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1.
A. De Smul J. Dries L. Goethals H. Grootaerd W. Verstraete 《Applied microbiology and biotechnology》1997,48(3):297-303
In a mesophilic (30–35 °C), sulphidogenic, ethanol-fed expanded-granular-sludge-blanket reactor, sulphate, at loading rates
of up to 10.0–12.0 g Sl−1␣day−1, was removed with an average efficiency of more than 80%. The pH was between 7.7 and 8.3 and the maximal total dissolved
sulphide concentration was up to 20 mM S (650 mg S/l). The alkaline pH was maintained by either a pH-control unit with sodium
hydroxide or by stripping part of the sulphide and CO2 from the recycle with nitrogen gas. The superficial upstream liquid velocity (v
up) was 3.0–4.5 m/h. The ratio of ethanol to sulphur was near stoichiometry. At alkaline pH, the activity of the acetotrophic
sulphate-reducing bacteria, growing on acetate, was strongly enhanced, whereas at pH below 7.7 the acetotrophic sulphate-reducing
bacteria were inhibited by aqueous H2S. With regard to the removal efficiency and operational stability, external stripping with N2 and pH control were equally successful.
Received: 2 December 1996 / Received revision: 13 March 1997 / Accepted: 15 March 1997 相似文献
2.
The effects of temperature on photosynthesis of a rosette plant growing at ground level, Acaena cylindrostachya R. et P., and an herb that grows 20–50 cm above ground level, Senecio formosus H.B.K., were studied along an altitudinal gradient in the Venezuelan Andes. These species were chosen in order to determine
– in the field and in the laboratory – how differences in leaf temperature, determined by plant form and microenvironmental
conditions, affect their photosynthetic capacity. CO2 assimilation rates (A) for both species decreased with increasing altitude. For Acaena leaves at 2900 m, A reached maximum values above 9 μmol m−2 s−1, nearly twice as high as maximum A found at 3550 m (5.2) or at 4200 m (3.9). For Senecio leaves, maximum rates of CO2 uptake were 7.5, 5.8 and 3.6 μmol m−2 s−1 for plants at 2900, 3550 and 4200 m, respectively. Net photosynthesis-leaf temperature relations showed differences in optimum
temperature for photosynthesis (A
o.t.) for both species along the altitudinal gradient. Acaena showed similar A
o.t. for the two lower altitudes, with 19.1°C at 2900 m and 19.6°C at 3550 m, while it increased to 21.7°C at 4200 m. Maximum
A for this species at each altitude was similar, between 5.5 and 6.0 μmol m−2 s−1. For the taller Senecio, A
o.t. was more closely related to air temperatures and decreased from 21.7°C at 2900 m, to 19.7°C at 3550 m and 15.5°C at 4200 m.
In this species, maximum A was lower with increasing altitude (from 6.0 at 2900 m to 3.5 μmol m−2 s−1 at 4200 m). High temperature compensation points for Acaena were similar at the three altitudes, c. 35°C, but varied in Senecio from 37°C at 2900 m, to 39°C at 3550 m and 28°C at 4200 m. Our results show how photosynthetic characteristics change along
the altitudinal gradient for two morphologically contrasting species influenced by soil or air temperatures.
Received: 5 July 1997 / Accepted: 25 October 1997 相似文献
3.
