Vaginal Microbial Environment Skews Macrophage Polarization and Contributes to Cervical Cancer Development.

As a common female reproductive system malignancy, cervical cancer (CC) disturbs numerous women's health. This study demonstrates the role of the vaginal microbial environment (Peptostreptococcus anaerobius) in cervical cancer. Functional assays, including cell proliferation assay, tube formation assay, and immunofluorescence staining, revealed the effect of Peptostreptococcus anaerobius-treated macrophages on cell proliferation and the angiogenesis process. The tube formation assay disclosed the function of Peptostreptococcus anaerobius-treated macrophages on angiogenesis. In vivo assays were also established to explore the impact of Peptostreptococcus anaerobius-treated macrophages on tumor migration. The results revealed that Peptostreptococcus anaerobius-induced macrophages boosted cervical cancer migration and angiogenesis both in vitro and in vivo. Then, this study unveiled that Peptostreptococcus anaerobius-induced macrophage secreted VEGF to stimulate the angiogenesis in cervical cancer. As a whole, Peptostreptococcus anaerobius-induced macrophage facilitates cervical cancer development through modulation of VEGF expression.

Peptostreptococcus anaerobius promotes colorectal carcinogenesis and modulates tumour immunity.

Emerging evidence implicates a role of the gut microbiota in colorectal cancer (CRC). Peptostreptococcus anaerobius (P. anaerobius) is an anaerobic bacterium selectively enriched in the faecal and mucosal microbiota from patients with CRC, but its causative role and molecular mechanism in promoting tumorigenesis remain unestablished. We demonstrate that P. anaerobius adheres to the CRC mucosa and accelerates CRC development in ApcMin/+ mice. In vitro assays and transmission electron microscopy revealed that P. anaerobius selectively adheres to CRC cell lines (HT-29 and Caco-2) compared to normal colonic epithelial cells (NCM460). We identified a P. anaerobius surface protein, putative cell wall binding repeat 2 (PCWBR2), which directly interacts with colonic cell lines via α2/ß1 integrin, a receptor frequently overexpressed in human CRC tumours and cell lines. Interaction between PCWBR2 and integrin α2/ß1 induces the activation of the PI3K-Akt pathway in CRC cells via phospho-focal adhesion kinase, leading to increased cell proliferation and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. NF-κB in turn triggers a pro-inflammatory response as indicated by increased levels of cytokines, such as interleukin-10 and interferon-γ in the tumours of P. anaerobius-treated ApcMin/+ mice. Analyses of tumour-infiltrating immune cell populations in P. anaerobius-treated ApcMin/+ mice revealed significant expansion of myeloid-derived suppressor cells, tumour-associated macrophages and granulocytic tumour-associated neutrophils, which are associated with chronic inflammation and tumour progression. Blockade of integrin α2/ß1 by RGDS peptide, small interfering RNA or antibodies all impair P. anaerobius attachment and abolish P. anaerobius-mediated oncogenic response in vitro and in vivo. Collectively, we show that P. anaerobius drives CRC via a PCWBR2-integrin α2/ß1-PI3K-Akt-NF-κB signalling axis and identify the PCWBR2-integrin α2/ß1 axis as a potential therapeutic target for CRC.

Indoleacrylic Acid Produced by Commensal Peptostreptococcus Species Suppresses Inflammation.

Host factors in the intestine help select for bacteria that promote health. Certain commensals can utilize mucins as an energy source, thus promoting their colonization. However, health conditions such as inflammatory bowel disease (IBD) are associated with a reduced mucus layer, potentially leading to dysbiosis associated with this disease. We characterize the capability of commensal species to cleave and transport mucin-associated monosaccharides and identify several Clostridiales members that utilize intestinal mucins. One such mucin utilizer, Peptostreptococcus russellii, reduces susceptibility to epithelial injury in mice. Several Peptostreptococcus species contain a gene cluster enabling production of the tryptophan metabolite indoleacrylic acid (IA), which promotes intestinal epithelial barrier function and mitigates inflammatory responses. Furthermore, metagenomic analysis of human stool samples reveals that the genetic capability of microbes to utilize mucins and metabolize tryptophan is diminished in IBD patients. Our data suggest that stimulating IA production could promote anti-inflammatory responses and have therapeutic benefits.

