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PubMed2007

RNA polymerase beta-subunit gene (rpoB) sequence analysis for the identification of Bacteroides spp.

Partial rpoB sequences (317 bp) of 11 species of Bacteroides, two Porphyromonas spp. and two Prevotella spp. were compared to delineate the genetic relationships among Bacteroides and closely related anaerobic species. The high level of inter-species sequence dissimilarities (7.6-20.8%) allowed the various Bacteroides spp. to be distinguished. The position of the Bacteroides distasonis and Bacteriodes merdae cluster in the rpoB tree was different from the position in the 16S rRNA gene tree. Based on rpoB sequence similarity and clustering in the rpoB tree, it was possible to correctly re-identify 80 clinical isolates of Bacteroides. In addition to two subgroups, cfiA-negative (division I) and cfiA-positive (division II), of Bacteroides fragilis isolates, two distinct subgroups were also found among Bacteroides ovatus and Bacteroides thetaiotaomicron isolates. Bacteroides genus-specific rpoB PCR and B. fragilis species-specific rpoB PCR allowed Bacteroides spp. to be differentiated from Porphyromonas and Prevotella spp., and also allowed B. fragilis to be differentiated from other non-fragilisBacteroides spp. included in the present study.

Bacterial Proteins↗
PubMed2000

Characterization of a Bacteroides mobilizable transposon, NBU2, which carries a functional lincomycin resistance gene.

The mobilizable Bacteroides element NBU2 (11 kbp) was found originally in two Bacteroides clinical isolates, Bacteroides fragilis ERL and B. thetaiotaomicron DOT. At first, NBU2 appeared to be very similar to another mobilizable Bacteroides element, NBU1, in a 2.5-kbp internal region, but further examination of the full DNA sequence of NBU2 now reveals that the region of near identity between NBU1 and NBU2 is limited to this small region and that, outside this region, there is little sequence similarity between the two elements. The integrase gene of NBU2, intN2, was located at one end of the element. This gene was necessary and sufficient for the integration of NBU2. The integrase of NBU2 has the conserved amino acids (R-H-R-Y) in the C-terminal end that are found in members of the lambda family of site-specific integrases. This was also the only region in which the NBU1 and NBU2 integrases shared any similarity (28% amino acid sequence identity and 49% sequence similarity). Integration of NBU2 was site specific in Bacteroides species. Integration occurred in two primary sites in B. thetaiotaomicron. Both of these sites were located in the 3' end of a serine-tRNA gene NBU2 also integrated in Escherichia coli, but integration was much less site specific than in B. thetaiotaomicron. Analysis of the sequence of NBU2 revealed two potential antibiotic resistance genes. The amino acid sequences of the putative proteins encoded by these genes had similarity to resistances found in gram-positive bacteria. Only one of these genes was expressed in B. thetaiotaomicron, the homolog of linA, a lincomycin resistance gene from Staphylococcus aureus. To determine how widespread elements related to NBU1 and NBU2 are in Bacteroides species, we screened 291 Bacteroides strains. Elements with some sequence similarity to NBU2 and NBU1 were widespread in Bacteroides strains, and the presence of linA(N) in Bacteroides strains was highly correlated with the presence of NBU2, suggesting that NBU2 has been responsible for the spread of this gene among Bacteroides strains. Our results suggest that the NBU-related elements form a large and heterogeneous family, whose members have similar integration mechanisms but have different target sites and differ in whether they carry resistance genes.

Amino Acid Sequence↗
PubMed1986

Effect of Bacteroides fragilis grown in the presence of clindamycin, metronidazole and fusidic acid on opsonization and killing of Escherichia coli.

Bactericidal action of human polymorphonuclear leucocytes on Escherichia coli in the presence of Bacteroides fragilis grown in subinhibitory concentrations of clindamycin, metronidazole and fusidic acid was studied. Bacteroides fragilis grown in the absence of drugs significantly inhibited the killing of Escherichia coli. Bacteroides fragilis grown in the presence of the drugs had a reduced inhibitory effect on the killing of Escherichia coli but this reduction was only significant for Bacteroides fragilis grown in 1/2 MIC of clindamycin. The phagocytosis of Bacteroides fragilis grown with and without clindamycin, as measured by killing, was the same. Complement consumption of Bacteroides fragilis grown with and without clindamycin did not differ. Clindamycin-treated Bacteroides fragilis fixed C3 to a significantly lower degree than did untreated bacteria. The chemiluminescence of Escherichia coli opsonized with serum preincubated with clindamycin-treated Bacteroides fragilis was significantly higher than with serum preincubated with untreated bacteria. These results suggested that in killing experiments of mixed Escherichia coli and Bacteroides fragilis, the mechanism underlying the reduced inhibitory capacity of clindamycin-exposed Bacteroides fragilis is related to greater availability of C3 in serum for opsonization of Escherichia coli.

