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  • 1
    Electronic Resource
    Electronic Resource
    Preliminary crystallographic analysis of an extremely thermostable glutamate dehydrogenase from the archaeon Pyrococcus woesei (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 395-398 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The extremely heat-stable glutamate dehydrogenase (GluDH) from Pyrococcus woesei was crystallized by the hanging-drop vapour-diffusion method. Crystals suitable for X-ray crystallographic investigations were obtained using polyethylene glycol (PEG) 4000 and ammonium acetate as precipitating agents. The crystals obtained diffract to a resolution of 2.8 Å, have a prismatic shape and grow up to 0.5 mm in their maximal dimension. They belong to the triclinic system (space group P1; a = 90.9, b = 92.8, c = 107.1 Å, α = 69.1, β = 80.7, Vγ = 65.0°) with a unit-cell volume of 765052 Å3 which accommodates one GluDH hexamer of 276 kDa. The averaged density of the crystal determined by Ficoll-gradient centrifugation is 1.15 g cm−3, which corresponds to a molecular mass of 255 kDa in the unit cell. A native data set has been collected on an MAR image-plate system using Cu Kα radiation. The completeness of the data set in the range 316–3 Å is 74%, and contains 64% of the data in the outer shell (3.4–2.8 Å), with an average Rmerge value of 9%. Calculation of self-rotation functions revealed the 32 symmetry of the hexamer; 3 non-crystallographic twofold axes were found at a distance of 120° in a plane perpendicular to the non-crystallographic threefold axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444994011224
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  • 2
    Electronic Resource
    Electronic Resource
    Physiology and enzymology of thermophilic anaerobic bacteria degrading starch (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 75 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The capability of secreting thermoactive enzymes exhibiting α-amylase and pullulanase with debraching activity, seems to be widely distributed amongst anaerobic thermophilic bacteria. Interestingly, pullulanase formed by these bacteria displays dual specificity by attacking α-1,6- as well as α-1,4-glycosidic linkages in branched glucose polymers. Unlike the enzyme system of aerobic microorganisms the majority of starch hydrolysing enzymes of anaerobic bacteria is metal indepedent and is extremely thermostable. This enzyme system is controlled by substrate induction and catabolite repression; enzyme expression is accomplished when maltose or maltose-containing carbohydrates are used as substrates. By developing a process in continuous culture we were able to greatly enhance enzyme synthesis and release by anaerobic thermophilic bacteria. An elevation in the specific activities of cell-free amylases and pullulanases could also be achieved by entrapping of bacteria in calcium alginate beads. The unique properties of extracellular enzymes of thermophilic anaerobic bacteria makes this group of organisms suitable candidates for inductrial application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04095.x
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  • 3
    Electronic Resource
    Electronic Resource
    Fermentation of extremophilic microorganisms (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 18 (1996), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The cultivation of the hyperthermophile Pyrococcus furiosus, the thermoacidophile Sulfolobus shibatae and the halophile Marinococcus M52 in dialysis membrane reactors resulted in cell yields of 2.6 g 1−1, 114 g 1−1 and 132 g 1−1 (cell dry weight), respectively. In the case of P. furiosus neither hydrogen (up to 160 μmol 1−1) nor the metabolic products were found to be responsible for growth cessation at a cultivation temperature of 90°C. The low cell yield at an agitation speed of above 1800 rpm demonstrates the sensitivity of P. furiosus to hydrodynamic stress. The oxygen transfer rate into culture medium at extreme temperatures was shown to be equal or even greater than that under mesophilic condition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1996.tb00243.x
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  • 4
    Electronic Resource
    Electronic Resource
    Extremely thermostable amylolytic enzyme from the archaebacterium Pyrococcus furiosus (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 71 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract One of the most thermostable and thermoactive enzymes ever described has been characterized from a hyperthermophilic archaebacterium Pyrococcus furiosus. The enzyme system of this bacterium was capable of hydrolyzing starch forming a mixture of various oligosaccharides. Unlike the amylases from aerobic bacteria this enzyme does not require metal ions for activity or stability. The enzyme is catalytically active over a very broad temperature range, namely between 40°C and 140°C. The half life of this peculiar enzyme during autoclaving at 120°C is 2 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb03792.x
