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1.
M. Pokkinen Z. R. Flores Bustamante H. Asama I. Endo P. Linko 《Bioprocess and biosystems engineering》1992,7(7):319-323
The on-line calculated specific rates of growth, substrate consumption and product formation were used to diagnose microbial activities during a lactic acid fermentation. The specific rates were calculated from on-line measured cell mass, and substrate and product concentrations. The specific rates were more sensitive indicators of slight changes in fermentation conditions than such monitored data as cell mass or product concentrations.List of Symbols
1/h
specific rate of cell growth
-
1/h
specific rate of substrate consumption
-
1/h
specific rate of product formation
-
*
dimensionless specific rate of cell growth
-
*
dimensionless specific rate of substrate consumption
-
*
dimensionless specific rate of product formation
-
max 1/h
maximum specific rate of cell growth
-
max 1/h
maximum specific rate of substrate consumption
-
max 1/h
maximum specific rate of product formation
-
X g/l
cell mass concentration
-
S g/l
substrate concentration
-
S
*
dimensionless substrate concentration
-
S
0 g/l
initial substrate concentration
-
P g/l
product concentration 相似文献
2.
Summary When more than the minimum number of variables are measured, and measurement error is taken into account, the results of parameter estimation depend on which of the measured variables are selected for this purpose. The reparameterization of Pirt's models for growth produces multiresponse models with common parameters. By using the covariate adjustment technique, a unit variate linear model with covariates is obtained. This allows a combined point and interval estimates of biomass energetic yield and maintenance coefficient to be obtained using standard multiple regression programmes. When this method was applied using form I and form II of the Pirt's models, good combined estimates were obtained and compared. Using data from the literature for Candida lipolytica produced reliable results. However, for Pseudomonas aeruginosa, which has been known to produce intermediate products, a modified Pirt's model is required for a good estimate of the biomass energetic yield.Nomenclature
a
Mole of ammonia per quantity of organic substrate containing 1 g atom carbon, g mole/g atom carbon
-
b
Moles of oxygen per quantity of organic substrate containing 1 g atom carbon, g mole/g atom carbon
-
c
Moles of water per quantity of organic substrate containing 1 g atom carbon, g mole/g atom carbon; no of covariates included in model
-
d
Moles of carbon dioxide per quantity of organic substrate containing 1 g atom carbon, g mole/g atom carbon
-
e
i
Error terms in Eqs. (6–8)
-
l
Atomic ratio of oxygen to carbon in organic substrate, dimensionless
-
m
Atomic ratio of hydrogen to carbon in organic substrate, dimensionless
-
m
e
Rate of organic substrate consumption for maintenance, g equiv. of available electrons in biomass (h) or kcal/Kcal of biomass(h)
-
n
Atomic ratio of oxygen to carbon in biomass, dimensionless
-
p
Atomic ratio of hydrogen to carbon in biomass, dimensionless
-
Q
CO
2
Rate of evolution of carbon dioxide, g moles/g dry wt (h)
-
Q
O
2
Rate of oxygen consumption, g moles/g dry wt (h)
-
Q
s
Rate of organic substrate consumption g/g dry wt (h)
-
q
Atomic ratio of nitrogen to carbon in biomass, dimensionless
-
r
Atom ratio of hydrogen to carbon in products, dimensionless; the number of parameters of interest
-
s
Atomic ratio of oxygen to carbon in products, dimensionless
-
t
Atomic ratio of nitrogen to carbon in products, dimensionless
-
r
Mean of k responses in Eq. (10)
-
x
ki
Kth response in the ith observation
-
y
c
Biomass carbon yield (fraction of organic substrate carbon in biomass), dimensionless
-
z
i
Covariate matrix
-
z
Fraction of organic substrate carbon in products, dimensionless
-
a
i
Parameters associated with covariates
- s
Reductance degree of biomass, equivalents of available electrons per gram atom carbon
-
Reductance degree of organic substrate, equivalents of available electrons per gram atom carbon
-
Fraction of energy in organic substrate which is evolved as heat, dimensionless
-
Fraction of available electrons transferred to biomass; biomass energetic yield
-
True growth yield
-
Specific growth rate, h-1
- p
Fraction of available electrons incorporated into products; product energetic yield
-
Correlation coefficient
-
Mass fraction carbon
- 2
Mean square error of model (10) 相似文献
3.
