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1.
Toxic at low concentrations, phenol is one of the most common organic pollutants in air and water. In this work, phenol biodegradation
was studied in extreme conditions (80°C, pH = 3.2) in a 2.7 l bioreactor with the thermoacidophilic archaeon Sulfolobus solfataricus 98/2. The strain was first acclimatized to phenol on a mixture of glucose (2000 mg l−1) and phenol (94 mg l−1) at a constant dissolved oxygen concentration of 1.5 mg l−1. After a short lag-phase, only glucose was consumed. Phenol degradation then began while glucose was still present in the
reactor. When glucose was exhausted, phenol was used for respiration and then for biomass build-up. After several batch runs
(phenol < 365 mg l−1), specific growth rate (μX) was 0.034 ± 0.001 h−1, specific phenol degradation rate (qP) was 57.5 ± 2 mg g−1 h−1, biomass yield (YX/P) was 52.2 ± 1.1 g mol−1, and oxygen yield factor
( \textY\textX/\textO 2 ) \left( {{\text{Y}}_{{{\text{X}}/{\text{O}}_{ 2} }} } \right) was 9.2 ± 0.2 g mol−1. A carbon recovery close to 100% suggested that phenol was exclusively transformed into biomass (35%) and CO2 (65%). Molar phenol oxidation constant
( \textY\textO 2 /\textP ) \left( {{\text{Y}}_{{{\text{O}}_{ 2} /{\text{P}}}} } \right) was calculated from stoichiometry of phenol oxidation and introducing experimental biomass and CO2 conversion yields on phenol, leading to values varying between 4.78 and 5.22 mol mol−1. Respiratory quotient was about 0.84 mol mol−1, very close to theoretical value (0.87 mol mol−1). Carbon dioxide production, oxygen demand and redox potential, monitored on-line, were good indicators of growth, substrate
consumption and exhaustion, and can therefore be usefully employed for industrial phenol bioremediation in extreme environments. 相似文献
2.
A spiral packed-bed bioreactor inoculated with microorganisms obtained from activated sludge was used to conduct a feasibility
study for phenol removal. The reactor was operated continuously at various phenol loadings ranging from 53 to 201.4 g m−3 h−1, and at different hydraulic retention times (HRT) in the range of 20–180 min to estimate the performance of the device. The
results indicated that phenol removal efficiency ranging from 82.9 to 100% can be reached when the reactor is operated at
an HRT of 1 h and a phenol loading of less than 111.9 g m−3 h−1. At an influent phenol concentration of 201.4 g m−3, the removal efficiency increased from 18.6 to 76.9% with an increase in the HRT (20–120 min). For treatment of phenol in
the reactor, the maximum biodegradation rate (V
m) was 1.82 mg l−1 min−1; the half-saturation constant (K
s), 34.95 mg l−1. 相似文献
3.
The biodegradation of phenol by a pure culture of Pseudomonas putida was investigated in a continuously fed stirred-tank reactor, under aerobic conditions. The dilution rate was varied between
0.0174 h−1 and 0.278 h−1, covering a wide range of dissolved oxygen and the inhibition region of phenol. Through non-linear analysis of the data,
a dual-substrate growth kinetics, Haldane kinetics for phenol and Monod kinetics for oxygen, was derived with high correlation
coefficients. Respective biokinetic parameters were evaluated as μm = 0.569 h−1, K
p = 18.539 mg/l, K
i = 99.374 mg/l, K
o = 0.048 mg/l, Y
x/p = 0.521 g microorganism/g phenol and Y
x/o = 0.338 g microorganism/g oxygen, being in good agreement with other studies in the literature. Maintenance factors for both
phenol and oxygen were calculated for the first time for P. putida while the saturation coefficient for oxygen, K
o, was genuinely evaluated from the constructed model, not imported or adapted from other studies as reported in the literature.
All pertinent biokinetic parameters for P. putida have been calculated from continuous system data, which are most appropriate for use in continuous bioprocess applications.
