2% of the kefir milk, interior starter grain, and exterior starter grain community, respectively. Of the Bacteroidetes assignments, Bacteriodaceae was the predominant bacterial family with 0.68% of assigned reads in the interior starter grain and 0.8% in the kefir milk (Fig. 3). Bacteroidetes was not detected in the exterior starter grain community. Of the Actinobacteria assignments,

Bifidobacteriaceae was the only bacterial family identified in the collective kefir starter grain and kefir milk. To our knowledge, bifidobacteria have not previously been identified as part of the kefir community (Farnworth, 2005; Lopitz-Otsoa et al., 2006). Here the Bifidobacterium population comprised just 0.2% of total taxa assignments in the collective starter grain VX-770 in vitro and 0.4% in kefir milk. blast hits with the same bit-score included Bifidobacterium breve, Bifidobacterium choerinum, Bifidobacterium longum, and Bifidobacterium pseudolongum in both the kefir starter grain and kefir milk. Culture-dependent methods failed to detect Bifidobacterium species in either sample, highlighting buy KPT-330 the benefits of utilizing a molecular approach. The low percentage

of reads corresponding to Bifidobacterium spp. indicates that other molecular approaches, such as DGGE or Sanger-based sequencing, would likely have also failed to detect this subpopulation (Ercolini, 2004). Further studies, involving a number of different grains, are required to establish if members of this generally gastrointestinal tract-associated genus are frequent members of kefir grain populations or if this represents an isolated case. It is CYTH4 interesting to note that using traditional, culture-dependent approaches, a greater than 1000-fold difference in presumptive Lactococcus (1.1 × 109 CFU mL−1), relative to presumptive Lactobacillus (3.5 × 105 CFU mL−1) populations was observed (Fig. 2a). However, sequencing data established that there is a less than a threefold difference between Streptococcaceae and Lactobacillaceae assignments. This dramatic difference between culture data vs. sequencing results most likely reflects the complex symbiotic relationship observed

within the kefir community (Farnworth & Mainville, 2003). It is likely that a number of lactobacilli present within this community cannot be cultivated using standard media and reagents resulting in an inaccurate representation of the overall community. In this study, the bacterial composition of an Irish kefir grain and its corresponding kefir milk were evaluated using a high-throughput parallel sequencing-based approach. This is the first report on the characterization of the kefir community associated with a bacteriocin-producing strain. Sequencing data confirmed previous findings using culture dependent approaches that the microbiota of kefir milk and the starter grain are quite different while at the same time, establishing that the microbial diversity of the starter grain is not uniform.

Between 2005 and 2010 between 1100 and 1300 children were born each year in the UK to diagnosed HIV-positive women. Since

virtually all diagnosed women in the last decade have taken ART to reduce the risk of MTCT, almost all of these children are uninfected. However, this means there are, in 2011, over 11 000 HIV-exposed uninfected children in the UK whose mothers conceived on combination ART (cART), or started ART during pregnancy [5]. The number of children this website diagnosed with vertically acquired HIV infection in the UK increased from about 70 a year in the early 1990s to a peak of 152 in 2004, and declined to 82 in 2009 [6]. During the last decade, about two-thirds of newly diagnosed children were born abroad. Owing to the

increasing prevalence of maternal infection, combined with increasing maternal diagnosis rates and decreasing MTCT rates, the estimated number of infected children born in the UK has remained stable over the last decade, at about 30–40 a year. More than 300 children have also been reported, mostly in the early years of the epidemic, with non-vertically acquired infection, the majority from blood or blood products. Among HIV-positive children with follow-up care in the UK and Ireland, the rate of AIDS and mortality combined declined from 13.3 cases per 100 person years before 1997 to 2.5 per 100 person years in 2003–2006 [7]. With improving survival, the median age selleck of children in follow-up increased from 5 years in 1996 to 12 years in 2010, by which time over 300 young people had transferred to

