without methanol addition, as well as, under methanol/CO₂ conditions. The culture characteristics (specific growth rate and H₂ consumption rate) under H₂/CO₂ conditions were greatly enhanced in the presence of methanol, by 4.0 and 2.7 times, respectively. However, the promoting effect of methanol was not significant under CO/CO₂ conditions. Proteomic fold changes in most enzyme expression levels in the Wood-Ljungdahl pathway and chemiosmotic energy conservation also exhibited high correspondence between methanol and H₂/CO₂ but not between methanol and CO/CO₂. These findings suggest the advantages of methanol addition to H₂/CO₂ for biomass enhancement and faster consumption of gaseous substrates during syngas fermentation.

Modulation of gut mucosal microbiota as a mechanism of probiotics-based adjunctive therapy for ulcerative colitis

This was a pilot study aiming to evaluate the effects of probiotics as adjunctive treatment for ulcerative colitis (UC). Twenty-five active patients with UC were assigned to the probiotic (n = 12) and placebo (n = 13) groups. The probiotic group received mesalazine (60 mg kg-1  day-1 ) and oral probiotics (containing Lactobacillus casei Zhang, Lactobacillus plantarum P-8 and Bifidobacterium animalis subsp. lactis V9) twice daily for 12 weeks, while the placebo group received the same amounts of mesalazine and placebo. The clinical outcomes were assessed. The gut mucosal microbiota was profiled by PacBio single-molecule, real-time (SMRT) sequencing of the full-length 16S rRNA of biopsy samples obtained by colonoscopy. A significantly greater magnitude of reduction was observed in the UC disease activity index (UCDAI) in the probiotic group compared with the placebo group (P = 0.043), accompanying by a higher remission rate (91.67% for probiotic-receivers versus 69.23% for placebo-receivers, P = 0.034). The probiotics could protect from diminishing of the microbiota diversity and richness. Moreover, the gut mucosal microbiota of the probiotic-receivers had significantly more beneficial bacteria like Eubacterium ramulus (P < 0.05), Pediococcus pentosaceus (P < 0.05), Bacteroides fragilis (P = 0.02) and Weissella cibaria (P = 0.04). Additionally, the relative abundances of the beneficial bacteria correlated significantly but negatively with the UCDAI score, suggesting that the probiotics might alleviate UC symptoms by modulating the gut mucosal microbiota. Our research has provided new insights into the mechanism of symptom alleviation in UC by applying probiotic-based adjunctive treatment.

Acetate-assisted increase of butyrate production by Eubacterium limosum KIST612 during carbon monoxide fermentation

The acetate-assisted cultivation of Eubacterium limosum KIST612 was found to provide a way for enhancing cell mass, the carbon monoxide (CO) consumption rate, and butyrate production using CO as an electron and energy source. Cell growth (146%), μ_max (121%), and CO consumption rates (151%) increased significantly upon the addition of 30mM acetate to microbial cultures. The main product of CO fermentation by E. limosum KIST612 shifted from acetate to butyrate in the presence of acetate, and 5.72mM butyrate was produced at the end of the reaction. The resting cell experimental conditions indicated acetate uptake and an increase in the butyrate concentration. Three routes to acetate assimilation and energy conservation were suggested based on given experimental results and previously genome sequencing data. Acetate assimilation via propionate CoA-transferase (PCT) was expected to produce 1.5mol ATP/mol butyrate, and was thus anticipated to be the most preferred route.

Innovation in microbiome-based strategies for promoting metabolic health

PURPOSE OF REVIEW

Update on the development of microbiome-based interventions and dietary supplements to combat obesity and related comorbidities, which are leading causes of global mortality.

RECENT FINDINGS

The role of intestinal dysbiosis, partly resulting from unhealthy diets, in the development of obesity and metabolic disorders, is well documented by recent translational research. Human experimental trials with whole-faecal transplants are ongoing, and their results will be crucial as proof of concept that interventions intended to modulate the microbiome composition and function could be alternatives for the management of obesity and related comorbidities. Potential next-generation probiotic bacteria (Akkermansia, Bacteroides spp., Eubacterium halli) and microbiota-derived molecules (e.g. membrane proteins, short-chain fatty acids) are being evaluated in preclinical and clinical trials to promote the development of innovative dietary supplements. The fact that live or inactivated bacteria and their products can regulate pathways that increase energy expenditure, and reduce energy intake, and absorption and systemic inflammation make them attractive research targets from a nutritional and clinical perspective.

