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1.
Isolation and Characterization of Acetate-Utilizing Anaerobes from a Freshwater Sediment 总被引:1,自引:0,他引:1
Acetate-degrading anaerobic microorganisms in freshwater sediment were quantified by the most probable number technique. From
the highest dilutions a methanogenic, a sulfate-reducing, and a nitrate-reducing microorganism were isolated with acetate
as substrate. The methanogen (culture AMPB-Zg) was non-motile and rod-shaped with blunted ends (0.5–1 μm × 3–4 μm long). Doubling
times with acetate at 30–35°C were 5.6–8.1 days. The methanogen grew only on acetate. Analysis of the 16S rRNA sequence showed
that AMPB-Zg is closely related toMethanosaeta concilii. The isolated sulfate-reducing bacterium (strain ASRB-Zg) was rod-shaped with pointed ends (0.5–0.7 μm × 1.5–3.5 μm long),
weakly motile, spore forming, and gram positive. At the optimum growth temperature of 30°C the doubling times with acetate
were 3.9–5.3 days. The bacterium grew on a range of organic acids, such as acetate, butyrate, fumarate, and benzoate, but
did not grow autotrophically with H2, CO2, and sulfate. The closest relative of strain ASRB-Zg isDesulfotomaculum acetoxidans. The nitrate-reducing bacterium (strain ANRB-Zg) was rod-shaped (0.5–0.7 μm × 0.7–1 μm long), weakly motile, and gram negative.
Optimum growth with acetate occurred at 20–25°C. The bacterium grew on a range of organic substrates, such as acetate, butyrate,
lactate, and glucose, and did grow autotrophically with H2, CO2, and oxygen but not with nitrate. In the presence of acetate and nitrate, thiosulfate was oxidized to sulfate. Phylogenetically,
the closest relative of strain ANRB-Zg isVariovorax paradoxus. 相似文献
2.
Melike Balk Hans G. H. J. Heilig Miriam H. A. van Eekert Alfons J. M. Stams Irene C. Rijpstra Jaap S. Sinninghe-Damsté Willem M. de Vos Servé W. M. Kengen 《Extremophiles : life under extreme conditions》2009,13(6):885-894
A novel anaerobic, thermophilic, Gram-positive, spore-forming, and sugar-fermenting bacterium (strain TLO) was isolated from
a geothermal spring in Ayaş, Turkey. The cells were straight to curved rods, 0.4–0.6 μm in diameter and 3.5–10 μm in length.
Spores were terminal and round. The temperature range for growth was 40–80°C, with an optimum at 70°C. The pH optimum was
between 6.3 and 6.8. Strain TLO has the capability to ferment a wide variety of mono-, di-, and polysaccharides and proteinaceous
substrates, producing mainly lactate, next to acetate, ethanol, alanine, H2, and CO2. Remarkably, the bacterium was able to grow in an atmosphere of up to 25% of CO as sole electron donor. CO oxidation was
coupled to H2 and CO2 formation. The G + C content of the genomic DNA was 35.1 mol%. Based on 16S rRNA gene sequence analysis and the DNA–DNA hybridization
data, this bacterium is most closely related to Thermoanaerobacter thermohydrosulfuricus and Thermoanaerobacter siderophilus (99% similarity for both). However, strain TLO differs from Thermoanaerobacter thermohydrosulfuricus in important aspects, such as CO-utilization and lipid composition. These differences led us to propose that strain TLO represents
a subspecies of Thermoanaerobacter thermohydrosulfuricus, and we therefore name it Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans. 相似文献
3.