adult care [8]. Pregnancies in vertically infected young women are now occurring [9]. Before the widespread implementation of the routine offer and recommendation of antenatal HIV screening in the UK, detection rates before delivery were poor. In the mid-1990s only about one-third of infected pregnant women were diagnosed, and most of those were aware of their infection status before they became pregnant [10]. In England, the routine offer and recommendation policy was implemented in 2000, and similar policies were subsequently adopted elsewhere in the UK. By the end of 2003, virtually all maternity units had implemented the antenatal screening policy, and over two-thirds had achieved >80% uptake, with about one-third reaching Thiamine-diphosphate kinase the 90% target [11]. Standards for monitoring antenatal screening were revised and updated in 2010 [12]. National uptake of antenatal HIV screening was reported to be 95% in 2008, up from 89% in 2005, and all regions reported at least 90% [13]. Between 2000 and 2004 the majority of HIV-positive women diagnosed before delivery were identified through antenatal screening. However, since 2005 the situation has reversed and in 2010 about three-quarters of women diagnosed before delivery were already aware of their infection before they conceived, many of them diagnosed in a previous pregnancy [5].

, 2006, 2007; Petkun et al., 2010). Surprisingly, several CBM3s appeared not to be associated with the cellulolytic system of this bacterium. Among these proteins, we discovered that Cthe_0059, Cthe_0267 and Cthe_0404 shared similar N-terminal segments (∼165 residues) MAPK Inhibitor Library concentration that resembled those of the B. subtilisσI-modulating factor RsgI (Fig. S1) and RsgI-like proteins in certain Firmicutes species

(data not shown). These ∼165-residue domains of the C. thermocellum hypothetical proteins were termed ‘RsgI-like domains’ here, and their sequences were used further in this study as queries to sequence similarity searches against the C. thermocellum genome databases (see next section). In lieu of a signal peptide motif, all nine RsgI-like proteins were predicted to contain three subdomains

– an ∼50- to 60-residue N-terminal region located inside the cell, followed by a single transmembrane helix (TMH) and a C-terminal region predicted to be localized on the cell exterior (Fig. 1). Putative TMHs were found to be located approximately at residues 55–85 in eight RsgI-like proteins. In one exception (Cthe_0260), a TMH carrying an ∼95 amino Protease Inhibitor Library ic50 acid (aa) insert was located at residues 150–172, and the gene encoding this protein is likely to be monocistronic without an upstream sigI-like gene (Fig. 2). Comparative sequence analysis of the RsgI-like domains from C. thermocellum with those of RsgI-like proteins from Bacillus and several other Clostridium species revealed a relatively high sequence divergence. Nevertheless, the three abovementioned subdomains were consistently predicted in all N-terminal sequences of the identified RsgI-like proteins (Fig. S1). Within the context of the present work, the N-terminal sequences that constitute the intracellular domain of approximately 40 different RsgI-like proteins were aligned, in order to establish a novel Pfam family, designated PF12791 or RsgI_N. Using this motif, approximately 150 RsgI-like proteins can be found in public protein databases (data not shown). Two other N-terminal subdomains of the RsgI-like proteins, a

TMH and a part of the predicted extracellular-sensing domain, also share a very weak, IMP dehydrogenase but recognizable conservation (Fig. S1). Analysis of the C. thermocellum ATCC 27405 genome (GenBank accession numbers CP000568 and NC_009012), using the ∼165 aa N-terminal sequences of the B. subtilis RsgI and its three C. thermocellum homologues as blast queries, revealed the presence of six additional ORFs (Fig. S1). Eight of the nine rsgI-like genes appeared to form bicistronic operons downstream of genes encoding proteins, which bear strong similarity to the B. subtilisσI factor (Fig. 2). Similar findings for the sigI- and corresponding rsgI-like genes were evident from analysis of the genomes of two other C. thermocellum strains: DSM 4150 (JW20) and DSM 2360 (LQR1). Extensive analysis of the B. subtilisσI and its putative C. thermocellum homologues revealed an atypical domain organization.