SUMMARY

Understanding which are the beneficial bacteria and their bioactive products is helping us to envisage innovative microbiome-based dietary interventions to tackle obesity. Advances will likely result from future refinements of these strategies according to the individual's microbiome configuration and its particular response to interventions, thereby progressing towards personalized nutrition.

Mitochondrial Genetics of Aging: Intergenomic Conflict Resolution

Mitochondria are the organelles of aerobic respiration. They consume the oxygen we breathe to stay alive and generate energy for cells to function. But oxygen can be dangerous. Indeed, mitochondria generate the majority of reactive oxygen species that are prime suspects among the causes of aging. Mitochondria have been influential elements of evolving eukaryotic cells for perhaps 2 billion years, since a eubacterium fused with an archaebacterium. The picture that has emerged from this long history of genomic fusion is that of a complex network of nuclear-mitochondrial cross-talk. Here, we discuss the biochemical and genetic conflicts between mitochondria and nucleus, which have shaped the role of mitochondria in aging, and point to new paths for further investigations.

Effects of dietary fibre-rich juice colloids from apple pomace extraction juices on intestinal fermentation products and microbiota in rats

Effects of colloids isolated from apple pomace extraction juices (so-called B-juices) produced by enzymic liquefaction on food intake, body and faecal weights, short-chain fatty acid (SCFA) profile and selected intestinal microbiota were investigated in rats. Ten male Wistar rats per group were fed diets without any apple dietary fibre (DF) (control) or supplement with 5 % B-juice colloids or an alcohol-insoluble substance (AIS) from apples for 6 weeks. Rats fed with apple DF (5 % B-juice colloids or AIS) gained less weight than control rats (P<0.05). B-juice colloids did not affect food intake, whereas feeding AIS resulted in a 10 % higher food consumption than in control rats. Both juice colloids and AIS increased the weight of caecal contents in rats and lowered luminal pH values (P<0.05). In addition, SCFA concentrations and total yields were also raised (P<0.05) in caecum of these rats indicating good fermentability of apple substrates by gut microflora. Distinctly higher concentrations of acetate and propionate were found in intestinal contents of juice colloid-fed rats (P<0.05), whereas AIS also increased butyrate yield. Changes in microbiota due to apple DF in diets were restricted in the caecum to the Eubacterium rectale cluster (AIS; P<0.05) and in faeces to the Bacteroidaceae (juice colloids and AIS; P<0.05). The present study shows the physiological effects of apple DF isolated from pomace extraction juices produced by enzymic liquefaction on intestinal fermentation. Results may be helpful for the development of such innovative juice products that are rich in DF of fruit origin.

Treatment of portal vein septic thrombosis by infusion of antibiotics and an antifungal agent into portal vein and superior mesenteric artery: a case report

A 44-year-old man was hospitalized because of right-sided abdominal pain and fever. On admission, he presented spike fever, jaundice, and renal failure. Abdominal ultrasonography and computed tomography showed extensive thrombus in the portal vein. Anaerobic bacteria were identified in arterial and portal blood cultures. Based on these findings, septic thrombosis of the portal vein was diagnosed. Intraportal infusion of antibiotics, urokinase and an antifungal agent, followed by infusion of antimicrobials, urokinase, and heparin into the superior mesenteric artery resulted in marked improvement of symptoms and signs. Diverticulitis of the ascending colon was later found to be the underlying disease. In the follow-up, there were no signs of recurrent disease.