J. Gerritse G. Kloetstra A. Borger G. Dalstra A. Alphenaar J. C. Gottschal 《Applied microbiology and biotechnology》1997,48(4):553-562
Anaerobic tetrachloroethene(C2Cl4)-dechlorinating bacteria were enriched in slurries from chloroethene-contaminated soil. With methanol as electron donor,
C2Cl4 and trichloroethene (C2HCl3) were reductively dechlorinated to cis-1,2-dichloroethene (cis-C2H2Cl2), whereas, with l-lactate or formate, complete dechlorination of C2Cl4 via C2HCl3, cis-C2H2Cl2 and chloroethene (C2H3Cl) to ethene was obtained. In oxic soil slurries with methane as a substrate, complete co-metabolic degradation of cis-C2H2Cl2 was obtained, whereas C2HCl3 was partially degraded. With toluene or phenol both of the above were readily co-metabolized. Complete degradation of C2Cl4 was obtained in sequentially coupled anoxic and oxic chemostats, which were inoculated with the slurry enrichments. Apparent
steady states were obtained at various dilution rates (0.02–0.4 h−1) and influent C2Cl4-concentrations (100–1000 μM). In anoxic chemostats with a mixture␣of␣formate and glucose as the carbon and electron source,
C2Cl4 was transformed at high rates (above␣140 μmol l−1 h−1, corresponding to 145 nmol Cl− min−1 mg protein−1) into cis-C2H2Cl2 and C2H3Cl. Reductive dechlorination was not affected by addition of 5 mM sulphate, but strongly inhibited after addition of 5 mM
nitrate. Our results (high specific dechlorination rates and loss of dechlorination capacity in the absence of C2Cl4) suggest that C2Cl4-dechlorination in the anoxic chemostat was catalysed by specialized dechlorinating bacteria. The partially dechlorinated
intermediates, cis-C2H2Cl2 and C2H3Cl, were further degraded by aerobic phenol-metabolizing bacteria. The maximum capacity for chloroethene (the sum of tri-,
di- and monochloro derivatives removed) degradation in the oxic chemostat was 95 μmol l−1 h−1 (20 nmol min−1 mg protein−1), and that of the combined anoxic → oxic reactor system was 43.4 μmol l−1 h−1. This is significantly higher than reported thus far.
Received: 17 April 1997 / Received revision: 6 June 1997 / Accepted: 7 June 1997 相似文献
4.
A number of nutritional factors influencing growth and glucose oxidase (EC 1.1.3.4) production by a newly isolated strain
of Penicillium pinophilum were investigated. The most important factors for glucose oxidase production were the use of sucrose as the carbon source,
and growth of the fungus at non-optimal pH 6.5. The enzyme was purified to apparent homogeneity with a yield of 74%, including
an efficient extraction step of the mycelium mass at pH 3.0, cation-exchange chromatography and gel filtration. The relative
molecular mass (M
r) of native glucose oxidase was determined to be 154 700 ± 4970, and 77 700 for the denatured subunit. Electron-microscopic
examinations revealed a sandwich-shaped dimeric molecule with subunit dimensions of 5.0 × 8.0 nm. Glucose oxidase is a glycoprotein
that contains tightly bound FAD with an estimated stoichiometry of 1.76 mol/mol enzyme. The enzyme is specific for d-glucose, for which a K
m value of 6.2 mM was determined. The pH optimum was determined in the range pH 4.0–6.0. Glucose oxidase showed high stability
on storage in sodium citrate (pH 5.0) and in potassium phosphate (pH 6.0), each 100 mM. The half-life of the activity was
considerably more than 305 days at 4 °C and 30 °C, and 213 days at 40 °C. The enzyme was unstable at temperatures above 40 °C
in the range pH 2.0–4.0 and at a pH above 7.0.
Received: 18 November 1996 / Received revision: 3 March 1997 / Accepted: 7 March 1997 相似文献
5.
Metabolism of EDTA and its metal chelates by whole cells and cell-free extracts of strain BNC1 总被引:5,自引:0,他引:5
The influence of metal ions on the metabolism of ethylenediaminetetraacetate (EDTA) by whole cells and cell-free extracts
of strain BNC1 was investigated. Metal-EDTA chelates with thermodynamic stability constants below 1012 were readily mineralized by whole cells with maximum specific turnover rates of 15 (MnEDTA) to 20 (Ca-, Mg-, and BaEDTA)
μmol g protein−1 min−1. With the exception of ZnEDTA, chelates with stability constants greater than 1012 were not oxidized at a significant rate. However, it was shown for Fe(III)EDTA that even strong complexes can be degraded
after pretreatment by addition of calcium and magnesium salts in the pH range 9–11. The range of EDTA chelates converted by
cell-free extracts of strain BNC1 did not depend on their thermodynamic stabilities. The EDTA chelates of Ba2+, Co2+, Mg2+, Mn2+, and Zn2+ were oxidized whereas Ca-, Cd-, Cu-, Fe-, Pb-, and SnEDTA were not. The first catabolic enzyme appears to be an EDTA monooxygenase
since it requires O2, NADH, and FMN for its activity and yields glyoxylate and ethylenediaminetriacetate as products. The latter is further degraded
via N,N′-ethylenediaminediacetate. The maximum specific turnover rate with MgEDTA, the favoured EDTA species, was 50–130 μmol g protein−1 min−1, and the K
m value was 120 μmol/l (K
s for whole cells = 8 μmol/l). Whole cells as well as cell-free extracts of strain BNC1 also converted several structural analogues
of EDTA.