Since 2000, about 10 transmissions from diagnosed women have been recorded each year in the UK, against a background of increasing prevalence. However, another 20–30 UK-born children are also diagnosed each year, at various ages, whose mothers were not known to have

been infected at the time of their birth [5]. Trametinib nmr An audit of the circumstances surrounding nearly 90 perinatal transmissions in England in 2002–2005 demonstrated that over two-thirds of these infants were born to women who had not been diagnosed before delivery [14]. About half of those undiagnosed women had declined antenatal testing. A smaller proportion had tested negative: these women presumably seroconverted in pregnancy, or while they were still breastfeeding. In 2009, the National Screening Committee considered the introduction of a routine repeat screening test in the third trimester to identify seroconversions in pregnancy, but concluded that a universal re-offer should not be introduced at that time. However, it was reiterated that women who declined the initial offer should be re-offered screening at about 28 weeks’ gestation, and that repeat tests could be offered to any woman who was thought to be at continuing risk of infection, and to any woman who requested a second or subsequent test [12]. It is the responsibility of PF-02341066 nmr clinicians caring for women with HIV and their children to report them prospectively

to the NSHPC. Aggregated data tables from the UK and Ireland of ARV exposure and congenital malformations are regularly Baf-A1 molecular weight sent to the Antiretroviral Pregnancy Registry (APR). Individual prospective reports should also be made to the APR antenatally with postnatal follow-up. Antiretroviral Pregnancy Registry Research Park, 1011 Ashes Drive, Wilmington, NC 28405, USA In UK call Tel: 0800 5913 1359; Fax: 0800 5812 1658; For forms visit: www.apregistry.com This is the UK and Ireland’s surveillance system for obstetric and paediatric HIV, based at the Institute of Child Health, University College London. HIV-positive children and children born to HIV-positive women are reported through the British Paediatric

Surveillance Unit of the Royal College of Paediatrics and Child Health, or in the case of some units with large caseloads, direct to the NSHPC. Diagnosed pregnant women are reported prospectively through a parallel reporting scheme run under the auspices of the Royal College of Obstetricians and Gynaecologists. Longer-term data on infected children are subsequently collected through the Collaborative HIV Paediatric Study (CHIPS). For further information see the NSHPC website (http://www.nshpc.ucl.ac.uk), the CHIPS website (http://www.chipscohort.ac.uk) or email NSHPC ([email protected]). “
“The role of α-ketoglutarate (KG) in the detoxification of reactive oxygen species (ROS) has only recently begun to be appreciated.

Supplementation of diet with dairy products fermented with LAB has the potential to reduce serum cholesterol levels in humans and animals (Pulusoni & Rao, 1983). A significant decrease in serum cholesterol level in rats fed milk fermented with L. acidophilus has been reported (Grunewald, 1982). Mann (1977) showed that large dietary intake of yogurt lowered the cholesterolemia

in humans. Experiments by Gilliland et al. Fulvestrant order (1985) have shown that dietary elevation of plasma cholesterol levels can be prevented by the introduction of a L. acidophilus strain that is bile resistant and assimilates cholesterol. These findings were supported by Pereira & Gibson (2002) who demonstrated that selleck products probiotic strains were able to assimilate cholesterol in the presence

of bile into their cellular membranes. Results, however, were influenced greatly by the bacterial growth stage, and inoculum using resting cells did not interact with cholesterol as also shown by studies conducted by Dambekodi & Gilliland (1998). St-Onge et al. (2000) extensively reviewed the existing studies from animal and human studies which detected that moderate cholesterol lowering was attributable to the consumption of fermented products containing probiotic bacteria. Studies by Gopal et al. (1996) also showed cholesterol removal by Bifidobacterium spp. and L. acidophilus. The possible mechanisms of action of probiotics are cholesterol assimilation by bacteria, deconjugation of bile salts, cholesterol binding to bacterial cell walls, and reduction in cholesterol biosynthesis (Pulusoni & Rao, 1983; Pereira & Gibson, 2002). The role of gut flora in the pathology of insulin resistance (type 2 diabetes) and obesity has been well documented by Ley et al. (2005). Animal and human studies have suggested that gut flora enhances the body weight gain and increases the insulin resistance, and these phenotypes