Melike Balk Farrakh Mehboob Antonie H. van Gelder W. Irene C. Rijpstra Jaap S. Sinninghe Damsté Alfons J. M. Stams 《Applied microbiology and biotechnology》2010,88(2):595-603
A mesophilic bacterium, strain An4, was isolated from an underground gas storage reservoir with methanol as substrate and
perchlorate as electron acceptor. Cells were Gram-negative, spore-forming, straight to curved rods, 0.5–0.8 μm in diameter,
and 2–8 μm in length, growing as single cells or in pairs. The cells grew optimally at 37°C, and the pH optimum was around
7. Strain An4 converted various alcohols, organic acids, fructose, acetoin, and H2/CO2 to acetate, usually as the only product. Succinate was decarboxylated to propionate. The isolate was able to respire with
(per)chlorate, nitrate, and CO2. The G+C content of the DNA was 42.6 mol%. Based on the 16S rRNA gene sequence analysis, strain An4 was most closely related
to Sporomusa ovata (98% similarity). The bacterium reduced perchlorate and chlorate completely to chloride. Key enzymes, perchlorate reductase
and chlorite dismutase, were detected in cell-free extracts. 相似文献
4.
Zhao W Weber C Zhang CL Romanek CS King GM Mills G Sokolova T Wiegel J 《Extremophiles : life under extreme conditions》2006,10(4):337-345
A novel thermophilic, alkali-tolerant, and CO-tolerant strain JW/WZ-YB58T was isolated from green mat samples obtained from the Zarvarzin II hot spring in the Uzon Caldera, Kamchatka (Far East Russia). Cells were Gram-type and Gram stain-positive, strictly aerobic, 0.7–0.8 μm in width and 5.5–12 μm in length and produced terminal spherical spores of 1.2–1.6 μm in diameter with the mother cell swelling around 2 μm in diameter (drumstick-type morphology). Cells grew optimally at pH25°C 8.2–8.4 and temperature 50–52°C and tolerated maximally 6% (w/v) NaCl. They were strict heterotrophs and could not use either CO or CO2 (both with or without H2) as sole carbon source, but tolerated up to 90% (v/v) CO in the headspace. The isolate grew on various complex substrates such as yeast extract, on carbohydrates, and organic acids, which included starch, d-galactose, d-mannose, glutamate, fumarate and acetate. Catalase reaction was negative. The membrane polar lipids were dominated by branched saturated fatty acids, which included iso-15:0 (24.5%), anteiso-15:0 (18.3%), iso-16:0 (9.9%), iso-17:0 (17.5%) and anteiso-17:0 (9.7%) as major constituents. The DNA G+C content of the strain is 45 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain JW/WZ-YB58T is distantly (<93% similarity) related to members of Bacillaceae. On the basis of 16S rRNA gene sequence, physiological and phenotypic characteristics, the isolate JW/WZ-YB58T (ATCC BAA-1258; DSM 17740) is proposed to be the type strain for the type species of the new taxa within the family Bacillaceae, Thermalkalibacillus uzoniensis gen. nov. sp. nov. The Genbank accession number for the 16S rRNA gene sequence is DQ221694.The Genbank accession number for the 16S rRNA gene sequence of strain JW/WZ-YB58T is DQ221694. 相似文献
5.
A. I. Saralov B. B. Kuznetsov E. M. Reutskikh R. V. Baslerov A. N. Panteleeva N. E. Suzina 《Microbiology》2012,81(5):582-588
A halophilic nonpigmented rod-shaped (0.8–1.0 × 2.0–2.5 μm), gram-negative bacterium with a single polar flagellum (strain RS91) was isolated from acidic brines of flotation enrichment of potassium minerals (Silvinit Co., Solikamsk, Russia). The strain grew in the media with 2 to 25% NaCl (optimum at 10–12%), 20–45°C (optimum at 37°C), and pH 5.5–8.5 (optimum 6.5–7.5). It was an aerobe or facultative anaerobe incapable of fermentation. The strain was characterized by the absence of growth on glucose, fructose, and citrate, extensive aerobic growth on n-hexadecane and in the mineral medium with H2 + O2 + CO2 in the gas phase, anaerobic nitrate reduction with acetate or hydrogen (under H2 + CO2 + N2), and variable fatty acid composition. The DNA G+C content was 68.2 mol %. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that while strain RS91 was most closely related to Arhodomonas aquaeolei HA-1T (98.3%) and Nitrococcus mobilis (98.1%), it was only remotely related to the halophilic phototroph Halorhodospira halophila (90.6%). Based on the combination of its phenotypic and genotypic characteristics, the organism was classified as a new species of the genus Arhodomonas, family Ectothiorhodospiraceae with the proposed name Arhodomonas recens sp. nov. The type strain is RS91T (= IEGM 796T = VKPM B-11280T). 相似文献
6.