Evolutionarily different RNA motifs and RNA-protein complexes to achieve selenoprotein synthesis

A wealth of RNAs or RNA motifs are instrumental in controlling a variety of post-transcriptional or post-translational regulations. In this regard, selenocysteine incorporation in response to a redefined UGA stop codon certainly constitutes an intriguing and fascinating process. Translation elongation factors specialized for selenocysteine are needed to decode UGA selenocysteine codons. Discrimination between UGA selenocysteine and UGA stop codons also necessitates selenoprotein mRNA hairpins, called SECIS, that are internal to the coding frame in eubacteria or contained in the 3' untranslated regions in archaea/eukaryotes. This dichotomy leads to SECIS RNAs with distinct sequences and structures that tether the specialized translation elongation factor in a direct or indirect fashion, depending on the location of the SECIS RNA. The scope of this review is to bring a sharper focus on the SECIS RNA structures and SECIS RNA-protein complexes involved. Obviously, the examples described here highlight once again the versatility in form and function of RNA.

An accurate mass tag strategy for quantitative and high-throughput proteome measurements

We describe and demonstrate a global strategy that extends the sensitivity, dynamic range, comprehensiveness, and throughput of proteomic measurements based upon the use of peptide "accurate mass tags" (AMTs) produced by global protein enzymatic digestion. The two-stage strategy exploits Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry to validate peptide AMTs for a specific organism, tissue or cell type from "potential mass tags" identified using conventional tandem mass spectrometry (MS/MS) methods, providing greater confidence in identifications as well as the basis for subsequent measurements without the need for MS/MS, and thus with greater sensitivity and increased throughput. A single high resolution capillary liquid chromatography separation combined with high sensitivity, high resolution and accurate FT-ICR measurements has been shown capable of characterizing peptide mixtures of significantly more than 10(5) components with mass accuracies of < 1 ppm, sufficient for broad protein identification using AMTs. Other attractions of the approach include the broad and relatively unbiased proteome coverage, the capability for exploiting stable isotope labeling methods to realize high precision for relative protein abundance measurements, and the projected potential for study of mammalian proteomes when combined with additional sample fractionation. Using this strategy, in our first application we have been able to identify AMTs for >60% of the potentially expressed proteins in the organism Deinococcus radiodurans.

Similarity relations of DNA and RNA polymerases investigated by the principal component analysis of amino acid sequences

The principal component analysis based on the physicochemical properties of amino acid residues is applied to DNA and RNA polymerases to assign the sequence motifs for the polymerization activities of these proteins. After the reconfirmation of the sequence motifs of families A and B of DNA polymerases indicated previously, it elucidates the sequence motifs for the polymerization activity of DNA polymerase III (family C) by the similarity to the polymerization center of multimeric DNA dependent RNA polymerases. This identification proceeds to clarify the sequence motifs for polymerization activities of primases; eukaryotic and archaebacterial primases carry motifs similar to those of family C, while the motifs of eubacterial primase fall into the category of the motifs in family B DNA polymerases such as alpha, delta, epsilon and II. This finding means that DNA dependent RNA polymerases are also divided into groups corresponding to three families, A, B and C, because the monomeric DNA dependent RNA polymerases in phages are reconfirmed to carry sequence motifs similar to those of family A DNA polymerases. Furthermore, the three families of polymerization motifs are found to fall within the variation range of polymerization motifs displayed by many RNA dependent RNA polymerases, suggesting a close evolutionary relation between them. The sequence motifs for polymerization activities of reverse transcriptase and telomerase seem to be the intermediate between family A DNA polymerase and some RNA dependent RNA polymerases, e.g., from Leviviridae. On the contrary, the sequence fragments similar to the nucleotidyltransferase superfamily including DNA polymerase beta are not found in any RNA dependent RNA polymerase, suggesting their other lineage of polymerization motifs.