Summary Three yeasts of the genus Candida (Candida intermedia, candida lipolytica and Candida tropicalis) were cultivated batchwise on three different carbon sources: glucose, acetate, and hexadecane. Growth curves, oxygen uptake rates, CO2 evolution rates and the amount of oxygen required for biomass production were determined. The data were compared and discussed from the point of maximum specific growth rate, maximum oxygen uptake rate, carbon conversion into CO2 and biomass, consumption of oxygen and available energy for cell synthesis. The results indicated a relationship between m
m, Ys, YO, and for different carbon sources. YO and were in the same order of magnitude for acetate (0.58 and 0.38 respectively) and hexadecane (0.45 and 0.40 respectively). These values were remarkably lower than those for glucose (1.26 and 0.54 respectively).Symbols av e–
Available electrons per mol of substrate (dimensionless)
- Eav
Energy available per mol of substrate (dimensionless)
- Cd
Dissimilated carbon (%)
-
m
Maximum specific rate of oxygen uptake (mMO2 h–1 g–1)
- RQ
CO2 evolved per O2 consumed
- mol. wt.
Molecular weight
- YATP
Biomass mass yield based on mol of ATP generated (g)
-
Biomass mass yield based on available energy (g)
- YM
Biomass mass yield based on mol of organic substrate (g)
- YO
Biomass mass yield based on oxygen consumed (gg–1)
- 1/YO
Oxygen consumed for one gram of biomass produced (gg–1)
- Ys
Biomass mass yield based on organic substrate (dimensionless)
- b
Reductance degree of biomass (equiv. available electrons/g atom carbon)
- s
Reductance degree of organic substrate (equiv. available electrons/g atom carbon)
-
Fraction of energy in organic substrate which is converted to biomass
- b
Weight fraction carbon in biomass (dimensionless)
- s
Weight fraction carbon in organic substrate (dimensionless)
- m
Maximum specific growth rate (h–1) 相似文献
4.
Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE
1,2-diaminoethane
- HPLC
high pressure liquid chromatography
- RNase
bovine pancreatic ribonuclease A, EC 3.1.4.22
- TEAB
triethylammonium bicarbonate
- tris
tris(hydroxymethyl)aminomethane
- UMP(S)
uridine monophosphorothioate
- U > p
uridine cyclic 2,3-phosphate
- U > p(S)
uridine cyclic 2,3-O, O-phosphorothioate
- Up(S)dT
(P-thio)uridylylthymidine
- U2p(Rp-S)5dT
(P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage 相似文献
5.
Summary The principal pancreatic islets of the teleost Scorpaena scropha are found ultrastructurally to contain four different kinds of parenchymal cells, viz.
1-(= D),
2-, -and agranular cells. The -cells show considerable variations in the shape of the secretory granules. A peculiar feature is that many of these granules are composed of fibrillar subunits, often in parallel arrangement. All -granules are surrounded by membranes and between the membrane and the granule core there is a moderately wide electron lucent space. The electron density of the cytoplasm in the -cells varies somewhat. The
2-cells possess typical secretory granules with an electron dense core and a closely applied membrane. The secretory granules in the
1-cells show also a closely applied membrane but a less dense core. Also in the -cells the electron opacity of the cytoplasm varies. The agranular cells are mainly characterized by low cytoplasmic electron density, narrow cisterns of endoplasmic reticulum and sometimes a laminated Golgi complex. Small immature secretory granules are occasionally seen in the cytoplasm of these cells. The significance of the fibrillar -granules remains obscure.This work was supported by grants from the Nordic Insulin Fund, the Town of Umeå, the Swedish Medical Research Council (Project No. B69-12X-718-04A), and by a postdoctoral fellowship from the United States Public Health Service. 相似文献
6.