A methanogen, strain AK-1, was isolated from permanently cold marine sediments, 38- to 45-cm below the sediment surface at
Skan Bay, Alaska. The cells were highly irregular, nonmotile coccoids (diameter, 1 to 1.2 μm), occurring singly. Cells grew
by reducing CO2 with H2 or formate as electron donor. Growth on formate was much slower than that on H2. Acetate, methanol, ethanol, 1- or 2-propanol, 1- or 2-butanol and trimethylamine were not catabolized. The cells required
acetate, thiamine, riboflavin, a high concentration of vitamin B12, and peptones for growth; yeast extract stimulated growth but was not required. The cells grew fastest at 25 °C (range 5
°C to 25 °C), at a pH of 6.0 – 6.6 (growth range, pH 5.5 – 7.5), and at a salinity of 0.25 – 1.25 M Na+. Cells of this and other H2-using methanogens from saline environments metabolized H2 to a very low threshold pressure (less than 1 Pa) that was dependent on the methane partial pressure. We propose that the
threshold pressure may be limited by the energetics of catabolism. The sequence of the 16S rDNA gene of strain AK-1 was most
similar (98%) to the sequences of Methanogenium cariaci JR-1 and Methanogenium frigidum Ace-2. DNA–DNA hybridization between strain AK-1 and these two strains showed only 34.9% similarity to strain JR-1 and 56.5%
similarity to strain Ace-2. These analyses indicated strain AK-1 should be classified as a new species within the genus Methanogenium. Phenotypic differences between strain AK-1 and these strains (including growth temperature, salinity range, pH range, and
nutrient requirements) support this. Therefore, a new species, Methanogenium marinum, is proposed with strain AK-1 as type strain.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
Chun-Wang Xiao Osbert J. Sun Guang-Sheng Zhou Jing-Zhu Zhao Gang Wu 《Trees - Structure and Function》2005,19(6):712-721
We studied the responses of leaf water potential (Ψw), morphology, biomass accumulation and allocation, and canopy productivity index (CPI) to the combined effects of elevated
CO2 and drought stress in Caragana intermedia seedlings. Seedlings were grown at two CO2 concentrations (350 and 700 μmol mol−1) interacted with three water regimes (60–70%, 45–55%, and 30–40% of field capacity of soil). Elevated CO2 significantly increased Ψw, decreased specific leaf area (SLA) and leaf area ratio (LAR) of drought-stressed seedlings, and increased tree height, basal
diameter, shoot biomass, root biomass as well as total biomass under the all the three water regimes. Growth responses to
elevated CO2 were greater in well-watered seedlings than in drought-stressed seedlings. CPI was significantly increased by elevated CO2, and the increase in CPI became stronger as the level of drought stress increased. There were significant interactions between
elevated CO2 and drought stress on leaf water potential, basal diameter, leaf area, and biomass accumulation. Our results suggest that
elevated CO2 may enhance drought avoidance and improved water relations, thus weakening the effect of drought stress on growth of C. intermedia seedings. 相似文献
8.
