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PubMed2006

A putative multicopper protein secreted by an atypical type II secretion system involved in the reduction of insoluble electron acceptors in Geobacter sulfurreducens.

Extracellular electron transfer onto Fe(III) oxides in Geobacter sulfurreducens is considered to require proteins that must be exported to the outer surface of the cell. In order to investigate this, the putative gene for OxpG, the pseudopilin involved in a type II general secretion pathway of Gram-negative bacteria, was deleted. The mutant was unable to grow with insoluble Fe(III) oxide as the electron acceptor. Growth on soluble Fe(III) was not affected. An analysis of proteins that accumulated in the periplasm of the oxpG mutant, but not in the wild-type, led to the identification of a secreted protein, OmpB. OmpB is predicted to be a multicopper protein, with highest homology to the manganese oxidase, MofA, from Leptothrix discophora. OmpB contains a potential Fe(III)-binding site and a fibronectin type III domain, suggesting a possible role for this protein in accessing Fe(III) oxides. OmpB was localized to the membrane fraction of G. sulfurreducens and in the supernatant of growing cultures, consistent with the type II secretion system exporting OmpB. A mutant in which ompB was deleted had the same phenotype as the oxpG mutant, suggesting that the failure to export OmpB was responsible for the inability of the oxpG-deficient mutant to reduce Fe(III) oxide. This is the first report that proposes a role for a multicopper oxidase-like protein in an anaerobic organism. These results further emphasize the importance of outer-membrane proteins in Fe(III) oxide reduction and suggest that outer-membrane proteins other than c-type cytochromes are required for Fe(III) oxide reduction in Geobacter species.

Bacterial Outer Membrane Proteins↗
PubMed2004

Description of heterotrophic bacteria occurring in paper mills and paper products.

AIMS: To isolate aerobic mesophilic bacilli and thermophilic bacteria from different paper mill samples and to evaluate their potential harmfulness. METHODS AND RESULTS: A total of 109 mesophilic and 68 thermophilic isolates were purified and characterized by automated ribotyping and partial 16S rDNA sequencing. The mesophilic isolates belonged to the genera Bacillus (13 taxa), Brevibacillus (three taxa) and Paenibacillus (five taxa). The thermophilic bacteria represented seven taxa of Bacillus, Geobacillus or Paenibacillus, four of proteobacteria and one of actinobacteria. The most frequently occurring bacteria were Bacillus cereus, B. licheniformis, Pseudoxanthomonas taiwanensis and bacteria closely related to Paenibacillus stellifer, P. turicensis or Leptothrix sp. One mill was contaminated throughout with bacteria of a novel mesophilic genus most closely related to Brevibacillus centrosporus and another with bacteria of a novel thermophilic genus most closely related to Hydrogenophilus thermoluteolus. One B. cereus isolate producing haemolytic diarrhoeal enterotoxin was detected and all the tested B. licheniformis isolates produced a metabolite toxic to boar sperm cells. CONCLUSIONS: The bacilli and thermophilic bacteria isolated represent species which should not present occupational hazards in paper mill environments. The most harmful bacterium detected was B. licheniformis and potentially also B. cereus. SIGNIFICANCE AND IMPACT OF THE STUDY: Knowledge of the microbial diversity in a paper mill provides a rational basis for development of an effective controlling programme. A database constructed from the fingerprints generated using automated ribotyping helps to identify and trace the contamination routes of bacteria occurring in paper mills.

Bacillus↗
PubMed1994

Investigation of an Iron-Oxidizing Microbial Mat Community Located near Aarhus, Denmark: Field Studies.