Selection and characterization of an anaerobic microbial consortium with high adaptation to crude glycerol for 1,3-propanediol production.

Crude glycerol is an ideal feedstock for bioproduction of 1,3-propanediol (1,3-PDO) while pure culture always shows low substrate tolerance and limited productivity. In this study, an anaerobic microbial consortium for conversion of crude glycerol was selected and its 1,3-PDO production capacity was evaluated. The consortium was obtained from anaerobic activated sludge by 19 serial transfers and mainly consisted of 94.64% Clostridiaceae and 4.47% Peptostreptococcaceae. The consortium adapted well with high glycerol concentration of 120 g/L as well as wide substrate concentration fluctuation from 15 to 80 g/L, producing 60.61 and 82.66 g/L 1,3-PDO in the batch and fed-batch fermentation, with the productivity of 3.79 and 3.06 g/(L∙h), respectively, which are among the best results published so far. Furthermore, mini consortia isolated by serial dilution exhibited similar microbial composition but gradually decreasing tolerance to crude glycerol. Four randomly selected Clostridium butyricum displayed different substrate tolerance and insufficient 1,3-PDO production capacity. This work demonstrated that the high adaptation to crude glycerol of the consortium was the collaborative effort of different individuals.

Moderate dietary protein restriction alters the composition of gut microbiota and improves ileal barrier function in adult pig model.

This study was conducted to investigate impacts of dietary protein levels on gut bacterial community and gut barrier. The intestinal microbiota of finishing pigs, fed with 16%, 13% and 10% crude protein (CP) in diets, respectively, were investigated using Illumina MiSeq sequencing. The ileal bacterial richness tended to decrease when the dietary protein concentration reduced from 16% to 10%. The proportion of Clostridium_sensu_stricto_1 in ileum significantly decreased, whereas Escherichia-Shigella increased with reduction of protein concentration. In colon, the proportion of Clostridium_sensu_stricto_1 and Turicibacter increased, while the proportion of RC9_gut_group significantly decreased with the dietary protein reduction. Notably, the proportion of Peptostreptococcaceae was higher in both ileum and colon of 13% CP group. As for metabolites, the intestinal concentrations of SCFAs and biogenic amines decreased with the dietary protein reduction. The 10% CP dietary treatment damaged ileal mucosal morphology, and decreased the expression of biomarks of intestinal cells (Lgr5 and Bmi1), whereas the expression of tight junction proteins (occludin and claudin) in 13% CP group were higher than the other two groups. In conclusion, moderate dietary protein restriction (13% CP) could alter the bacterial community and metabolites, promote colonization of beneficial bacteria in both ileum and colon, and improve gut barrier function.

Filifactor alocis collagenase can modulate apoptosis of normal oral keratinocytes.

To successfully colonize host cells, pathogenic bacteria must circumvent the host's structural barrier such as the collagen-rich extracellular matrix (ECM), as a preliminary step to invasion and colonization of the periodontal tissue. Filifactor alocis possesses a putative Peptidase U32 family protein (HMPREF0389_00504) with collagenase activity that may play a significant role in colonization of host tissue during periodontitis by breaking down collagen into peptides and disruption of the host cell. Domain architecture of the HMPREF0389_00504 protein predicted the presence of a characteristic PrtC-like collagenase domain, and a peptidase domain. Our study demonstrated that the recombinant F. alocis peptidase U32 protein (designated PrtFAC) can interact with, and degrade, type I collagen, heat-denatured collagen and gelatin in a calcium-dependent manner. PrtFAC decreased viability and induced apoptosis of normal oral keratinocytes (NOKs) in a time and dose-dependent manner. Transcriptome analysis of NOK cells treated with PrtFAC showed an upregulation of the genes encoding human pro-apoptotic proteins: Apoptotic peptidase activating factor 1 (Apaf1) cytochrome C, as well as caspase 3 and caspase 9, suggesting the involvement of the mitochondrial apoptotic pathway. There was a significant increase in caspase 3/7 activity in NOK cells treated with PrtFAC. Taken together, these findings suggest that F. alocis PrtFAC protein may play a role in the virulence and pathogenesis of F. alocis.

