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Per Halkjær Nielsen - One of the best experts on this subject based on the ideXlab platform.

  • population dynamics of Filamentous Bacteria in danish wastewater treatment plants with nutrient removal
    Water Research, 2012
    Co-Authors: Artur Tomasz Mielczarek, Caroline Kragelund, Poul Svante Eriksen, Per Halkjær Nielsen
    Abstract:

    Bulking and foaming are two frequently occurring operational problems in activated sludge wastewater treatment plants, and these problems are mainly associated with excessive growth of Filamentous Bacteria. In this study, a comprehensive investigation of the identity and population dynamics of Filamentous Bacteria in 28 Danish municipal treatment plants with nutrient removal has been carried out over three years. Fluorescence in situ hybridization was applied to quantify more than twenty probe-defined populations of Filamentous Bacteria that in total constituted a large fraction of the entire microbial community, on average 24%. Despite the majority being present within the flocs, they occasionally caused settling problems in most of the plants. A low diversity of probe-defined Filamentous Bacteria was found in the plants with Microthrix and various species belonging to phylum Chloroflexi (e.g., type 0803 and type 0092) as the most abundant. Few other Filamentous probe-defined species were found revealing a large similarity between the Filamentous populations in the plants investigated. The composition of Filamentous populations was stable in each plant with only minor changes in relative abundances observed during the three-year study period. The relative composition of the different species was unique to each plant giving a characteristic "fingerprint". Comprehensive statistical analyses of the presence and abundance of the Filamentous organisms did not reveal many correlations with a particular plant design or process parameter.

  • Identity and ecophysiology of Filamentous Bacteria in activated sludge.
    FEMS microbiology reviews, 2009
    Co-Authors: Per Halkjær Nielsen, Caroline Kragelund, Robert J. Seviour, Jeppe Lund Nielsen
    Abstract:

    Excessive growth of Filamentous Bacteria in activated sludge wastewater treatment plants (WWTPs) can cause serious operational problems. With some filaments there may be the problem of bulking, where inadequate flocculation and settling of the biomass in the secondary clarifier results in a carryover of solids with the final treated liquid effluent. Their proliferation often encourages the development of stable foams on the surface of the reactors, and these foams may impact negatively on plant performance and operation. The availability of culture-independent molecular methods now allows us to identify many of the more common Filamentous organisms encountered in WWTPs, which are phylogenetically diverse, affiliating to seven separate Bacterial phyla. Furthermore, the extensive data published in the past decade on their in situ behaviour from the application of these culture-independent methods have not been summarized or reviewed critically. Hence, here, we attempt to discuss what we now know about their identity, ecophysiology and ecological niches and its practical value in better managing activated sludge processes. Some of this knowledge is already being applied to control and manage full-scale WWTPs better, and the hope is that this review will contribute towards further developments in this field of environmental microbiology.

  • amyloid like adhesins produced by floc forming and Filamentous Bacteria in activated sludge
    Applied and Environmental Microbiology, 2008
    Co-Authors: Poul Larsen, Daniel E. Otzen, Jeppe Lund Nielsen, Per Halkjær Nielsen
    Abstract:

    Amyloid proteins (fimbriae or other microbial surface-associated structures) are expressed by many types of Bacteria, not yet identified, in biofilms from various habitats, where they likely are of key importance to biofilm formation and biofilm properties. As these amyloids are potentially of great importance to the floc properties in activated sludge wastewater treatment plants (WWTP), the abundance of amyloid adhesins in activated sludge flocs from different WWTP and the identity of Bacteria producing these were investigated. Amyloid adhesins were quantified using a combination of conformationally specific antibodies targeting amyloid fibrils, propidium iodide to target all fixed Bacterial cells, confocal laser scanning microscopy, and digital image analysis. The biovolume fraction containing amyloid adhesins ranged from 10 to 40% in activated sludge from 10 different WWTP. The identity of Bacteria producing amyloid adhesins was determined using fluorescence in situ hybridization with oligonucleotide probes in combination with antibodies or thioflavin T staining. Among the microcolony-forming Bacteria, amyloids were primarily detected among Alpha- and BetaproteoBacteria and ActinoBacteria. A more detailed analysis revealed that many denitrifiers (from Thauera, Azoarcus, Zoogloea, and Aquaspirillum-related organisms) and ActinoBacteria-related polyphosphate-accumulating organisms most likely produced amyloid adhesins, whereas nitrifiers did not. Many Filamentous Bacteria also expressed amyloid adhesins, including several AlphaproteoBacteria (e.g., Meganema perideroedes), some BetaproteoBacteria (e.g., Aquaspirillum-related filaments), GammaproteoBacteria (Thiothrix), Bacteroidetes, Chloroflexi (e.g., Eikelboom type 1851), and some foam-forming ActinoBacteria (e.g., Gordonia amarae). The results show that amyloid adhesins were an abundant component of activated sludge extracellular polymeric substances and seem to have unexpected, divers functions.

