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Microflora
Kinds of Microflora Selected AbstractsEFFECTIVENESS OF CHLORINE AND NISIN-EDTA TREATMENTS OF WHOLE MELONS AND FRESH-CUT PIECES FOR REDUCING NATIVE MICROFLORA AND EXTENDING SHELF-LIFE,JOURNAL OF FOOD SAFETY, Issue 4 2002DIKE O. UKUKU ABSTRACT Efficacy of nisin-EDTA treatments as a sanitizing treatment for reducing native microflora of whole melons and extending shelf-life of fresh-cut pieces was compared to chlorine treatments. Whole cantaloupe and honeydew melons were washed with water, nisin (10 ,g/mL)-EDTA (0.02 M), or 200 ppm chlorine for 5 min at , 20C before fresh-cut preparation and storage at 5C for 15 days with periodic microbiological sampling. In addition, some fresh-cut pieces were washed with 10 ,g/mL nisin-EDTA or 50 ppm chlorine for 1 min before storage. Changes in appearance, odor, overall acceptability and the shelf-life of the minimally processed fresh-cut melons were investigated. Preliminary studies indicated that water washes, EDTA (0.002 to 0.2 M) or nisin (5 to 10 ,g/mL) were not effective in reducing the microflora of whole melon when used individually. Nisin-EDTA and chlorine treatments were significantly (P < 0.05) more effective in reducing native microflora than water washes. Nisin-EDTA treatments were significantly (P < 0.05) more effective than chlorine in reducing populations of yeast and mold and Pseudomonas spp. on whole melon surfaces but were not as effective as chlorine treatments for reducing aerobic mesophilic bacteria, lactic acid bacteria and total gram-negative bacteria. Microbial contaminants on fresh-cut pieces washed with 50 ppm chlorine or nisin-EDTA were further reduced. However, microbial populations increased throughout refrigerated storage irrespective of treatments. Odor, appearance, and overall acceptability ratings for cantaloupe and honeydew fresh-cut pieces treated with nisin-EDTA or chlorine were not significantly (P > 0.05) different from each other throughout the storage period (15 to 21 days). However, both treatments led to significantly (P < 0.05) improved ratings compared to the controls for the fresh-cut pieces at 9 to 12 days of storage and thereafter. The results of this study suggest that treatments with nisin-EDTA before and after fresh-cut processing would improve the quality and extend the shelf-life of fresh-cut melon. [source] INFLUENCE OF WASHING TREATMENT ON NATIVE MICROFLORA AND ESCHERICHIA COLI POPULATION OF INOCULATED CANTALOUPESJOURNAL OF FOOD SAFETY, Issue 1 2001DIKE O. UKUKU ABSTRACT The influence of chlorine or hydrogen peroxide treatment on populations of Escherichia coli 25922 on the external surface of inoculated cantaloupe was investigated. Surface treatment with 70% EtOH, followed by immersion in 108 CFU/mL E. coli inoculum deposited an average of 4.4 log10CFU/cm2 cell population on the cantaloupe surface. The efficncy of washing inoculated cantaloupe was dependent on storage interval between inoculation and treatment. Dipping the cantaloupes in solutions containing 1000 mg/L chlorine or 5% peroxide for 5 min, within 24 h of inoculation, caused a 2 log10 CFU/cm2 reduction of the indigenous surface microflora and a 3,4.0 log10 CFU/cm2 reduction in E. coli. The efficacy was less when the interval between inoculation and treatment exceeded 24 h. Chlorine appeared in be a better antimicrobial agent than hydrogen peroxide against F. coli ATCC 25922 inoculated on cantaloupe surfaces while hydrogen peroxide was better in reducing surface microflora of cantaloupe. [source] Microflora of blanched minimally processed fresh vegetables as components of commercial chilled ready-to-use mealsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2001Robert Edgar No abstract is available for this article. [source] Reduction of Microflora of Whole Pickling Cucumbers by BlanchingJOURNAL OF FOOD SCIENCE, Issue 8 2000F. Breidt ABSTRACT: There is increasing interest in developing methods to control the presence of pathogenic and spoilage microorganisms on fresh fruits and vegetables. Blanching whole pickling cucumbers for 15 s at 80 °C reduced microbial cell counts by 2 to 3 log cycles from an initial population of typically 106 CFU/g. Vegetative microorganisms survived this blanching process (10,fold greater in number than the spore count), presumably because they were located beneath the surface of the cucumber. The sensitivity to heat of selected populations was measured by determining D values for pooled microorganisms (termed D values) isolated from fresh cucumbers. The Enterobacteriaceae population and the total aerobic microflora had similar Dp values to each other and to the D value for a selected lactic acid bacterium. [source] Bioactive Isoflavones in Functional Foods: The Importance of Gut Microflora on BioavailabilityNUTRITION REVIEWS, Issue 6 2003Nicola J. Turner B.Sc.Tech Isoflavones present in soy may have risk and benefits to human health. Human gut microflora have been shown to exert metabolic activities on isoflavones, which influences bioavailability and bioactivity. Absorption of isoflavones is likely to occur in the small intestine where there is a diverse range of microfloral species able to hydrolyze conjugated isoflavones, releasing the bioactive aglycone for absorption or further metabolism and reconjugation. The identification of gut microbes that metabolize isoflavone aglycones is not well established. Such information may lead to a better understanding of the bioavailability of isoflavones in functional foods. [source] Lower Jurassic