Degradation of spent craft brewer's yeast by caprine rumen hyper ammonia-producing bacteria.

UNLABELLED: Spent yeast from craft beers often includes more hops (Humulus lupulus L.) secondary metabolites than traditional recipes. These compounds include α- and ß- acids, which are antimicrobial to the rumen hyper ammonia-producing bacteria (HAB) that are major contributors to amino acid degradation. The objective was to determine if the hops acids in spent craft brewer's yeast (CY; ~ 3·5 mg g(-1) hops acids) would protect it from degradation by caprine rumen bacteria and HAB when compared to a baker's yeast (BY; no hops acids). Cell suspensions were prepared by harvesting rumen fluid from fistulated goats, straining and differential centrifugation. The cells were re-suspended in media with BY or CY. After 24 h (39°C), HAB were enumerated and ammonia was measured. Fewer HAB and less ammonia was produced from CY than from BY. Pure culture experiments were conducted with Peptostreptococcus anaerobiusBG1 (caprine HAB). Ammonia production by BG1 from BY was greater than from CY. Ammonia production was greater when exogenous amino acids were included, but similar inhibition was observed in CY treatments. These results indicate that rumen micro-organisms deaminated the amino acids in CY to a lesser degree than BY. SIGNIFICANCE AND IMPACT OF THE STUDY: Spent brewer's yeast has long been included in ruminant diets as a protein supplement. However, modern craft beers often include more hops (Humulus lupulus L.) than traditional recipes. These compounds include α- and ß- acids, which are antimicrobial to the rumen hyper ammonia-producing bacteria (HAB) that are major contributors to amino acid degradation. This study demonstrated that hops acids in spent craft brewer's yeast protected protein from destruction by HABin vitro. These results suggest that the spent yeast from craft breweries, a source of beneficial hops secondary metabolites, could have value as rumen-protected protein.

Biodegradation of kraft lignin by a newly isolated anaerobic bacterial strain, Acetoanaerobium sp. WJDL-Y2.

UNLABELLED: An anaerobic kraft lignin (KL)-degrading bacterial strain was isolated from sludge of a pulp and paper mill. It was characterized as Acetoanaerobium sp. WJDL-Y2 by 16S rRNA gene sequencing. The maximum KL degradation capability of strain Y2 was determined to be 24·9% on a COD basis under an optimal condition with temperature of 31·5°C, initial pH of 6·8 and KL to nitrogen (as NH4 Cl) ratio of 6·5 by mass. Growth kinetic studies showed that the KL tolerance of strain Y2 was relatively high (Ki  = 8120·45 mg l(-1) ). Analysing KL degradation products by GC-MS revealed the formation of low-molecular-weight aromatic compounds (LMWACs), including benzene-propanoic acid, syringic acid and ferulic acid. This indicates that strain Y2 can oxidize lignin structure's p-hydroxyphenyl (H) units, guaiacyl (G) units and syringyl (S). In addition, the inoculated sample also contained low-molecular acid compounds, such as hexanoic acid, adipic acid and 2-hydroxybutyric acid, further validating strain Y2's ability to degrade KL. SIGNIFICANCE AND IMPACT OF THE STUDY: Kraft lignin containing effluents discharged from pulp and paper industries causes serious environmental pollution in developing countries. Due to the immense environmental adaptability and biochemical versatility, bacterial ligninolytic potential deserve to be studied for application in effluent treatment of pulp and paper industry. In this study, an anaerobic lignin-degrading bacterium, Acetoanaerobium sp. WJDL-Y2 (accession no. KF176997),was isolated from the sludge of a pulp and paper mill. Strain Y2 can play an important role in treating pulp and paper wastewater, as well as breaking down materials for biofuel and chemical production.