Received: 4 July 1997 / Received revision: 25 September 1997 / Accepted: 29 September 1997 相似文献
6.
G. R. V. Babu O. K. Vijaya V. L. Ross J. H. Wolfram K. D. Chapatwala 《Applied microbiology and biotechnology》1996,45(1-2):273-277
Our isolate, Pseudomonas putida, is known to be capable of utilizing cyanides as the sole source of carbon (C) and nitrogen (N) both in the form of free cells
and cells immobilized in calcium alginate. In the present study, the cell-free extract(s) were prepared from the cells of
P. putida grown in the presence of sodium cyanide. The ability of enzyme(s) to convert cyanides, cyanates, thiocyanates, formamide and
cyanide-containing mine waters into ammonia (NH3) was studied at pH 7.5 and pH 9.5. The kinetic analysis of cyanide and formamide conversion into NH3 at pH 7.5 and pH 9.5 by the cell-free extract(s) of P. putida was also studied. The K
m and V
max values for cyanide/formamide were found to be 4.3/8 mM and 142/227 μmol NH3 released mg protein-1 min-1 respectively at pH 7.5 and 5/16.67 mM and 181/434 μmol NH3 released mg protein-1 h-1 respectively at pH 9.5. The study thus concludes that the cell-free extract(s) of P. putida is able to metabolize not only cyanides, cyanates, thiocyanates, and formamide but also cyanide-containing mine waters to
NH3.
Received: 10 April 1995/Received revision: 24 July 1995/Accepted: 22 August 1995 相似文献
7.
K D Chapatwala G R V Babu O K Vijaya K P Kumar J H Wolfram 《Journal of industrial microbiology & biotechnology》1998,20(1):28-33
Pseudomonas putida utilizes cyanide as the sole source of carbon and nitrogen. Agar, alginate, and carrageenan were screened as the encapsulating
matrices for P. putida. Alginate-immobilized cells of P. putida degraded sodium cyanide (NaCN) more efficiently than non-immobilized cells or cells immobilized in agar or carrageenan. The
end products of biodegradation of cyanide were identified as ammonia (NH3) and carbon dioxide (CO2). These products changed the medium pH. In bioreactors, the rate of cyanide degradation increased with an increase in the
rate of aeration. Maximum utilization of cyanide was observed at 200 ml min−1 of aeration. Immobilized cells of P. putida degraded cyanides, cyanates and thiocyanates to NH3 and CO2. Use of Na[14C]-CN showed that 70% of carbon of Na[14C]-CN was converted into 14CO2 and only 10% was associated with the cell biomass. The substrate-dependent kinetics indicated that the K
m and V
max values of P. putida for the substrate, NaCN were 14 mM and 29 nmol of oxygen consumed mg protein−1 min−1 respectively.
Received 29 January 1996/ Accepted in revised form 19 September 1997 相似文献
8.
