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Ergosterol Content in Various Fungal Species and Biocontaminated Building Materials

Pasanen, Anna-Liisa; Yli-Pietilä, Kati; Pasanen, Pertti; Kalliokoski, Pentti; Tarhanen, Juhani
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/1999 EN
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This paper reports the ergosterol content for microbial cultures of six filamentous fungi, three yeast species, and one actinomycete and the ergosterol levels in 40 samples of building materials (wood chip, gypsum board, and glass wool) contaminated by microorganisms. The samples were hydrolyzed in alkaline methanol, and sterols were silylated and analyzed by gas chromatography-mass spectrometry. The average ergosterol content varied widely among the fungal species over the range of 2.6 to 42 μg/ml of dry mass or 0.00011 to 17 pg/spore or cell. Ergosterol could not be detected in the actinomycete culture. The results for both the fungal cultures and building material samples supported the idea that the ergosterol content reflects the concentration of filamentous fungi but it underestimates the occurrence of yeast cells. The ergosterol content in building material samples ranged from 0.017 to 68 μg/g of dry mass of material. A good agreement between the ergosterol concentration and viable fungal concentrations was detected in the wood chip (r > 0.66, P ≤ 0.009) and gypsum board samples (r > 0.48, P ≤ 0.059), whereas no relationship between these factors was observed in the glass wool samples. For the pooled data of the building materials...

Bacterial Resistance to Ultrasonic Waves under Pressure at Nonlethal (Manosonication) and Lethal (Manothermosonication) Temperatures

Pagán, R.; Mañas, P.; Raso, J.; Condón, S.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/1999 EN
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The decimal reduction times of Streptococcus faecium, Listeria monocytogenes, Salmonella enteritidis, and Aeromonas hydrophila corresponding to heat treatment at 62°C were 7.1, 0.34, 0.024, and 0.0096 min, and those corresponding to manosonication treatment (40°C, 200 kPa, 117 μm) were 4.0, 1.5, 0.86, and 0.90 min, respectively. The manosonication decimal reduction times of the four species investigated decreased sixfold when the amplitude was increased from 62 to 150 μm and fivefold when the relative pressure was raised from 0 to 400 kPa. In L. monocytogenes, S. enteritidis, and A. hydrophila, the lethal effect of manothermosonication was the result of the addition of the lethal effects of heat and manosonication, whereas in S. faecium it was a synergistic effect.

Genotype Analysis of Escherichia coli Strains Isolated from Children and Chickens Living in Close Contact

Kariuki, S.; Gilks, C.; Kimari, J.; Obanda, A.; Muyodi, J.; Waiyaki, P.; Hart, C. A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /02/1999 EN
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Escherichia coli isolates from rectal swabs from 62 chickens and stools from 42 children living in close contact with chickens on the same farms in Kiambu district, Kenya, were compared for their genetic relatedness. Antibiotic susceptibility profiles broadly categorized isolates from the children and from the chickens into two separate clusters: the majority (144; 85.5%) of the E. coli isolates from children were multidrug resistant, while the majority (216; 87.1%) of the E. coli isolates from chickens were either fully susceptible or resistant only to tetracycline. Sixty- and 100- to 110-MDA plasmids were found to encode the transferable resistance to co-trimoxazole and tetracycline. HindIII restriction endonuclease digestion of the 60- and 100- to 110-MDA plasmids produced four distinct patterns for isolates from children and three distinct patterns for isolates from chickens. XbaI digestion of genomic DNA followed by pulsed-field gel electrophoresis (PFGE) analysis produced 14 distinct clusters. There were six distinct PFGE clusters among the isolates from children, while among the isolates from chickens there were seven distinct clusters. Only one PFGE cluster contained isolates from both children and chickens, with the isolates displaying an approximately 60% coefficient of similarity. This study showed that although several different genotypes of E. coli were isolated from children and chickens from the same farms...