Some nutritional characteristics of predominant culturable ruminal bacteria

Bryant, M. P. (U.S. Department of Agriculture, Beltsville, Md.) and I. M. Robinson. Some nutritional characteristics of predominant culturable ruminal bacteria. J. Bacteriol. 84:605-614. 1962.-The effect of enzymatic hydrolysate of casein, NH(4) (+), a mixture of volatile fatty acids (acetic, n-valeric, isovaleric, 2-methylbutyric, and isobutyric), hemin, and ruminal fluid on growth of 89 freshly isolated strains of predominant culturable ruminal bacteria was studied, using basal media containing glucose, cellobiose, or maltose as energy source, minerals, cysteine, and S(=) as reducing agents, and H(2)CO(3)-HCO(3) (-) buffer. Of these strains, 13% (four morphological groups) grew poorly or not at all in defined medium plus casein hydrolysate; 6% (one morphological group) required casein hydrolysate; 56% (four morphological groups) grew with either NH(4) (+) or casein hydrolysate as the main source of nitrogen; and NH(4) (+), but not casein hydrolysate, was essential for 25% of the strains (five morphological groups). The volatile fatty acid mixture excluding acetate was essential for 19% of the strains (five morphological groups), and this mixture and acetate were necessary for good growth of 23% of the strains (one morphological group) when casein hydrolysate was excluded from the medium; 30% of the strains (one morphological group) required hemin. Similar studies are reported on 35 old laboratory strains of ruminal bacteria, most of which were previously identified. The results indicate that most strains of ruminal bacteria can be grown in defined media, and suggest the relative importance of NH(4) (+) and volatile fatty acids and the relative lack of importance of organic nitrogen compounds such as amino acids in the nutrition of these bacteria.

BIOHYDROGENATION OF UNSATURATED FATTY ACIDS BY RUMEN BACTERIA

Polan, C. E. (North Carolina State of the University of North Carolina, Raleigh), J. J. McNeill, and S. B. Tove. Biohydrogenation of unsaturated fatty acids by rumen bacteria. J. Bacteriol. 88:1056-1064. 1964.-A simple, rapid, specific assay for the biohydrogenation of unsaturated fatty acids was developed. With this assay, it was shown that washed suspensions of mixed rumen bacteria hydrogenate linoleic and oleic acids. Butyrivibrio fibrisolvens, a common rumen bacterium, is capable of hydrogenating linoleic acid to octadecenoic acid but not to stearic acid. Complete anaerobiosis is required, and with mixed rumen bacteria more activity is obtained in an atmosphere of hydrogen than of either nitrogen or helium, whereas carbon dioxide is inhibitory. The extent of biohydrogenation varies with the season of the year, and a variable stimulatory effect is obtained upon the addition of boiled rumen fluid. Biohydrogenation activity in B. fibrisolvens is markedly dependent upon the age of the organism and concentration of cells used in the medium. The presence of certain other rumen bacteria, which by themselves are incapable of carrying out the biohydrogenation reaction, can prevent loss of activity of B. fibrisolvens due to age or dilution. Two systems are involved in the complete hydrogenation of linoleic acid: one specific for the conversion of linoleic acid to a monoenoic acid, and the other for the hydrogenation of a monoenoic acid to stearic acid.

Introducing mutations into a chromosomal rRNA gene using a genetically modified eubacterial host with a single rRNA operon

Gene-inactivation techniques were employed to construct a eubacterial organism harbouring a single functional rRNA operon. This mutant of Mycobacterium smegmatis permits replacement of the single remaining rRNA operon with a homologous fragment from a vector-borne gene. By homologous recombination with the chromosome a plasmid-borne rDNA segment with resistance markers substitutes for the corresponding region of the chromosomal rRNA operon, resulting in a homogeneous population of mutated ribosomes in the cell. As a first result we demonstrate that the single allelic knock-out strain allows for isolation of rRNA mutants with a drug-resistant phenotype, circumventing the problem of recessivity which prohibits the isolation of such mutants in organisms with multiple rRNA operons. Subsequently, by allelic exchange experiments, it was demonstrated that the rRNA mutation found indeed confers drug resistance in vivo. This system provides intriguing potential for the study of the structure and function of ribosomal RNAs.