We investigated the microbial community that developed at an iron seep where anoxic groundwater containing up to 250 muM Fe flowed out of a rock wall and dense, mat-like aggregations of ferric hydroxides formed at the oxic-anoxic interface. In situ analysis with oxygen microelectrodes revealed that the oxygen concentrations in the mat were rarely more than 50% of air saturation and that the oxygen penetration depth was quite variable, ranging from <0.05 cm to several centimeters. The bulk pH of the mat ranged from 7.1 to 7.6. There appeared to be a correlation between the flow rates at different subsites of the mat and the morphotypes of the microorganisms and Fe oxides that developed. In subsites with low flow rates (<2 ml/s), the iron-encrusted sheaths of Leptothrix ochracea predominated. Miniature cores revealed that the top few millimeters of the mat consisted primarily of L. ochracea sheaths, only about 7% of which contained filaments of cells. Deeper in the mat, large particulate oxides developed, which were often heavily colonized by unicellular bacteria that were made visible by staining with acridine orange. Direct cell counts revealed that the number of bacteria increased from approximately 10 to 10 cells per cm and the total iron concentration increased from approximately 0.5 to 3 mmol/cm with depth in the mat. Primarily because of the growth of L. ochracea, the mat could accrete at rates of up to 3.1 mm/day at these subsites. The iron-encrusted stalks of Gallionella spp. prevailed in localized zones of the same low-flow-rate subsites, usually close to where the source water emanated from the wall. These latter zones had the lowest O(2) concentrations (<10% of the ambient concentration), confirming the microaerobic nature of Gallionella spp. In subsites with high flow rates (>6 ml/s) particulate Fe oxides were dominant; direct counts revealed that up to 10 cells of primarily unicellular bacteria per cm were associated with these particulate oxides. These zones exhibited little vertical stratification in either the number of cells or iron concentration. Finally, mat samples incubated anaerobically in the presence of acetate or succinate exhibited significant potential for iron reduction, suggesting the possibility that a localized iron cycle could occur within the mat community.

Journal Article↗
PubMed1994

Investigation of an Iron-Oxidizing Microbial Mat Community Located near Aarhus, Denmark: Laboratory Studies.

We constructed a small flow chamber in which suboxic medium containing 60 to 120 muM FeCl(2) flowed up through a sample well into an aerated reservoir, thereby creating an suboxic-oxic interface similar to the physicochemical conditions that exist in natural iron seeps. When microbial mat material from the Marselisborg iron seep that contained up to 10 bacterial cells per cm (D. Emerson and N. P. Revsbech, Appl. Environ. Microbiol. 60:4022-4031, 1994) was placed in the sample well of the chamber, essentially all of the Fe flowing through the sample well was oxidized at rates of up to 1,200 nmol of Fe oxidized per h per cm of mat material. The oxidation rates of samples of the mat that were pasteurized prior to inoculation were only about 20 to 50% of the oxidation rates of unpasteurized samples. Sodium azide also significantly inhibited oxidation. These results suggest that at least 50% and up to 80% of the Fe oxidation in the chamber were actively mediated by the microbes in the mat. It also appeared that Fe stimulated the growth of the community since chambers fed with FeCl(2) accumulated masses of either filamentous or particulate growth, both in the sample well and attached to the walls of the chamber. Control chambers that did not receive FeCl(2) showed no sign of such growth. Furthermore, after 4 to 5 days the chambers fed with FeCl(2) contained 35 to 75% more protein than chambers not supplemented with FeCl(2). Leptothrix ochracea and, to a lesser extent, Gallionella spp. were responsible for the filamentous growth, and the sheaths and stalks, respectively, of these two organisms harbored large numbers of Fe-encrusted, nonappendaged unicellular bacteria. In chambers where particulate growth predominated, the unicellular bacteria alone appeared to be the primary agents of iron oxidation. These results provide the first clear evidence that the "iron bacteria" commonly found associated with neutral-pH iron seeps are responsible for most of the iron oxidation and that the presence of ferrous iron appears to stimulate the growth of these organisms.

Journal Article↗
PubMed1994

Structure and composition of biological slimes on paper and board machines.