Isolation and Characterization of a Mycobacterium Species Capable of Degrading Three- and Four-Ring Aromatic and Aliphatic Hydrocarbons

Churchill, Sharon A.; Harper, Jennifer P.; Churchill, Perry F.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /02/1999 EN
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Mycobacterium sp. strain CH1 was isolated from polycyclic aromatic hydrocarbon (PAH)-contaminated freshwater sediments and identified by analysis of 16S rDNA sequences. Strain CH1 was capable of mineralizing three- and four-ring PAHs including phenanthrene, pyrene, and fluoranthene. In addition, strain CH1 could utilize phenanthrene or pyrene as a sole carbon and energy source. A lag phase of at least 3 days was observed during pyrene mineralization. This lag phase decreased to less than 1 day when strain CH1 was grown in the presence of phenanthrene or fluoranthene. Strain CH1 also was capable of using a wide range of alkanes as sole carbon and energy sources. No DNA hybridization was detected with the nahAc gene probe, indicating that enzymes involved in PAH metabolism are not related to the well-characterized naphthalene dioxygenase gene. DNA hybridization was not detected when the alkB gene from Pseudomonas oleovorans was used under high-stringency conditions. However, there was slight but detectable hybridization under low-stringency conditions. This suggests a distant relationship between genes involved in alkane oxidation.

Diversity of Bacteroides fragilis Strains in Their Capacity To Recover Phages from Human and Animal Wastes and from Fecally Polluted Wastewater

Puig, Anna; Queralt, Nuria; Jofre, Juan; Araujo, Rosa
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/1999 EN
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Great differences in capability to detect bacteriophages from urban sewage of the area of Barcelona existed among 115 strains of Bacteroides fragilis. The capability of six of the strains to detect phages in a variety of feces and wastewater was studied. Strains HSP40 and RYC4023 detected similar numbers of phages in urban sewage and did not detect phages in animal feces. The other four strains detected phages in the feces of different animal species and in wastewater of both human and animal origin. Strain RYC2056 recovered consistently higher counts than the other strains and also detected counts ranging from 101 to approximately 103 phages per ml in urban sewage from different geographical areas. This strain detected bacteriophages in animal feces even though their relative concentration with respect to the other fecal indicators was significantly lower in wastewater polluted with animal feces than in urban sewage.

Degradation of Chlorobenzenes at Nanomolar Concentrations by Burkholderia sp. Strain PS14 in Liquid Cultures and in Soil

Rapp, Peter; Timmis, Kenneth N.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/1999 EN
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The utilization of 1,2,4,5-tetrachloro-, 1,2,4-trichloro-, the three isomeric dichlorobenzenes and fructose as the sole carbon and energy sources at nanomolar concentrations was studied in batch experiments with Burkholderia sp. strain PS14. In liquid culture, all chlorobenzenes were metabolized within 1 h from their initial concentration of 500 nM to below their detection limits of 0.5 nM for 1,2,4,5-tetrachloro- and 1,2,4-trichlorobenzene and 7.5 nM for the three dichlorobenzene isomers, with 63% mineralization of the tetra- and trichloroisomers. Fructose at the same initial concentration was, in contrast, metabolized over a 4-h incubation period down to a residual concentration of approximately 125 nM with 38% mineralization during this time. In soil microcosms, Burkholderia sp. strain PS14 metabolized tetrachlorobenzene present at 64.8 ppb and trichlorobenzene present at 54.4 ppb over a 72-h incubation period to below the detection limits of 0.108 and 0.09 ppb, respectively, with approximately 80% mineralization. A high sorptive capacity of Burkholderia sp. strain PS14 for 1,2,4,5-tetrachlorobenzene was found at very low cell density. The results demonstrate that Burkholderia sp. strain PS14 exhibits a very high affinity for chlorobenzenes at nanomolar concentrations.

Enhancement of Solubilization and Biodegradation of Polyaromatic Hydrocarbons by the Bioemulsifier Alasan

Barkay, T.; Navon-Venezia, S.; Ron, E. Z.; Rosenberg, E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/1999 EN
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Alasan, a high-molecular-weight bioemulsifier complex of an anionic polysaccharide and proteins that is produced by Acinetobacter radioresistens KA53 (S. Navon-Venezia, Z. Zosim, A. Gottlieb, R. Legmann, S. Carmeli, E. Z. Ron, and E. Rosenberg, Appl. Environ. Microbiol. 61:3240–3244, 1995), enhanced the aqueous solubility and biodegradation rates of polyaromatic hydrocarbons (PAHs). In the presence of 500 μg of alasan ml−1, the apparent aqueous solubilities of phenanthrene, fluoranthene, and pyrene were increased 6.6-, 25.7-, and 19.8-fold, respectively. Physicochemical characterization of the solubilization activity suggested that alasan solubilizes PAHs by a physical interaction, most likely of a hydrophobic nature, and that this interaction is slowly reversible. Moreover, the increase in apparent aqueous solubility of PAHs does not depend on the conformation of alasan and is not affected by the formation of multimolecular aggregates of alasan above its saturation concentration. The presence of alasan more than doubled the rate of [14C]fluoranthene mineralization and significantly increased the rate of [14C]phenanthrene mineralization by Sphingomonas paucimobilis EPA505. The results suggest that alasan-enhanced solubility of hydrophobic compounds has potential applications in bioremediation.