are Oxalosuccinic acid transmittable with gut flora during the implantation studies of microbiota from obese to normal and germ-free mice (Ley et al., 2006; Turnbaugh et al., 2006). The mechanisms associated with gut flora–mediated pathology of obesity and diabetes are through (1) increased energy harvest, (2) increased blood LPS levels (endotoxemia), and (3) low-grade inflammation (Delzenne et al., 2011). Therefore, modulation of gut flora has been considered as a potential target to treat against obesity and diabetes. Probiotics are novel gut flora modulators, and their role in the prevention of and treatment for diabetes and obesity has been implicated in recent past by Yadav et al. (2007a, b, 2008). Yadav et al.

, 1989). This strategy may be particularly relevant to tetronasin, because it has a much greater affinity for divalent, particularly Ca2+, than monovalent ions, in contrast to other feedlot ionophores, including monensin and lasalocid (Grandjean & Laszlo, 1983). Ca2+ ions are present at much lower concentrations (0.7–11.2 mM) than Na+ (77–157 mM) or K+ (22–68 mM) in the rumen (Durand & Kawashima,

1979); therefore, it seems possible that the potency of an ionophore that carries Ca2+ ions may be more readily enhanced than those that carry the more abundant monovalent ions. The aim of the experiments described in this paper was to determine how varying the ionic composition of the medium affects the toxicity of monensin Selleck Metformin and tetronasin to selected species of ruminal bacteria and ion gradients in sensitive bacteria. Prevotella albensis

M384 (DSM 11370), Lactobacillus casei LB17 and Streptococcus bovis C277 were isolated from the rumen of sheep and are maintained in the culture collection at the Rowett Institute. Eubacterium ruminantium 2388 was originally obtained from the National Collection of Dairy Organisms, Reading. The liquid form of general-purpose, ruminal fluid–containing medium 2 of Hobson (Hobson, 1969) was used as the basal medium for growth experiments with all four bacteria. The C sources contained in this medium are glucose, maltose, cellobiose and lactate. Modifications to the mineral content were made by adding more K+ as phosphate salts and Na+ and Ca+ as chloride salts. The final concentrations of the cations in the control and amended media, CH5424802 solubility dmso respectively, were as follows: Na+, 137 and 172 mM; K+, 19 and 35 mM; Ca2+, 2.8 and 7.4 mM. In experiments to determine Δp and ion gradients in E. ruminantium, cation concentrations

in the medium were Thalidomide 19 mM K+, 149 mM Na+ and 2.8 mM Ca2+. Media were prepared, and cultures were maintained, under O2-free CO2. Growth and incubation temperature was 39 °C. A fresh overnight culture was used to inoculate (7%, v/v) media in Hungate tubes to which ionophores had been added in ethanolic solution (1 μL mL−1) before autoclaving. The concentration of ionophores was serially doubled in these tubes, as described previously (Newbold et al., 1988). Growth was measured by optical density at 650 nm after 48 h. The toxicity of the ionophore was assessed by determining the concentration of ionophore at which growth was inhibited by 50% (IC50). Tetronasin or monensin was added to late-exponential phase cultures of E. ruminantium or cultures that had been in stationary phase for 30 h as ethanolic solutions at 0.064 and 0.256 μg mL−1. Ethanol (1 μL mL−1) was added to control incubations. Intracellular pH was determined 2 h after the addition of ionophore by the distribution of radiolabelled benzoic acid (Rottenberg, 1979). Culture (1 mL) was incubated under CO2 with [carboxy-14C] benzoate (0.25 μCi, 22 mCi mmol−1) and 3H2O (2.