Received: 29 July 1996 / Received revision: 18 November 1996 / Accepted: 23 November 1996 相似文献
4.
Hollow-fiber membrane bioreactors were developed with granular activated carbon (GAC) for the biodegradation of phenol using
Pseudomonas putida. Hollow fibers showed similar structure with/without GAC incorporated; while GAC hollow fiber had a stronger phenol adsorption
capacity. In batch biotransformation experiments, complete depletion of 1000 mg phenol l−1 (at which concentration free cells cannot grow) was accomplished in the reactor within 18 h in the hybrid bioreactor, comparing
with 23 h in the GAC free bioreactor. Desorption and bioregeneration of the hollow-fiber membrane were believed to be the
key for the enhancement of bioreactor performance. At continuous running, the GAC bioreactor showed its superiority over the
GAC free bioreactor during start-up and elevated loading phase. More than 90% of the phenol was transformed in the GAC bioreactor
when the phenol loading was <24 mg h−1. The better bioreactor performance may be due to the enhanced mass transportation and adsorption capacity with the incorporation
of GAC. 相似文献
5.
Nicola D’Amelio Luca Fontanive Fulvio Uggeri Furio Suggi-Liverani Luciano Navarini 《Food biophysics》2009,4(4):321-330
Caffeine complexation by chlorogenic acid (3-caffeoylquinic acid, CAS Number [327-97-9]) in aqueous solution as well as caffeine–chlorogenate
complex in freshly prepared coffee brews have been investigated by high-resolution 1H-NMR. Caffeine and chlorogenic acid self-associations have also been studied and self-association constants have been determined
resorting to both classical isodesmic model and a recently introduced method of data analysis able to provide also the critical
aggregation concentration (cac). Furthermore, caffeine–chlorogenate association constant was measured. For the caffeine, the
average value of the self-association constant determined by isodesmic model (K
i = 7.6 ± 0.5 M−1) is in good agreement with the average value (K
a = 10 ± 1.8 M−1) determined with the method which permits the determination of the cac (8.43 ± 0.05 mM). Chlorogenic acid shows a slight
decreased tendency to aggregation with a lower average value of association constants (K
i = 2.8 ± 0.6 M−1; K
a = 3.4 ± 0.6 M−1) and a critical concentration equal to 24 ± 1 mM. The value of the association constant of the caffeine–chlorogenate complex
(30 ± 4 M−1) is compatible with previous studies and within the typical range of reported association constants for other caffeine–polyphenol
complexes. Structural features of the complex have also been investigated, and the complex conformation has been rediscussed.
Caffeine chemical shifts comparison (monomeric, complexed, coffee brews) clearly indicates a significant amount of caffeine
is complexed in beverage real system, being chlorogenate ions the main complexing agents. 相似文献
6.
Covalent immobilization of Aspergillus awamori NRRL 3112 was conducted onto modified polyacrylonitrile membrane with glutaraldehyde as a coupling agent. The polymer carrier
was preliminarily modified in an aqueous solution of NaOH and 1,2-diaminoethane. The content of amino groups was determined
to be 0.58 mgeq g−1. Two ways of immobilization were used—in the presence of 0.2 g l−1 phenol and without phenol. The capability of two immobilized system to degrade phenol (concentration—0.5 g l−1) as a sole carbon and energy source was investigated in batch experiments. Seven cycles of phenol biodegradation were conducted.
Better results were obtained with the immobilized system prepared in the presence of phenol, regarding degradation time and
phenol biodegradation rate. Scanning electron micrographs of the polyacrylonitrile membrane/immobilized Aspergillus awamori NRRL at the beginning of repeated batch cultivation and after the 7th cycle were compared. After the 7th cycle of cultivation
the observations showed large groups of cells. The results from the batch experiments with immobilized system were compared
to the results produced by the free strain. Phenol biodegradation experiments were carried out also in a bioreactor with spirally
wound membrane with bound Aspergillus awamori NRRL 3112 in a regime of recirculation. 10 cycles of 0.5 g l−1 phenol biodegradation were run consecutively to determine the degradation time and rate for each cycle. The design of the
bioreactor appeared to be quite effective, providing large membrane surface to bind the strain. 相似文献
7.