M. J. Artolozaga E. Kubátová J. Volc H. M. Kalisz 《Applied microbiology and biotechnology》1997,47(5):508-514
Pyranose 2-oxidase (P2O) was purified 43-fold to apparent homogeneity from the basidiomycete Phanerochaete chrysosporium using liquid chromatography on phenyl Sepharose, Mono Q (twice) and phenyl Superose. The native enzyme has a molecular mass
of about 250 kDa (based on native PAGE) and is composed of four identical subunits of 65 kDa. It contains three isoforms of
isoelectric point (pI) 5.0, 5.05 and 5.15 and does not appear to be a glycoprotein. P2O is optimally stable at pH 8.0 and
up to 60 °C. It is active over a broad pH range (5.0–9.0) with maximum activity at pH 8.0–8.5 and at 55 °C, and a broad substrate
specificity. d-Glucose is the preferred substrate, but 1-β-aurothioglucose, 6-deoxy-d-glucose, l-sorbose, d-xylose, 5-thioglucose, d-glucono-1,5-lactone, maltose and 2-deoxy-d-glucose are also oxidised at relatively high rates. A Ping Pong Bi Bi mechanism was demonstrated for the P2O reaction at
pH 8.0, with a catalytic constant (k
cat) of 111.0 s−1 and an affinity constant (K
m) of 1.43 mM for d-glucose and 83.2 μM for oxygen. Whereas the steady-state kinetics for glucose oxidation were unaffected by the medium at
pH ≥ 7.0, at low pH both pH and buffer composition affected the P2O kinetics with the k
cat/K
m value decreasing with decreasing pH. The greatest effect was observed in acetate buffer (0.1 M, pH 4.5), where the k
cat decreased to 60.9 s−1 and the K
m increased to 240 mM. The activity of P2O was completely inhibited by 10 mM HgCl2, AgNO3 and ZnCl2, and 50% by lead acetate, CuCl2 and MnCl2.
Received: 28 August 1996 / Received revision: 25 November 1996 / Accepted: 29 November 1996 相似文献
9.
C. E. Crocker J. J. Cech Jr. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(1):50-60
The effect of environmental hypercapnia on respiratory and acid-base variables was studied in white sturgeon, Acipenser transmontanus. Blood PCO2, PO2, pH, hemoglobin concentration, and plasma lactate, glucose, catecholamines and cortisol were measured first under normocapnia
(water PCO2 < 0.5 Torr, 1 Torr = 133.32 Pa), then under hypercapnia (25–35 Torr) and a final return to normocapnia at 19 ± 0.5 °C. Acute
(≤ 2h) hypercapnia significantly increased arterial PCO2 (8-fold increase), ventilation frequency (2-fold increase), plasma HCO3
− (2.3-fold) and decreased arterial pH (to 7.15 ± 0.02). After 24 h, norepinephrine, epinephrine and cortisol, were significantly
increased, and arterial pH reached its nadir (7.10 ± 0.03). During the 72- and 96-h-periods, arterial PCO2 (24 ± 4.4 Torr) and ventilatory frequency (105 ± 5 breaths min−1) stabilized, HCO3
− reached its apparent maximum (23.6 ± 0.0 mmol−1), glucose decreased by 32%, and pH increased significantly to 7.31 + 0.03. The return to normocapnia completely restored
arterial PCO2 (2.5 ± 0.14 Torr), HCO3
− (7.4 ± 0.59 mmol · l−1), ventilation frequency (71 ± 7 breaths · min−1), and pH (7.75 ± 0.04). Overall, hypercapnia produced a respiratory acidosis, hyperventilation, a transient norepinephrine
“spike”, and increased plasma catecholamines, cortisol, and arterial PO2. The respiratory acidosis was only partially compensated (35% pH restoration) 96 h after the onset of hypercapnia and resulted
in a significantly decreased blood-O2 affinity (Bohr effect), as determined by construction of in vitro blood O2 equilibrium curves at 15 °C and 20 °C. Prolonged exposure to hypercapnia may lead to acid-base disturbances and negatively
affect growth of white sturgeon.
Accepted: 17 August 1997 相似文献
10.