Anti-Bacterial Agents↗
PubMed1989

Prevalence of black-pigmented bacteroides species in root canal infections.

The prevalence of black-pigmented Bacteroides species in the root canals of 72 teeth with apical periodontitis was evaluated. Twenty-two of the canals contained one or more species of black-pigmented Bacteroides. Bacteroides intermedius (14 strains) and Bacteroides endodontalis (5 strains) were most common. Of the species Bacteroides gingivalis, Bacteroides loeschei, and Bacteroides denticola, 2, 3, and 1 strains, respectively, were isolated. The median number of bacterial cells recovered from the root canals containing black-pigmented Bacteroides was 2.8 x 10(5) and from the other canals 3.0 x 10(3). The mean number of strains was 7.9 and 3.3, respectively. Sixteen of the 22 root canals containing black-pigmented Bacteroides species were associated with acute apical abscesses and purulent drainage through the root canal. The other six teeth with black-pigmented Bacteroides were asymptomatic. One additional abscess was present among the 72 cases. This root canal contained Actinomyces israelii and Actinomyces naeslundii.

Actinomyces↗
PubMed1983

Use of randomly cloned DNA fragments for identification of Bacteroides thetaiotaomicron.

Randomly cloned fragments of DNA from Bacteroides thetaiotaomicron were used as hybridization probes for differentiation of B. thetaiotaomicron from closely related Bacteroides species. HindIII digestion fragments of DNA from B. thetaiotaomicron (type strain) were inserted into plasmid pBR322 and labeled with [alpha-32P]dCTP by nick translation. These labeled plasmids were screened for hybridization to HindIII digests of chromosomal DNA from type strains of the following human colonic Bacteroides species: B. thetaiotaomicron, Bacteroides ovatus, reference strain 3452-A (formerly part of B. distasonis), Bacteroides uniformis, Bacteroides fragilis, Bacteroides vulgatus, Bacteroides distasonis, Bacteroides eggerthii, and reference strain B5-21 (formerly B. fragilis subsp. a). Two of the five cloned fragments hybridized only to DNA from B. thetaiotaomicron. Each of these two fragments hybridized to the same DNA restriction fragment in five strains of B. thetaiotaomicron other than the strain from which the DNA was cloned. One of the cloned fragments (pBT2) was further tested for specificity by determining its ability to hybridize to DNA from 65 additional strains of colonic Bacteroides.

Bacteroides↗
PubMed1982

The direct immunofluorescence in the presumptive identification of Bacteroides species.

Two kits containing fluorescein labeled-polyvalent antisera to Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides vulgatus (Fluoretec-F) and to Bacteroides melaninogenicus subsp. melaninogenicus and intermedius and to Bacteroides asaccharolyticus (non-oral strains) (Fluoretec-M) were evaluated for the identification of the respective organisms in bacterial cultures and clinical specimens. In both cases immunofluorescent tests were compared to the bacteriological data. The results clearly demonstrated that Fluoretec-F has a specificity 97% and a sensitivity 96%. The corresponding values for Fluoretec-M were 99% and 87.5% respectively, either clinical specimens or pure cultures were examined. The presence of aerobic of facultative anaerobic bacteria and obligate anaerobic bacteria other than those to which antisera were included in the test kits did not seem to influence the test result. No cross-reactivity between Fluoretec-F and -M were observed. Also, no positive fluorescence was obtained when other anaerobic bacteria than Bacteroides spp. were tested. The same was also the case with various aerobic or facultative anaerobic bacteria. The use of Fluoretec-F and -M is considered as a useful tool for the early accurate identification of the Bacteroides species mentioned, which may serve as a guide for an appropriate prompt therapy which is especially needed in serious anaerobic infections.

Bacteriological Techniques↗
PubMed1988

Respiration supported nitrogenase activity of isolated Rhizobium meliloti bacteroids.