However, other bacterial skills such as hydrogen peroxide, bacteriocin and acid production,

and resistance to antibiotics, selleck screening library low pH, and spermicidal compounds, among other properties, have to be taken into account to do the correct selection of a vaginal probiotic (Martín et al., 2008a, b). Besides, nowadays, there is a tendency to use a combination of various strains to cover the whole range of characteristics required in a vaginal probiotic. Surface and secreted protein extracts are important to detect potential mucin-binding proteins. Among the surface proteins, ornithine carbamoyltransferase (R16) and amino acid ABC transporter periplasmic protein and high-affinity cystine-binding protein (both in band R126) of L. vaginalis Lv67 bound mucin. High-affinity cystine-binding proteins are surface proteins that are frequently suggested to be putative adhesions. For instance, BspA, a cystine-binding protein of Lactobacillus fermentum

BR11, has been described as a collagen-binding protein (Hung et al., 2005). Among the secreted protein fraction, an extracellular form of GADPH was able to bind mucin. The presence of surface-associated GAPDH is well known in a huge variety of microorganisms (Sánchez et al., 2008). As a secreted form, GAPDH has been shown Selleckchem PD0325901 to be a plasminogen- and fibrinogen-binding protein in E. coli (Egea et al., 2007). Furthermore, Neissera meningitidis GAPDH-deficient mutant showed a significant reduction in adhesion to human epithelial and endothelial cells compared to the wild-type and complemented mutant (Tunio et al., 2010). However, care should be taken in the interpretation of these results, because the only criteria applied for identification have been the comparison between

their electrophoretical mobility with respect to the surface protein profiles. In conclusion, the ability to adhere to mucin and to the epithelial cell cultures seems to be strain specific although some association with origin has been found for HT-29 cells. Some of the strains analyzed have good capacities on the models tested 17-DMAG (Alvespimycin) HCl being good candidates to be used as vaginal probiotics alone or with other lactobacilli. The data presented in this work also suggest that certain extracellular proteins produced by intestinal and vaginal lactobacilli could act as potential mediators in the molecular interaction with both epithelial cells and pathogens. Further research is needed to establish the precise molecular mechanism of action of these proteins using convenient genetically modified strains. This work was supported by the CICYT grant AGL2010-15097 and RM2010-00012-00-00 from the Ministry of Science and Innovation (Spain) and the FEDER Plan. R.M. was holder of a scholarship from FICYT (Principado de Asturias), and B.S. is holder of a Juan de la Cierva postdoctoral contract from the Ministry of Science and Innovation (Spain). “
“Acquisition of a mature dendritic morphology is critical for neural information processing.

3). Notably, Compound Library molecular weight qChIP experiments revealed that CtrA occupied the fliF promoter at similar levels in ΔfliG and ΔtipF (99 ± 4% and 80 ± 6% relative to WT, respectively) (Fig. 3), indicating that the increase in class II flagellar gene transcription

in ΔfliG and ΔtipF mutants is not due to an elevated occupancy of CtrA at the promoter(s). Consistent with fliF upregulation seen in ΔfliG and ΔtipF by the β-galactosidase assay, qChIP revealed that the occupancy of FlbD (repressing class II genes) was decreased at the fliF promoter in the ΔfliG (45 ± 1%) and ΔtipF (51 ± 8%) strains (Fig. 4a). FliX, the regulatory factor that links the status of flagellar assembly to FlbD activity (Muir & Gober, 2005), was present at the class II promoters, at higher levels than WT, in ΔfliG (170