Biological slimes (biofilms) collected from the wet end of paper and board machines were examined by electron microscopy and analyzed for fatty acid composition, neutral sugar composition, and ATP. Electron microscopy revealed minuscule prokaryotic organisms (diameter, 0.2 to 0.4 mum). Larger cells morphologically resembling Sphaerotilus and Leptothrix spp. were found in slimes from machines using recycled fiber or unbleached pulp. The bacteria were embedded in a slimy matrix and often contained reserve materials microscopically resembling poly-beta-hydroxybutyrate and glycogen. Fatty acid analysis of the slimes revealed bacterial signature fatty acids in concentrations equivalent to the presence of 2 x 10 to 2.6 x 10 (average, 7 x 10) bacterial cells (live and dead) per g (dry weight) of slime. The slimes contained several known components of bacterial polysaccharides in addition to glucose, indicating that the slime body consisted of bacterial polysaccharides. The slimes contained uronic acids equivalent to a binding capacity of 12.5 to 50 mumol of divalent cations per g (dry weight) of slime. The uronic acid-containing polysaccharides may be responsible for the accumulation of heavy metals in the slime. Calculation of the ATP contents of the slimes resulted in an estimate of 5 x 10 cells per g (dry weight) of slime when calibrated with pure bacterial cultures isolated from the slimes. From electron micrographs, an estimate ranging from 1 x 10 to 1.5 x 10 (average, 4 x 10) cells per g (dry weight) of slime was obtained.

Journal Article↗
PubMed1998

Specific ribosomal DNA sequences from diverse environmental settings correlate with experimental contaminants.

Phylogenetic analysis of 16S ribosomal DNA (rDNA) clones obtained by PCR from uncultured bacteria inhabiting a wide range of environments has increased our knowledge of bacterial diversity. One possible problem in the assessment of bacterial diversity based on sequence information is that PCR is exquisitely sensitive to contaminating 16S rDNA. This raises the possibility that some putative environmental rRNA sequences in fact correspond to contaminant sequences. To document potential contaminants, we cloned and sequenced PCR-amplified 16S rDNA fragments obtained at low levels in the absence of added template DNA. 16S rDNA sequences closely related to the genera Duganella (formerly Zoogloea), Acinetobacter, Stenotrophomonas, Escherichia, Leptothrix, and Herbaspirillum were identified in contaminant libraries and in clone libraries from diverse, generally low-biomass habitats. The rRNA sequences detected possibly are common contaminants in reagents used to prepare genomic DNA. Consequently, their detection in processed environmental samples may not reflect environmentally relevant organisms.

Animals↗
PubMed1991

Freeze-substitution of gram-negative eubacteria: general cell morphology and envelope profiles.

Freeze-substitution was performed on strains of Escherichia coli, Pasteurella multocida, Campylobacter fetus, Vibrio cholerae, Pseudomonas aeruginosa, Pseudomonas putida, Aeromonas salmonicida, Proteus mirabilis, Haemophilus pleuropneumoniae, Caulobacter crescentus, and Leptothrix discophora with a substitution medium composed of 2% osmium tetroxide and 2% uranyl acetate in anhydrous acetone. A thick periplasmic gel ranging from 10.6 to 14.3 nm in width was displayed in E. coli K-12, K30, and His 1 (a K-12 derivative containing the K30 capsule genes), P. multocida, C. fetus, P. putida, A. salmonicida, H. pleuropneumoniae, and P. mirabilis. The other bacteria possessed translucent periplasms in which a thinner peptidoglycan layer was seen. Capsular polysaccharide, evident as electron-dense fibers radiating outward perpendicular to the cell surface, was observed on E. coli K30 and His 1 and P. mirabilis cells. A more random arrangement of fibers forming a netlike structure was apparent surrounding cells of H. pleuropneumoniae. For the first time a capsule, distinct from the sheath, was observed on L. discophora. In all instances, capsular polysaccharide was visualized in the absence of stabilizing agents such as homologous antisera or ruthenium red. Other distinct envelope structures were observed external to the outer membrane including the sheath of L. discophora and the S layers of A. salmonicida A450 and C. crescentus CB15A. We believe that the freeze-substitution technique presents a more accurate image of the structural organization of these cells and that it has revealed complex ultrastructural relationships between cell envelope constituents previously difficult to visualize by more conventional means of preparation.

Cell Membrane↗
PubMed1984

Nocardia gypsoides corneal ulcer.

Nocardia gypsoides, a species characterised by its ability to produce calcium sulphate granules, has been isolated for the first time from a corneal ulcer. In vivo this pseudomycete also forms gypsum. Every effort should be made to identify Actinomycetales to species level. The names Leptothrix and Streptothrix should be abandoned.

Aged↗
PubMed1987

Bacterial flora in bottled uncarbonated mineral drinking water.