This article reports studies on a continuous pulsed plate bioreactor (PPBR) with the cells of Pseudomonas desmolyticum (NCIM2112) immobilized on granular activated carbon (GAC) used as a biofilm reactor for biodegradation of phenol. Almost complete removal of 200 ppm phenol could be achieved in this bioreactor. Biofilm structure and characteristics are influenced by hydrodynamic and shear conditions in bioreactors. In this article, the effect of shear stress induced by frequency of pulsation on biofilm characteristics during the startup period in the PPBR is reported. The startup time decreased with the increase in frequency of pulsation. The formation of biofilm in PPBR was found to have three phases: accumulation, compaction, and plateau. The effect of frequency on production of exoploymeric substances (EPS) such as, protein, carbohydrate, and humic substance is reported. An increase in shear stress induced by the frequency of pulsation increased the production of exopolymeric substances in the biofilm during startup of the bioreactor. Increase in shear stress caused a decrease in biofilm thickness and an increase in dry density of the biofilm. Increase in shear stress resulted in a smoother and thinner biofilm surface with more compact and dense structure. 相似文献
8.
9.
Continuous production of lactic acid from lactose has been carried out in a stirred-tank reactor with non-growing Lactobacillus helveticus entrapped in calcium alginate beads. A considerably longer operation half-life was obtained in a continuously operated reactor
than in a batch-operated reactor. It is possible to simulate the action of entrapped non-growing cells on the basis of information
from diffusion and kinetic experiments with suspended free cells. The simulation fit the experimental data over a broad range
of substrate concentrations if the specific lactic acid production rate, q
P, was used as a variable parameter in the model. The dynamic mathematical model used is divided into three parts: the reactor
model, which describes the mass balance in a continuously operated stirred-tank reactor with immobilized biomass, the mass-transfer
model including both external diffusion and internal mass transfer, and the kinetic model for uptake of substrate on the basis
of a Michaelis-Menten-type mechanism. From kinetic data obtained for free biomass experiments it was found, with the use of
non-linear parameter estimation techniques, that the conversion rate of lactose by L. helveticus followed a Michaelis-Menten-type mechanism with K
S at half-saturation=0.22±0.01 g/l. The maximum specific lactose uptake rate for growing cells, q
S,max, varied between 4.32±0.02 g lactose g cells-1 h-1 and 4.89 ±0.02 g lactose g cells-1 h-1. The initial specific lactose uptake rate for non-growing cells, q
S,0, was found to be approximately 40% of the maximum specific lactose uptake rate for growing cells.
Received: 4 October 1995/Received last revision: 23 April 1996/Accepted: 29 April 1996 相似文献
10.
Ribitsch D Karl W Wehrschütz-Sigl E Tutz S Remler P Weber HJ Gruber K Stehr R Bessler C Hoven N Sauter K Maurer KH Schwab H 《Applied microbiology and biotechnology》2009,81(5):875-886
In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out.
With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of
purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15–70 °C). Specific activities
were determined toward choline chloride (4.70 ± 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium
chloride (0.05 ± 0.45 × 10–2 U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 ± 0.12 × 10–2 U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic
parameters in atmorspheric oxygen resulted in K
M = 1.51 ± 0.09 mM and V
max = 42.73 ± 0.42 mU/min for choline chloride and K
M = 4.77 ± 0.76 mM and V
max = 48.40 ± 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic
analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine
aldehyde exists also free in solution. 相似文献
11.
The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM
IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction
medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained
in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were
compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of
lauric acid. Kinetic parameters were calculated based on this model as follows: V
max = 5.80 mmol l−1 min−1 g enzyme−1, K
m,A = 0.70 mmol l−1 g enzyme−1, K
m,B = 115.48 mmol l−1 g enzyme−1, K
i = 11.25 mmol l−1 g enzyme−1. The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found
as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid
to farnesyl laurate was 98.07±0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two
models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model
and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited. 相似文献
12.