Bacteroids having a high level of respiration-supported nitrogenase activity were isolated from nitrogen-fixing alfalfa root nodules. Gentle maceration under anaerobic conditions in the presence of sodium succinate and a fatty acid scavenging agent were employed in this method. A large proportion of isolated bacteroids retained a triple membrane structure as shown by transmission electron microscopy. Dicarboxylic acids of the TCA cycle (malate, fumarate, succinate), but not glutamate or aspartate, supported sufficient respiratory activity to supply the nitrogenase system with ATP and reducing equivalents and to protect the nitrogenase system from inactivation by 4% oxygen over a period of 20-30 min. Sugars did not support nitrogenase activity in intact bacteroids. The properties of the isolated bacteroids were ascribed to minimal damage to the cytoplasmic membrane and peribacteroidal membrane during isolation. With succinate as substrate and oxygen as terminal electron acceptor, initial nitrogenase activity was determined at 4% oxygen in the gas phase of the assay system employed. At this oxygen concentration, the sustained rate of acetylene reduction by respiring bacteroids was linear up to 30 min. Bacteroid activity declined rapidly with time of exposure to oxygen above 4% in the gas phase. The optimum temperature range for this activity was 10-20 degrees C. Nitrogenase activity was measurable at incubation temperatures below 10 degrees C under 4% oxygen. Functionally intact bacteroids had little nitrogenase activity under anaerobic conditions in the presence of an external source of ATP and reductant. Treatment of the bacteroids with chlorpromazine eliminated respiration-supported activity and rendered the bacteroid cell membrane permeable to external ATP. Bacteroids treated with chlorpromazine had high acetylene reducing activity with external ATP and dithionite in the absence of oxygen.

Carboxylic Acids↗
PubMed2005

Do antimicrobial susceptibility patterns of colonic isolates of Bacteroides species change after antibiotic prophylaxis with cefoxitine during elective abdominal surgery?

The objectives of the study were to investigate and compare the susceptibility profiles of preoperative and postoperative intestinal Bacteroides fragilis and Bacteroides thetaiotaomicron strains against antimicrobials to evaluate their resistance development patterns due to prophylactic antibiotic administration. Preoperative and postoperative stool samples were obtained from patients undergoing elective abdominal surgery with a "clean-contaminated" wound categorization. All patients received cefoxitin 2 g as prophylaxis. Isolates of Bacteroides species were identified. Susceptibility tests against ampicillin, piperacillin, cefoxitin, clindamycin, chloramphenicol, metronidazole, imipenem, and amoxicillin-clavulanate were performed. Stool samples were collected from 40 patients at two settings: before and after the operation. Most of the patients (53%) were operated on because of colorectal carcinoma and underwent surgery that included colectomy or anterior resection. Bacteroides fragilis and Bacteroides thetaiotaomicron were isolated in both samples obtained from 22 and 34 patients, respectively. In the present study 95% to 100%, 50% to 74%, 46% to 64%, and 18% to 35% of preoperatively isolated Bacteroides species were resistant to ampicillin, cefoxitin, clindamycin, and piperacillin, respectively. Although there were no statistically significant difference, postoperative strains were more resistant than preoperative isolates, and the resistance rates were found to be 95% to 100%, 55% to 82%, 46% to 86%, and 37% to 41%, respectively. Both Bacteroides species isolated from all specimens before and after the surgery were uniformly susceptible to amoxicillin-clavulanate, imipenem, metronidazole, and chloramphenicol.Our data revealed that Bacteroides strains revealed high resistance to ampicillin, cefoxitin, piperacillin, and clindamycin. Metronidazole, imipenem, and amoxicillin-clavulanate seem highly effective against both Bacteroides species. Cefoxitin prophylaxis did not significantly increase the resistance patterns against antimicrobial agents.

Adult↗
PubMed1986

Induction of subcutaneous and intraperitoneal abscesses in mice by Neisseria gonorrhoeae and Bacteroides species.