Antipsicóticos para la esquizofrenia: paradigma de los medicamentos psiquiátricos / Antipsychotics for schizophrenia: the paradigm of psychiatric drugs

Los antipsicóticos no parecen revertir las causas de la esquizofrenia y, aunque son fármacos que pueden aliviar los síntomas a corto y mediano plazo, a largo plazo pueden no ser beneficiosos e incluso ser contraproducentes. Su empleo debería limitarse a situaciones agudas con agitación y tensión incapacitante. Presentan considerables efectos adversos y, ante la negativa de una persona a seguir tomándolos, adoptar una estrategia de reducción de daños apoyando y supervisando la retirada puede ser preferible a la coerción. Existen alternativas a los neurolépticos. Los prescriptores deberían estar más atentos y considerar las valoraciones que los usuarios hacen de sus efectos. El apego a las guías de tratamiento es escaso, seguramente por basarse en ensayos clinicos de calidad deficente, que deben mejorar y prolongarse en el tiempo. La raíz del problema probablemente se encuentra en la tautología sobre la etiología y naturaleza biológica de lo que llaman esquizofrenia, que realmente no parece ser más que un constructo ideológico-comercial.(AU)

Antipsychotic drugs do not appear to reverse the causes of schizophrenia, and although they can relieve symptoms in the short to medium term, in the long term they may not be beneficial and could even be counterproductive. Their use should be limited to acute situations in which agitation and tension is disabling. The drugs have significant adverse effects, and given the refusal of a person to continue taking them, a harm reduction strategy to support and monitor the withdrawal may be preferable to coercion. There are alternatives to neuroleptics. Prescribers should be more vigilant and consider the assessments of users regarding the drugs effects. Adherence to treatment guidelines is low, probably because the guidelines are based on clinical trials of deficient quality which consequently should be improved and extended over a greater period of time. The root of the problem is likely the tautology on the etiology and biological nature of what is known as schizophrenia, which in fact does not seem to be more than a commercial and ideological construct.(AU)

Antipsicóticos para la esquizofrenia: paradigma de los medicamentos psiquiátricos / Antipsychotics for schizophrenia: the paradigm of psychiatric drugs

Los antipsicóticos no parecen revertir las causas de la esquizofrenia y, aunque son fármacos que pueden aliviar los síntomas a corto y mediano plazo, a largo plazo pueden no ser beneficiosos e incluso ser contraproducentes. Su empleo debería limitarse a situaciones agudas con agitación y tensión incapacitante. Presentan considerables efectos adversos y, ante la negativa de una persona a seguir tomándolos, adoptar una estrategia de reducción de daños apoyando y supervisando la retirada puede ser preferible a la coerción. Existen alternativas a los neurolépticos. Los prescriptores deberían estar más atentos y considerar las valoraciones que los usuarios hacen de sus efectos. El apego a las guías de tratamiento es escaso, seguramente por basarse en ensayos clinicos de calidad deficente, que deben mejorar y prolongarse en el tiempo. La raíz del problema probablemente se encuentra en la tautología sobre la etiología y naturaleza biológica de lo que llaman esquizofrenia, que realmente no parece ser más que un constructo ideológico-comercial.

Antipsychotic drugs do not appear to reverse the causes of schizophrenia, and although they can relieve symptoms in the short to medium term, in the long term they may not be beneficial and could even be counterproductive. Their use should be limited to acute situations in which agitation and tension is disabling. The drugs have significant adverse effects, and given the refusal of a person to continue taking them, a harm reduction strategy to support and monitor the withdrawal may be preferable to coercion. There are alternatives to neuroleptics. Prescribers should be more vigilant and consider the assessments of users regarding the drugs' effects. Adherence to treatment guidelines is low, probably because the guidelines are based on clinical trials of deficient quality which consequently should be improved and extended over a greater period of time. The root of the problem is likely the tautology on the etiology and biological nature of what is known as schizophrenia, which in fact does not seem to be more than a commercial and ideological construct.

A kinetic study of domain swapping of Protein L.

Domain swapping of the B1 domain of Protein L isolated from Peptostreptococcus magnus can be induced by rational mutation. We show that the monomeric and the domain swapped dimeric forms of the G55A mutant of Protein L are directly observable by solution NMR spectroscopy under equilibrium conditions. The kinetics of the domain swapping process can be characterized by real-time NMR spectroscopic techniques, and the free energy landscape for domain swapping of Protein L can be probed by variation of denaturant concentration. Our data suggest that domain swapping of Protein L proceeds through a compact transition state, with an accessible surface area that is similar in size to the transition state for folding and unfolding. It is thus conceivable that domain swapping and folding of Protein L are mechanistically related at the level of their rate-limiting step(s), which might represent a branching point along the folding pathway.