Granular activated carbon (GAC) was incorporated into hollow fiber membrane bioreactors for the biodegradation of 1,000 mg
phenol l−1 through immobilization of Pseudomonas
putida. The phenol was removed within 25 h in the hybrid bioreactor, comparing with 31 h for a GAC-free bioreactor. Sorption, biodegradation,
desorption, and bioregeneration were four steps for the phenol removal during batch operation. 相似文献
13.
Acinetobacter sp. XMZ-26 (ACCC 05422) was isolated from soil samples obtained from glaciers in Xinjiang Province, China. The partial nucleotide
sequence of a lipase gene was obtained by touchdown PCR using degenerate primers designed based on the conserved domains of
cold-adapted lipases. Subsequently, a complete gene sequence encoding a 317 amino acid polypeptide was identified. Our novel
lipase gene, lipA, was overexpressed in Escherichia coli. The recombinant protein (LipA) was purified by Ni-affinity chromatography, and then deeply characterised. The LipA resulted
to hydrolyse pNP esters of fatty acids with acyl chain length from C2 to C16, and the preferred substrate was pNP octanoate showing a k
cat = 560.52 ± 28.32 s−1, K
m = 0.075 ± 0.008 mM, and a k
cat/K
m = 7,377.29 ± 118.88 s−1 mM−1. Maximal LipA activity was observed at a temperature of 15°C and pH 10.0 using pNP decanoate as substrate. That LipA peaked at such a low temperature and remained most activity between 5°C and 35°C indicated
that it was a cold-adapted enzyme. Remarkably, this lipase retained much of its activity in the presence of commercial detergents
and organic solvents, including Ninol, Triton X-100, methanol, PEG-600, and DMSO. This cold-adapted lipase may find applications
in the detergent industry and organic synthesis. 相似文献
14.
Christopher A. Dieni Kenneth B. Storey 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(8):1133-1142
Glucose-6-phosphate dehydrogenase (G6PDH) and the pentose phosphate pathway play a key role in reductive biosynthesis and
antioxidant defense, while diverting glucose from other cellular functions. G6PDH was isolated from liver of the wood frog,
Rana sylvatica, a freeze tolerant species that uses glucose as a cryoprotectant. Analysis of kinetic parameters (K
m and V
max) of G6PDH showed a significant increase in K
m G6P (from 98.2 ± 3.8 to 121 ± 5.3 μM) and K
m NADP+ (from 65.5 ± 2.3 to 89.1 ± 4.8 μM) in frogs following freezing exposure, indicating lower affinity for G6PDH substrates in
this state. Subsequent analyses indicated that differential phosphorylation of G6PDH between the two states was responsible
for the altered kinetic properties. Thus, two differentially charged forms of G6PDH were resolved by DEAE ion-exchange chromatography
and, compared with controls, the proportion of G6PDH activity in peak I decreased and in peak II increased in liver from frozen
frogs. G6PDH in peak I had a K
m G6P of 94.1 ± 1.1 μM and K
m NADP+ of 61.2 ± 3.5 μM, whereas Peak II G6PDH showed higher values (K
m G6P was 172 ± 4.3 μM, K
m NADP+ was 98.2 ± 3.3 μM). G6PDH from each peak was incubated with ions and second messengers to stimulate the actions of protein
kinases with results indicating that G6PDH can be phosphorylated by protein kinase G, protein kinase C, AMP-activated protein
kinase, or calmodulin-dependent protein kinase. The data indicate that in control frogs, G6PDH is in a high phosphate form
and displays a high substrate affinity, whereas in frozen frogs G6PDH is less phosphorylated, with lower substrate affinity. 相似文献
15.