Olfa Ben Dhia Thabet Terres Wafa Khelifi Eltaief Jean-Luc Cayol Moktar Hamdi Guy Fauque Marie-Laure Fardeau 《Current microbiology》2011,62(2):486-491
A new moderately halophilic sulfate-reducing bacterium (strain H1T) was enriched and isolated from a wastewater digestor in Tunisia. Cells were curved, motile rods (2–3 x 0.5 μm). Strain H1T grew at temperatures between 22 and 43°C (optimum 35°C), and at pH between 5.0 and 9.2 (optimum 7.3–7.5). Strain H1T required salt for growth (1–45 g of NaCl/l), with an optimum at 20–30 g/l. Sulfate, sulfite, thiosulfate, and elemental sulfur
were used as terminal electron acceptors but not nitrate and nitrite. Strain H1T utilized lactate, pyruvate, succinate, fumarate, ethanol, and hydrogen (in the presence of acetate and CO2) as electron donors in the presence of sulfate as electron acceptor. The main end-products from lactate oxidation were acetate
with H2 and CO2. The G + C content of the genomic DNA was 55%. The predominant fatty acids of strain H1T were C15:0 iso (38.8%), C16:0 (19%), and C14:0 iso 3OH (12.2%), and menaquinone MK-6 was the major respiratory quinone. Phylogenetic analysis of the small-subunit (SSU)
ribosomal RNA (rRNA) gene sequence indicated that strain H1T was affiliated to the genus Desulfovibrio. On the basis of SSU rRNA gene sequence comparisons and physiological characteristics, strain H1T is proposed to be assigned to a novel species of sulfate reducers of the genus Desulfovibrio, Desulfovibrio legallis sp. nov. (= DSM 19129T = CCUG 54389T). 相似文献
9.
Anne E. Taylor Daniel J. Arp Peter J. Bottomley Lewis Semprini 《Applied microbiology and biotechnology》2010,87(6):2293-2302
Nocardioides sp. strain JS614 grows on the C2 alkenes ethene (Eth), vinyl chloride, and vinyl fluoride as sole carbon sources. The presence of 400–800 μM ethene oxide
(EtO) extended the growth substrate range to propene (C3) and butene (C4). Propene-dependent growth of JS614 was CO2 dependent and was prevented by the carboxylase/reductase inhibitor 2-bromoethanesulfonic acid, sodium salt (BES), while growth
on Eth was not CO2 dependent or BES sensitive. Although unable to promote growth, both propene and propene oxide (PrO)-induced expression of
the genes encoding the alpha subunit of alkene monooxygenase (etnC) and epoxyethane CoM transferase (etnE) to similar levels as did Eth and EtO. Propene was transformed by Eth-grown and propene-grown/EtO-induced JS614 to PrO at
a rate 4.2 times faster than PrO was consumed. As a result PrO accumulated in growth medium to 900 μM during EtO-induced growth
on propene. PrO (50–100 μM) exerted inhibitory effects on growth of JS614 on both acetate and Eth, and on EtO-induced growth
on Eth. However, higher EtO concentrations (300–400 μM) overcame the negative effects of PrO on Eth-dependent growth. 相似文献
10.
The extremely thermophilic ethanol-producing strain A3 was isolated from a hot spring in Iceland. The cells were rod-shaped,
motile, and had terminal spores; cells from the mid-to-late exponential growth phase stained gram-variable but had a gram-positive
cell wall structure when viewed by transmission electron microscopy. Strain A3 used a number of carbohydrates as carbon sources,
including xylan, but did not utilize microcrystalline cellulose. Fermentation end products were ethanol, acetate, lactate,
CO2, and H2. The temperature optimum for growth was between 70 and 75° C, and growth occurred in the range of 50–75° C. The pH range
for growth was 4.7–8.8, with an optimum at pH 7.0. Strain A3 was sensitive to tetracycline, chloramphenicol, penicillin G,
neomycin, and vancomycin at 100 mg/l but was not sensitive to chloramphenicol and neomycin at 10 mg/l, which indicates that
strain A3 belongs to the eubacteria. Addition of 50.66 kPa H2 or 2% NaCl did not affect growth. The isolate grew in the presence of exogenously added 4% (w/v) ethanol. The G+C ratio was
37 mol%. 16S rDNA studies revealed that strain A3 belongs to the genus Thermoanaerobacter. Genotypic and phenotypic differences between strain A3 and other related species indicate that strain A3 can be assigned
to a new species, and the name Thermoanaerobacter mathranii is proposed.