In vivo VL-targeted microbial superantigen induced global shifts in the B cell repertoire.

To subvert host defenses, some microbial pathogens produce proteins that interact with conserved motifs in V regions of B cell Ag receptor shared by large sets of lymphocytes, which define the properties of a superantigen. Because the clonal composition of the lymphocyte pool is a major determinant of immune responsiveness, this study was undertaken to examine the in vivo effect on the host immune system of exposure to a B cell superantigen, protein L (PpL), a product of the common commensal bacterial species, Finegoldia magna, which is one of the most common pathogenic species among Gram-positive anaerobic cocci. Libraries of Vκ L chain transcripts were generated from the spleens of control and PpL-exposed mice, and the expressed Vκ rearrangements were characterized by high-throughput sequencing. A total of 120,855 sequencing reads could be assigned to a germline Vκ gene, with all 20 known Vκ subgroups represented. In control mice, we found a recurrent and consistent hierarchy of Vκ gene usage, as well as patterns of preferential Vκ-Jκ pairing. PpL exposure induced significant targeted global shifts in repertoire with reduction of Vκ that contain the superantigen binding motif in all exposed mice. We found significant targeted reductions in the expression of clonotypes encoded by 14 specific Vκ genes with the predicted PpL binding motif. These rigorous surveys document the capacity of a microbial protein to modulate the composition of the expressed lymphocyte repertoire, which also has broad potential implications for host-microbiome and host-pathogen relationships.

Crystal structure of a mucus-binding protein repeat reveals an unexpected functional immunoglobulin binding activity.

Lactobacillus reuteri mucus-binding protein (MUB) is a cell-surface protein that is involved in bacterial interaction with mucus and colonization of the digestive tract. The 353-kDa mature protein is representative of a broadly important class of adhesins that have remained relatively poorly characterized due to their large size and highly modular nature. MUB contains two different types of repeats (Mub1 and Mub2) present in six and eight copies, respectively, and shown to be responsible for the adherence to intestinal mucus. Here we report the 1.8-A resolution crystal structure of a type 2 Mub repeat (184 amino acids) comprising two structurally related domains resembling the functional repeat found in a family of immunoglobulin (Ig)-binding proteins. The N-terminal domain bears striking structural similarity to the repeat unit of Protein L (PpL) from Peptostreptococcus magnus, suggesting binding in a non-immune Fab-dependent manner. A distorted PpL-like fold is also seen in the C-terminal domain. As with PpL, Mub repeats were able to interact in vitro with a large repertoire of mammalian Igs, including secretory IgA. This hitherto undetected activity is consistent with the current model that antibody responses against commensal flora are of broad specificity and low affinity.

Bacterial conversion of secoisolariciresinol and anhydrosecoisolariciresinol.

AIMS: It has been investigated whether secoisolariciresinol (SECO) and anhydrosecoisolariciresinol (AHS), an acid degradation product of SECO, could be fermented in a similar way, and to a similar extent, by members of the intestinal microbiota. METHODS AND RESULTS: AHS and SECO were demethylated by Peptostreptococcus productus, Eubacterium limosum and Clostridium methoxybenzovorans. These bacteria have been identified as members of the human intestinal flora or closely related species. Demethylated AHS and demethylated SECO were purified by preparative RP-HPLC, and subsequently subjected to fermentation with Eggerthella lenta, Clostridium scindens and Clostridium hiranonis. Eggerthella lenta efficiently dehydroxylated demethylated SECO to enterodiol, whereas the other bacteria showed no dehydroxylation activity. CONCLUSIONS: The conversion of the diol structure of SECO into the furan ring in AHS did not influence the demethylation capability of the tested bacteria. The results also showed that the extent of dehydroxylation of demethylated AHS was much lower than that of demethylated SECO. SIGNIFICANCE AND IMPACT OF THE STUDY: Plant lignans are converted into bioactive mammalian lignans by the human intestinal bacteria. This study showed that the modification of plant lignans resulted in the formation a new type of mammalian lignan.