Foraminifera and Calcified Microflora from Gibraltar, Western MediterraneanPALAEONTOLOGY, Issue 4 2001M. K. Boudagher-Fadel Benthic foraminifera are described for the first time from the Gibraltar Limestone Formation of the Rock of Gibraltar. The new species Siphovalvulina colomiS. gibraltarensisRiyadhella praeregularis occur with Duotaxis metula Kristan, Everticyclammina praevirguliana Fugagnoli, Siphovalvulina sp.,an atypically early example of Textulariopsis sp., and Nodosaria sp. Microflora are present as the probable cyanobacterium Cayeuxia ?piae Frollo, the alga Palaeodasycladus ?mediterraneus (Pia), and the disputed alga Thaumatoporella ?parvovesiculifera (Raineri). The foraminifera compare most closely with poorly-known taxa from Italy, Spain and Morocco, and are consistent with an Early Jurassic (Sinemurian) age for the upper part of the &62;460-m-thick Gibraltar Limestone. Most are textulariids and more primitive than species well known from the later Early Jurassic (Pliensbachian) of the Mediterranean region, especially Morocco and Italy. The biota as a whole is characteristic of inner carbonate platform environments widespread along the rifted western margins of the Early Jurassic Tethys, notably those recorded from Morocco, Italy and Greece as well as southern Spain. [source] Oncotic colpocytology stained with Harris,Shorr in the observation of vaginal microorganismsDIAGNOSTIC CYTOPATHOLOGY, Issue 6 2008Agenor Storti-Filho Especialist Abstract The purpose of this work was to evaluate the efficacy of oncotic colpocytology stained with Harris,Shorr in the identification of the cervicovaginal microflora and infectious agents. Results of microbiologic evaluation carried out in colpocytology exams, bacterioscopy (Gram), and direct exams of 2,017 women aged from 13 to 80 years were compared. Of these, 83.1% agreed between cytology and Gram, 3.6% partially agreed, and 12.8% disagreed. The predominant microflora was of lactobacilli (63.3%), followed by mixed flora (32.1%). The results of sensitivity to lactobacilli were 96.1% and to mixed flora 88.0%; the specificity values were 91.2 and 92.0%, respectively. Colpocytology detected all the instances of trichomoniasis observed at direct exam (0.6%). The most frequent infectious agents were of candidiasis (14.8%, sensitivity 80.3%) and bacterial vaginosis (11.9%, sensitivity 68.1%). Thus, Harris,Shorr stained cytology was shown to be an excellent diagnostic method for T. vaginalis, lactobacilli, mixed flora, and candidiasis. Diagn. Cytopathol. 2008;36:358,362. © 2008 Wiley-Liss, Inc. [source] Salient virulence factors in anaerobic bacteria, with emphasis on their importance in endodontic infectionsENDODONTIC TOPICS, Issue 1 2004Ingar Olsen Endodontic infections by microbial invasion of the necrotic pulp lead to apical periodontitis of both acute and chronic forms. Acute lesions often develop from multiplication of bacteria in primary infections. Such lesions may also occur as exacerbations of chronic forms provoked for example in conjunction with endodontic treatment measures. The clinical course appears related to the character of the microflora. While primary infections are predominated by a mixed flora of anaerobic bacteria and resembles that of aggressive marginal periodontitis, chronic forms of apical periodontitis emerge following regression of the acute infection, whereupon prevailing bacteria have assumed low activity. The significance of virulence factors is easy to understand as far as acute inflammatory conditions are concerned. The role of virulence factors for sustaining chronic inflammation is more unclear and complex. This review is about salient virulence factors in some selected bacterial genera such as Peptostreptococcus, Porphyromonas, Prevotella and Fusobacterium, which often predominate the root canal microbiota in the acute phase of endodontic infections. [source] Persistent, recurrent, and acquired infection of the root canal system post-treatmentENDODONTIC TOPICS, Issue 1 2003Markus Haapasalo Apical periodontitis is an inflammatory process in the periradicular tissues caused by microorganisms in the necrotic root canal. Accordingly, to achieve healing of apical periodontitis, the main goal of the treatment must be elimination of the infection and prevention of re-infection. As shown by recent epidemiological studies in several countries around the world, post-treatment endodontic disease is a far too common finding. To understand the reasons for survival of resistant bacteria in the filled root canal, it is important to know in detail the interaction between treatment procedures and the root canal flora in primary apical periodontitis. Therefore, in the first half of this review, the focus is placed on control of infection in primary apical periodontitis. This is followed by a detailed description of the resistant root canal microflora and a discussion about the present and future strategies to eliminate even the most resistant microbes in post-treatment disease. [source] Acclimation Strategy of a Biohydrogen Producing Population in a Continuous-Flow Reactor with Carbohydrate FermentationENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2006Q. Ren Abstract Poor startup of biological hydrogen production systems can cause an ineffective hydrogen production rate and poor biomass growth at a high hydraulic retention time (HRT), or cause a prolonged period of acclimation. In this paper a new startup strategy was developed in order to improve the enrichment of the hydrogen-producing population and the efficiency of hydrogen