Received: 7 October 1996 / Accepted: 14 March 1997 相似文献
11.
Beate Jochimsen Susanne Peinemann-Simon Horst Völker Doris Stüben Reiner Botz Peter Stoffers Paul R. Dando Michael Thomm 《Extremophiles : life under extreme conditions》1997,1(2):67-73
A new hyperthermophilic, strictly anaerobic crenarchaeote, Stetteria hydrogenophila DSM11227 representing a new genus within the family of Desulfurococcaceae, was isolated from the sediment of a marine hydrothermal system at Paleohori Bay in Milos, Greece. Cells are gram-negative
irregular and disc-shaped cocci, 0.5–1.5 μm in diameter, which are flagellate and can form cytoplasmatic protrusions up to
2 μm in length. The strain grew optimally at 95°C at pH 6.0 and at a NaCl concentration of 3%. The organism grew mixotrophically
on peptide substrates. It required elemental sulfur as an external electron acceptor, and in addition, its growth was completely
dependent on the presence of molecular hydrogen. Sulfur could be replaced by thiosulfate. H2S, CO2, acetate, and ethanol were identified as products of metabolism. The G + C content of DNA was 65 mol%. Analysis of its phylogenetic
position by sequence analysis of 16S rRNA placed this organism in the family of Desulfurococcaceae. The dependence of this organism on both hydrogen and sulfur during growth on peptide substrates distinguishes Stetteria from all previously described species of Crenarchaeota.
Received: September 4, 1996 / Accepted: November 12, 1996 相似文献
12.
Lubomír Adamec 《Ecological Research》2009,24(2):327-333
Aquatic carnivorous plants usually grow in shallow dystrophic waters poor in inorganic N and P. Utricularia australis was chosen as a model plant for its prolific distribution and great ecological plasticity. The photosynthetic CO2 compensation point and factors associated with investment in carnivory and capture of prey were measured in 17 U. australis micropopulations in Třeboň basin, Czech Republic, together with water chemistry factors at these sites differing greatly
in their trophic level, water hardness, and prey availability. Apical shoot growth rate was estimated at some oligotrophic
sites. The micropopulations differed greatly in the proportion of traps with animal prey (2.7–70%, mean 26%), trap proportion
to total biomass (1.4–42%, mean 26%), mean trap biomass (0.7–63 μg trap−1, mean 19 μg), and maximum trap size (1–3 mm, mean 2.0 mm). CO2 compensation points ranged from 0.7 to 6.1 μM (mean 2.6 μM). A weak HCO3
− use (compensation point 0.51 mM) was found in plants growing in alkaline water. Trap biomass proportion did not correlate
significantly with prey capture and CO2 compensation points with ambient [CO2]. A very rapid apical growth (2.5–4.2 new nodes day−1) occurred in sand pits. Thus, HCO3
− use in U. australis can be induced by growing at very high pH. CO2 compensation points resembled those known in other aquatic non-carnivorous plants. They did not reflect carnivory. In spite
of very rapid apical shoot growth, the relative growth rate of U. australis can be zero in oligotrophic habitats without prey. 相似文献
13.