Kerstin Hauschild Manfred K. Grieshaber 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(5):378-388
The lugworm Arenicola marina is a typical inhabitant of intertidal flats. In its L-shaped burrow the animal is exposed to varying concentrations of O2 and toxic sulfide depending on the tides. The lugworm is able to detoxify sulfide through its oxidation to thiosulfate. When
exposed to declining O2 tensions Arenicola marina reacted as an oxyconformer. In the presence of 25 μmol · l−1 sulfide the respiration was not affected. In contrast, the lugworm consumed significantly less O2 at any Po2 in the presence of 200 μmol · l−1 sulfide. Without sulfide anaerobic metabolism started at a Po2 of approximatedly 10 kPa. Even at high O2 tensions animals exposed to sulfide produced significantly more anaerobic metabolites compared with the controls. Accordingly
the critical value PcM, the ambient Po2 below which anaerobic metabolism starts, was shifted towards normoxia. Since O2 supply was sufficient for aerobic metabolism, anaerobiosis was induced by sulfide. An influx of sulfide was observed at 25
as well as at 200 μmol · l−1 sulfide. The main product of sulfide detoxification in the lugworm was thiosulfate. Its synthesis increased with ambient
Po2 and depended on the sulfide concentration. Sulfide and thiosulfate were detected in the coelomic fluid, the blood, and the
body wall of Arenicola marina. Only about 2% of the ambient O2 was used for sulfide detoxification at 25 μmol · l−1 sulfide and about 50% at 200 μmol · l−1 sulfide, respectively. Even at the low sulfide concentration Arenicola marina's capacity to detoxify sulfide was too low to maintain a complete aerobic metabolism.
Accepted: 19 February 1997 相似文献
11.
A fluidized-bed reactor (FBR) was used to enrich an aerobic chlorophenol-degrading microbial culture. Long-term continuous-flow
operation with low effluent concentrations selected oligotrophic microorganisms producing good-quality effluent for pentachlorophenol(PCP)-contaminated
water. PCP biodegradation kinetics was studied using this FBR enrichment culture. The results from FBR batch experiments were
modeled using a modified Haldane equation, which resulted in the following kinetic constants: q
max = 0.41 mg PCP mg protein−1 day−1, K
S = 16 μg l−1, K
i = 5.3 mg l−1, and n = 3.5. These results show that the culture has a high affinity for PCP but is also inhibited by relatively low PCP concentrations
(above 1.1 mg PCP l−1). This enrichment culture was maintained over 1 year of continuous-flow operation with PCP as the sole source of carbon and
energy. During continuous-flow operation, effluent concentrations below 2 μg l−1 were achieved at 268 min hydraulic retention time (t
HR) and 2.5 mg PCP l−1 feed concentration. An increase in loading rate by decreasing t
HR did not significantly deteriorate the effluent quality until a t
HR decrease from 30 min to 21 min resulted in process failure. Recovery from process failure was slow. Decreasing the feed PCP
concentration and increasing t
HR resulted in an improved process recovery.
Received: 10 October 1996 / Received revision: 21 January 1997 / Accepted: 24 January 1997 相似文献
12.
The effects of light and elevated temperatures on the efficiency of energy conversion in PSII [?PSII = (Fm′−Fs)/Fm′], pigment composition and heat tolerance of shade-acclimated Alocasia macrorrhiza were investigated. Leaf discs were exposed for 3 h to high light (HL; 1600 μmol photons · m−2 · s−1) or low light (LL; 20 μmol photons · m−2 · s−1) and a series of constant temperatures ranging from 30 to 49 °C. All HL treatments led to rapid and severe decreases in ?PSII. During the 2-h recovery period (LL, 25 °C) following the HL treatments, fast and slow recovery phases could be distinguished.
Leaf discs that had experienced HL and 30 °C recovered completely while no recovery of ?PSII was seen after a 3-h exposure to HL and 45 °C. A 3-h exposure to 45 °C at LL led to a less severe decrease in ?PSII and complete recovery was accomplished after less than 1 h. Under LL conditions a temperature of 49 °C was necessary to cause
an irreversible decrease in ?PSII, followed by necrosis the next day. Streptomycin had no effect on the degree of reduction and recovery in ?PSII discs exposed to HL and 35–45 °C, but partially inhibited recovery in discs exposed to HL and 30 °C. Streptomycin led to
a more severe decrease in ?PSII at LL and 49 °C and completely inhibited recovery. Streptomycin had no effect on the conversion of the xanthophyll-cycle
pigments during the treatment or the recovery. The epoxidation state was roughly the same in all leaf discs after a 3-h HL
treatment (0.270–0.346) irrespective of the exposure temperature. The back-conversion of zeaxanthin into violaxanthin after
a 2-h recovery period was only seen in leaf discs that had been exposed to HL and 30 °C. The thermotolerance of shade A. macrorrhiza leaves of 49.0 ± 0.7 °C (determined by fluorescence) coincided with the temperature at which damage occurred in leaf discs
exposed to LL. However, under HL the critical temperature under which necrosis occurred was much lower (42 °C). The thermotolerance
of A. macrorrhiza shade leaves could be increased by a short exposure (<20 min) to slightly elevated temperatures.