production. A continuously-stirred tank reactor (CSTR) and molasses were used to evaluate the hydrogen productivity of the sewage sludge microflora at a temperature of 35,°C. The experimental results indicated that the feed to microorganism ratio (F/M ratio) was a key parameter for the enrichment of hydrogen producing sludge in a continuous-flow reactor. When the initial biomass was inoculated with 6.24,g of volatile suspended solids (VSS)/L, an HRT of 6,h, an initial organic loading rate (OLR) of 7.0,kg chemical oxygen demand (COD)/(m3,×,d) and an feed to microorganism ratio (F/M) ratio of about 2,3,g COD/(g of volatile suspended solids (VSS) per day) were maintained during startup. Under these conditions, a hydrogen producing population at an equilibrium state could be established within 30,days. The main liquid fermentation products were acetate and ethanol. Biogas was composed of H2 and CO2. The hydrogen content in the biogas amounted to 47.5,%. The average hydrogen yield was 2.01,mol/mol hexose consumed. It was also observed that a special hydrogen producing population was formed when this startup strategy was used. It is supposed that the population may have had some special metabolic pathways to produce hydrogen along with ethanol as the main fermentation products. [source] Use of episcopic differential interference contrast microscopy to identify bacterial biofilms on salad leaves and track colonization by Salmonella ThompsonENVIRONMENTAL MICROBIOLOGY, Issue 4 2008J. C. Warner Summary Zoonotic pathogens such as Salmonella can cause gastrointestinal illness if they are ingested with food. Foods such as salads pose a greater risk because they are consumed raw and have been the source of major outbreaks of disease from fresh produce. The novel light microscopy methods used in this study allow detailed, high resolution imaging of the leaf surface environment (the phyllosphere) and allow pathogen tracking. Episcopic differential interference contrast microscopy coupled with epifluorescence was used to view the natural microflora in situ on salad leaves and their topographical distribution. Fluorescent nucleic acid staining was used to differentiate between bacterial colonists and inorganic debris. Salmonella enterica serovar Thompson expressing green fluorescent protein was inoculated onto individual spinach leaves for 24 h at 22°C in order to observe spatial and temporal patterning of colonization on the two surfaces of each leaf under different osmotic conditions. The results obtained show that salad leaves are host to high numbers of bacteria, typically 105 per square millimetre. Cells are present in complex three-dimensional aggregations which often have a slimy appearance, suggesting the presence of biofilms. Washing of the leaves had little effect on the number of adherent pathogens, suggesting very strong attachment. Episcopic differential interference contrast microscopy is a rapid alternative to both scanning electron microscopy and confocal laser scanning microscopy for visualizing leaf topography and biofilm formation in the natural state. [source] Ascomycete communities in the rhizosphere of field-grown wheat are not affected by introductions of genetically modified Pseudomonas putida WCS358rENVIRONMENTAL MICROBIOLOGY, Issue 11 2005Mareike Viebahn Summary A long-term field experiment (1999,2002) was conducted to monitor effects on the indigenous microflora of Pseudomonas putida WCS358r and two transgenic derivatives constitutively producing phenazine-1-carboxylic acid (PCA) or 2,4-diacetylphloroglucinol (DAPG). The strains were introduced as seed coating on wheat into the same field plots each year. Rhizosphere populations of ascomycetes were analysed using denaturing gradient gel electrophoresis (DGGE). To evaluate the significance of changes caused by the genetically modified microorganisms (GMMs), they were compared with effects caused by a crop rotation from wheat to potato. In the first year, only the combination of both GMMs caused a significant shift in the ascomycete community. After the repeated introductions this effect was no longer evident. However, cropping potato significantly affected the ascomycete community. This effect persisted into the next year when wheat was grown. Clone libraries were constructed from samples taken in 1999 and 2000, and sequence analysis indicated ascomycetes of common genera to be present. Most species occurred in low frequencies, distributed almost evenly in all treatments. However, in 1999 Microdochium occurred in relatively high frequencies, whereas in the following year no Microdochium species were detected. On the other hand, Fusarium -like organisms were low in 1999, and increased in 2000. Both the DGGE and the sequence analysis revealed that repeated introduction of P. putida WCS358r had no major effects on the ascomycete community in the wheat rhizosphere, but demonstrated a persistent difference between the rhizospheres of potato and wheat. [source] Persistence of vibrios in marine bivalves: the role of interactions with haemolymph componentsENVIRONMENTAL MICROBIOLOGY, Issue 6 2005Carla Pruzzo Summary Marine bivalves are widespread in coastal environments and, due to their filter-feeding habit, they can accumulate large numbers of bacteria thus acting as passive carriers of human pathogens. Bivalves possess both humoral and cellular defence mechanisms that operate in a co-ordinated way to kill and eliminate infecting bacteria. Vibrio species are very abundant in coastal waters and are commonly isolated from edible bivalves