Since the thermophilic bacterium Moorella sp. HUC22-1 produces 120 mM acetate and 5.2 mM ethanol from H2–CO2, several candidate genes, which were predicted to code for three alcohol dehydrogenases (AdhA, B, C) and one acetaldehyde
dehydrogenase (Aldh), were cloned from HUC22-1. The cloned genes were subcloned into a His-tagged expression vector and expressed
in Escherichia coli. Recombinant AdhA and B were both dependent on NADP(H) but independent of NAD(H), and their reduction activities from aldehyde
to alcohol were higher than their oxidation activities. In contrast with AdhA and B, no activity of AdhC was observed in either
reaction. On the other hand, Aldh was active toward both NADP(H) and NAD(H). The enzyme activity of Aldh was directed toward
the thioester cleavage and the thioester condensation. When 50 μg of AdhA and 50 μg Aldh were added to the buffer solution
(pH 8.0) containing NADPH, NADH and acetyl-CoA at 60°C, 1.6 mM ethanol was produced from 3 mM acetyl-CoA after 90 min. Expression
analysis of the mRNAs revealed that the expression level of aldh was threefold higher in the H2–CO2 culture than that in the fructose culture, but levels of adhA, B and C were decreased. 相似文献
14.
CO2 exchange of the endolithic lichen Verrucaria baldensis was measured in the laboratory under different conditions of water content, temperature, light, and CO2 concentration. The species had low CO2 exchange rates (maximum net photosynthesis: c. 0.45 μmol CO2 m−2 s−1; maximum dark respiration: c. 0.3 μmol CO2 m−2 s−1) and a very low light compensation point (7 μmol photons m−2 s−1 at 8°C). The net photosynthesis/respiration quotient reached a maximum at 9–15°C. Photosynthetic activity was affected only
after very severe desiccation, when high resaturation respiratory rates were measured. Microclimatic data were recorded under
different weather conditions in an abyss of the Trieste Karst (northeast Italy), where the species was particularly abundant.
Low photosynthetically active radiation (normally below 40 μmol photons m−2 s−1), very high humidities (over 80%), and low, constant temperatures were measured. Thallus water contents sufficient for CO2 assimilation were often measured in the absence of condensation phenomena.
Received: 22 September 1996 / Accepted: 26 April 1997 相似文献
15.
Mei-Chin Lai Chi-Ming Shu Ming-Shing Chiou Tong-Yung Hong Ming-Jen Chuang Jack Jay Hua 《Current microbiology》1999,39(2):79-84
A new methanogenic isolate, designated as strain N2M9705 (=OCM 668), was isolated from an aquaculture fishpond near Wang-gong,
Taiwan. This strain grew on trimethylamine and methanol, but it did not catabolize H2-CO2, acetate, or formate. The cells were stained Gram-negative, nonmotile, irregular coccus 0.6–0.8 μm in diameter. Gas vacuoles
were observed and cell aggregated to form various sizes of granules. Cells grew optimally at 32°–37°C with 1% NaCl. The pH
range of growth was 6.2–7.4, and higher pH inhibited the cell growth. The cells grew well in minimal medium, but growth was
greatly stimulated by yeast extract and peptone. A comparison of 16S rDNA sequences of this organism phylogenetically related
to Methanosarcina mazei. This is the first report of methyltrophic methanogenic isolated from an aquaculture fishpond.
Received: 16 March 1999 / Accepted: 16 April 1999 相似文献
16.