The pathogenicity in relation to encapsulation and potential for synergy between Neisseria gonorrhoeae and Bacteroides spp. was studied by subcutaneous and intraperitoneal inoculation of single organisms or mixtures of these organisms into mice. Ten isolates of N. gonorrhoeae and 12 isolates of Bacteroides spp. were studied. When injected alone, only heavily encapsulated organisms induced subcutaneous and intraperitoneal abscesses. However, N. gonorrhoeae did not induce intraperitoneal abscesses and did not survive in intraperitoneal abscesses even when inoculated with Bacteroides spp. Abscesses developed after subcutaneous inoculation of mixtures of heavily encapsulated Bacteroides and heavily or slightly encapsulated N. gonorrhoeae or of slightly encapsulated Bacteroides and heavily encapsulated N. gonorrhoeae. Heavily encapsulated N. gonorrhoeae did not survive in subcutaneous abscesses longer than 3 days after being inoculated alone and survived no longer than 7 days after inoculation with heavily encapsulated Bacteroides spp. An increase in the colony-forming units of Bacteroides spp. per abscess was observed when they were inoculated with N. gonorrhoeae. When mixed with heavily encapsulated isolates, slightly encapsulated N. gonorrhoeae or Bacteroides isolates became heavily encapsulated. These data demonstrate the effect of encapsulation on the relationship between N. gonorrhoeae and Bacteroides spp. and the potential for synergy between these organisms.

Abscess↗
PubMed1995

A re-appraisal of the biological activity of bacteroides LPS.

Lipopolysaccharides (LPS) were extracted from seven Bacteroides strains by three different techniques: the phenol-water (PW), phenol-chloroform-petroleum (PCP) and Triton-Mg2+ methods. The strains selected included two different B. fragilis strains, one of which was grown in two different media. Yields varied between the strains, growth media and extraction technique, but generally the highest yield by weight was from the PCP method and the lowest from the PW method. The PW method was selected for the greatest amounts of carbohydrate and KDO, and the PCP method for the least. Phosphorus levels were more uniform among all extraction methods. Protein contamination was found in all Bacteroides LPS extracts, with extremely low levels in PW-LPS and the highest levels in material extracted by the PCP and Triton-Mg2+ techniques. No protein contamination could be detected after proteinase K treatment. After silver staining LPS PAGE profiles showed ladder patterns characteristics of smooth LPS for B. vulgatus, B. thetaiotaomicron and the control Escherichia coli O18:K- strains, whereas the other Bacteroides strains showed mainly rough and low M(r) material only. The PCP method did not select for high M(r) material in the B. fragilis strains; otherwise the LPS profiles for all extraction methods were identical. The biological activities of native and sodium salt form LPS were investigated on a weight for weight basis and compared to that of E. coli O18:K- PW-LPS. Amongst the LPS from Bacteroides strains, those prepared by the PW method were found to have a significantly higher activity in a galactosamine mouse lethality model, in induction of TNF and the Limulus amoebocyte lysate (LAL) assay, than LPS extracted by the PCP or Triton-Mg2+ methods. LPS from Bacteroides strains extracted by the PCP method had consistently low activity in all assays. Comparing PW-LPS from Bacteroides strains with that from E. coli O18:K- in the galactosamine mouse model, the E. coli O18:K- LPS was c. 5000-fold more active than the most active bacteroides LPS. However, in the LAL assay native PW-LPS from both the B. fragilis strains, and B. caccae had higher activities (up to 30-fold) than E. coli O18:K- LPS, with the PW-LPS from the other Bacteroides spp. being up to 15-fold less active than the E. coli O18:K- PW-LPS. In the TNF induction assay, E. coli O18:K- PW-LPS was 4-50-fold more active than bacteroides PW-LPS.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Properties of the penicillin-binding proteins of four species of the genus Bacteroides.

The penicillin-binding proteins (PBPs) of four species of the genus Bacteroides were examined in cell envelope preparations from exponentially growing cultures and intact cells. Upon examination by sodium dodecyl sulfate-polyacrylamide electrophoresis, three major high-molecular-weight PBPs (molecular weight, 58,000 to 82,000) were resolved, and low-molecular-weight PBPs were seen in all strains except Bacteroides fragilis. The sporadic appearance of PBP 4 in B. fragilis (molecular weight, approximately 45,000) was shown not to be influenced by the concentration of free iron available in the medium or by the stage of growth at which the batch culture was harvested. No PBP that was inhibited by an aerobic environment was demonstrated. The affinity of 35 beta-lactam antibiotics for the PBPs from envelope preparations was examined and correlated with the morphological response. Most compounds bound initially to PBP 2 and then PBP 1, correlating with a primary response of filamentation and then spheroplasting and lysis. Compounds such as clavulanic acid bound to PBP 3 at concentrations causing round cells. Based on the data from this study, it is proposed that the three high-molecular-weight PBPs of Bacteroides fragilis, Bacteroides vulgatus, Bacteroides thetaiotaomicron, and Bacteroides ovatus correlate to the three high-molecular-weight PBPs of Escherichia coli and that the PBPs of Bacteroides species perform the same enzymic role in cell wall biosynthesis as their counterparts in E. coli. Therefore, the components of PBP 1 are involved in cell elongation, PBP 2 is involved in septum formation, and PBP 3 is involved in maintenance of cell shape (i.e., PBP 2 in Bacteroides spp. = PBP 3 in E. coli, and PBP 3 in Bacteroides spp. = BPB 2 in E. coli).