ROLE OF FERREDOXIN IN THE METABOLISM OF MOLECULAR HYDROGEN

Valentine, R. C. (University of Illinois, Urbana) and R. S. Wolfe. Role of ferredoxin in the metabolism of molecular hydrogen. J. Bacteriol. 85:1114-1120. 1963.-The metabolism of molecular hydrogen by Clostridium pasteurianum, Micrococcus lactilyticus (Veillonella alcalescens), and several other anaerobic bacteria was studied. Oxidation of hydrogen, using several electron-accepting substrates including triphosphopyridine nucleotide, uric acid, xanthine, nitrite, and hydroxylamine, required ferredoxin in conjunction with hydrogenase. Evolution of hydrogen from pyruvate, alpha-ketoglutarate, hypoxanthine, and dithionite was mediated by ferredoxin. On the basis of these findings, a unitary hypothesis for biological hydrogen evolution is proposed in which ferredoxin plays a key role.

METABOLIC ROLE OF THE BR FACTOR IN BUTYRIBACTERIUM RETTGERI

Kline, Leo (University of California, Berkeley), L. Pine, and H. A. Barker. Metabolic role of the BR factor in Butyribacterium rettgeri. J. Bacteriol. 85:967-975. 1963.-The BR factor, which is replaceable by lipoic acid, was shown to be required for the decomposition of lactate by Butyribacterium rettgeri. Since the factor was not required for the fermentation of pyruvate or glucose by this organism, the results indicate that BR factor is essential only for some reaction involved in the oxidation of lactate to pyruvate, possibly the transport of electrons from lactate to the ultimate anaerobic electron-acceptor systems. The same products, namely, acetate, butyrate, and carbon dioxide, are formed from glucose or pyruvate in the presence or absence of BR factor and from lactate in the presence of the factor. Thus the factor is not required for the conversion of glucose or pyruvate to acetate, butyrate, or carbon dioxide. Although B. rettgeri does not require the BR factor for growth on glucose, growth of lactate-adapted cells on glucose is slow and is markedly stimulated by addition of the factor. Such cells growing on glucose do not show any ability to decompose lactate; consequently, an additional function of the BR factor, probably associated with the conversion of glucose to pyruvate, is indicated. Cells fully adapted to glucose grow rapidly on this substrate and do not respond to the factor. Lactate is formed during growth of glucose-adapted cells on glucose, although such cells cannot decompose lactate.

Effect of orally administered Eubacterium coprostanoligenes ATCC 51222 on plasma cholesterol concentration in laying hens

Thirty normocholesterolemic laying hens were used to investigate the effect of oral administration of Eubacterium coprostanoligenes on plasma cholesterol concentrations. Hens were divided randomly into three treatment groups (active, inactive, and control) with 10 hens in each group. The active group received 0.5 mL of E. coprostanoligenes suspension (approximately 2 x 10(7) cells per milliliter) daily for 4 wk; the inactive group received the same dosage of killed (boiled) bacterial suspension; and the control group received no supplemental bacteria. After bacterial feeding, the coprostanol to cholesterol ratio in feces of the active group was significantly greater than ratios of the inactive and control groups, indicating that E. coprostanoligenes was colonized in the intestine of hens and was converting intestinal cholesterol to coprostanol. Plasma cholesterol concentrations, however, were not affected by the bacterial treatment.

Hypocholesterolemic effect of Eubacterium coprostanoligenes ATCC 51222 in rabbits

Recently, a unique bacterium, Eubacterium coprostanoligenes ATCC 51222, that reduces cholesterol to coprostanol was isolated. Because coprostanol is absorbed poorly, it was hypothesized that oral administration of Eu. coprostanoligenes might decrease cholesterol concentration in blood because the micro-organisms will decrease the absorption of endogenous and dietary cholesterol by conversion to coprostanol. To test the hypothesis, three adult New Zealand White rabbits received 4 ml of Eu. coprostanoligenes suspension (ca 2 x 10(7) cells ml-1) daily per os for 10 d; three other adult New Zealand White rabbits received the same dosage of boiled bacterial suspension. Plasma cholesterol concentration of experimental rabbits (183.3 +/- 11.0 mg dl-1, mean +/- S.E.) was significantly lower (P < 0.001) than that of controls (248.8 +/- 12.3 mg dl-1, mean +/- S.E.). The coprostanol-to-cholesterol ratios in contents of digestive tracts of experimental rabbits were greater than those of controls. The data indicate that oral administration of Eu. coprostanoligenes caused a significant hypocholesterolemic effect in rabbits and that this effect can be explained by the conversion of cholesterol to coprostanol in the intestine.