  • quantification of cell specific substrate uptake by probe defined Bacteria under in situ conditions by microautoradiography and fluorescence in situ hybridization
    Environmental Microbiology, 2003
    Co-Authors: Jeppe Lund Nielsen, Dinna Christensen, Marie Kloppenborg, Per Halkjær Nielsen
    Abstract:

    : A technique based on quantitative microautoradiography (QMAR) and fluorescence in situ hybridization (FISH) was developed and evaluated in order to determine the quantitative uptake of specific substrates in probe-defined Filamentous Bacteria directly in a complex system. The technique, QMAR-FISH, has a resolution of a single cell and is based on an improved fixation protocol and the use of an internal standard of Bacteria with known specific radioactivity. The method was used to study the in situ ecophysiology of the Filamentous Bacteria 'Candidatus Meganema perideroedes' and Thiothrix sp. directly in an activated sludge system. The cellular uptake rate of tritium-labelled substrates revealed an average cell-specific uptake rate of 4.1 yen 10-15 mol of acetate cell-1 h-1 and 3.1 yen 10-15 mol of acetate cell-1 h-1 for the two Filamentous species respectively. The two Filamentous species had very similar activity in all cells along each filament. Surprisingly, the filaments within both probe-defined populations had threefold variation in activity between the different filaments, demonstrating a large variation in activity level within a single population in a complex system. The substrate affinity (Ks) for uptake of acetate of the cells within the two Filamentous Bacteria was determined by incubation with variable concentrations of labelled acetate. The Ks values of the 'Candidatus Meganema perideroedes' and the Thiothrix Filamentous Bacteria were determined to be 1.8 micro M and 2.4 micro M acetate respectively.

  • in situ studies of the phylogeny and physiology of Filamentous Bacteria with attached growth
    Environmental Microbiology, 2002
    Co-Authors: Trine Rolighed Thomsen, Philip Hugenholtz, Jeppe Lund Nielsen, Birthe V Kjellerup, Per Halkjær Nielsen
    Abstract:

    Among the Filamentous Bacteria occasionally causing bulking problems in activated sludge treatment plants, three morphotypes with attached microbial growth are common, Eikelboom Type 0041, Type 1851 and Type 1701. A better knowledge of the phylogeny and physiology of these Filamentous Bacteria is necessary in order to develop control strategies for bulking. In this study we have used a combination of fluorescence in situ hybridization (FISH) and microautoradiography (MAR) to investigate the identity and in situ physiology of the Type 0041-morphotype and its attached Bacteria in two wastewater treatment plants. Identification and enumeration of Type 0041 using group-specific 16S rRNA-targeted FISH probes revealed that approximately 15% of the filaments hybridized with a gene probe specific for the TM7 group, a recently recognized major lineage in the Bacterial domain. All other filaments morphologically identified as Type 0041 only hybridized to the general Bacterial EUB338-probe, indicating that they probably do not belong to commonly isolated Bacterial phyla such as the ProteoBacteria , Firmicutes , ActinoBacteria and Bacteroidetes , for which group-specific probes were used. The phylogenetic heterogeneity of Type 0041 again highlights the inadequacy of a morphology-based classification system. Like the filaments, most of the attached microbial cells were not identified beyond their affiliation to the Bacteria using the group-specific FISH probes. However, several different Bacterial phyla were represented in the identified fraction suggesting that the attached microorganisms are phylogenetically diverse. The study of the in situ physiology of Type 0041 using MAR-FISH revealed that both the filaments and the attached Bacteria on Type 0041 were versatile in the use of organic substrates and electron acceptors. It was observed that all Type 0041 could consume glucose, but none of the filaments were able to consume acetate under any conditions tested, in contrast to some of the attached Bacteria. No significant physiological differences were found between TM7-positive and TM7-negative Type 0041 filaments, and only minor differences were observed between the two treatment plants tested. These are the first data on the physiology of the almost entirely uncharacterized TM7 phylum and show that TM7 Filamentous Bacteria can uptake carbon substrates under aerobic and anaerobic conditions.