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  • 5
    Electronic Resource
    Electronic Resource
    Production of novel pullulanases at high concentrations by two newly isolated thermophilic clostridia (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 69 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two thermophilic bacteria, which are capable of growing on starch at 60–70°C under anaerobic conditions, were isolated from a sugar refinery in Uelzen and from Solar lake in Israel. On the basis of their physiological characteristics they were identified as Clostridium thermohydrosulfuricum Uel 1 and C. thermohydrosulfuricum Sol 1, respectively. The product pattern of glucose polymer hydrolysis showed that both strains secreted enzymes' that possess amylolytic and pullulytic activities. The major product formed was maltose. In addition, α-glucosidase activity could be detected in the supernatants of Uel 1 strain. Compared to most anaerobes investigated these isolates secreted extremely high concentrations of pullulanases in batch culture. Up to 85% of the total enzyme synthesized was detected in the culture fluid. Unlike the pullulanases of tyoe I, which can only attack the α-1,6-glycosidic linkages, the pullulanases of both clostridial strains were also capable of hydrolyzing α-1,4-linkages. The enzyme system of both bacteria was found to be highly thermoactive; optimal activity was detected at pH 5.0 and 85°C. Even at 95°C and without the addition of metal ions still 15% to 25% of enzymatic activity was detectable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04191.x
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  • 6
    Electronic Resource
    Electronic Resource
    Purification and properties of a thermostable pullulanase from Clostridium thermosulfurogenes EM1 which hydrolyses both α-1,6 and α-1,4-glycosidic linkages (1990)
    Springer
    Applied microbiology and biotechnology 33 (1990), S. 511-518 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A novel thermostable pullulanase, secreted by the thermophilic anaerobic bacterium Clostridium thermosulfurogenes EM1, was purified and characterized. Applying anion exchange chromatography and gel filtration the enzyme was purified 47-fold and had a specific activity of 200 units/mg. The molecular mass of this thermostable enzyme was determined to be 102 000 daltons and consisted of a single subunit. The enzyme was able to attack specifically the α-1,6-glycosidic linkages in pullulan and caused its complete hydrolysis to maltotriose. Surprisingly and unlike the enzyme from Klebsiella pneumoniae, the purified enzyme from this anaerobic thermophile exhibited, in addition to its debranching and pullulanase activity, an α-1,4 hydrolysing activity as well. By the action of this single polypeptide chain various branched and linear polysaccharides were completely converted to two major products, namely maltose and maltotriose. The K m values of this enzyme for pullulan and amylose were determined to be 1.33 mg/ml and 0.38 mg/ml, respectively. This debranching enzyme displays a temperature optimum at 60°–65° C and a pH optimum at 5.5–6.0. The application of this new class of pullulanase (pullulanase type II) in industry will significantly enhance the starch saccharification process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172543
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  • 7
    Electronic Resource
    Electronic Resource
    Thermococcus siculi sp. nov., a novel hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent at the Mid-Okinawa Trough (1999)
    Springer
    Extremophiles 3 (1999), S. 55-62 
    Details
    ISSN: 1433-4909
    Keywords: Key words Archaea ; Hyperthermophiles ; Deep-sea ; Hydrothermal vent ; Thermococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel coccoid-shaped, hyperthermophilic, anaerobic archaeon, strain RG-20, was isolated from a deep-sea hydrothermal vent fluid sample taken at 1394-m depth at the Mid-Okinawa Trough (27°32.7′N, 126°58.5′E). Cells of this isolate occur singly or in pairs and are about 0.8 to 2 μm in diameter. Growth was observed at temperatures between 50° and 93°C, with an optimum at 85°C. The pH range for growth is 5.0–9.0, with an optimum around 7.0. Strain RG-20 requires 1%–4% of NaCl for growth, and cell lysis occurs at concentrations below 1%. The newly isolated strain grows preferentially in the presence of elemental sulfur on proteinaceous substrates such as yeast extract, peptone, or tryptone, and no growth was observed on carbohydrates, carboxylic acids, alcohols, or lipids. This microorganism is resistant to streptomycin, chloramphenicol, ampicillin, and kanamycin at concentrations up to 150 μg/ml, but is susceptible to rifampicin. Analysis of the hydrolyzed core lipids by thin-layer chromatography (TLC) revealed the presence of archaeol and caldarchaeol. The mol% G+C content of the DNA is 55.8. Partial sequencing of the 16S rDNA indicates that strain RG-20 belongs to the genus Thermococcus. Considering these data and on the basis of the results from DNA-DNA hybridization studies, we propose that this strain should be classified as a new species named Thermococcus siculi (si′cu.li. L. gen. n. siculi, of the deep-sea [siculum, deep-sea in literature of Ovid], referring to the location of the sample site, a deep-sea hydrothermal vent). The type strain is isolate RG-20 (DSM No. 12349).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050099