tissues where they can persist after depuration processes in controlled waters. Such observations indicate that vibrios are regular components of bivalve microflora and that the molluscs can represent an important ecological niche for these bacteria. Here we tried to summarize data on the interactions between vibrios and bivalve haemolymph; the available evidence supports the hypothesis that persistence of bacteria in bivalve tissues depends, at least in part, on their sensitivity to the bactericidal activity of the haemolymph. Results obtained with an in vitro model of Vibrio cholerae challenged against Mytilus galloprovincialis haemocytes indicate that bacterial surface components, soluble haemolymph factors and the signalling pathways of the haemocyte host are involved in determining the result of vibrio,haemolymph interactions. [source] Characterization of bacterial pectinolytic strains involved in the water retting processENVIRONMENTAL MICROBIOLOGY, Issue 9 2003Elena Tamburini Summary Pectinolytic microorganisms involved in the water retting process were characterized. Cultivable mesophilic anaerobic and aerobic bacteria were isolated from unretted and water-retted material. A total of 104 anaerobic and 23 aerobic pectinolytic strains were identified. Polygalacturonase activity was measured in the supernatant of cell cultures; 24 anaerobic and nine aerobic isolates showed an enzymatic activity higher than the reference strains Clostridium felsineum and Bacillus subtilis respectively. We performed the first genotypic characterization of the retting microflora by a 16S amplified ribosomal DNA restriction analysis (ARDRA). Anaerobic isolates were divided into five different groups, and the aerobic isolates were clustered into three groups. 84.6% of the anaerobic and 82.6% of the aerobic isolates consisted of two main haplotypes. Partial 16S rRNA gene sequences were determined for 12 strains, representative of each haplotype. All anaerobic strains were assigned to the Clostridium genus, whereas the aerobic isolates were assigned to either the Bacillus or the Paenibacillus genus. Anaerobic isolates with high polygalacturonase (PG) activity belong to two clearly distinct phylogenetic clusters related to C. acetobutylicum,C. felsineum and C. saccharobutylicum species. Aerobic isolates with high PG activity belong to two clearly distinct phylogenetic clusters related to B. subtilisT and B. pumilusT. [source] ,, ,-Unsaturated sulfophenylcarboxylates as degradation intermediates of linear alkylbenzenesulfonates: Evidence for ,-oxygenation followed by ,-oxidations by liquid chromatography-mass spectrometryENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2002Peter Eichhorn Abstract Liquid chromatography with an electrospray interface to a mass spectrometer (LC-ES-MS) and LC-ES coupled to a tandem MS (LC-ES-MS/MS) were used to detect and identify intermediates excreted transiently during the aerobic degradation of linear alkylbenzenesulfonates (LAS) in fixed-bed bioreactors (FBBR). The inoculum for the FBBR was the microflora of the River Rhine, Germany. Two major phenomena were observed on the addition of 100 mg/L LAS to the system, sorption and then biodegradation. Disappearance due to sorption was followed in an inhibited FBBR. Biodegradation of LAS started on day 7 and was accompanied by the transient excretion of intermediates, which were later largely degraded. We detected not only the sulfophenylcarboxylates (SPCs) observed previously but also the ,, ,-unsaturated SPCs (SPC-2H), which have not been reported before. Experiments with the (4-sulfophenyl)dodecanes (C12-LAS), which had minor contaminants of C11-LAS, showed C12-, C10-, C8-, C6-, and C4-SPCs when LAS was degraded as well as traces of C9-, C7-, and C5-SPCs. Signals from the SPC-2H species were usually some 10% of those from the corresponding SPCs. Samples from these experiments were also examined by gas chromatography-mass spectrometry (GC-MS), but no desulfonated intermediates were detected. We interpret the data to mean that the only attack on LAS was by ,-oxygenation; there was no visible initial desulfonation. The products of ,-oxygenation were oxidized to the corresponding SPC and subject to ,-oxidation, as evidenced not only by the pattern of C-2 units in the excreted SPCs but also in the corresponding series of SPC-2H, representing the intermediates in ,-oxidation. [source] Do horses suffer from irritable bowel syndrome?EQUINE VETERINARY JOURNAL, Issue 9 2009J. O. HUNTER Summary Irritable bowel syndrome (IBS) in man is not a single entity but has several causes. One of the most common forms has similarities with colic and laminitis in horses. Undigested food residues may pass from the small intestine into the colon where bacterial fermentation produces chemicals that lead to disease. In horses the consequences may be disastrous, but in healthy humans such malabsorption may not be harmful. After events such as bacterial gastroenteritis or antibiotic treatment, an imbalance of the colonic microflora with overgrowth of facultative anaerobes may arise, leading to malfermentation and IBS. It is not known whether such subtle changes may likewise be present in the microflora of horses who are susceptible to colic and laminitis. Metabolomic studies of urine and faeces may provide a suitable way forward to identify such changes in the horse's gut and thus help to identify more accurately those at risk and to provide opportunities for the development of improved treatment. [source] TLR2-independent induction and regulation of