Yoshinori Umesaki - One of the best experts on this subject based on the ideXlab platform.

  • gut residing segmented Filamentous Bacteria drive autoimmune arthritis via t helper 17 cells
    Immunity, 2010
    Co-Authors: Hsin Jung Wu, Ivaylo I. Ivanov, Dan R Littman, Jaime Darce, Kimie Hattori, Tatsuichiro Shima, Yoshinori Umesaki, Christophe Benoist
    Abstract:

    Commensal microbes can have a substantial impact on autoimmune disorders, but the underlying molecular and cellular mechanisms remain largely unexplored. We report that autoimmune arthritis was strongly attenuated in the K/BxN mouse model under germ-free (GF) conditions, accompanied by reductions in serum autoantibody titers, splenic autoantibody-secreting cells, germinal centers, and the splenic T helper 17 (Th17) cell population. Neutralization of interleukin-17 prevented arthritis development in specific-pathogen-free K/BxN mice resulting from a direct effect of this cytokine on B cells to inhibit germinal center formation. The systemic deficiencies of the GF animals reflected a loss of Th17 cells from the small intestinal lamina propria. Introduction of a single gut-residing species, segmented Filamentous Bacteria, into GF animals reinstated the lamina propria Th17 cell compartment and production of autoantibodies, and arthritis rapidly ensued. Thus, a single commensal microbe, via its ability to promote a specific Th cell subset, can drive an autoimmune disease.

  • differential roles of segmented Filamentous Bacteria and clostridia in development of the intestinal immune system
    Infection and Immunity, 1999
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Hiromi Setoyama, Satoshi Matsumoto, Kikuji Itoh
    Abstract:

    The presence of microflora in the digestive tract promotes the development of the intestinal immune system. In this study, to evaluate the roles of two types of indigenous microbe, segmented Filamentous Bacteria (SFB) and clostridia, whose habitats are the small and large intestines, respectively, in this immunological development, we analyzed three kinds of gnotobiotic mice contaminated with SFB, clostridia, and both SFB and clostridia, respectively, in comparison with germfree (GF) or conventionalized (Cvd) mice associated with specific-pathogen-free flora. In the small intestine, the number of alpha beta T-cell receptor-bearing intraepithelial lymphocytes (alpha betaIEL) increased in SFB-associated mice (SFB-mice) but not in clostridium-associated mice (Clost-mice). There was no great difference in Vbeta usage among GF mice, Cvd mice, and these gnotobiotic mice, although the association with SFB decreased the proportion of Vbeta6(+) cells in CD8beta- subsets to some extent, compared to that in GF mice. The expression of major histocompatibility complex class II molecules on the epithelial cells was observed in SFB-mice but not in Clost-mice. On the other hand, in the large intestine, the ratio of the number of CD4(-) CD8(+) cells to that of CD4(+) CD8(-) cells in alpha betaIEL increased in Clost-mice but not in SFB-mice. On association with both SFB and clostridia, the numbers and phenotypes of IEL in the small and large intestines changed to become similar to those in Cvd mice. In particular, the ratio of the number of CD8alpha beta+ cells to that of CD8alpha alpha+ cells in alpha betaIEL, unusually elevated in the small intestines of SFB-mice, decreased to the level in Cvd mice on contamination with both SFB and clostridia. The number of immunoglobulin A (IgA)-producing cells in the lamina propria was more elevated in SFB-mice than in Clost-mice, not only in the ileum but also in the colon. The number of IgA-producing cells in the colons of Clost-mice was a little increased compared to that in GF mice. Taken together, SFB and clostridia promoted the development of both IEL and IgA-producing cells in the small intestine and that of only IEL in the large intestine, respectively, suggesting the occurrence of compartmentalization of the immunological responses to the indigenous Bacteria between the small and large intestines.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction of major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially αβ T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmented Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of αβTCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction fo major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially alpha beta T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmental Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of alpha beta TCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

Akemi Imaoka - One of the best experts on this subject based on the ideXlab platform.