I. V. K. Subrahmanya Sastry G. Pavan Kumar M. Chidambaram 《Bioprocess and biosystems engineering》1994,10(3):127-130
The effect of time delay in specific growth rate () on the periodic operation of bioreactors with input multiplicities is theoretically analyzed for productivity improvement. A periodic rectangular pulse is applied either in feed substrate concentration (Sf) or in dilution rate (D). Periodic operation under feed substrate concentration cycling gives improvement in productivity at lower value of ¯Sf of the two steady-state multiplicities of Sf only when the time delay in is larger. Whereas the larger value of ¯Sf gives improvement in average productivity for all values of time delay. Dilution rate (D) cycling gives an improvement in average productivity particularly for larger time delay in . This improvement in average productivity is obtained only at smaller value of dilution rate out of the two steady-state input multiplicities of D.List of Symbols D 1/h
dilution rate
- F
memory function
- g
dummy variable
- Ki g/l
substrate inhibition constant
- Km g/l
substrate saturation constant
- P g/l
product concentration
- Pm g/l
product saturation constant
- Q g/(hl)
product cell produced per unit time
- S g/l
substrate concentration
- Sf g/l
feed substrate concentration
- Sf,p g/l
feed substrate concentration during fraction of a period
- X g/l
biomass concentration
- YX/S g/g
cell mass yield
- w
variable either S or Z
- Z g/l
weighted average of substrate concentration
Greek Letters
1/h
time delay parameter
-
1
,
2
product yield parameters, g/g and 1/h
-
pulse width expressed as a fraction of a period
-
1/h
specific growth rate
-
m 1/h
maximum specific growth rate
- h
period of oscillation
- –
average value 相似文献
7.
Summary We have studied the reactions between adenosine 5-phosphorimidazolide and 9-(2-amino-2-deoxyxylofuranosyl) adenine (I) or 3-methylamino-3-deoxyadenosine (II), both with and without a poly (U) template. We find that both amino compounds react much more rapidly than does adenosine, in the absence of a template. The rate of reaction is greatly enhanced by a poly (U) template in the case of I, but the enhancement is slight in the case of II.Abbreviations A
adenosine
- xylo ANH2
9-(2-amino-2-deoxy--D-xylofuranosyl) adenine
- ANHMe
3-methylamino-3-deoxyadenosine
- ImpA
adenosine 5-phosphorimidazolide
- A3 pA
adenylyl-[35]-adenosine
- A2 pA
adenylyl-[25]-adenosine
- UNPA
adenylyl-[52]-2-amino-2-deoxyuridine
- xylo ANPA
9-[adenylyl-(52)-2-amino-2-deoxy--D-xylofuranosyl]adenine
- A(NMe)pA
adenylyl-[53]-3-methylamino-3-deoxyadenosine
- pA
adenosine 5phosphate
- AppA
P1, P2-diadenosine 5pyrophosphate
- (pA)n
n = 2, 3 [2-5]-linked oligomers of pA
- A2 pA2 pA
[2-5]-linked trinucleoside diphosphate of A
- poly (U)
polyuridylic acid 相似文献
8.