Received: 11 June 1997 / Accepted: 9 September 1997 相似文献
13.
Harald Kosegarten Franz Grolig Andreas Esch Karl-Heinz Glüsenkamp Konrad Mengel 《Planta》1999,209(4):444-452
A fluorimetric ratio technique was elaborated to measure apoplastic pH in the outer root cortex of maize (Zea mays L.) grown hydroponically. A newly synthesized fluorescent probe, fluorescein boronic acid (pKa = 5.48), which covalently binds to the cell wall of the outer cell layers, was used. Under conditions of saturating ion concentrations
the apoplastic pH was determined along the root axis ranging from 1 to 30 mm behind the root tip. Apoplastic pH was recorded
for root segment areas (1 mm2), and pH values of high statistical significance were obtained. With an external solution of pH 5, the apoplastic pH was
about pH 5.1 in the division zone, between pH 4.8 and 4.9 in the elongation region and about pH 4.9 in the root hair zone.
At an external pH of 8.6, the difference between the external pH and the apoplastic pH was considerably more, with a pH of
5.2–5.3 in all root zones. Addition of 1 mM NH4
+ caused a small apoplastic pH decrease (0.05 of a pH unit) in all root zones. Apoplastic alkalization upon application of
6 mM NO3
− was highest (0.3 of a pH unit) in the zone where root hairs emerge; in the division and early elongation zones, apoplastic
pH increased only transiently. In the presence of 10 mM HCO3
−, NO3
− elicited a higher and persistent alkalization (0.06–0.25 of a pH unit) in all root zones. Application of fusicoccin reduced
apoplastic pH from 4.85 to 4.75 in the elongation zone, while inhibition of the H+-ATPase with vanadate alkalized the apoplast in the root hair zone from pH 5.4 to 5.6. The observed pH differences along the
root axis upon differential N supply and application of HCO3
− provide evidence that this new pH technique is a useful tool with which to measure apoplastic pH, and in future may permit
measurements at microsites at the cell level by use of microscope imaging.
Received: 26 August 1998 / Accepted: 4 May 1999 相似文献
14.
S A Shaikh J M Khire M I Khan 《Journal of industrial microbiology & biotechnology》1997,19(4):239-245
A thermostable β-galactosidase was produced extracellularly by a thermophilic Rhizomucor sp, with maximum enzyme activity (0.21 U mg−1) after 4 days under submerged fermentation condition (SmF). Solid state fermentation (SSF) resulted in a nine-fold increase
in enzyme activity (2.04 U mg−1). The temperature range for production of the enzyme was 38–55°C with maximum activity at 45°C. The optimum pH and temperature
for the partially purified enzyme was 4.5 and 60°C, respectively. The enzyme retained its original activity on incubation
at 60°C up to 1 h. Divalent cations like Co2+, Mn2+, Fe2+ and Zn2+ had strong inhibitory effects on the enzyme activity. The K
m and V
max for p-nitrophenyl-β- D-galactopyranoside and o-nitrophenyl-β - D-galactopyranoside were 0.39 mM, 0.785 mM and 232.1 mmol min−1 mg−1 respectively. The K
m and V
max for the natural substrate lactose were 66.66 μM and 0.20 μ mol min−1 mg−1.
Received 10 March 1997/ Accepted in revised form 17 July 1997 相似文献
15.
Bustard MT McEvoy EM Goodwin JA Burgess JG Wright PC 《Applied microbiology and biotechnology》2000,54(3):424-431
The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was
investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The
consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 × 109 cells ml−1. Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth
rates (μmax) calculated. At 20 °C, μ
max values were calculated to be 0.0305 h−1 and 0.1093 h−1 on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 °C and
45 °C. Temperature shock responses by the microbial consortium at temperatures above 45 °C were demonstrated by considerable
cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the μ
max from 0.1093 h−1 to 0.0715 h−1. Maximum achievable biodegradation rates of propanol and IPA were 6.11 × 10−3% (v/v) h−1 and 2.72 × 10−3% (v/v) h−1, respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of
0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing
waste streams.