  • complete genome sequences of rat and mouse segmented Filamentous Bacteria a potent inducer of th17 cell differentiation
    Cell Host & Microbe, 2011
    Co-Authors: Tulika Prakash, Kenshiro Oshima, Hidetoshi Morita, Shinji Fukuda, Akemi Imaoka, Naveen Kumar, Vineet K Sharma, Mahoko Takahashi, Naruya Saitou, Todd D Taylor
    Abstract:

    Summary Segmented Filamentous Bacteria (SFB) are noncultivable commensals inhabiting the gut of various vertebrate species and have been shown to induce Th17 cells in mice. We present the complete genome sequences of both rat and mouse SFB isolated from SFB-monocolonized hosts. The rat and mouse SFB genomes each harbor a single circular chromosome of 1.52 and 1.59 Mb encoding 1346 and 1420 protein-coding genes, respectively. The overall nucleotide identity between the two genomes is 86%, and the substitution rate was estimated to be similar to that of the free-living E. coli . SFB genomes encode typical genes for anaerobic fermentation and spore and flagella formation, but lack most of the amino acid biosynthesis enzymes, reminiscent of pathogenic Clostridia , exhibiting large dependency on the host. However, SFB lack most of the clostridial virulence-related genes. Comparative analysis with clostridial genomes suggested possible mechanisms for host responses and specific adaptations in the intestine.

  • differential roles of segmented Filamentous Bacteria and clostridia in development of the intestinal immune system
    Infection and Immunity, 1999
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Hiromi Setoyama, Satoshi Matsumoto, Kikuji Itoh
    Abstract:

    The presence of microflora in the digestive tract promotes the development of the intestinal immune system. In this study, to evaluate the roles of two types of indigenous microbe, segmented Filamentous Bacteria (SFB) and clostridia, whose habitats are the small and large intestines, respectively, in this immunological development, we analyzed three kinds of gnotobiotic mice contaminated with SFB, clostridia, and both SFB and clostridia, respectively, in comparison with germfree (GF) or conventionalized (Cvd) mice associated with specific-pathogen-free flora. In the small intestine, the number of alpha beta T-cell receptor-bearing intraepithelial lymphocytes (alpha betaIEL) increased in SFB-associated mice (SFB-mice) but not in clostridium-associated mice (Clost-mice). There was no great difference in Vbeta usage among GF mice, Cvd mice, and these gnotobiotic mice, although the association with SFB decreased the proportion of Vbeta6(+) cells in CD8beta- subsets to some extent, compared to that in GF mice. The expression of major histocompatibility complex class II molecules on the epithelial cells was observed in SFB-mice but not in Clost-mice. On the other hand, in the large intestine, the ratio of the number of CD4(-) CD8(+) cells to that of CD4(+) CD8(-) cells in alpha betaIEL increased in Clost-mice but not in SFB-mice. On association with both SFB and clostridia, the numbers and phenotypes of IEL in the small and large intestines changed to become similar to those in Cvd mice. In particular, the ratio of the number of CD8alpha beta+ cells to that of CD8alpha alpha+ cells in alpha betaIEL, unusually elevated in the small intestines of SFB-mice, decreased to the level in Cvd mice on contamination with both SFB and clostridia. The number of immunoglobulin A (IgA)-producing cells in the lamina propria was more elevated in SFB-mice than in Clost-mice, not only in the ileum but also in the colon. The number of IgA-producing cells in the colons of Clost-mice was a little increased compared to that in GF mice. Taken together, SFB and clostridia promoted the development of both IEL and IgA-producing cells in the small intestine and that of only IEL in the large intestine, respectively, suggesting the occurrence of compartmentalization of the immunological responses to the indigenous Bacteria between the small and large intestines.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction of major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially αβ T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmented Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of αβTCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction fo major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially alpha beta T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmental Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of alpha beta TCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

Hiromi Setoyama - One of the best experts on this subject based on the ideXlab platform.