[The therapy of urinary tract infections in sows]

Fifteen sows spontaneously infected with Eubacterium suis were treated with enrofloxacin and, if necessary, with ampicillin. Before and after treatment different blood and urine parameters were determined with regard to renal function and the condition of the urinary bladder was examined by cystoscopy. Besides results of a controlled treatment in a breeding herd with a high frequency of urinary tract infections are referred. Duration of treatment with appropriate dosage should be at least 10 days. Even when a haemorrhagic inflammation was present therapy of infections with Eubacterium suis showed no problems, if the alterations were restricted to the bladder. In sows with renal insufficiency in case of ascending infection treatment is also possible on principle, but intensive infusion therapy is necessary in addition to antibiosis. Reliable estimation of the renal function can be obtained by measurement of creatinine and urea blood levels. Enrofloxacin treatment of urinary tract infections was successful in a breeding herd. An insufficient water supply and a high incidence of crystalluria were important predisposing factors.

Development and diversification of the Last Universal Ancestor

The majority of evolutionary steps in the development of basic cellular processes took place in the time interval after the "First Cell" arose until the time of the "Last Universal Ancestor". During this period, life evolved in a monophyletic way in which no stable diversity arose; i.e. although side branches developed, only one survived because of simple "survival of the fittest". The myriad of enzymes and processes developed in this time interval can be grouped in eight qualitatively different categories. In many cases, the evolution of a particular gene was dependent on the concomitant improvement of the cellular machinery generally, including developments in other categories. Eventually several individuals arose (the immediate descendants of the Last Universal Ancestor) that made stable diversity possible because they developed alternative non-competing strategies. These diverse strategies subsequently led to eubacteria, archaebacteria, and eukaryotes (and viruses, plasmids, etc). This paper considers the evolutionary developments in this monophyletic epoch. It depends on three assertions: first, that there is no trivial spontaneous mechanism for the introduction of polynucleotides into a living cell and thus transfer of genes from organism to organism did not occur; second, that the number of accessible habitats and niches was very limited; and third, that the major factor that led to stable diversity was three nearly simultaneous developments. Two were radically different and independent solutions of the problem of overcoming cellular osmotic stress and the third was the development of methanogenesis. Sufficient osmotic pressure could create a high turgor pressure and destructive tension in the wall. However, osmotic stress only became a problem with development of improved metabolism, which resulted in greater success in the accumulation of cellular macromolecules and soluble constituents. One solution preventing osmotic rupture of the cell was the development of mechano-proteins and associated elements of the cytoskeleton by the predecessors of future eukaryotes. The second solution was the development of the murein sacculus (i.e. a covalently closed, cross-linked fabric made of peptidoglycan) by the predecessors of future eubacteria. The former allowed larger cells with flexible cell membranes to evolve and the latter to the development of a strong elastic "exoskeleton" providing ability to survive in extreme environments. Each of these diverse strategies allow both cell types to resist turgor pressure and led to independent non-competing organisms. Interwoven with these developments was the concomitant development of methanogenesis (the third change needed to generate three Kingdoms), which provided the first truly large-scale generation of metabolic energy.(ABSTRACT TRUNCATED AT 400 WORDS)

[Scanning electron microscopic studies of the urinary bladder of sows with special reference to a Eubacterium suis infection]