chronic intestinal inflammationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2010Olivier Boulard Abstract Interactions between the intestinal microflora and host innate immune receptors play a critical role in intestinal homeostasis. Several studies have shown that TLR2 can modulate inflammatory responses in the gut. TLR2 signals enhance tight junction formation and fortify the epithelial barrier, and may play a crucial role in driving acute inflammatory responses towards intestinal bacterial pathogens. In addition, TLR2 agonists can have direct effects on both Th1 cells and Treg. To define the role of TLR2 in the induction and regulation of chronic intestinal inflammation we examined the effects of TLR2 deletion on several complementary models of inflammatory bowel disease. Our results show that TLR2 signals are not required for the induction of chronic intestinal inflammation by either innate or adaptive immune responses. We further show that TLR2,/, mice harbor normal numbers of Foxp3+ Treg that are able to suppress intestinal inflammation as effectively as their WT counterparts. We also did not find any intrinsic role for TLR2 for pathogenic effector T-cell responses in the gut. Thus, in contrast to their role in acute intestinal inflammation and repair, TLR2 signals may have a limited impact on the induction and regulation of chronic intestinal inflammation. [source] Microbial colonization induces oligoclonal expansions of intraepithelial CD8 T cells in the gutEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2004Lars Helgeland Abstract Two populations of CD8+ IEL generally express restricted, but apparently random and non-overlapping TCR repertoires. Previous studies in mice suggested that this could be explained by a dual origin of CD8+ IEL, i.e. that CD8,,+ IEL derive from a few peripheral CD8+ T cell lymphoblasts stimulated by microbial antigens in gut-associated lymphoid tissue, whereas CD8,,+ IEL descend from an inefficient intestinal maturation pathway. We show here that the gut mucosa, instead, becomes seeded with surprisingly broad and generally non-overlapping CD8 IEL repertoires and that oligoclonality is induced locally after microbial colonization. In germ-free (GF) rats, both CD8,,+ and CD8,,+ IEL displayed surprisingly diverse TCR V, repertoires, although ,-chain diversity tended to be somewhat restricted in the CD8,,+ subset. CDR3 length displays in individual V,-C, and V,-J, combinations generally revealed polyclonal distributions over 6,11 different lengths, similar to CD8+ lymph node T cells, and CDR3, sequencing provided further documentation of repertoire diversity. By contrast, in ex-GF rats colonized with normal commensal microflora, both CD8,,+ and CD8,,+ IEL displayed oligoclonal CDR3 length distributions for most of the V, genes analyzed. Our data suggest that microbial colonization induces apparently random clonal expansions of CD8,,+ and CD8,,+ IEL locally in the gut. [source] Endogenous microflora in turbid virgin olive oils and the physicochemical characteristics of these oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2008Anastasios Koidis Abstract Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5,µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5,60,µm) deriving from the olive fruit. They are present in small amounts (12,460,mg/kg oil). In the newly produced olive oil, containing 0.17,0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3,log,cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product. [source] Probiotics: do they have a role in oral medicine and dentistry?EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2005Jukka H. Meurman This review describes current knowledge on probiotic bacteriotherapy from the oral health perspective. Recent experimental studies and results from randomized controlled trials have shown that certain gut bacteria, in particular species of Lactobacillus and Bifidobacterium, may exert beneficial effects in the oral cavity by inhibiting cariogenic streptococci and Candida sp. Probiotics have been successfully used to control gastro-intestinal diseases. They also appear to alleviate symptoms of allergy and diseases with immunological pathology. The mechanisms of probiotic action appear to link with colonization resistance and immune modulation. Lactic acid bacteria can produce different antimicrobial components such as organic acids, hydrogen peroxide, carbon peroxide, diacetyl, low molecular weight antimicrobial substances, bacteriocins, and adhesion inhibitors, which also affect oral microflora. However, data is still sparse on the probiotic action in the oral cavity. More information is needed on the colonization of probiotics in the mouth and their possible effect on and within oral biofilms. There is every reason to believe that the putative probiotic mechanisms of action are the same in the mouth as they are in other parts of the gastrointestinal tract. Because of the increasing global problem with antimicrobial drug resistance, the concept of probiotic therapy is interesting and pertinent, and merits further research in the fields of oral medicine and dentistry. [source] The dynamics of organic matter in rock fragments in soil investigated by 14C dating and measurements of 13CEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2002A. Agnelli Summary Rock fragments in soil can contain significant amounts of organic carbon. We investigated the nature and dynamics of organic matter in rock fragments in the upper horizons of a forest soil derived from sandstone and compared them