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of gassing, agitation, substrate supplementation and dialysis on the growth of an extremely thermophilic archaeon Pyrococcus woesei (1992)
    Springer
    Applied microbiology and biotechnology 37 (1992), S. 501-504 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Growth of an extremely thermophilic archaeon, Pyrococcus woesei, at 90°C in a 2–1 fermentor was significantly enhanced by gassing with N2/CO2 (95%/5%). Both growth and α-amylase activity were also positively influenced by increasing the agitation speed up to 1200 rpm under continuous gassing at 0.2 vvm. However, increasing the agitation speed to 2400 rpm led to decreases in the maximum cell concentration and α-amylase activity. Fed-batch cultivation resulted in increases in the specific growth rate, maximum cell concentration and α-amylase activity. Although the latter two parameters were higher when the broth was supplemented with both starch and concentrated medium, the specific growth rate was relatively smaller. Cultivation in a dialysis reactor gave a cell concentration of 2 × 109 cells/ml, which represents a 2.8-fold increase over that obtained in ordinary batch cultivation. This increase in the cell concentration was accompanied by a 5.2-fold increase in α-amylase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180977
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of the kinetic parameters during continuous cultivation of the lipase-producing thermophile Bacillus sp. IHI-91 on olive oil (1997)
    Springer
    Applied microbiology and biotechnology 48 (1997), S. 184-190 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A thermostable lipase was produced in continuous cultivation of a newly isolated thermophilic Bacillus sp. strain IHI-91 growing optimally at 65 °C. Lipase activity decreased with increasing dilution rate while lipase productivity showed a maximum of 340 U l−1 h−1 at a dilution rate of 0.4 h−1. Lipase productivity was increased by 50% compared to data from batch fermentations. Up to 70% of the total lipase activity measured was associated to cells and by-products or residual substrate. Kinetic and stoichiometric parameters for the utilisation of olive oil were determined. The maximal biomass output method led to a saturation constant K S of 0.88 g/l. Both batch growth data and a washout experiment yielded a maximal specific growth rate, μmax, of 1.0 h−1. Oxygen uptake rates of up to 2.9 g l−1h−1 were calculated and the yield coefficient, Y X/O, was determined to be 0.29 g dry cell weight/g O2. From an overall material balance the yield coefficient, Y X/S, was estimated to be 0.60 g dry cell weight/g olive oil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051036
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of amylolytic and pullulytic enzymes from thermophilic archaea and from a newFervidobacterium species (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 239-245 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Nine extremely thermophilic archaea and one novel thermophilic bacterium were screened for their ability to produce amylolytic and pullulytic enzymes. Cultivation of these micro-organisms was performed in the absence of elemental sulphur with starch as the major carbon source. Enzymatic activity was mainly detected in two archaea belonging to the order Thermoproteales,Desulfurococcus mucosus andStaphylothermus marinus, in two archaea belonging to the order Thermococcales,Thermococcus celer andT. litoralis and in two novel archaeal strains, TYS and TY previously isolated from the Guaymas Basin in the Gulf of California. Both amylolytic and pullulytic activities were also detected in a newly isolated thermophilic bacterium belonging to the order Thermotogales and previously described asFervidobacterium pennavorans. Best yields for enzyme production were obtained in 1–1 batch cultures with the strains TYS (13 units U/1 of amylase, 6 U/1 of pullulanase),F. pennavorans (2.5 U/l of amylase, 4.5 U/l of pullulanase) andT. litoralis (3.0 U/l of amylase). Enzymes were in general characterized by temperature optima around 90–100°C, pH optima around 5.5–6.5 and a high degree of thermostability. Due to the remarkable properties of these enzymes, they are of interest for biotechnological applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902723
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