The effects of elevated CO2 concentrations on stomatal movement, anion- and K+-channel activities were examined in guard cells from epidermal strips of Vicia faba. Membrane voltage was measured using intracellular, double-barrelled microelectrodes and ion-channel currents were recorded
under voltage clamp during exposure to media equilibrated with ambient (350 μl · l−1), 1000 μl · l−1 and 10 000 μl · l−1 CO2 in 20% O2 and 80% N2. The addition of 1000 μl · l−1 CO2 to the bathing solution caused stomata to close with a halftime of approx. 40 min, and with 10 000 μl · l−1 CO2 closure occurred with a similar time course. Under voltage clamp, exposure to 1000 μl · l−1 and 10 000 μl · l−1 CO2 resulted in a rapid increase (mean, 1.5 ± 0.2-fold, n = 8; range 1.3- to 2.5-fold) in the magnitude of current carried by outward-rectifying K+ channels (IK,out). The effect of CO2 on IK,out was essentially complete within 30 s and was independent of clamp voltage, but was associated with 25–40% (mean, 30 ± 4%)
decrease in the halftime for current activation. Exposure to CO2 also resulted in a four-fold increase in background current near the free-running membrane voltage, recorded as the instantaneous
current at the start of depolarising and hyperpolarising voltage steps, and a decrease in the magnitude of current carried
by inward-rectifying K+ channels (IK,in). The effect of CO2 on IK,in was generally slower than on IK,out; it was allied with a transient acceleration of its activation kinetics during the first 60–120 s of treatment; and it was
associated with a negative shift in the voltage-sensitivity of gating over a period of 3–5 min. Measurements carried out to
isolate the background currents attributable to anion channels (ICl), using tetraethylammonium chloride and CsCl, showed that CO2 also stimulated ICl and dramatically altered its relaxation kinetics. Within the timeframe of CO2 action at the membrane, no significant effect was observed on cytosolic pH, measured using the fluorescent dye 2′,7′-bis-(2-carboxyethyl)-5,6-carboxyflourescein
(BCECF) and ratio fluorescence microphotometry. These results are broadly consistent with the pattern of guard-cell response
to abscisic acid, and indicate that guard cells control both anion and K+ channels to achieve net solute loss in CO2. By contrast with the effects of abscisic acid, however, the data indicate that CO2 action is not mediated through changes in cytosolic pH and thereby implicate new and, as yet, unidentified pathway(s) for
channel regulation in the guard cells.
Received: 8 January 1997 / Accepted: 28 February 1997 相似文献
17.
R. Huber Josef Stöhr Sabine Hohenhaus Reinhard Rachel Siegfried Burggraf Holger W. Jannasch Karl O. Stetter 《Archives of microbiology》1995,164(4):255-264
From a hydrothermal vent site off the Mexican west coast (20°50′N, 109°06′W) at a depth of 2,600 m, a novel, hyperthermophilic,
anaerobic archaeum was isolated. Cells were round to slightly irregular cocci, 1.2–2.5 μm in diameter and were motile by means
of a tuft of flagella. The new isolate grew between 60 and 93°C (optimum: 85°C), from pH 3.5 to 9 (optimum: pH 6.7), and from
0.8 to 8% NaCl (optimum: 2%). The isolate was an obligate organotroph, using chitin, yeast extract, meat extract, and peptone
for growth. Chitin was fermented to H2, CO2, NH3, acetate, and formate. H2S was formed in the presence of sulfur. The chitinoclastic enzyme system was oxygen-stable, cell-associated, and inducible
by chitin. The cell wall was composed of a surface layer of hex- americ protein complexes arranged on a p6 lattice. The core
lipids consisted of glycerol diphytanyl diethers and acyclic and cyclic glycerol diphytanyl tetraethers. The G+C content was
46.5 mol%. DNA/DNA hybridization and 16S rRNA sequencing indicated that the new isolate belongs to the genus Thermococcus, representing a new species, Thermococcus chitonophagus. The type strain is isolate GC74, DSM 10152.
Received: 8 May 1995 / Accepted: 26 June 1995 相似文献
18.
Photosynthesis rates of selected tree species in lowland dipterocarp rainforest of Sabah, Malaysia 总被引:3,自引:0,他引:3
Diurnal courses of net photosynthesis, transpiration and water potential of leaves of ten woody species from the natural
lowland dipterocarp forests in Sabah (North Borneo, Malaysia) and one exotic tree species were studied in the field. The indigenous
species represent different ecological niches and successional stages in the various layers of the dipterocarp forest, such
as pioneers, trees of the understorey or main canopy and emergents. Diurnal changes in CO2 exchange and transpiration reflected primarily differences in irradiance. The diurnal courses of water potential mainly tracked
the rate of transpiratory water loss. Light-dependency describes most of the diurnal variations of leaves’ gas exchange. Light
response curves of net photosynthesis of the investigated species of the Dipterocapaceae were almost equal (light saturated
assimilation rate, Amax: 5.0–7.2 μmol CO2 m–2 s–1), while those of the other species exhibited remarkable differences (Amax: 5.5–14.2 μmol CO2 m–2 s–1). Leaf area, chlorophyll content and specific leaf dry weight as the reference parameters for assimilation gave a general
ranking of the Amax, which is highest for the pioneering species, less for the understorey trees and lowest for emergents. Light compensation
points and light saturation of net photosynthesis were attained mainly between 6 and 9 μmol photons m–2 s–1 and between 230 and 534 μmol photons m–2 s–1, respectively, but were higher for pioneering species. Photosynthetic performance may be a diagnostic feature of the successional
and ecological status of species, i.e. to characterize pioneering species from understorey species or from emergents of the
dipterocarp forest.