with the fine earth fraction (<2 mm). The organic C content and its distribution among humic, humin and non-humic fractions, as well as the isotopic signatures (,14C and ,13C) of organic carbon and of CO2 produced during incubation of samples, all show that altered rock fragments contain a dynamic component of the carbon cycle. Rock fragments, especially the highly altered ones, contributed 4.5% to the total organic C content in the soil. The bulk organic matter in both fine earth and highly altered rock fragments in the A1 horizon contained significant amounts of recent C (bomb 14C), indicating that most of this C is cycled quickly in both fractions. In the A horizons, the mean residence times of humic substances from highly altered rock fragments were shorter than those of the humic substances isolated in the fine earth. Values of ,14C of the CO2 produced during basal respiration confirmed the heterogeneity, complexity and dynamic nature of the organic matter of these rock fragments. The weak 14C signatures of humic substances from the slightly altered rock fragments confirmed the importance of weathering in establishing and improving the interactions between rock fragments and surrounding soil. The progressive enrichment in 13C from components with high- 14C (more recent) to low- 14C (older) indicated that biological activity occurred in both the fine and the coarse fractions. Hence the microflora utilizes energy sources contained in all the soil compartments, and rock fragments are chemically and biologically active in soil, where they form a continuum with the fine earth. [source] Immunomodulatory effects of probiotic bacteria DNA: IL-1 and IL-10 response in human peripheral blood mononuclear cellsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2003Karen Manon Lammers Abstract A new therapeutic approach for inflammatory bowel diseases is based on the administration of probiotic bacteria. Prokaryotic DNA contains unmethylated CpG motifs which can activate immune responses, but it is unknown whether bacterial DNA is involved in the beneficial effects obtained by probiotic treatment. Peripheral blood mononuclear cells (PBMC) from healthy donors were incubated with pure DNA of eight probiotic strains and with total bacterial DNA from human feces collected before and after probiotic ingestion. Cytokine production was analyzed in culture supernatants. Modification of human microflora after probiotic administration was proven by polymerase chain reaction analysis. Here we show that Bifidobacterium genomic DNA induced secretion of the antiinflammatory interleukin-10 by PBMC. Total bacterial DNA from feces collected after probiotic administration modulated the immune response by a decrease of interleukin-1, and an increase of interleukin-10. [source] Usage of Aplysia lectin interactions with T antigen and poly- N -acetyllactosamine for screening of E. coli strains which bear glycoforms cross-reacting with cancer-associated antigensFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2001Nechama Gilboa-Garber Abstract Aplysia gonad lectin (AGL), which strongly agglutinates cancer cells, was found, in the present study, to bind to erythrocyte T antigen, in addition to its affinity to Ii system antigens. These antigens were reported to be overexpressed and to contribute to tumor progression and invasion. In healthy human sera, there are antibodies against them, stimulated by the normal intestinal microflora, which bear similar glycoforms. Since the levels of these antibodies were reported to be lower in most cancer patients' sera, we have examined the applicability of AGL to isolation of enteric commensal Escherichia coli strains which bear glycoforms cross-reacting with the cancer-associated antigens. Among 30 E. coli isolates examined, two were agglutinated by AGL. One of them was also agglutinated by certain related galactophilic lectins, which bind to the T and Tn antigens. The agglutination of the two bacteria by healthy human sera, as a group, was stronger than that displayed by the cancer patients' sera. These results indicate that AGL might be useful for identification of the desired bacteria, which could potentially serve for cancer diagnosis and therapy. [source] Herbivory in an acid streamFRESHWATER BIOLOGY, Issue 4 2000Mark E. Ledger Summary 1Spatial and temporal variation in the distribution and feeding of non-predatory macroinvertebrates was investigated in a first-order, acid stream in the Ashdown Forest, southern England. 2Stonefly (Nemouridae) and chironomid (Orthocladiinae) larvae were abundant on the upper surfaces of mineral substrata of three sizes (small stones, large stones, bedrock). The density of larvae in each taxonomic group did not vary among substrata of different sizes, although strong seasonal variation existed. 3Nemourids and chironomids (H. marcidus) collected from the upper surfaces of substrata exhibited generalist feeding habits, consuming algae (diatoms, coccoid and filamentous green algae), detritus (biofilm matrix material and fine particulate organic matter (FPOM)) and inorganic debris. 4There was spatial variation in the gut contents of nemourids. The proportion of algae in the guts of larvae often increased with the size of the substratum from which they were collected. Strong temporal variation in the composition of the diet also existed. Nemourids ingested a large quantity of attached algae and biofilm matrix from the biofilm in spring and winter, but consumed loose FPOM and associated microflora in summer and autumn. 