Alexander A. Kolobov Nikolai I. Kolodkin Cynthia Tuthill Yury A. Zolotarev Elena V. Navolotskaya 《International journal of peptide research and therapeutics》2008,14(2):97-103
Tritium-labeled dipeptide bestim (γ-D-Glu-L-Trp) with a specific activity of 45 Ci/mmol was obtained by the high-temperature solid-state catalytic isotope exchange (HSCIE)
reaction. [3H]bestim was found to bind with high affinity to mouse peritoneal macrophages (K
d
2.1 ± 0.1 nM) and thymocytes (K
d
3.1 ± 0.2 nM) and also plasma membranes isolated from these cells (K
d
18.6 ± 0.2 and 16.7 ± 0.3 nM respectively). The specific bonding of [3H]bestim with macrophages and thymocytes was inhibited by unlabeled dipeptide thymogen (L-Glu-L-Trp) (K
i
0.9 ± 0.1 and 1.1 ± 0.1 nM respectively). Treatment of the macrophages and thymocytes with trypsin led to their loss of capacity
to bind [3H]bestim. Bestim at concentrations range of 0.1–1000 nМ reduced the adenylate cyclase activity in macrophage and thymocyte
membranes. 相似文献
16.
The protein bCblC (bCblCpro) is a bovine homolog of a human B12 trafficking chaperone that is responsible for the processing of vitamin B12 and its escorted delivery in intracellular B12 metabolism. In this study, we found that bCblCpro is highly thermolabile with a T
m = 42.0 ± 0.2 °C as shown for the human homolog, suggesting thermal regulation of these proteins. Binding of the reduced form
of glutathione (GSH) that is a predominant cellular thiol increased the T
m of bCblCpro from 42 °C to ~45 °C (ΔT
m max = 3.1 ± 0.2 °C and AC50 = 2.1 ± 0.5 mM). Binding of vitamin B12 and its derivatives also stabilized bCblCpro increasing the T
m to a different extent and vitamin B12 (cyanocobalamin, CNCbl) was the least efficient (ΔT
m max = 4.3 ± 0.3 °C and AC50 = 291 ± 36 μM). However, the stabilizing effect of CNCbl was significantly greater for GSH-bound bCblCpro (ΔT
m max = 12.8 ± 0.6 °C and AC50 = 9.3 ± 1.6 μM) than for GSH-free bCblCpro. In addition, the stabilizing effect of GSH was also greater for CNCbl-bound bCblCpro
(ΔT
m max = 9.3 ± 0.3 °C and AC50 = 57.0 ± 6.8 μM). Limited proteolysis revealed that thermal stabilization of bCblCpro is derived from conformational changes
of the protein induced by binding of the ligands. The results in this study indicate that GSH cooperates with vitamin B12 in thermal stabilization of bCblCpro and is a positive regulator of the protein. 相似文献
17.
Performance evaluation and kinetic modeling of the start-up of a UASB reactor treating municipal wastewater at low temperature 总被引:1,自引:0,他引:1
F. Ilter Turkdogan-Aydinol Kaan Yetilmezsoy Sezen Comez Hurrem Bayhan 《Bioprocess and biosystems engineering》2011,34(2):153-162
A kinetic modeling-based study was carried out to evaluate the start-up performance of a 10-L up-flow anaerobic sludge blanket
(UASB) reactor treating municipal wastewater under different organic and hydraulic loading conditions. The reactor was operated
for 105 days (around 4 months) below 20 °C and with three different hydraulic retention times of 24, 12 and 5 h. Imposed volumetric
organic loading rates (OLR) ranged from 0.57 (±0.05) to 11.78 (±0.85) kg TCOD/m3-day. Although relatively high incoming volumetric OLR values were employed to the system, the UASB reactor demonstrated a
favorable performance on the anaerobic treatability of municipal wastewater, and no process failure was recorded in the start-up
stage. On the basis of experimental results, the modified Stover–Kincannon model was successfully applied to define the start-up
kinetics with a very high value of the correlation coefficient (R = 0.9729). Maximum substrate utilization rate constant and saturation constant of the modified Stover–Kincannon model were
determined as U
max = 1.996 g/L-day and K
B = 1.536 g/L-day, respectively. 相似文献
18.