Optimization of Simultaneous Chemical and Biological Mineralization of Perchloroethylene†

Büyüksönmez, Fatih; Hess, Thomas F.; Crawford, Ronald L.; Paszczynski, Andrzej; Watts, Richard J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/1999 EN
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Optimization of the simultaneous chemical and biological mineralization of perchloroethylene (PCE) by modified Fenton’s reagent and Xanthobacter flavus was investigated by using a central composite rotatable experimental design. Concentrations of PCE, hydrogen peroxide, and ferrous iron and the microbial cell number were set as variables. Percent mineralization of PCE to CO2 was investigated as a response. A second-order, quadratic response surface model was generated and fit the data adequately, with a correlation coefficient of 0.72. Analysis of the results showed that the PCE concentration had no significant effect within the tested boundaries of the model, while the other variables, hydrogen peroxide and iron concentrations and cell number, were significant at α = 0.05 for the mineralization of PCE. The 14C radiotracer studies showed that the simultaneous chemical and biological reactions increased the extent of mineralization of PCE by more than 10% over stand-alone Fenton reactions.

Reductive Dechlorination of Chlorinated Ethenes and 1,2-Dichloroethane by “Dehalococcoides ethenogenes” 195

Maymó-Gatell, Xavier; Anguish, Timothy; Zinder, Stephen H.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/1999 EN
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“Dehalococcoides ethenogenes” 195 can reductively dechlorinate tetrachloroethene (PCE) completely to ethene (ETH). When PCE-grown strain 195 was transferred (2% [vol/vol] inoculum) into growth medium amended with trichloroethene (TCE), cis-dichloroethene (DCE), 1,1-DCE, or 1,2-dichloroethane (DCA) as an electron acceptor, these chlorinated compounds were consumed at increasing rates over time, which indicated that growth occurred. Moreover, the number of cells increased when TCE, 1,1-DCE, or DCA was present. PCE, TCE, 1,1-DCE, and cis-DCE were converted mainly to vinyl chloride (VC) and then to ETH, while DCA was converted to ca. 99% ETH and 1% VC. cis-DCE was used at lower rates than PCE, TCE, 1,1-DCE, or DCA was used. When PCE-grown cultures were transferred to media containing VC or trans-DCE, products accumulated slowly, and there was no increase in the rate, which indicated that these two compounds did not support growth. When the intermediates in PCE dechlorination by strain 195 were monitored, TCE was detected first, followed by cis-DCE. After a lag, VC, 1,1-DCE, and trans-DCE accumulated, which is consistent with the hypothesis that cis-DCE is the precursor of these compounds. Both cis-DCE and 1,1-DCE were eventually consumed...

Comparative Survival of Free Shiga Toxin 2-Encoding Phages and Escherichia coli Strains outside the Gut

Muniesa, Maite; Lucena, Francisco; Jofre, Juan
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/1999 EN
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The behavior outside the gut of seeded Escherichia coli O157:H7, naturally occurring E. coli, somatic coliphages, bacteriophages infecting O157:H7, and Shiga toxin 2 (Stx2)-encoding bacteriophages was studied to determine whether the last persist in the environment more successfully than their host bacteria. The ratios between the numbers of E. coli and those of the different bacteriophages were clearly lower in river water than in sewage of the area, whereas the ratios between the numbers of the different phages were similar. In addition, the numbers of bacteria decreased between 2 and 3 log units in in situ survival experiments performed in river water, whereas the numbers of phages decreased between 1 and 2 log units. Chlorination and pasteurization treatments that reduced by approximately 4 log units the numbers of bacteria reduced by less than 1 log unit the numbers of bacteriophages. Thus, it can be concluded that Stx2-encoding phages persist longer than their host bacteria in the water environment and are more resistant than their host bacteria to chlorination and heat treatment.