± 7%) and ΔtipF (144 ± 4%), consistent with the decreased levels of FlbD at the fliF promoter (Fig. 4a). FliX has been shown to interact with FlbD and block its access to enhancer DNA sequences in vitro (Dutton et al., 2005), and this new qChIP-based approach further suggests that FliX occupies the promoters to modulate FlbD activity at the class II-fliF promoter in vivo. Next, we determined the presence of FlbD and FliX at the class III-flgE and class IV-fljL promoters. qChIP showed that FlbD occupancy at the class III-flgE promoter was reduced in ΔfliG (68 ± 5%) and ΔtipF strains (75 ± 10%) (Fig. 4b), while that of FliX was elevated (155 ± 5% in ΔfliG and 227 ± 9% in ΔtipF) (Fig. 4b). These data demonstrate that the ΔtipF

strain is similar to the ΔfliG mutant strain with regard to the occurrence of FlbD LEE011 nmr and FliX at the flgE promoter. It is further consistent with the view that FliX is also present at class III promoters to block FlbD access. The class IV-fljL promoter, however, had an abundance of FlbD similar to WT (123 ± 8%) and decreased levels of FliX (64 ± 7%) in ΔtipF, while the ΔfliG mutant had decreased FlbD (20 ± 2%) and increased FliX (200 ± 9%) (Fig. 4c). These results, also supported by the β-galactosidase promoter-probe assays (Fig. 2), suggest that, unlike FliG, TipF is not necessary to confer the transcription of class IV flagellar genes. Both flbD∷Tn5 and fliX∷Tn5 mutant strains were included as controls. Accordingly, FlbD was considerably Epigenetics inhibitor decreased at the fliF (7 ± 1%), flgE (22 ± 3%), and fljL (7 ± 1%) promoters in the flbD∷Tn5 mutant compared with WT (Fig. 4a–c). Similarly, the fliX∷Tn5 mutant had decreased levels of FliX at the fliF (8 ± 2%), flgE (15 ± 1%), and fljL (15 ± 1%) promoters (Fig. 4a–c). The ΔtipN mutant possessed lowered levels of FlbD at the fliF (69 ± 5%) and flgE (57 ± 3%) promoters, while fljL (103 ± 9%) was near WT levels (Fig. 4a–c). FliX was present at the fliF (109 ± 8%), flgE (166 ± 9%), and fljL (129 ± 25%) promoters in the ΔtipN mutant relative to WT. Because the ΔtipN mutant frequently possesses multiple flagella that are often misplaced (Huitema et al., 2006; Lam et al.

To identify proteins other than gingipains secreted by the PorSS, we compared the proteomes of P. gingivalis strains kgp rgpA rgpB (PorSS-proficient strain) and kgp rgpA rgpB porK (PorSS-deficient strain) using two-dimensional gel Selleckchem Navitoclax electrophoresis and peptide-mass fingerprinting. Sixteen spots representing 10 different proteins were present in the particle-free culture supernatant of

the PorSS-proficient strain but were absent or faint in that of the PorSS-deficient strain. These identified proteins possessed the C-terminal domains (CTDs), which had been suggested to form the CTD protein family. These results indicate that the PorSS is used for secretion of a number of proteins other than gingipains and that the CTDs of the proteins are associated with the PorSS-dependent secretion. The Gram-negative bacterium Porphyromonas gingivalis, a major pathogen of www.selleckchem.com/products/R788(Fostamatinib-disodium).html periodontal disease, possesses a number of virulence factors, including fimbriae, hemagglutinins, lipopolysaccharides

and proteinases. Extracellular and surface proteinases with high hydrolytic activities named gingipains are of particular importance as they have the ability to destroy periodontal tissue directly and/or indirectly (Potempa et al., 2000; Andrian et al., 2007). Gingipains are encoded by three separate genes, rgpA, rgpB and kgp, on the P. gingivalis chromosome (Curtis et al., 1999). The kgp and rgpA genes encode polyproteins comprising the signal peptide, propeptide, Lys-