Purified ribulose-bisphosphate carboxylase (EC 4.1.1.39) was strongly and equally inhibited either by ADP or GDP and to a lesser extent by IDP. AMP or ATP exerted little effect on activity. Inhibition by the nucleotide diphosphates was competitive with respect to RuBP and non-competitive with respect to CO2 and Mg2+, respectively. Treatment of the enzyme with urea or guanidine-HCl resulted in rapid loss of activity that was not restored by dialysis even in the presence of Mg2+ and cysteine. Sodium dodecyl sulfate electrophoresis of 8.0 M urea treated enzyme revealed the presence of a fast-moving (small) sub-unit with molecular weight 14150 and a slower moving (large) sub-unit with molecular weight 68000. Examination of native enzyme by sodium dodecyl sulfate electrophoresis gave sub-units of 13700 and 55500 respectively. The amino acid content standardized to phenylalanine was essentially similar to that from other sources. Arrhenius plots showed a break at 29°C with an E
a of 12.34 kcal per mole for the steeper part of the curve and a H of 11.43 kcal per mole while for the less steep region, the E
a was 1.04 kcal per mole and the H 1.92 kcal per mole.Abbreviations ADP
adenosine-5-diphosphate
- AMP
adenosine-5-monophosphate
- ATP
adenosine-5-triphosphate
- CDP
cytidine-5-diphosphate
- CMP
cytidine-5-monophosphate
- CTP
cytidine-5-triphosphate
- FDP
fructose-1,6-diphosphate
- F6P
fructose-6-phosphate
- GDP
guanosine-5-diphosphate
- GMP
guanosine-5-monophosphate
- G6P
glucose-6-phosphate
- GTP
guanosine-5-triphosphate
- IDP
inosine-5-diphosphate
- IMP
inosine-5-monophosphate
- PEP
phosphoenolpyruvate
- 6PG
6-phosphogluconate
- R1P
ribose-1-phosphate
- R5P
ribose-5-phosphate
- RuBP
ribulose-1,5-bisphosphate
- SDS
sodium dodecyl sulfate
- TDP
thymidine-5-diphosphate
- TMP
thymidine-5-monophosphate
- TTP
thymidine-5-triphosphate
- UDP
uridine-5-diphosphate
- UMP
uridine-5-monophosphate
- UTP
uridine-5-triphosphate 相似文献
9.
Minimal photosynthetic catalytic F1() core complexes, containing equimolar ratios of the and subunits, were isolated from membrane-bound spinach chloroplast CF1 and Rhodospirillum rubrum chromatophore RrF1. A CF1-33 hexamer and RrF1-11 dimer, which were purified from the respective F1() complexes, exhibit lower rates and different properties from their parent F1-ATPases. Most interesting is their complete resistance to inhibition by the general F1 inhibitor azide and the specific CF1 inhibitor tentoxin. These inhibitors were earlier reported to inhibit multisite, but not unisite, catalysis in all sensitive F1-ATPases and were therefore suggested to block catalytic site cooperativity. The absence of this typical property of all F1-ATPases in the 11 dimer is consistant with the view that the dimer contains only a single catalytic site. The 33 hexamer contains however all F1 catalytic sites. Therefore the observation that CF1-33 can bind tentoxin and is stimulated by it suggests that the F1 subunit, which is required for obtaining inhibition by tentoxin as well as azide, plays an important role in the cooperative interactions between the F1-catalytic sites.Abbreviations CF0F1
chloroplast F0F1
- CF1
chloroplast F1
- CF1
chloroplast F1 subunit
- CF1
chloroplast F1 subunit
- CF1()
a complex containing equal amounts of the CF1 and subunits
- MF1
mitochondrial F1
- RrF0F1
Rhodospirillum rubrum F0F1
- RrF1
R. rubrum F1
- RrF1
R. rubrum F1 subunit
- RrF1
R. rubrum F1 subunit
- RrF1()
a complex containing equal amounts of the RrF1 and subunits
- Rubisco
Ribulose-1,5-bisphosphate carboxylase
- TF1
thermophilic bacterium PS3 F1 相似文献
10.
The nanosecond fluorescence depolarization method was applied to measure the fluorescence lifetime () and the rotational correlation time () of bovine serum albumin (BSA) labeled with 1-dimethylaminonaphthalene-5-sulfonyl chloride (dansyl-Cl). Changes of and of dansyl BSA in the guanidine denaturation and in the thermal denaturation were examined. In parallel, the secondary structural change of dansyl BSA was followed by circular dichroism measurements. The magnitude of was almost unchanged between 1 and 2 M guanidine, where the secondary structure of the protein was predominantly disrupted; whereas that of began to increase before the disruption of secondary structure in the guanidine denaturation. In the thermal denaturation, in contrast, changes of both and occurred in a temperature range where the secondary structure was predominantly disrupted. The volume of equivalent sphere (V
e
) and the axial ratio () for the BSA were 3.6–3.8×10–19 cm3 and 3.6 at 2M guanidine as against 2.1×10–19 cm3 and 2.2 in the absence of guanidine (25°C), respectively. The magnitudes ofV
e
and were 4.9×10–19 cm3 and 4.5 at 65°C, respectively. Although the secondary structural change of dansyl BSA was irreversible in the thermal denaturation,V
e
and were reversible. 相似文献
11.
Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E
0=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.Non-standard abbreviations glc
Gas liquid chromatography
- HPLC
high performance liquid chromatography
- RP
reverse phase; Mediators (the figures in parenthesis of the mediators are redox potentials E
0 in mV)
- CAV2+
carbamoylmethylviologen, 1,1-carbamoyl-4,4-dipyridinium dication (E
0=-296 mV)
- BV2+
benzylviologen, 1,1-dibenzyl-4,4-dipyridinium dication (E
0=-360 mV)
- MV
methylviologen, 1,1-dimethyl-4,4-dipyridinium-dication (E
0=-444 mV)
- DMDQ2+
dimethyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-ethylendication (E
0=-514 mV)
- TMV2+
tetramethylviologen, 1,1,4,4-tetramethyl-4,4-dipyridinium dication (E
0=-550 mV)
- PDQ2+
propyldiquat, 2,2-dipyridino-1,1-propenyl dication (E
0=-550 mV)
- DMPDQ2+
dimethylpropyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-propenyl dication (E
0=-656 mV)
- PN
productivity number=mmol product (obtained by the uptake of one pair of electrons) x (biocatalyst (dry weight) kg)-1×h-1 相似文献
12.
In crown-gall tumor tissue obtained from leaves of Bryophyllum daigremontianum an adenosine 3:5-cyclic phosphate (3:5-cyclic-AMP) degrading activity increases up to 2.5 fold until the fifth day after inoculation with Agrobacterium tumefaciens, declining to the value of the control in the solid tumor. Theophylline up to 1 mmol l–1 given to wounded leaves of Bryophyllum daigremontianum has no effect on the number of tumors. The effect of higher concentrations given over extended periods can be explained otherwise. Therefore it seems likely that the 3:5-cyclic-AMP phosphodiesterase (EC 3.1.4.17) has no effect on transformation and growth of crown-gall tumors in Bryophyllum daigremontianum. 相似文献
13.
M. Unkaševié 《International journal of biometeorology》1989,33(3):184-195
It is shown that better results are obtained in calculating the surface albedo of a plant stand for near-infrared solar radiation using the modified two-stream approximation in favor of the Schwarzschild one. These evaluations of the plant stand surface albedo were obtained by assuming the values for scattering parameters of upward 0 and diffusive solar radiation in the plant stand, by applying the delta-Eddington approximation. However, more accurate evaluations of 0 and can be obtained by using Rayleigh's phase scattering functions for radiative scattering in a plant stand. Furthermore, much attention is devoted to testing the influence of the plant stand albedo for the visible part of solar radiation (for which the Schwarzchild approximation is valid) on ground surface temperature. The ground surface temperature was calculated by the force-restore method; the greatest ground surface temperature corrections were obtained in cases where the surface beneath the plant stand is covered with snow. The influence on ground surface temperature of high absorption and scattering in dense plant stands with horizontal foliage was also tested. Again significant corrections of ground surface temperature were obtained, taking into consideration the given characteristics of a plant stand compared to a standard albedo value.List of symbols
A
albedo of direct radiation in plant canopy
-
A
D
albedo of diffuse radiation in plant canopy
-
A
p
albedo of the ground surface
-
A
Q
total albedo in plant canopy
-
a
proportion of gaps in plant canopy characteristic of surface evaporation
-
w
constant
-
parameter of upward scattering diffuse radiation
- 0
parameter of upward scattering direct radiation
-
C
g
soil volumetric heat capacity
-
C
p
air specific heat
-
C
DH
aerodynamic transfer coefficient for heat
-
C
DE
aerodynamic transfer coefficient for moisture
-
d
depth of soil
-
sun's declination
-
azimuth of incident radiation
-
azimuth of diffuse radiation