  • differential roles of segmented Filamentous Bacteria and clostridia in development of the intestinal immune system
    Infection and Immunity, 1999
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Hiromi Setoyama, Satoshi Matsumoto, Kikuji Itoh
    Abstract:

    The presence of microflora in the digestive tract promotes the development of the intestinal immune system. In this study, to evaluate the roles of two types of indigenous microbe, segmented Filamentous Bacteria (SFB) and clostridia, whose habitats are the small and large intestines, respectively, in this immunological development, we analyzed three kinds of gnotobiotic mice contaminated with SFB, clostridia, and both SFB and clostridia, respectively, in comparison with germfree (GF) or conventionalized (Cvd) mice associated with specific-pathogen-free flora. In the small intestine, the number of alpha beta T-cell receptor-bearing intraepithelial lymphocytes (alpha betaIEL) increased in SFB-associated mice (SFB-mice) but not in clostridium-associated mice (Clost-mice). There was no great difference in Vbeta usage among GF mice, Cvd mice, and these gnotobiotic mice, although the association with SFB decreased the proportion of Vbeta6(+) cells in CD8beta- subsets to some extent, compared to that in GF mice. The expression of major histocompatibility complex class II molecules on the epithelial cells was observed in SFB-mice but not in Clost-mice. On the other hand, in the large intestine, the ratio of the number of CD4(-) CD8(+) cells to that of CD4(+) CD8(-) cells in alpha betaIEL increased in Clost-mice but not in SFB-mice. On association with both SFB and clostridia, the numbers and phenotypes of IEL in the small and large intestines changed to become similar to those in Cvd mice. In particular, the ratio of the number of CD8alpha beta+ cells to that of CD8alpha alpha+ cells in alpha betaIEL, unusually elevated in the small intestines of SFB-mice, decreased to the level in Cvd mice on contamination with both SFB and clostridia. The number of immunoglobulin A (IgA)-producing cells in the lamina propria was more elevated in SFB-mice than in Clost-mice, not only in the ileum but also in the colon. The number of IgA-producing cells in the colons of Clost-mice was a little increased compared to that in GF mice. Taken together, SFB and clostridia promoted the development of both IEL and IgA-producing cells in the small intestine and that of only IEL in the large intestine, respectively, suggesting the occurrence of compartmentalization of the immunological responses to the indigenous Bacteria between the small and large intestines.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction of major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially αβ T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmented Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of αβTCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

  • segmented Filamentous Bacteria are indigenous intestinal Bacteria that activate intraepithelial lymphocytes and induce mhc class ii molecules and fucosyl asialo gm1 glycolipids on the small intestinal epithelial cells in the ex germ free mouse
    Microbiology and Immunology, 1995
    Co-Authors: Yoshinori Umesaki, Akemi Imaoka, Satoshi Matsumoto, Yasushi Okada, Hiromi Setoyama
    Abstract:

    In ex-germ-free mice conventionalized by association with fecal microorganisms, the induction fo major histocompatibility complex class II molecules and fucosylation of asialo GM1 glycolipid occur in the small intestinal epithelial cells (IEC). The intestinal intraepithelial lymphocytes (IEL), especially alpha beta T-cell receptor-bearing ones, also remarkably expand and show cytolytic activity. In this study, we investigated the immunological and physiological characteristics of the small intestine induced by a kind of indigenous Bacteria of the small intestine, segmental Filamentous Bacteria (SFB), among chloroform-resistant intestinal Bacteria. Monoassociation of SFB with germ-free mice was confirmed by the determination of the base sequences of polymerase chain reaction products of 16S rRNA genes of the fecal Bacteria of these mice and in situ hybridization using fluorescein-labeled probes based on them. SFB increased the number of alpha beta TCR-bearing IEL and induced Thy-1 expression and cytolytic activity of IEL. The induction of MHC class II molecules and fucosyl asialo GM1 glycolipids and the increases in the mitotic activity and the ratio of the number of columnar cells to those of goblet cells also occurred in the small intestinal epithelial cells on monoassociation of these Bacteria. SFB are important indigenous Bacteria for the development of the mucosal architecture and immune system in the small intestine, at least in mice.