A quantitative study of bacterial populations in mineral water was carried out. Samples were stored at 6 and 20 degrees C, and the colony counts were determined on tryptone agar plates incubated at 22 and 37 degrees C. Samples were collected from the spring source in sterile glass flasks and from the bottling factory in conventional plastic and glass containers. In both cases, the initial population (10(1)-10(2) cfu/mL water) increased to 10(5)-10(6) cfu/mL after 3 days storage as determined from plate counts incubated at 22 degrees C. The levels reached by this population were similar to those of samples of mineral water obtained at the market stage. Results from plate counts incubated at 37 degrees C showed that populations in samples collected at the bottling factory reached 10(2)-10(3) cfu/mL. No growth was observed in water collected from spring source. Bacterial multiplication was not stopped even when water was stored at 6 degrees C. Caulobacter was the genus found most frequently in both types of samples, followed by Sphaerotilus-Leptothrix. Acinetobacter calcoaceticus and Pseudomonas fluorescens were frequently found in only two springs, and Pseudomonas putida, Arthrobacter, Aeromonas hydrophilia, and Corynebacterium were isolated less frequently. Janthinobacterium was recovered only once from a single spring. A giant bacterium closely resembling Hyphomicrobium and a budding one similar to Pasteuria were recovered from all samples of a single spring and from some of the commercial samples.

Bacteria↗
PubMed1975

[Therapeutic results achieved through the advantage of a combination of oral metronidazole and vaginal natamycin tablets in urogenital protozoan, trichobacterial and blastomyces infections].

Vaginal inflammations caused by Trichomonas, Leptothrix vaginalis or Candida and other less common organisms respectively, were treated very successfully with a combination of metronidazole orally and a natamycin preparation vaginally (Pimafucin vaginal tablets). In women with urogenital Trichomoniasis a cure was obtained in 96,1% of the cases (microbiologically controlled); Candida mycoses of the vagina were cured clinically in 89% of the cases after the first course of treatment and mycologically in 79% of the cases. Of special importance is the rapid and successful elimination of the mixed infection before birth, because this diminishes perinatal morbidity of the fetus. The combination treatment of bilateral, constantly interchanging Candida and Trichomonas infections of the vagina is of importance to both sexes, especially with respect to the elimination of sterility. From the onco-gynecological point of view the combination treatment with metronidazole and natamycin appeared to be of value as it limits the incidence of dyskariosis of the epithelial cells, which occur frequently in cases of inflammation of the vagina or cervix uteri. No teratogenic effect was observed with this combination when applied during pregnancy.

Administration, Oral↗
PubMed1999

Marine Bacillus spores as catalysts for oxidative precipitation and sorption of metals.

The oxidation of soluble manganese(II) to insoluble Mn(III,IV) oxide precipitates plays an important role in the environment. These Mn oxides are known to oxidize numerous organic and inorganic compounds, scavenge a variety of other metals on their highly charged surfaces, and serve as electron acceptors for anaerobic respiration. Although the oxidation of Mn(II) in most environments is believed to be bacterially-mediated, the underlying mechanisms of catalysis are not well understood. In recent years, however, the application of molecular biological approaches has provided new insights into these mechanisms. Genes involved in Mn oxidation were first identified in our model organism, the marine Bacillus sp. strain SG-1, and subsequently have been identified in two other phylogenetically distinct organisms, Leptothrix discophora and Pseudomonas putida. In all three cases, enzymes related to multicopper oxidases appear to be involved, suggesting that copper may play a universal role in Mn(II) oxidation. In addition to catalyzing an environmentally important process, organisms capable of Mn(II) oxidation are potential candidates for the removal, detoxification, and recovery of metals from the environment. The Mn(II)-oxidizing spores of the marine Bacillus sp. strain SG-1 show particular promise, due to their inherent physically tough nature and unique capacity to bind and oxidatively precipitate metals without having to sustain growth.

Bacillus↗
PubMed1986

[Morphology of fungi in the slides prepared from esophageal balloons].