-
characteristic of the radiative sources
-
G
foliage orientation function
-
g
parameter in delta-Eddington approximation
-
g
z
parameter for near-infrared radiation
- L
scattering phase function radiation
-
D
diffuse solar radiation flux
-
G
soil heat flux
-
H
air sensible heat flux
-
L
air latent heat flux
-
O
solar constant
-
R
net longwave radiation flux
-
S
direct solar radiation flux
-
h
o
height of the sun
-
i
intensity of diffuse radiation
-
k
von Karman constant
-
L
leaf area index
-
L
v
coefficient for latent heat of evaporation
-
g
soil heat conductivity
-
n/N
relative cloudiness
-
solid angle
-
frequency of temperature wave
-
Q
a
specific humidity of air
-
Q
w
specific humidity of saturated air
-
R
L
coefficient of plant reflectivity
-
r
direction of diffuse radiation
-
direction of incident radiation
-
r
o
direction of solar radiation
-
r
s
resistance of the leaf stomata
-
p
o
air density
-
S
intensity of direct solar radiation
-
Stefan-Boltzman constant
-
T
a
air temperature
-
T
G
ground surface temperature
-
T
c
cloud temperature
-
T
1
feaf temperature
-
T
*
air temperature scale
-
t
time
-
t
time step
-
zenith angle of diffuse radiation
-
zenith angle of incident radiation
- 0
zenith angle of solar radiation
-
U
*
friction velocity scale
-
V
near-surface wind velocity
-
W
g
soil water content
-
W
L
scattering coefficient in plant canopy
-
W
sat
saturated soil water content
-
z
vertical direction 相似文献
14.
Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: Vmax = 591.2molg–1h–1,
K
s=262.3M, nitrate+nitrite: V
max=12.9molg–1h–1, K
s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source. 相似文献
15.
Electron transport-linked proton translocation at nitrite reduction inCampylobacter sputorum subspeciesbubulus 总被引:1,自引:0,他引:1
Wytske de Vries H. G. D. Niekus Hugerien van Berchum A. H. Stouthamer 《Archives of microbiology》1982,131(2):132-139
Campylobacter sputorum subspeciesbubulus contains a membrane-bound nitrite reductase which catalyses the six-electron reduction of nitrite to ammonia. Formate andL-lactate are used as hydrogen donors. Cells ofC. sputorum grown with nitrate or nitrite contain cytochromes of theb-andc-type and a carbon monoxide-binding cytochromec. In addition, a special membrane-bound carbon monoxide-binding pigment is found. Nitrite reduction with formate orL-lactate as a hydrogen donor is strongly inhibited by 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Nitrite reduction by bacterial suspensions with lactate as a hydrogen donor is strongly inhibited by carbonylcyanide-m-chlorophenyl-hydrazone (CCCP) whereas nitrite reduction with formate as a hydrogen donor is not inhibited at all. H+/O values and H+/NO
2
-
values were measured with ascorbate + N,N,N,N-tetramethyl-p-phenylenediamine (TMPD), formate (in the absence and presence of carbonic anhydrase) andL-lactate as a hydrogen donor. The results are summarized in a scheme for electron transport from formate or lactate to oxygen or nitrite which shows a periplasmic orientation of formate dehydrogenase and nitrite reductase and a cytoplasmic orientation of lactate dehydrogenase and oxygen reduction, and which shows proton translocation with a H+/2e value of 2.0. The H+/O and H+/NO
2
-
values predicted by this scheme are in good agreement with the experimental values.Abbreviations CCCP
carbonylcyanide-m-chlorophenylhydrazone
- HQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- MTPP+
methyltriphenylphosphonium cation
- TMPD
N,N,N,N-tetramethyl-p-phenylenediamine; H+/O (H+/NO
2
-
), number of protons liberated in the outer bulk phase at the reduction of one atom O (one ion NO
2
-
); H+/2e (q+/2e), number of protons (charges) translocated across the cytoplasmic membrane during flow of two electrons to an acceptor 相似文献
16.