The ability of non-bacteriocin producing Streptococcus bovis strains to bind and transfer bovicin HC5 to other sensitive bacteria.

Streptococcus bovis HC5 produces a broad spectrum lantibiotic (bovicin HC5), but S. bovis JB1 does not have antimicrobial activity. Preliminary experiments revealed an anomaly. When S. bovis JB1 cells were washed in stationary phase S. bovis HC5 cell-free culture supernatant, the S. bovis JB1 cells were subsequently able to inhibit hyper-ammonia producing ruminal bacteria (Clostridium sticklandii, Clostridium aminophilum and Peptostreptococcus anaerobius). Other non-bacteriocin producing S. bovis strains also had the ability to bind and transfer semi-purified bovicin HC5. Bovicin HC5 that was bound to S. bovis JB1 was much more resistant to Pronase E than cell-free bovicin HC5, but it could be inactivated if the incubation period was 24 h. Acidic NaCl treatment (100 mM, pH 2.0) liberates half of the bovicin HC5 from S. bovis HC5, but it did not prevent bovicin HC5 from binding to S. bovis JB1. Acidic NaCl liberated some bovicin HC5 from S. bovis JB1, but the decrease in activity was only 2-fold. Bovicin HC5 is a positively charged peptide, and the ability of S. bovis JB1 to bind bovicin HC5 could be inhibited by either calcium or magnesium (100 mM). Acidic NaCl-treated S. bovis JB1 cells were unable to accumulate potassium, but they were still able to bind bovicin HC5 and prevent potassium accumulation by untreated S. bovis JB1 cells. Based on these results, bovicin HC5 bound to S. bovis JB1 cells still acts as a pore-forming lantibiotic.

Purification and partial characterization of a bacteriocin produced by Eikenella corrodens.

AIMS: The purpose of this study was to purify and characterize a bacteriocin produced by Eikenella corrodens A32E2. METHODS AND RESULTS: Peptostreptococcus anaerobius ATCC27337 was used as indicator strain in antagonistic assays for bacteriocin-producing E. corrodens A32E2. Protein extraction was influenced by pH and buffer composition. The protein was active in the pH range 6-8. Inhibitory activity was lost by both heating and treatment with proteolytic enzymes and decreased with organic solvents. The substance is rather unstable but maintains 100% of its activity after being exposed to acetone and when stored at -70 degrees C. The antagonistic substance was first precipitated by ammonium sulfate and further partially purified by Mono-Q FPLC and C-18 HPLC. Mass spectrometry analysis showed that the molecular mass was 23 625 Da, and the sequence obtained for the N-terminus was: Met-Asn-Phe-Asp-Glu-Lys-Val-Gly-Lys-Val-X-Phe-Lys-Val-Gly-Asp. CONCLUSIONS: The evidence presented in this study supports the idea that an antagonistic substance produced by E. corrodens A32E2 isolated from a periodontal diseased site is a novel bacteriocin, which we designate corrodecin. SIGNIFICANCE AND IMPACT OF THE STUDY: We anticipated that corrodecin might play an important role at the periodontal site. This compound could also be attractive in biotechnological applications as an interesting tool for oral ecosystem control.

Characterization of the protein unfolding processes induced by urea and temperature.

Correct folding is critical for the biological activities of proteins. As a contribution to a better understanding of the protein (un)folding problem, we studied the effect of temperature and of urea on peptostreptococcal Protein L destructuration. We performed standard molecular dynamics simulations at 300 K, 350 K, 400 K, and 480 K, both in 10 M urea and in water. Protein L followed at least two alternative unfolding pathways. Urea caused the loss of secondary structure acting preferentially on the beta-sheets, while leaving the alpha-helices almost intact; on the contrary, high temperature preserved the beta-sheets and led to a complete loss of the alpha-helices. These data suggest that urea and high temperature act through different unfolding mechanisms, and protein secondary motives reveal a differential sensitivity to various denaturant treatments. As further validation of our results, replica-exchange molecular dynamics simulations of the temperature-induced unfolding process in the presence of urea were performed. This set of simulations allowed us to compute the thermodynamical parameters of the process and confirmed that, in the configurational space of Protein L unfolding, both of the above pathways are accessible, although to a different relative extent.