and Arg-specific proteinase domains, adhesin domains and C-terminal Orotidine 5′-phosphate decarboxylase domain (CTD). The rgpB gene encodes a protein comprising the signal peptide, propeptide, Arg-specific proteinase domain and CTD. These proteins are synthesized as polyproteins in the cytoplasm, are translocated across two membranes, inner and outer membranes, and secreted onto the bacterial cell surface. In our previous studies (Sato et al., 2010; Shoji et al., 2011) we found that gene products of rgpA, rgpB and kgp were translocated across the outer membrane by the Por secretion system (PorSS) in which porK, porL, porM, porN, porO, porP, porQ, porT, porU, porV (PG27, lptO), porW and sov genes were involved. Expression of some of these genes is regulated by a two-component system, the PorX response regulator and PorY histidine sensor kinase (Sato et al., 2010). Primary gene products of rgpA, rgpB and kgp have common motifs in their CTD regions. The P. gingivalis genome encodes a number of putative CTD-containing proteins (Seers et al., 2006). Nguyen et al. (2007) showed that CTD-containing proteins were also found in predicted proteins of other bacteria in the Bacteroidetes phylum, such as Prevotella intermedia and Tannerella forsythia. Among P.

5–1 mm in diameter, which appeared during the performance of the agar shake method, to modified BM containing betaine as a substrate. Strain Esp was isolated from agar shakes supplemented with lactate. New cocultivation of strain Sp3T and the

methanogen Methanoculleus, strain MAB1, resulted in acetate degradation and this website methane production, indicating the acetate-oxidizing capability of Sp3T. Despite the first appearance in fructose-supplemented agar shakes, neither strain Sp3T nor strain Esp used this compound as a substrate. However, both the strains utilized ethanol, betaine and lactate. In addition, strain Esp used cysteine, pyruvate and raffinose. For all substrates, yeast extract was required for growth. Both strains to

some extent also grew only with yeast extract, which could be one possible explanation for colonies appearing in fructose-supplemented agar shakes. Compounds not supporting the growth of either strain included formate, acetate (25 mM), pyruvate, malate, citrate, benzoic acid, fumarate, methanol, 2-propanol, 1,2-propanediol, 1-butanol, 2,3-butanediol, glycerol, glucose, fructose, galactose, sucrose, mannose, maltose, lactose, cellobiose, Selleck Dabrafenib mannitol, ribose, salicin, sorbitol, leucine, proline, acetoine, arabinose, methylamine, dimethylamine, asparagine, histidine, methionine, serine, phenylalanine, casamino acids, tryptone, ethylene glycol (5 mM), syringate (2 mM), vanillate (3 mM), xylose, CO (101 kPa) and H2/CO2 (80 : 20 v/v, 81 kPa). In the presence Idoxuridine of acetate (25 mM), sulfate, sulfur, fumarate, glycine, nitrate (10 mM), FeCl3 (0.1 M), thiosulfate (20 mM), nitrite and sulfite (2.5 mM) were not used as electron acceptors. The narrow substrate spectrum of strain Sp3T is in correspondence with the previously characterized syntrophic acetate-oxidizing

bacteria T. phaeum and C. ultunense. In contrast, the thermophilic syntrophic acetate-oxidizing bacterium T. lettingae is able to use a wide range of substrates for growth. In pure culture, strain Sp3T grew at 25–40 °C, pH 6.0–8.0 (initial value), and up to 0.6 M NH4Cl. Strain Esp grew at 25–45 °C and initial pH 5.0–9.0, and tolerated up to 0.7 M NH4Cl. The relatively high ammonium tolerance of the strains probably confers the bacteria with a competitive advantage in ammonia-stressed systems. In biogas processes operating at mesophilic temperatures, high ammonia levels have been shown to be one important factor regulating the shift from the aceticlastic mechanism to syntrophic acetate oxidation (Schnürer et al., 1999; Schnürer & Nordberg, 2008). A strong inhibitory effect of ammonia on the aceticlastic methanogens in comparison with the hydrogenotrophs (Koster & Lettinga, 1984; Sprott & Patel, 1986) is the likely cause of this shift. Despite several months of growth under optimal conditions, strain Sp3T achieved an extremely low cell density, which impeded the performance of chemotaxonomic analyses of the strain.