J. Colin Murrel 《Archives of microbiology》1988,150(5):489-495
Nitrogenase activity in the obligate methaneoxidizing bacterium Methylococcus capsulatus (Bath) was added ammonia. This observation was extended to include other ammonia. This observation was extended to include other representative N2-fixing species of methanotrophs. The ammonia switch-off of nitrogenase in M. capsulatus (Bath) was reversed on washing cells to remove excess ammonia, in the presence of chloramphenicol, suggesting that a form of covalent modification of nitrogenase may occur. Replacing the oxidizable substrate methanol with formaldehyde, formate, ethanol or hydrogen had no effect on nitrogenase switch-off. A number of potential nitrogen sources or intermediates of nitrogen metabolism such as glutamine, asparagine, glutamate and alanine when tested, did not effect switch-off. However, the rapid inhibition of nitrogenase activity of M. capsulatus (Bath) could be achieved by adding the uncoupler carbonylcyanide m-chlorophenylhydrazone or nitrite. The glutamine synthetase inhibitor methionine sulphoximine blocked the switch-off effect of ammonia, indicating that the metabolism of ammonia may be essential for switch-off to occur. Inhibitors of glutamate synthase did not alleviate the ammonia switch-off response. Methionine sulphoximine did not alleviate the rapid inhibition of nitrogenase by carbonylcyanide m-chlorophenylhydrazone indicating that the shortterm regulation of nitrogenase by uncouplers and ammonia proceed via different mechanisms.Abbreviations MSX
methionine-DL-sulphoximine
- DON
6-diazo-5-oxo-L-norleucine
- GS
glutamine synthetase
- GOGAT
glutamine 2-oxoglutarate aminotransferase (glutamate synthase)
- CCCP
carbonylcyanide m-chlorophenyl hydrazone 相似文献
17.
Problems in estimating growth rates of marine phytoplankton from short-term14C assays 总被引:1,自引:0,他引:1
Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added14C-HCO3
– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the14C technique for the two remaining species: up to 40% at a steady-state of 1.0 day–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies. 相似文献
18.
H. M. Torbati R. A. Raiders E. C. Donaldson M. J. McInerney G. E. Jenneman R. M. Knapp 《Journal of industrial microbiology & biotechnology》1986,1(4):227-234
Summary The in situ growth of microorganisms in Berea sandstone cores preferentially plugged the larger pore entrances. The largest pore entrance sizes after microbial plugging ranged from 20 to 38 m, compared with 59 to 69 m before plugging. The pore entrance size distribution of plugged cores was shifted to smaller sizes. A mathematical model based on Poiseuille's equation was found to adequately predict permeability reductions (greater than 90%) caused by microbial growth in the large pore entries.Nomenclature
Q
volumetric flow rate (L
3/t)
-
C
orifice constant (dimensionless)
-
A
cross-sectional area (L
2)
-
g
gravity (L/t
2)
-
h
pieziometric head (L)
- s
transmittivity (L
2)
-
R
e
Reynolds number (dimensionless)
-
a
constant (dimensionless)
-
density (M/L
3)
-
viscosity (M/Lt)
-
d
diameter (L)
-
L
length (L)
- P
pressure change (M/L
2) 相似文献
19.