Maximizing Plasmid Stability and Production of Released Proteins in Yersinia enterocolitica

Li, Huaiyu; Bhaduri, Saumya; Magee, Wayne E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/1998 EN
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Virulent serotypes of Yersinia enterocolitica carry a plasmid (pYV) encoding a family of proteins that are released into the medium and whose expression is temperature and calcium regulated. The plasmid is easily lost from cells during their growth in the laboratory. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with a monoclonal antibody (3.2C) that is specific for a 25-kDa released protein to show that 32°C is the lowest temperature at which plasmid-encoded proteins are expressed in quantity. The highest calcium concentration allowing full expression of these proteins was 445 to 545 μM at 32°C. Calcium concentrations of 745 μM and above at 37°C completely prevented the loss of pYV during multiple subcultures, while at 32°C, calcium concentrations of 245 μM and greater were sufficient to stabilize the plasmid. Growth of Y. enterocolitica at pH 5.5 was slower than at neutral pH values, but it also resulted in greatly increased stability of pYV. These studies showed that bacterial growth, retention of pYV, and expression of plasmid-encoded proteins may be maximized at 32°C with 445 μM calcium and that pYV stability is enhanced by growth at low pH. These observations suggest new approaches for isolation of plasmid-bearing virulent strains of Y. enterocolitica from samples contaminated with this organism and also may improve our understanding of pYV retention in vivo.

Surface Charge Properties of and Cu(II) Adsorption by Spores of the Marine Bacillus sp. Strain SG-1

He, Lee M.; Tebo, Bradley M.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/1998 EN
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Spores of marine Bacillus sp. strain SG-1 are capable of oxidizing Mn(II) and Co(II), which results in the precipitation of Mn(III, IV) and Co(III) oxides and hydroxides on the spore surface. The spores also bind other heavy metals; however, little is known about the mechanism and capacity of this metal binding. In this study the characteristics of the spore surface and Cu(II) adsorption to this surface were investigated. The specific surface area of wet SG-1 spores was 74.7 m2 per g of dry weight as measured by the methylene blue adsorption method. This surface area is 11-fold greater than the surface area of dried spores, as determined with an N2 adsorption surface area analyzer or as calculated from the spore dimensions, suggesting that the spore surface is porous. The surface exchange capacity as measured by the proton exchange method was found to be 30.6 μmol m−2, which is equal to a surface site density of 18.3 sites nm−2. The SG-1 spore surface charge characteristics were obtained from acid-base titration data. The surface charge density varied with pH, and the zero point of charge was pH 4.5. The titration curves suggest that the spore surface is dominated by negatively charged sites that are largely carboxylate groups but also phosphate groups. Copper adsorption by SG-1 spores was rapid and complete within minutes. The spores exhibited a high affinity for Cu(II). The amounts of copper adsorbed increased from negligible at pH 3 to maximum levels at pH >6. Their great surface area...

Degradation and Fate of Carbon Tetrachloride in Unadapted Methanogenic Granular Sludge

Van Eekert, Miriam H. A.; Schröder, Thomas J.; Stams, Alfons J. M.; Schraa, Gosse; Field, Jim A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/1998 EN
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The potential of granular sludge from upflow anaerobic sludge blanket (UASB) reactors for bioremediation of chlorinated pollutants was evaluated by using carbon tetrachloride (CT) as a model compound. Granular sludges cultivated in UASB reactors on methanol, a volatile fatty acid mixture, or sucrose readily degraded CT supplied at a concentration of 1,500 nmol/batch (approximately 10 μM) without any prior exposure to organohalogens. The maximum degradation rate was 1.9 μmol of CT g of volatile suspended solids−1 day−1. The main end products of CT degradation were CO2 and Cl−, and the yields of these end products were 44 and 68%, respectively, of the initial amounts of [14C]CT and CT-Cl. Lower chlorinated methanes accumulated in minor amounts temporarily. Autoclaved (dead) sludges were capable of degrading CT at rates two- to threefold lower than those for living sludges, indicating that abiotic processes (mediated by cofactors or other sludge components) played an important role in the degradation observed. Reduced components in the autoclaved sludge were vital for CT degradation. A major part (51%) of the CT was converted abiotically to CS2. The amount of CO2 produced (23%) was lower and the amount of Cl− produced (86%) was slightly higher with autoclaved sludge than with living sludge. Both living and autoclaved sludges could degrade chloroform. However...