Degradation of serine-containing oligopeptides by Peptostreptococcus micros ATCC 33270.

BACKGROUND/AIMS: Microorganisms of Peptostreptococcus micros are asaccharolytic, anaerobic gram-positive cocci that are frequently isolated from human oral sites such as periodontal pockets. Preliminary study showed that several amino acids, including serine, enhanced slightly the growth of P. micros. Therefore, we investigated the degradation of serine and serine-containing oligopeptides. METHODS: Metabolic end products were determined with high-performance liquid chromatography. The related enzymatic activities in cell-free extract were also assayed. RESULTS: Washed P. micros degraded serine-tripeptides (Ser-Ser-Ser), and produced formate, pyruvate, acetate, and ammonia. They also degraded serinyl-tyrosine (Ser-Tyr) to the same products. Related enzymatic activities, such as serine dehydratase, pyruvate formate-lyase, formate dehydrogenase, pyruvate oxidoreductase, phosphate acetyltransferase, and acetate kinase, were detected in the cell-free extract, indicating that the organisms produced ATP in the serine metabolism. CONCLUSION: P. micros utilized serine-containing oligopeptides as exogenous metabolic substrates rather than serine itself, and degraded Ser-Ser-Ser and Ser-Tyr to formate, pyruvate, acetate, and ammonia with ATP generation.

Hemin nutritional stress inhibits bacterial invasion of radicular dentine by two endodontic anaerobes.

AIM: To determine if anaerobic bacteria routinely found in infected dentine and root canals require the presence of heme in the environment in order for them to invade dentinal tubules. METHODOLOGY: Noncarious, unrestored human teeth with single root canals were prepared for invasion experiments and soaked in either TSB-M supplemented with hemin (5 microg mL(-1)) (n = 12 roots), TSB-M media (n = 12 roots) or TSB-M media followed by hemin soak (n = 12 roots) for 2 days, then inoculated with either Prevotella intermedia ATCC 25611 or Peptostreptococcus micros ATCC 33270 and incubated anaerobically for 14 days. Roots were prepared for light microscopy, stained with Brown and Brenn or antisera raised to the bacteria, and invasion within tubules assessed using a tubule invasion index (TI). Data were analysed using Student's t-test and Mann-Whitney U-test. RESULTS: Prevotella intermedia (TI = 0.7 +/- 0.04) and P. micros (TI = 0.96 +/- 0.08) showed low invasion when grown in the presence of hemin with cells generally restricted to the superficial 20 microm of the tubules, whilst neither bacteria invaded tubules (TI = 0) when hemin was absent from the growth media (P < 0.01). CONCLUSIONS: Hemin was required in the growth medium for P. intermedia and P. micros to invade dentinal tubules.

Production of indolic compounds by rumen bacteria isolated from grazing ruminants.

AIM: To screen rumen bacterial cultures and fresh ruminal isolates for indole and skatole production. METHODS AND RESULTS: Culture collection strains and fresh bacterial isolates from rumen contents of sheep and dairy cows were screened for the production of indolic compounds. Clostridium aminophilum FT, Peptostreptococcus ssp. S1, Fusobacterium necrophorum D4 produced indole and Clostridium sticklandii SR produced indoleacetic acid. Fresh isolates from sheep (TrE9262 and TrE7262) and dairy cows (152R-1a, 152R-1b, 152R-3 and 152R-4) produced indole, indolepropionic acid, tryptophol and skatole from the fermentation of tryptophan and indoleacetic acid. Glucose altered the indolic compounds produced in some, but not all, isolates. TrE7262 and 152R-4 were identified as Clostridium sporogenes and 152R-1b as a new Cl. aminophilum strain. Isolates TrE9262, 152R-1a and 152R-3 were not closely related to any described species but belong to Megasphaera, Prevotella and Actinomyces genera, respectively. CONCLUSIONS: Rumen bacteria that produced a range of indolic compounds were identified. Some isolates are distinct from the previously described bacteria and may represent novel species. SIGNIFICANCE AND IMPACT OF THE STUDY: These observations will contribute to understanding skatole and indole formation in the rumen and will lead to methods that control the formation of indolic compounds in pasture-grazed ruminants.