Jacques Raymond Brahim Mimouni Jean-Louis Azanza 《Plant Systematics and Evolution》1994,193(1-4):69-79
The seed storage globulins from sixHelianthus and four hybrids were studied using mono and bidimensional gel SDS electrophoresis (+ 2 mercaptoethanol). The polypeptide composition of each subunit was determined. Different pairs are specifically expressed according to the species studied. Three typical patterns were discriminated. All the studied species exhibit five subunits: two of them are expressed in all the species (11 and 22). The subunit corresponding to the 11 pair is present inH. petiolaris and in the three populations ofH. annuus studied. The 2b2 pair is common toH. annuus andH. argophyllus. H. petiolaris presents two specific 2a2 and 44 pairs andH. annuus a specific 33 pair. InH. argophyllus 11 33 or 44 are never observed but are replaced by 13 and 31 pairs. Some globulins, poorly represented, are of forms but present chains of higher molecular weights (in the range 54–56 kDa). Expressing variations in the banding patterns between these species by the use of a similarity index reveals complete identity between the three populations ofH. annuus. Identity between the twoH. petiolaris studied is also observed.H. annuus andH. argophyllus appear to be closer to each other thanH. petiolaris concerning the seed storage globulins. 相似文献
20.
The possibility of solving the mass balances to a multiplicity of substrates within a CSTR in the presence of a chemical reaction following Michaelis-Menten kinetics using the assumption that the discrete distribution of said substrates is well approximated by an equivalent continuous distribution on the molecular weight is explored. The applicability of such reasoning is tested with a convenient numerical example. In addition to providing the limiting behavior of the discrete formulation as the number of homologous substrates increases, the continuous formulation yields in general simpler functional forms for the final distribution of substrates than the discrete counterpart due to the recursive nature of the solution in the latter case.List of Symbols
C{N. M} mol/m3
concentration of substrate containing N monomer residues each with molecular weight M
-
{N, M}
normalized value of C{N. M}
-
C
{M} mol/m3 da
concentration of substrate of molecular weight M
-
in
normalized value of C
{M} at the i-th iteration of a finite difference method
-
{M}
normalized value of C
{M}
-
C
0{N.M} mol/m3
inlet concentration of substrate containing N monomer residues each with molecular weight M
-
{N ·M}
normalized value of C0{N. M}
-
0
i
normalized value of C
0
{M} at the i-th iteration of a finite difference method
-
C
0
{M} mol/m3
da initial concentration of substrate of molecular weight M
-
C
tot mol/m3
(constant) overall concentration of substrates (discrete model)
-
C
tot
mol/m3
(constant) overall concentration of substrates (continuous model)
-
D
deviation of the continuous approach relative to the discrete approach
-
i
dummy integer variable
-
I
arbitrary integration constant
-
j
dummy integer variable
-
k
dummy integer variable
-
K
m
mol/m3
Michaëlis-Menten constant for the substrates
-
l
dummy integer variable
-
M da
molecular weight of substrate
-
M
normalized value of M
-
M
da
maximum molecular weight of a reacting substrate
-
N
number of monomer residues of a reacting substrate
-
N
maximum number of monomer residues of a reacting substrate
-
N
total number of increments for the finite difference method
-
Q m3/s
volumetric flow rate of liquid through the reactor
-
S
inert product molecule
-
S
i
substrate containing i monomer residues
-
V m3
volume of the reactor
-
v
max mol/m3 s
reaction rate under saturating conditions of the enzyme active site with substrate
-
v
max{N. M} mol/m3 s
reaction rate under saturating conditions of the enzyme active site with substrate containing N monomer residues with molecular weight M
-
max{N · M}
dimensionless value of vmax{N. M} (discrete model)
-
max{M}
dimensionless value of v
max
{M} (continuous model)
-
mol/m3 s
molecular weight-averaged value of vmax (discrete model)
-
mol.da/m3s
molecular weight-averaged value of vmax (continuous model)
-
v
max
{M} mol.da/m3s
reaction rate under saturating conditions of the enzyme active site with substrate with molecular weight M
-
max
{M}
dimensionless value of vmax{M}
-
max, (i)
dimensionless value of vmax{M} at the i-th iteration of a finite difference method
-
v
max
mol/m3 s
reference constant value of v
max
Greek Symbols
dimensionless operating parameter (discrete distribution)
-
dimensionless operating parameter (continuous distribution)
-
M da
(average) molecular weight of a monomeric subunit
-
M
selected increment for the finite difference method
-
auxiliary corrective factor (discrete model) 相似文献