Scanning electron microscopy was performed on bladder biopsies from 20 sows with cystitis. Results were compared with those of healthy control animals. Biopsy specimens were taken from nine sows infected only with commensal bacteria (E. coli, streptococci, staphylococci) and from 11 sows, where Eubacterium suis (E. suis) was involved in urinary tract infection and had caused a haemorrhagic cystitis. Increased losses of normal superficial cells covered with microplicae could be seen depending on the degree of cystitis. Desquamation of the surface layer exposed smaller cells patterned with short microvilli. These cells were presumed to be immature intermediate cells and goblet cells. Goblet cells were found only in infected organs. The varying surface structure of epithelial cells in relation to receptor quality is important for the bacterial adherence to bladder mucosa. All examined bladders infected with E. suis showed a total loss of superficial cells. Luminal cells covered with multiple short microvilli were accompanied by cells with long pleomorphic processes. Accumulating cell necrosis was indicated by a smooth surface structure. Funnel-shaped orifices between the epithelial cells were identified as excretory ducts of mucus-filled cysts, which are formed by the confluence of degenerating goblet cells. E. suis infection of the porcine bladder causes more severe alterations than infections due to other bacteria. However, debilitation of the urothelium due to previous infection is necessary to support infection of the bladder with E. suis.

[The treatment of Eubacterium suis infections in boars]

The main habitat of Eubacterium suis (E. suis) is the preputial diverticulum of male pigs. E. suis can be transmitted from boars to sows at the time of mating, and ascending urinary tract infections (cystitis and pyelonephritis) in sows may develop. In this paper different methods of treatment were investigated to eliminate E. suis from the diverticulum of carrier boars (n = 33). Local therapy and feed medication were administered separately or in combination. For local instillation into the preputial sac penicillin, penicillin/streptomycin or enrofloxacin were used, while medicated feed contained enrofloxacin. None of the treatments resulted in boars, which were persistently free from E. suis. Also additional hygiene measures as washing of boars and disinfection of pens could not improve the results. At the latest 18 days after treatment E. suis could be detected again in the preputial diverticulum of all boars. Short duration of action of antibiotics in the preputial sac as well as re-colonisation of the diverticulum by contaminated pens are discussed. In herds in which urinary tract infections are troublesome it is worthwhile using artificial insemination to prevent transmission of E. suis to the sow. Treatment of unspecific urinary tract infections in sows may be also important, because alterations of bladder mucosa due to other bacteria may support the colonisation of E. suis.

Bacterial invasion of non-exposed dental pulp

Anaerobic procedures were adopted to demonstrate the early bacterial invasion of non-exposed dental pulps, and to isolate and identify the bacteria. Of 19 freshly extracted teeth which originally exhibited deep dentinal lesions, clinical examination and electric pulp testing showed that nine of them had no pulpal exposure. Thus the pulps of these teeth were covered by clinically sound dentine beneath the carious lesion. Bacteria were found to have invaded the pulps of six of these nine teeth. The predominant bacteria were obligate anaerobes belonging to the genera Eubacterium, Propionibacterium and Actinomyces. Other obligate anaerobes were Lactobacillus, Peptostreptococcus, Veillonella and Streptococcus. The bacterial composition resembled that of the deep layers of dentinal lesions described previously, suggesting that the bacteria isolated in this study had passed through some individual dentinal tubules, to invade the dental pulp.

Epidural abscess and subdural empyema

Epidural abscess and subdural empyema are serious intracranial infections that result in significant morbidity and mortality. Frequently, they are secondary to sinusitis or middle ear disease, and the bacteria involved are inhabitants of the upper respiratory tract. Symptoms may be mild and mimic the symptoms of the underlying infection. However, especially with subdural empyema, alteration in the level of consciousness and focal neurologic deficits are common. Morbidity and mortality are minimized by early diagnosis, which is best made with computed tomography scanning, and proper therapy, which consists of surgical drainage and administration of appropriate antimicrobials. It is important that primary care physicians be aware of the clinical features of these potentially fatal complications of common infections.

[Cervicovaginal cytology in women wearing intrauterine devices]

Cervical and vaginal smears in 300 women using (a) intrauterine devices (IUD) and in 300 age matched control subjects (b), have been examined. In women using IUD, endometrial cells have been observed also in the second half of menstrual cycle, conversely these cells are present in women belonging to the control group, just in the first half of the cycle. Pattern of cervico-vaginitis due to Chlamydiae, Actinomyces and Eubacteria have been observed in higher percentage in women IUD wearers 58% of (a) group and 19.3% of (b) group (P less than 0.005). These patterns have often been characterized by the presence of repair cells. Implications in the evaluation of vaginal smears are discussed.