Fenglin Yang - One of the best experts on this subject based on the ideXlab platform.

  • impact of Filamentous Bacteria on properties of activated sludge and membrane fouling rate in a submerged mbr
    Separation and Purification Technology, 2008
    Co-Authors: Fenglin Yang, Dieudonneguy Ohandja, Fooksin Wong, Hweechuan Chua
    Abstract:

    Abstract This study presents the results from the continuous microfiltration of activated sludge with different Filamentous Bacteria density (expressed as filament index (FI)) in a submerged membrane bioreactor (MBR). During the entire experimental duration of 120 days, the Filamentous Bacteria density increased gradually from FI = 2 to 6 in the beginning, thereafter maintained at a plateau of FI = 6 for about 20 days, and decreased to FI = 4 at the end of the experiment. The relationship between FI and other properties of activated sludge were analysed using statistical analysis. It was found that Filamentous Bacteria density has no significant effect on bound extracellular polymeric substances (bound EPS, rp = −0.343, p = 0.080) and soluble microbial products (SMPs, rp = 0.221, p = 0.267). However, it has an important impact on floc size (rp = 0.944, p = 0.000) and floc structure (rp = −0.752, p = 0.000). High FI favored the formation of bigger flocs with a loose structure, and vice versa. Further studies on the impact of the activated sludge properties on membrane-fouling rate indicated that variations of the bound EPS may be the major factor contributing to the membrane-fouling rate. Although Filamentous Bacteria have the ability to change the floc morphology, the effect on the membrane-fouling rate may be negligible.

  • effect of hydraulic retention time on membrane fouling and biomass characteristics in submerged membrane bioreactors
    Bioprocess and Biosystems Engineering, 2007
    Co-Authors: Fangang Meng, Baoqiang Shi, Fenglin Yang, Hanmin Zhang
    Abstract:

    In this paper, three identical membrane bioreactors (MBRs) were operated in parallel in order to specify the influence mechanism of hydraulic retention time (HRT) on MBR. The results showed that the removal efficiency of chemical oxygen demand (COD) was stable though it decreased slightly as HRT decreased, but biomass activity and dissolved oxygen (DO) concentration in sludge suspension decreased as HRT decreased. The Filamentous Bacteria grew easily with decreasing HRT. The extracellular polymeric substances (EPS) concentration and sludge viscosity increased significantly as Filamentous Bacteria excessively grew. The over growth of Filamentous Bacteria, the increase of EPS and the decrease of shear stress led to the formation of large and irregular flocs. Furthermore, the mixed liquid suspended solids (MLSS) concentration and sludge viscosity increased significantly as HRT decreased. The results also indicated that sludge viscosity was the predominant factor that affecting hydrodynamic conditions of MBR systems.

  • effect of Filamentous Bacteria on membrane fouling in submerged membrane bioreactor
    Journal of Membrane Science, 2006
    Co-Authors: Fangang Meng, Hanmin Zhang, Fenglin Yang, Jingni Xiao, Xingwen Zhang
    Abstract:

    Abstract Membrane fouling is the major problem that hinders the practical application of membrane bioreactor (MBR) systems. Since the MBR system includes living microorganisms and their metabolites, the fouling mechanism is even more complex than that of conventional membrane separation processes. This paper provides an improved understanding of the influence of Filamentous Bacteria on membrane fouling in microfiltration of activated sludge wastewater. In order to make clear the membrane fouling mechanism of Filamentous Bacteria, the physicochemical characteristics of sludge flocs, including extracellular polymeric substance (EPS), zeta potential, relative hydrophobicity (RH) and floc morphology were systematically investigated. The results showed that the sludge flocs with negligible Filamentous Bacteria led to severe membrane pore blocking, and the sludge flocs with Filamentous Bacteria created the formation of a non-porous cake layer on the membrane surface. The excess growth of Filamentous Bacteria resulted in much more release of EPS, lower zeta potential, higher hydrophobicity of sludge flocs and more irregularly shaped flocs, which did great harm to membrane filtration. The sludge flocs with a small quantity of Filamentous Bacteria had a positive effect on membrane permeation. It is important to control Filamentous Bacteria concentration in the operation of MBRs.