Received: 14 December 1999 / Received revision: 3 April 2000 / Accepted: 7 April 2000 相似文献
16.
Haemolymph samples were withdrawn from routinely active male intermoult Glyptonotus held at 0 ± 0.5°C, and analysed for blood-gas and acid-base variables. In both the arterialised (a) and venous (v) haemolymph,
over 50% of the oxygen was transported as dissolved oxygen at PaO2 and PvO2 levels of 12.0 ± 1.15 and 7.70 ± 1.89 kPa, respectively. The maximum oxygen-carrying capacity of the haemocyanin (CmaxHcO2) was relatively low at 0.19 ± 0.05 mmol l−1, accompanied by relatively low protein and [Cu2+] levels indicating low circulating haemocyanin concentrations. Arterialised haemolymph had a mean pH of 7.88 ± 0.02(6) at
a PCO2 of 0.12 ± 0.01(6) kPa and a bicarbonate level of 12.95 ± 0.80(6) mequiv l−1 with small differences in PCO2 and pH between arterial and venous haemolymph. The non-bicarbonate buffering capacity of Glyptonotus haemolymph was low at −2.0 mequiv l−1 HCO3
− pH unit−1. Haemolymph [l-lactate] and [d-glucose] levels were similar at < 1 mmol l−1 in animals held in the laboratory and those sampled in Antarctica. The blood-gas and acid-base status of Glyptonotus haemolymph may be a reflection of the low and stable temperatures experienced by this Antarctic crustacean.
Received: 14 August 1996 / Accepted: 3 November 1996 相似文献
17.
Removal of nitrate and phosphate ions from water, by using the thermophilic cyanobacterium Phormidium laminosum, immobilized on cellulose hollow fibres in the tubular photobioreactor at 43 °C, was studied by continuously supplying dilute
growth medium for 7 days and then secondarily treated sewage (STS) for 12 days. The concentrations of NO−
3 and PO3−
4 in the effluent from the dilute growth medium decreased from 5.0 mg N/l to 3.1 mg N/l, and from 0.75 mg P/l to 0.05 mg P/l
respectively, after a residence time of 12 h. The concentrations of NO−
3 and PO3−
4 in the effluent from STS decreased from 11.7 mg N/l to 2.0 mg N/l, and from 6.62 mg P/l to 0.02 mg P/l respectively, after
a residence time of 48 h. The removal rates of nitrogenous␣and phosphate ions from STS were 0.24 and 0.11 mmol day−1 l reactor−1 respectively, under the same conditions. Although, among nitrogenous ions, nitrate and ammonium ions were efficiently removed
by P.␣laminosum, the nitrite ion was released into the effluent when STS was used as influent. Treatment of water with thermophilic P. laminosum immobilized on hollow fibres thus appears to be an appropriate means for the removal of inorganic nitrogen and phosphorus
from treated wastewater.
Received: 15 August 1997 / Received last revision: 18 November 1997 / Accepted: 29 November 1997 相似文献
18.
E. P. W. Kets M. Nierop Groot E. A. Galinski J. A. M. De Bont 《Applied microbiology and biotechnology》1997,48(1):94-98
The aim of this work was to study the physiological response of Lactobacillus plantarum subjected to osmotic stress in the presence of three structurally related compatible solutes. Either betaine, choline or
acetylcholine was accumulated by osmotically stressed cells when provided in the chemically defined medium. Choline and acetylcholine
were accumulated to maximum concentrations of 139 and 222 μmol g (dry weight) of cells−1 respectively and were not converted to betaine. Addition of 0.5 mM choline or 0.5 mM acetylcholine to the medium increased
the growth rates of cells in media with various amounts of added sodium chloride. Both choline and acetylcholine are positively
charged compounds; therefore, it was presumed that charged intracellular solutes could counterbalance the excess of positive
charge. Intracellular inorganic ion levels (K+, SO2−
4, PO3−
4 and Cl−) of cells cultured under conditions of osmotic stress remained similar in the presence of either betaine, choline or acetylcholine.