Anti-Bacterial Agents↗
PubMed1987

Enzymatic and antigenic characterization of immunoglobulin A1 proteases from Bacteroides and Capnocytophaga spp.

Bacteroides and Capnocytophaga species have been implicated as periodontal pathogens. Some of these species possess immunoglobulin A1 (IgA1) proteases that are capable of cleaving the human IgA1 molecule in the hinge region, leaving intact Fc alpha and Fab alpha fragments. The purpose of this study was to characterize this activity. In addition to IgA1 protease activity in already known species, IgA1 protease activity was a feature of Bacteroides buccalis, Bacteroides oralis, Bacteroides veroralis, Bacteroides capillus, and Bacteroides pentosaceus. Results of immunoelectrophoretic and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses suggested that all species cleave the alpha-chain at the same peptide bond, i.e., the prolyl-seryl bond between residues 223 and 224 in the hinge region. The Bacteroides proteases could be classified as thiol proteases, which were at the same time dependent on metal ions, while the Capnocytophaga proteases were metallo enzymes. None of the proteases were inhibited by the physiologic proteases inhibitors alpha 2-macroglobulin and alpha 1-proteinase inhibitor. Investigations with enzyme-neutralizing antibodies raised in rabbits against protease preparations from the respective type strains revealed that, despite otherwise identical characteristics, the IgA1 protease of each Bacteroides species was antigenically distinct. Bacteroides buccae and the two later synonymous species B. capillus and B. pentosaceus produced identical proteases. In contrast, IgA1 proteases from Capnocytophaga ochracea and Capnocytophaga sputigena strains were apparently identical, while Capnocytophaga gingivalis had a protease that differed from those of the other Capnocytophaga species.

Amino Acid Sequence↗
PubMed1995

Tumor necrosis factor induction by an aqueous phenol-extracted lipopolysaccharide complex from Bacteroides species.

The stimulation of macrophages and monocytes by lipopolysaccharide (LPS) results in the secretion of tumor necrosis factor (TNF), a cytokine which is thought to play a pivotal role in subsequent host responses. Its induction is thought to be facilitated by the binding of complexes of LPS and LPS-binding protein to CD14. The LPS of Bacteroides species was considered a weak endotoxin; however, in a recent study we have shown that the biological activity and chemical composition of the LPS from Bacteroides species are dependent on the extraction method. The present study determines the capacity of LPS extracted by aqueous phenol (the method for producing an LPS of high endotoxic activity) from four species of Bacteroides to induce TNF. Induction was investigated from human mononuclear leukocytes (MNL), THP-1 cells (with and without enhancement by vitamin D2 for CD14), and peritoneal macrophages from C3H/HeJ (LPS nonresponder) and C3H/HeN (LPS responder) mice. Escherichia coli O18K- LPS, a typical smooth LPS of heterogeneous molecular mass, was used as a control throughout. The stimulation of TNF production by E. coli LPS was between two- and fourfold more than that by Bacteroides LPS in MNL, in THP-1 cells (with enhancement for CD14), and in peritoneal macrophages from C3H/HeN mice. In THP-1 cells (without enhancement for CD14), there was no significant difference in TNF production between E. coli and Bacteroides LPSs. In peritoneal macrophages from C3H/HeJ mice, E. coli LPS stimulated no TNF production, but there was no significant difference in TNF production from peritoneal macrophages from C3H/HeJ and C3H/HeN mice by Bacteroides LPS. In all cell populations, there was a peak of TNF production after approximately 4 h of stimulation with all LPSs tested. However, other peaks of TNF production were seen in MNL and THP-1 cells (with enhancement for CD14) after stimulation with E. coli LPS only. In stimulation assays in which Bacteroides LPS was together with but in excess of E. coli LPS, it was found that TNF production from MNL and THP-1 cells (with and without enhancement for CD14) was comparable to that of Bacteroides LPS alone and not E. coli LPS alone. An anti-CD14 monoclonal antibody did not inhibit Bacteroides LPS-stimulated TNF production. However, E. coli LPS-stimulated TNF release was inhibited by an anti-CD14 monoclonal antibody, most noticeably in MNL and THP-1 cells (with enhancement for CD14).(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1990

Correlation between ultrastructural differentiation of bacteroids and nitrogen fixation in alfalfa nodules.