Felix M. Ferroni María G. Rivas Alberto C. Rizzi María E. Lucca Nora I. Perotti Carlos D. Brondino 《Biometals》2011,24(5):891-902
The purification and biochemical characterization of the respiratory membrane-bound nitrate reductase from Sinorhizobium meliloti 2011 (Sm NR) is reported together with the optimal conditions for cell growth and enzyme production. The best biomass yield was obtained
under aerobic conditions in a fed-batch system using Luria–Bertani medium with glucose as carbon source. The highest level
of Sm NR production was achieved using microaerobic conditions with the medium supplemented with both nitrate and nitrite. Sm NR is a mononuclear Mo-protein belonging to the DMSO reductase family isolated as a heterodimeric enzyme containing two subunits
of 118 and 45 kDa. Protein characterization by mass spectrometry showed homology with respiratory nitrate reductases. UV–Vis
spectra of as-isolated and dithionite reduced Sm NR showed characteristic absorption bands of iron-sulfur and heme centers. Kinetic studies indicate that Sm NR follows a Michaelis–Menten mechanism (K
m = 97 ± 11 μM, V = 9.4 ± 0.5 μM min−1, and k
cat = 12.1 ± 0.6 s−1) and is inhibited by azide, chlorate, and cyanide with mixed inhibition patterns. Physiological and kinetic studies indicate
that molybdenum is essential for NR activity and that replacement of this metal for tungsten inhibits the enzyme. Although
no narGHI gene cluster has been annotated in the genome of rhizobia, the biochemical characterization indicates that Sm NR is a Mo-containing NR enzyme with molecular organization similar to NarGHI. 相似文献
19.
Riddhika Kalle Tharmalingam Ramesh Qamar Qureshi Kalyanasundaram Sankar 《Acta theriologica》2011,56(4):335-342
Density of tiger Panthera tigris and leopard Panthera pardus was estimated using photographic capture–recapture sampling in a tropical deciduous forest of Mudumalai Tiger Reserve, southern
India, from November 2008 to February 2009. A total of 2,000 camera trap nights for 100 days yielded 19 tigers and 29 leopards
within an intensive sampling area of 107 km2. Population size of tiger from closed population estimator model Mb Zippin was 19 tigers (SE = ±0.9) and for leopards Mh Jackknife estimated 53 (SE = ±11) individuals. Spatially explicit maximum likelihood and Bayesian model estimates were 8.31
(SE = ±2.73) and 8.9 (SE = ±2.56) per 100 km2 for tigers and 13.17 (SE = ±3.15) and 13.01 (SE = ±2.31) per 100 km2 for leopards, respectively. Tiger density for MMDM models ranged from 6.07 (SE = ±1.74) to 9.72 (SE = ±2.94) per 100 km2 and leopard density ranged from 13.41 (SE = ±2.67) to 28.91 (SE = ±7.22) per 100 km2. Spatially explicit models were more appropriate as they handle information at capture locations in a more specific manner
than some generalizations assumed in the classical approach. Results revealed high density of tiger and leopard in Mudumalai
which is unusual for other high density tiger areas. The tiger population in Mudumalai is a part of the largest population
at present in India and a source for the surrounding Reserved Forest. 相似文献
20.
Lipase-catalyzed synthesis of isoamyl acetate in hexane at 10–250 MPa at 80°C and 1–100 MPa at 40°C resulted in activation
volumes of −12.9 ± 1.7 and −21.6 ± 2.9 cm3 mol−1, respectively. Increasing pressure from 10 to 200 MPa resulted in approximately 10-fold increase in V
max at both 40 and 80°C. Pressure increased the K
m from 2.4 ± 0.004 to 38 ± 0.78 mM at 40°C. In contrast, at 80°C the pressure did not affect the K
m. 相似文献