However, cells cultured in the presence of choline or acetylcholine accumulated an additional quantity of approximately 125
or 200 μmol.glutamate (dry weight) cells−1 respectively, as compared to cells grown in the presence of betaine. Hence glutamate appears to be the counterion for choline
and acetylcholine. This is the first study demonstrating accumulation of choline and acetylcholine in lactic acid bacteria
subjected to osmotic stress.
Received: 5 February 1997 / Received revision: 15 April 1997 / Accepted: 19 April 1997 相似文献
19.
O. Brix K. D. Clements R. M. G. Wells 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(4-5):329-334
Haemoglobin components were analysed for nine species of New Zealand triplefins and their isoelectric points (pI) ranged
from 5.1 to 7.0. The number of well-expressed isohaemoglobins was larger in shallow-water and tidal pool species, ranging
from four in Grahamina signata to eight in Grahamina capito, and were relatively cathodal. Two strongly anodal isohaemoglobins were expressed in the mid-depth species Ruanoho decemdigitatus and Ruanoho whero, and one in the deeper water species Karalepis stewarti and Forsterygion malcolmi. The red blood cell oxygen-binding properties were determined at 15 °C and 25 °C in the pH range 6.7–7.9 for the shallow-water
species G. capito, the shallow to mid-depth species Forsterygion varium, and the deep-water species F. malcolmi. Oxygen affinity was highest for G. capito and the magnitude of the Bohr effect lower (Δlog P
50/ΔpH = −0.37 at 25 °C, where P
50 is the half-saturation coefficient) compared to the two Forsterygion species (Δlog P
50/ΔpH = −0.52 to −0.59). Further, the cooperativity factor, n
50, was lower in G. capito thus maintaining oxygen transport over a wide range of environmental oxygen pressures. Oxygen binding was similarly influenced
by temperature in both G. capito and F. malcolmi (maximum heat of oxygenation ΔHmax = −27 kJ mol−1 and −37 kJ mol−1, respectively). Thus, triplefin fishes living in shallow, thermally unstable habitats possess a greater number of cathodally
migrating isohaemoglobins, and their red blood cells have a higher oxygen affinity and reduced cooperativity which is less
sensitive to changes in pH than do species occurring in more stable, deeper water habitats. Our analysis of an assemblage
of closely related species circumvents some of the difficulties inherent in studies where interpretation of experimental results
is confounded by phylogeny.
Accepted: 18 March 1999 相似文献
20.
A. Pires S. L. Coon M. G. Hadfield 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(3):187-194
The content of catecholamines and dihydroxyphenylalanine in larvae of the nudibranch Phestilla sibogae was analyzed by high-performance liquid chromatography with electrochemical detection. Dihydroxyphenylalanine, norepinephrine
and dopamine were identified in larvae of all ages examined (5 through 12 days post-fertilization). Dihydroxyphenylalanine
could be accurately quantified only in larvae of ages 8 through 12 days, when its average concentration increased from 0.62
to 6.71 × 10−2 pmol μg protein−1. Between ages 5 and 12 days dopamine rose from 0.081 to 0.616 pmol μg protein−1, and norepinephrine from 0.45 to 2.17 × 10−2 pmol μg protein−1. Dihydroxyphenylalanine, dopamine and norepinephrine were also measured at different stages of metamorphic progress in 10-
to 12-day larvae. Dihydroxyphenylalanine increased by a factor of 2.4 between the onset and completion of metamorphosis, but
levels of dopamine and norepinephrine remained stable. One millimolar alpha-methyl-dl-m-tyrosine, an inhibitor of catecholamine synthesis, inhibited natural metamorphosis and depleted endogenous norepinephrine
and especially dopamine, respectively, to 75% and 35% of control values. The existence of unexpectedly high levels of catecholamines
in metamorphically competent larvae, and the association of catecholamine depletion with inhibition of metamorphosis, indicate
that these compounds may participate in the control of gastropod development.
Accepted: 18 April 1997 相似文献