Bacteroid differentiation was examined in developing and mature alfalfa nodules elicited by wild-type or Fix- mutant strains of Rhizobium meliloti. Ultrastructural studies of wild-type nodules distinguished five steps in bacteroid differentiation (types 1 to 5), each being restricted to a well-defined histological region of the nodule. Correlative studies between nodule development, bacteroid differentiation, and acetylene reduction showed that nitrogenase activity was always associated with the differentiation of the distal zone III of the nodule. In this region, the invaded cells were filled with heterogeneous type 4 bacteroids, the cytoplasm of which displayed an alternation of areas enriched with ribosomes or with DNA fibrils. Cytological studies of complementary halves of transversally sectioned mature nodules confirmed that type 4 bacteroids were always observed in the half of the nodule expressing nitrogenase activity, while the presence of type 5 bacteroids could never be correlated with acetylene reduction. Bacteria with a transposon Tn5 insertion in pSym fix genes elicited the development of Fix- nodules in which bacteroids could not develop into the last two ultrastructural types. The use of mutant strains deleted of DNA fragments bearing functional reiterated pSym fix genes and complemented with recombinant plasmids, each carrying one of these fragments, strengthened the correlation between the occurrence of type 4 bacteroids and acetylene reduction. A new nomenclature is proposed to distinguish the histological areas in alfalfa nodules which account for and are correlated with the multiple stages of bacteroid development.

Bacteroides↗
PubMed1991

Multivariate analyses of cellular fatty acids in Bacteroides, Prevotella, Porphyromonas, Wolinella, and Campylobacter spp.

The genera Bacteroides, Wolinella, and Campylobacter contain several similar species that require taxonomic revision. Fatty acid profiles of whole bacterial cells have proven useful for taxonomy. In this study, cellular fatty acids from Bacteroides, Prevotella, Porphyromonas, Wolinella, and Campylobacter spp. were identified and quantitated by gas chromatography and gas chromatography-mass spectrometry, and the data were subjected to principal component analyses. Bacteroides fragilis, the type species of the genus Bacteroides, was distinct from the other organisms. While Bacteroides gracilis, Wolinella succinogenes, Wolinella curva, Wolinella recta, and Campylobacter fetus subsp. venerealis were close to each other, Prevotella (Bacteroides) buccae, Prevotella oralis, Prevotella oris, Prevotella disiens, Prevotella veroralis, Prevotella heparinolyticus, Porphyromonas (Bacteroides) endodontalis, and Bacteroides ureolyticus could be distinguished. B. fragilis was characterized by the presence of C3OH-i-1-, Ca-15, and Ci-15 and the absence of C12:0 and unsaturated fatty acids. For comparison, B. gracilis, B. ureolyticus, W. succinogenes, W. curva, W. recta, and Campylobacter fetus subsp. venerealis contained C12:0, C16:1, C18:1, and C3-OH-14 acids but lacked branched hydroxy and branched nonhydroxy acids. B. gracilis and B. ureolyticus are not "true" bacteroides.

Bacteria↗
PubMed1987

Carbohydrate, organic Acid, and amino Acid composition of bacteroids and cytosol from soybean nodules.

Metabolites in Bradyrhizobium japonicum bacteroids and in Glycine max (L.) Merr. cytosol from root nodules were analyzed using an isolation technique which makes it possible to estimate and correct for changes in concentration which may occur during bacteroid isolation. Bacteroid and cytosol extracts were fractionated on ion-exchange columns and were analyzed for carbohydrate composition using gas-liquid chromatography and for organic acid and amino acid composition using high performance liquid chromatography. Analysis of organic acids in plant tissues as the phenacyl derivatives is reported for the first time and this approach revealed the presence of several unknown organic acids in nodules. The time required for separation of bacteroids and cytosol was varied, and significant change in concentration of individual compounds during the separation of the two fractions was estimated by calculating the regression of concentration on time. When a statistically significant slope was found, the true concentration was estimated by extrapolating the regression line to time zero. Of 78 concentration estimates made, there was a statistically significant (5% level) change in concentration during sample preparation for only five metabolites: glucose, sucrose, and succinate in the cytosol and d-pinitol and serine in bacteroids. On a mass basis, the major compounds in bacteroids were (descending order of concentration): myo-inositol, d-chiro-inositol, alpha,alpha-trehalose, sucrose, aspartate, glutamate, d-pinitol, arginine, malonate, and glucose. On a proportional basis (concentration in bacteroid as percent of concentration in bacteroid + cytosol fractions), the major compounds were: alpha-aminoadipate (94), trehalose (66), lysine (58), and arginine (46). The results indicate that metabolite concentrations in bacteroids can be reliably determined.