Detection of Hemolysin Variants of Shiga Toxin-Producing Escherichia coli by PCR and Culture on VancomycinCefixime-Cefsulodin Blood Agar

Lehmacher, Anselm; Meier, Heidi; Aleksic, Stojanka; Bockemühl, Jochen
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/1998 EN
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The presence of a hemolysin-encoding gene, elyA or hlyA, from Shiga toxin-producing Escherichia coli (STEC) was detected by PCR in each of 95 strains tested. PCR products of elyA from human STEC isolates of serovars frequently detected in Germany, such as O157:H−, O103:H2, O103:H−, O26:H11, and O26:H−, showed nucleotide sequences identical to previously reported ones for O157:H7 and O111:H− strains. Compared to them, four elyA amplicons derived from human isolates of rare STEC serovars showed identity of about 98% but lacked an AluI restriction site. However, the nucleotide sequence of an amplicon derived from a porcine O138:K81:H− STEC strain was identical to the corresponding region of hlyA, encoding alpha-hemolysin, from E. coli. This hlyA amplicon showed 68% identity with the nucleotide sequence of the corresponding elyA fragment. It differed from the elyA PCR product in restriction fragments generated by AluI, EcoRI, and MluI. Of the 95 representative STEC strains, 88 produced hemolysin on blood agar supplemented with vancomycin (30 mg/liter), cefixime (20 μg/liter), and cefsulodin (3 mg/liter) (BVCC). The lowest added numbers of two to six STEC CFU per g of stool or per ml of raw milk were detectable on BVCC plates after seeding of the preenrichment broth...

Distribution of Clostridium perfringens and Fecal Sterols in a Benthic Coastal Marine Environment Influenced by the Sewage Outfall from McMurdo Station, Antarctica†

Edwards, Diane D.; McFeters, Gordon A.; Venkatesan, M. Indira
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/1998 EN
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The spatial distribution, movement, and impact of the untreated wastewater outfall from McMurdo Station, Antarctica, were investigated under early austral summer conditions. The benthic environment was examined to determine the distribution of Clostridium perfringens in sediment cores and the intestinal contents of native invertebrates and fish along a transect of stations. These stations extended ca. 411 m south of the outfall. The findings revealed that the concentration of C. perfringens decreased with depth in the sediment and distance from the outfall. High percentages of tunicates and sea urchins were colonized with this bacterium along the transect. Coprostanol concentrations were also measured in sediment samples taken from each of the transect stations, and a similar trend was observed. These results are in agreement with the findings of previous studies performed with the water column and collectively provide evidence that the disposal of domestic wastes deserves special consideration in polar marine environments.

Lyme Disease Borrelia Species in Northeastern China Resemble Those Isolated from Far Eastern Russia and Japan

Li, Muqing; Masuzawa, Toshiyuki; Takada, Nobuhiro; Ishiguro, Fubito; Fujita, Hiromi; Iwaki, Atsue; Wang, Haipeng; Wang, Jichun; Kawabata, Masato; Yanagihara, Yasutake
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/1998 EN
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Fifty-nine Borrelia burgdorferi sensu lato culture isolates collected from northeastern China were characterized by 5S-23S rRNA intergenic spacer restriction fragment length polymorphism (RFLP) analysis and reactivity with monoclonal antibodies (MAbs). Among 59 culture isolates, 30 (50.8%) were Borrelia garinii and 17 (28.8%) were Borrelia afzelii, 2 were mixtures composed of B. garinii with RFLP pattern B and B. garinii with pattern C, and 9 were mixtures composed of B. garinii and B. afzelii. One isolate, ChY13p, produced a unique pattern and was identified as B. garinii based on analyses of 16S rRNA gene sequence, flagellin PCR-RFLP typing, and MAb reactivities. No Borrelia burgdorferi sensu stricto or Borrelia japonica isolates were detected. The results indicate that Lyme disease Borrelia species in northeastern China resemble those of Borrelia isolates from far eastern Russia and Japan.

A Bioluminescence Assay Using Nitrosomonas europaea for Rapid and Sensitive Detection of Nitrification Inhibitors

Iizumi, Taro; Mizumoto, Masahiro; Nakamura, Kanji
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /10/1998 EN
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An expression vector for the luxAB genes, derived from Vibrio harveyi, was introduced into Nitrosomonas europaea. Although the recombinant strain produced bioluminescence due to the expression of the luxAB genes under normal growing conditions, the intensity of the light emission decreased immediately, in a time-and dose-dependent manner, with the addition of ammonia monooxygenase inhibitors, such as allylthiourea, phenol, and nitrapyrin. When whole cells were challenged with several nitrification inhibitors and toxic compounds, a close relationship was found between the change in the intensity of the light emission and the level of ammonia-oxidizing activity. The response of bioluminescence to the addition of allylthiourea was considerably faster than the change in the ammonia-oxidizing rate, measured as both the O2 uptake and NO2− production rates. The bioluminescence of cells inactivated by ammonia monooxygenase inhibitor was recovered rapidly by the addition of certain substrates for hydroxylamine oxidoreductase. These results suggested that the inhibition of bioluminescence was caused by the immediate decrease of reducing power in the cell due to the inactivation of ammonia monooxygenase, as well as by the destruction of other cellular metabolic pathways. We conclude that the assay system using luminous Nitrosomonas can be applied as a rapid and sensitive detection test for nitrification inhibitors...