Received: 3 March 1997 / Accepted: 15 December 1997 相似文献
19.
Summary
Hosta ‘Blue Vision’, a shade-adapted perennial, was successfully acclimatized in high, natural light conditions in the research
AcclimatronTM at Clemson University, Clemson, SC during the summer of 2000. The supplemental CO2 levels achieved during acclimatization were 710±113, 2396±121, and 5641±119 μmol mol−1, approximately 2×, 6×, and 15× ambient CO2. Plants were maintained in H2O-saturated atmospheres and protected from temperature increases associated with high light intensity. In the 5 wk following
ex vitro transfer, plantlet roots grew at the 2× CO2 level, but shoot biomass was unaffected. Results for the 6× and 15× CO2 levels were comparable and provided the best plantlet growth. The “doubling time’ that is characteristic of exponential growth
was 10.8 and 9.8 d for root and shoot dry weights, respectively. There was no indication of light saturation of net photosynthetic
rate (NPR) over the photosynthetic photon flux density (PPFD) range of 100–1200 μmolm−2s−1 experienced during this study. An interaction between CO2 and light intensity levels was detected for NPR of Hosta ‘Blue Vision’ with CO2 saturation occurring at approximately 2800 μmol mol−1. regardless of light level. Furthermore, at the optimal CO2 level, NPR increased quadratically as light intensity increased, and NPR was greatest at the maximum light intensity (PPFD:
1200 μmol m−2s−1). 相似文献
20.
Pathways of autotrophic CO2 fixation and of dissimilatory nitrate reduction to N2O in Ferroglobus placidus 总被引:1,自引:0,他引:1
J. A. Vorholt Doris Hafenbradl Karl O. Stetter Rudolf K. Thauer 《Archives of microbiology》1997,167(1):19-23
The strictly anaerobic Archaeon Ferroglobus placidus was grown chemolithoautotrophically on H2 and nitrate and analyzed for enzymes and coenzymes possibly involved in autotrophic CO2 fixation. The following enzymes were found [values in parentheses = μmol min–1 (mg protein)–1]: formylmethanofuran dehydrogenase (0.2), formylmethanofuran:tetrahydromethanopterin formyltransferase (0.6), methenyltetrahydromethanopterin
cyclohydrolase (10), F420-dependent methylenetetrahydromethanopterin dehydrogenase (1.5), F420-dependent methylenetetrahydromethanopterin reductase (0.4), and carbon monoxide dehydrogenase (0.1). The cells contained
coenzyme F420 (0.4 nmol/mg protein), tetrahydromethanopterin (0.9 nmol/ mg protein), and cytochrome b (4 nmol/mg membrane protein). From the enzyme and coenzyme composition of the cells, we deduced that autotrophic CO2 fixation in F. placidus proceeds via the carbon monoxide dehydrogenase pathway as in autotrophically growing Archaeoglobus and Methanoarchaea species. Evidence is also presented that cell extracts of F. placidus catalyze the reduction of two molecules of nitrite to 1 N2O with NO as intermediate (0.1 μmol N2O formed per min and mg protein), showing that – at least in principle –F. placidus has a denitrifying capacity.
Received: 23 August 1996 / Accepted: 6 November 1996 相似文献