Journal Article↗
PubMed1991

Effects of Salt Stress on Amino Acid, Organic Acid, and Carbohydrate Composition of Roots, Bacteroids, and Cytosol of Alfalfa (Medicago sativa L.).

Ethanol-soluble organic acid, carbohydrate, and amino acid constituents of alfalfa (Medicago sativa) roots and nodules (cytosol and bacteroids) have been identified by gas-liquid chromatography and high performance liquid chromatography. Among organic acids, citrate was the predominant compound in roots and cytosol, with malonate present in the highest concentration in bacteroids. These two organic acids together with malate and succinate accounted for more than 85% of the organic acid pool in nodules and for 97% in roots. The major carbohydrates in roots, nodule cytosol, and bacteroids were (descending order of concentration): sucrose, pinitol, glucose, and ononitol. Maltose and trehalose appeared to be present in very low concentrations. Asparagine, glutamate, alanine, gamma-aminobutyrate, and proline were the major amino acids in cytosol and bacteroids. In addition to these solutes, serine and glutamine were well represented in roots. When alfalfa plants were subjected to 0.15 m sodium chloride stress for 2 weeks, total organic acid concentration in nodules and roots were depressed by more than 40%, whereas lactate concentration increased by 11, 27, and 94% in cytosol, roots, and bacteroids, respectively. In bacteroids, lactate became the most abundant organic acid and might contribute partly to the osmotic adjustment. On the other hand, salt stress induced a large increase in the amino acid and carbohydrate pools. Within the amino acids, proline showed the largest increase, 11.3-, 12.8-, and 8.0-fold in roots, cytosol, and bacteroids, respectively. Its accumulation reflected an osmoregulatory mechanism not only in roots but also in nodule tissue. In parallel, asparagine concentration was greatly enhanced; this amide remained the major nitrogen solute and, in bacteroids, played a significant role in osmoregulation. On the contrary, the salt treatment had a very limited effect on the concentration of other amino acids. Among carbohydrates, pinitol concentration was increased significantly, especially in cytosol and bacteroids (5.4- and 3.4-fold, respectively), in which this cyclitol accounted for more than 35% of the total carbohydrate pool; pinitol might contribute to the tolerance to salt stress. However, trehalose concentration remained low in both nodules and roots; its role in osmoregulation appeared unlikely in alfalfa.

Journal Article↗
PubMedDate not supplied

Pathogenicity of the Bacteroides fragilis group.

The Bacteroides fragilis group is one of the most important pathogens in polymicrobial infections. The distribution of the different members of the B. fragilis group in clinical infections varies. Bacteroides fragilis accounts for 63 percent of all the group isolates, Bacteroides thetaiotaomicron for 14 percent, Bacteroides vulgatus and Bacteroides ovatus for seven percent each, Bacteroides distasonis for six percent and Bacteroides uniformis for two percent. All members of the group induced bacteremia that was associated with an average mortality of 27 percent. The B. fragilis group resist beta lactam antibiotics by producing the enzyme beta-lactamase. This enzyme can be detected in abscess fluid, and can interfere with the eradication of other bacteria that are susceptible to penicillins and cephalosporins. All members of the B. fragilis group can become encapsulated during an inflammatory process as was demonstrated in a subcutaneous abscess model in mice. Non-encapsulated strains can become encapsulated with the assistance of their aerobic counterparts. These encapsulated strains are more virulent to the host than non-encapsulated strains. This increased virulence can be demonstrated by a higher rate of induction of bacteremia, and a greater enhancement of growth of other bacteria in mixed infection. Antimicrobial therapy directed only at the eradication of the aerobic bacteria did not prevent encapsulation, or reduce the number of Bacteroides species. The virulence of all members of the B. fragilis group highlights the need to direct antimicrobial therapy against all members of this group.

Abscess↗