1,762 cases were selected at random from 17,000 persons screened by esophageal balloon in 4 communes of Linxian County. The morphologic appearance of fungi was studied in 4 slides of each case selected. According to the shape of clumps formed by fungi and bacteria in the slides, morphologic 4 types were seen: cotton-like, camel hair-like, hair-like and tree-branch-like. In the preliminary microscopic analysis, the following species of fungi were noted: Candida, Leptothrix, Actinomyces, Alternaria, Fusarium and Penicillium. Some of the fungi in the slides may have been taken from the oral or pharyngeal cavity, which may be due to, at least in part, the poor oral hygiene in the population examined. A positive association was shown between the quantity of fungi in the slides and the esophageal epithelial dysplasia and carcinoma, but its biological significance should be studied further.

Actinomyces↗
PubMed1979

[The role of anaerobe adhesion in the colonization of the vaginal mucosa].

Some our previous research works on bacterial adhesion to vaginal cells in the different phases of the menstruum showed that adhesion changes depending on changing environmental conditions. We therefore considered interesting to extend our investigations to anaerobic flora, in the light of recent observations intended to attribute an important role to anaerobic flora in the pathogenesis of vaginitis. The results obtained so far indicate that the maximum adhesion capability is found in the middle of the menstruum. The very low adhesion of bacteria belonging to the Leptothrix genus remains substantially unaltered throughout the menstruum. Low adhesion is also found in sporogenic bacteria, whereas the coccoid ones have a stronger adhesion, particularly about the middle of the menstruum. With lower pH values adhesion of the anaerobic flora is enhanced, whereas in the final phase of the menstruum, with higher pH values, adhesion is reduced. Competition tests evidence a stronger adhesion of coccoid as compared to bacillar types.

Adult↗
PubMed1982

The clinical diagnosis of trichomoniasis.

Two hundred twenty-six consecutive women attending an inner-city clinic for sexually transmitted diseases were evaluated. Problem-directed histories and physical examinations were conducted and vaginal specimens for wet preparation and Trichomonas vaginalis culture were obtained from each patient. One hundred patients were found to be infected. Patients with multiple sex partners were found to be at increased risk of trichomoniasis (P less than .05). Those with abnormal discharge noted on examination had a higher frequency of positive cultures for T vaginalis (P less than .001). Only 50% of patients with trichomoniasis had an abnormal discharge. Patients with greater than 10 white blood cells per high power field on wet preparation, regardless of whether trichomonads were visualized, had a higher incidence of trichomoniasis (P less than .01). Factors that were not associated with Trichomonas infection included patient age, frequency of coitus, date of most recent coitus, day of menstrual cycle on which patient was examined, recent antibiotic use, use of contraceptives or specific contraceptive methods, symptoms of discharge or pruritus, or the finding of Leptothrix on wet preparation. These data support the contention that the classic description of trichomoniasis cannot be uniformly relied upon for diagnosis, but that patients with multiple sex partners, abnormal vaginal discharge and/or greater than 10 white blood cells per high power field on wet preparation are at increased risk of infection by T vaginalis.

Adult↗
PubMed1997

[Laboratory diagnosis of bacterial vaginosis].

Microbiological analysis of discharge from the genitals in passenger car conductors (5787 women and 1496 men aged 20 to 40) showed Gardnerella vaginalis to be the most frequent agent of urogenital infection. It was isolated in 26% cases, whereas Trichomonas were isolated in 2.5%, fungi in 1.5%, and gonococci in 0.27% cases. The diagnosis of gardnerellosis is reliable if the key cells are found. Monoinfection with G. vaginalis was diagnosed in 80% patients, the overwhelming majority (74%) of carriers of this bacterium had no inflammatory symptoms, and in only 26% the carrier state was associated with the presence of leukocytes and histiocytes, more often in the cervix. In men the carrier state was detected in 0.4% cases. The clinical picture of Gardnerella infection is similar to that of infection with Mobiluncus, which is little known. This infection occurred 10 times less frequently (2.5%) than gardnerellosis, but in 92% cases it was a component of mixed infection, most frequently in association with G. vaginalis. A little known fungus Leptothrix was found in the genital discharge of 4% examinees, mostly women, but sometimes in men as well; it is represented by 3 types of ramifying threads. The practitioners are to know these infections causing specific diseases, such as bacterial vaginosis, which are often responsible for serious complications in gynecology and obstetrics.

Adult↗