5We conclude that, in this acid stream, the trophic linkage between algae and grazers is maintained by ,detritivorous' stonefly and chironomid species. The relationship between the feeding habits of these larvae and other life-history attributes, such as mouthpart morphology and mobility, is discussed. [source] The microfood web of grassland soils responds to a moderate increase in atmospheric CO2GLOBAL CHANGE BIOLOGY, Issue 7 2005Ilja Sonnemann Abstract The response of the soil microfood web (microflora, nematodes) to a moderate increase in atmospheric CO2 (+20%) was investigated by means of a free air CO2 enrichment experiment. The study was carried out in a seminatural temperate grassland for a period of 4 consecutive years (1 year before fumigation commenced and 3 years with fumigation). Several soil biological parameters showed no change (microbial biomass, bacterial biomass) or decline (microbial respiration) in the first year of elevated CO2 treatment as compared with controls. Each of these parameters were higher than controls, however, after 3 years of treatment. The relative abundance of predaceous nematodes also decreased in year 1 of the experiment, increased in year 2, but decreased again in year 3. In contrast, the relative abundance of root hair feeding nematodes, at first, increased under elevated CO2 and then returned to the initial level again. Increased microbial biomass indicates enhanced C storage in the labile carbon pool of the active microfood web in subsequent years. According to measurements on the amounts of soil extractable C, changes in resource availability seem to be key to the response of the soil microfood web. We found a strong response of bacteria to elevated CO2, while the fungal biomass remained largely unchanged. This contrasts to findings reported in the literature. We hypothesize that this may be because of contrasting effects of different levels of CO2 enrichment on the microbial community (i.e. stimulation of bacteria at moderate levels and stimulation of fungi at high levels of CO2 enrichment). However, various CO2 effects observed in our study are similar in magnitude to those observed in other studies for a much higher level of atmospheric carbon. These include the particular sensitivity of predaceous nematodes and the long-term increase of microbial respiration. Our findings confirm that the potential of terrestrial ecosystems to accumulate additional carbon might be lower than previously thought. Furthermore, CO2 -induced changes of temperate grassland ecosystems might emerge much earlier than expected. [source] Molecular mechanisms of portal vein toleranceHEPATOLOGY RESEARCH, Issue 5 2008Tomohiro Watanabe The liver has been considered as a tolerogenic organ in the sense that favors the induction of peripheral tolerance. The administration of antigens (Ags) via the portal vein causes tolerance, which is termed portal vein tolerance and can explain the occurrence of tolerogenic responses in the liver. Here we discuss the fundamental mechanisms accounting for portal vein tolerance. Antigen-presenting cells (APCs) in the liver, especially dendritic cells and sinusoidal endothelial cells, have limited the ability to produce pro-inflammatory cytokines upon stimulation with endotoxin, an effect that could be due to the continuous exposure to bacterial Ags derived from intestinal microflora. Ag presentation by liver APCs results in T cell tolerance through clonal deletion and selection of regulatory T cells. Thus, APCs with immunosuppressive functions are associated with the achievement of portal vein tolerance via the induction of clonal deletion and generation of regulatory T cells. [source] Prebiotics in chronic intestinal inflammationINFLAMMATORY BOWEL DISEASES, Issue 3 2009Mirjam A.C. Looijer, Van Langen MD Abstract Prebiotics are nondigestible fermentable fibers that are reported to have health benefits for the host. Older as well as more recent studies show beneficial effects in experimental colitis and lately also in human inflammatory bowel diseases (IBD), such as Crohn's disease, ulcerative colitis, and chronic pouchitis. In this review we give an overview of the benefits of prebiotics in rodent IBD models and in IBD patients and discuss their possible protective mechanisms. Commensal intestinal bacteria induce and perpetuate chronic intestinal inflammation, whereas others are protective. However, most of the current medications are directed against the exaggerated proinflammatory immune response of the host, some of them toxic and costly. Feeding prebiotics changes the composition of the intestinal microflora toward more protective intestinal bacteria and alters systemic and mucosal immune responses of the host. Therapy for IBD targeting intestinal bacteria and their function is just emerging. Prebiotics have the promise to be relatively safe, inexpensive, and easy to administer. Unraveling their protective mechanisms will help to develop rational applications of prebiotics. However, the initial promising results with dietary prebiotics in preclinical trials as well as small studies in human IBD will need to be confirmed in large randomized controlled clinical trials. (Inflamm Bowel Dis 2008) [source] Early bacterial dependent induction of inducible nitric oxide synthase (iNOS) in epithelial cells upon transfer of CD45RBhigh CD4+ T cells in a model for experimental colitisINFLAMMATORY BOWEL DISEASES, Issue 12 2007Gerard Dijkstra MD Abstract Background: Both the role of inducible nitric oxide synthase (iNOS) in the development of inflammatory bowel disease (IBD) as well