Aerobic Growth on Nitroglycerin as the Sole Carbon, Nitrogen, and Energy Source by a Mixed Bacterial Culture

Accashian, John V.; Vinopal, Robert T.; Kim, Byung-Joon; Smets, Barth F.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/1998 EN
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Nitroglycerin (glycerol trinitrate [GTN]), an explosive and vasodilatory compound, was metabolized by mixed microbial cultures from aeration tank sludge previously exposed to GTN. Aerobic enrichment cultures removed GTN rapidly in the absence of a supplemental carbon source. Complete denitration of GTN, provided as the sole C and N source, was observed in aerobic batch cultures and proceeded stepwise via the dinitrate and mononitrate isomers, with successive steps occurring at lower rates. The denitration of all glycerol nitrate esters was found to be concomitant, and 1,2-glycerol dinitrate (1,2-GDN) and 2-glycerol mononitrate (2-GMN) were the primary GDN and GMN isomers observed. Denitration of GTN resulted in release of primarily nitrite-N, indicating a reductive denitration mechanism. Biomass growth at the expense of GTN was verified by optical density and plate count measurements. The kinetics of GTN biotransformation were 10-fold faster than reported for complete GTN denitration under anaerobic conditions. A maximum specific growth rate of 0.048 ± 0.005 h−1 (mean ± standard deviation) was estimated for the mixed culture at 25°C. Evidence of GTN toxicity was observed at GTN concentrations above 0.3 mM. To our knowledge, this is the first report of complete denitration of GTN used as a primary growth substrate by a bacterial culture under aerobic conditions.

Comparison of Energy and Growth Yields for Desulfitobacterium dehalogenans during Utilization of Chlorophenol and Various Traditional Electron Acceptors

Mackiewicz, M.; Wiegel, J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/1998 EN
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Desulfitobacterium dehalogenans grew with formate as the electron donor and 3-chloro-4-hydroxyphenylacetate (3-Cl-4-OHPA) as the electron acceptor, yielding YX/formate, YX/2e−, and YX/ATP ranging from 3.2 to 11.3 g of biomass (dry weight)/mol, thus indicating that energy was conserved through reductive dechlorination. Pyruvate was utilized as the electron donor and acceptor, yielding stoichiometric amounts of acetate and lactate, respectively, and a YX/reduced acceptor of 13.0 g of biomass (dry weight)/mol. The supplementation of pyruvate-containing medium with additional electron acceptors, such as 3-Cl-4-OHPA, nitrate, fumarate, or sulfite, caused pyruvate to be replaced as the electron acceptor and nearly doubled the YX/ATP (YX/acetate formed). A comparison of the yields for 3-Cl-4-OHPA with those for other traditional electron acceptors indicates that the dehalogenation reaction led to the formation of similar amounts of energy equivalents. The various electron acceptors were used concomitantly with 3-Cl-4-OHPA in nonacclimated cultures, but the utilization rates and amounts utilized differed.

Impact of Inoculation Protocols, Salinity, and pH on the Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) and Survival of PAH-Degrading Bacteria Introduced into Soil

Kästner, Matthias; Breuer-Jammali, Maren; Mahro, Bernd
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/1998 EN
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Degradation of polycyclic aromatic hydrocarbons (PAHs) and survival of bacteria in soil was investigated by applying different inoculation protocols. The soil was inoculated with Sphingomonas paucimobilis BA 2 and strain BP 9, which are able to degrade anthracene and pyrene, respectively. CFU of soil bacteria and of the introduced bacteria were monitored in native and sterilized soil at different pHs. Introduction with mineral medium inhibited PAH degradation by the autochthonous microflora and by the strains tested. After introduction with water (without increase of the pore water salinity), no inhibition of the autochthonous microflora was observed and both strains exhibited PAH degradation.