as the molecular details governing its mucosal induction remain unclear. Methods: In the present study we evaluated the role of the residing intestinal microflora in the induction of epithelial iNOS upon transfer of CD45RBhigh CD4+ T cells to SCID mice. CB-17 SCID mice were reared with conventional flora (CNV) or germfree CB-17 SCID mice were monoassociated with Helicobacter muridarum, act A(,) mutant Listeria monocytogenes, segmented filamentous bacteria (SFB), or Ochrobactrum anthropi. Results: Within 2 weeks CNV SCID mice injected with CD45RBhigh CD4+ T cells showed a focal, epithelial iNOS expression on the apical site of villi that preceded the infiltration of CD4+ T cells and cytokine production followed by extension of this expression to the entire surface along the whole crypt axis as the colitis progressed. SCID mice monoassociated with H. muridarum developed a severe colitis and showed high epithelial iNOS expression. CNV-SCID mice without T cells and SCID mice monoassociated with SFB did not show any iNOS expression, whereas SCID mice monoassociated with act A(,) mutant L. monocytogenes and O. anthropi showed some scattered epithelial iNOS staining on the apical site of a few villi, but none of these mice developed colitis. Conclusions: These findings demonstrate that the expression of epithelial iNOS is highly bacterium-specific and correlates with the severity of disease, suggesting an important role for this enzyme in the development of IBD. (Inflamm Bowel Dis 2007) [source] Segmented filamentous bacteria in a defined bacterial cocktail induce intestinal inflammation in SCID mice reconstituted with CD45RBhigh CD4+ T cellsINFLAMMATORY BOWEL DISEASES, Issue 10 2007Renata Stepankova PhD Abstract Background: The aim was to analyze the influence of intestinal microbiota on the development of intestinal inflammation. We used the model of chronic inflammation that develops spontaneously in the colon of conventional severe combined immunodeficiency (SCID) mice restored with the CD45 RBhigh subset of CD4+T cells isolated from the spleen of normal BALB/c mice. Methods: A CD4+CD45RBhigh subpopulation of T cells was purified from the spleen of conventional BALB/c mice by magnetic separation (MACS) and transferred into immunodeficient SCID mice. Germ-free (GF) SCID mice or SCID mice monoassociated with Enterococcus faecalis, SFB (segmented filamentous bacteria), Fusobacterium mortiferum, Bacteroides distasonis, and in combination Fusobacterium mortiferum + SFB or Bacteroides distasonis + SFB were used as recipients. SCID mice were colonized by a defined cocktail of specific pathogen-free (SPF) bacteria. Mice were evaluated 8,12 weeks after the cell transfer for clinical and morphological signs of inflammatory bowel disease (IBD). Results: After the transfer of the CD4+CD45RBhigh T-cell subpopulation to SCID mice severe colitis was present in conventional animals and in mice colonized with a cocktail of SPF microflora plus SFB. Altered intestinal barrier in the terminal ileum of mice with severe colitis was documented by immunohistology using antibodies to ZO-1 (zona occludens). Conclusions: Only SFB bacteria together with a defined SPF mixture were effective in triggering intestinal inflammation in the model of IBD in reconstituted SCID mice, while no colitis was detected in GF mice or in mice colonized either with SPF microflora or monoassociated only with SFB or colonized by Bacteroides distasonis + SFB or Fusobacterium mortiferum + SFB. (Inflamm Bowel Dis 2007) [source] Bacterial population analysis of human colon and terminal ileum biopsies with 16S rRNA-based fluorescent probes: Commensal bacteria live in suspension and have no direct contact with epithelial cellsINFLAMMATORY BOWEL DISEASES, Issue 10 2005Laurens A van der Waaij PhD Abstract Background: The commensal intestinal microflora has important metabolic and perhaps also immune modulatory functions. Evidence has accumulated that the microflora plays a role in the pathogenesis of inflammatory bowel disease. Therefore, there is a growing interest in the intestinal microflora and its interaction with the host. Presumably, this interaction takes place at the mucus layer. In this study, we investigated the microflora that is present at the mucus layer and addressed the following questions. Does a specific mucus-adherent microflora exist? Is there direct contact between commensal bacteria and epithelial cells? Methods: Snap-frozen biopsies were taken of 5 colon regions and of the terminal ileum in 9 subjects with a normal colon. Fecal samples were also collected. Bacteria were detected in cryosections with fluorescent in situ hybridization (FISH) with 16S ribosomal (r)RNA-targeted probes for all bacteria and specific probes for the major representatives of anaerobic microflora (bifidobacteria, Bacteroides, clostridia, atopobia) and aerobic microflora (Enterobacteriaceae, enterococci, streptococci, lactobacilli). Results: With this sensitive technique, bacteria were only observed at the luminal side of the intestinal mucus layer. Very few microcolonies were present at the mucus layer, and the composition of the bacterial microflora present in the feces was similar to that at the mucus layer of the terminal ileum and colon regions. Conclusions: We did not observe direct contact between bacteria and epithelial cells. The equal distribution of bacterial species suggests that intestinal commensal bacteria live in suspension in the lumen and that there is no specific mucus-adherent microflora. [source] | ||||||||||||||||||||||||||||||||||