共查询到20条相似文献,搜索用时 31 毫秒
1.
Candida utiilis NRRL Y-900 was grown on pineapple cannery waste as the sole carbon and energy source in a chemostat at dilution rates ranging
between 0.05 and 0.65 h−1 to determine the growth kinetics. The cell yield coefficient varied with dilution rate and a maximum value of 0.662 ± 0.002
gx/gcarb was obtained at a dilution rate of 0.4 h−1. At steady state, the concentrations of carbohydrate, reducing sugar, and chemical oxygen demand (COD) appeared to follow
Monod kinetics. At maximum specific growth rate (μmax) 0.65 h−1, the saturation constants for carbohydrate, reducing sugar and COD were 0.51 ± 0.02 gcarb/1, 0.046 ± 0.003 grs/1, and 1.036 ± 0.001 gCOD/1, respectively. Maximum biomass productivity (Q
x max) 2.8 ± 0.03 gx/1 h was obtained at a dilution rate of 0.5 h−1. At this dilution rate, only 71.0 ± 0.41% COD was removed whereas at a dilution rate of 0.1 h−1, 98.2 ± 0.35% reduction in COD was achieved. At a dilution rate of 0.4 h−1, the optimal yeast productivity and reduction in COD were 2.7 ± 0.13 gp/1 h, and 84.2 ± 0.42%, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Candida utilis was grown on a pineapple cannery effluent in a chemostat at dilution rates ranging between 0.05 and 0.65 h–1 to establish optimal conditions for biomass production and chemical oxygen demand (COD) reduction. Sucrose, fructose and glucose were the main sugars in the effluent. Maximum value for cell yield coefficient and productivity were (0.686, gx/gs) and (2.96, gx/l/h) at a dilution rate of 0.425 and 0.475 h–1, respectively, while maximum COD reduction (98%) was attained at a dilution rate of 0.1 h–1. The maintenance coefficient attained a value of (0.093, gs/gx/h). An increase in dilution rate produced a higher protein content of the biomass. 相似文献
3.
Synthesis of Large Surface‐Area g‐C3N4 Comodified with MnOx and Au‐TiO2 as Efficient Visible‐Light Photocatalysts for Fuel Production
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fazal Raziq Liqun Sun Yuying Wang Xuliang Zhang Muhammad Humayun Sharafat Ali Linlu Bai Yang Qu Haitao Yu Liqiang Jing 《Liver Transplantation》2018,8(3)
Herein, this study successfully fabricates porous g‐C3N4‐based nanocomposites by decorating sheet‐like nanostructured MnOx and subsequently coupling Au‐modified nanocrystalline TiO2. It is clearly demonstrated that the as‐prepared amount‐optimized nanocomposite exhibits exceptional visible‐light photocatalytic activities for CO2 conversion to CH4 and for H2 evolution, respectively by ≈28‐time (140 µmol g?1 h?1) and ≈31‐time (313 µmol g?1 h?1) enhancement compared to the widely accepted outstanding g‐C3N4 prepared with urea as the raw material, along with the calculated quantum efficiencies of ≈4.92% and 2.78% at 420 nm wavelength. It is confirmed mainly based on the steady‐state surface photovoltage spectra, transient‐state surface photovoltage responses, fluorescence spectra related to the produced ?OH amount, and electrochemical reduction curves that the exceptional photoactivities are comprehensively attributed to the large surface area (85.5 m2 g?1) due to the porous structure, to the greatly enhanced charge separation and to the introduced catalytic functions to the carrier‐related redox reactions by decorating MnOx and coupling Au‐TiO2, respectively, to modulate holes and electrons. Moreover, it is suggested mainly based on the photocatalytic experiments of CO2 reduction with isotope 13CO2 and D2O that the produced ?CO2 and ?H as active radicals would be dominant to initiate the conversion of CO2 to CH4. 相似文献
4.
Growth, photosynthesis, dark respiration and pigment contents were monitored in adult sporophytes of the Antarctic brown alga Desmarestia menziesii J. Agardh grown under fluctuating Antarctic daylength conditions. Growth rates were closely coupled to daylength variations with values varying from 0.05% d?1 in winter condition (July-August) to 0.5% d?1 in early summer (December). Photosynthetic pigments had maximum values of 1.8 mg g?1 FW (chlorophyll a), 0.4 mg g?1 FW (chlorophyll c) and 0.9 mg g?1 FW (fucoxanthin) in summer. These changes were also closely related to individual size and biomass of the plants. Net photosynthesis (Pmax), on a fresh weight basis, showed a clear seasonal pattern with highest rates of 25μmol O2 g?1 FW h?1 in October and minima close to 9μmol O2 g?1 FW h?1 in April. Dark respiration was high in spring (13μmol O2 g?1 FW h?1) approximately coinciding with growth peaks. Likewise, photosynthetic efficiency (α) and the initial saturating light point of photosynthesis (lk) increased significantly in spring [1.3 μimol O2 g?1 FW h?1 (μmol m?2 s?1)?1 and 26μmol photons m?2 s?1, respectively]. In the case of α, no significant differences between fresh weight and Chl a based rates were found. The results of the present study are the first that demonstrate seasonality of physiological parameters in D. menziesii sporophytes and confirm also that phenology and physiology of macroalgae can be simulated in the laboratory. On the other hand this study adds new elements to the explanation of the life strategy of D. menziesii, in particular that algal growth and photosynthesis occur under a programmed seasonal pattern. 相似文献
5.
Carlos Soccol José Rodríguez León Bernard Marin Sevastianos Roussos Maurice Raimbault 《Biotechnology Techniques》1993,7(8):563-568
Summary Growth kinetics of Rhizopus arrhizus MUCL 28168 were determined for different treatments of cassava during solid state fermentation. The best case gave a specific growth rate () of 0.24 h-1, a yield calculated on a basis that oxygen consumption (Yx/o) was 2.9 g biomass. g-1 O2 consumed and the maintenance coefficient (m) was 0.004 g O2 consumed. g-1 biomass. h-1. 相似文献
6.
The growth performance of malolactic fermenting bacteria Oenococcus oeni NCIMB 11648 and Lactobacillus brevis X2 was assessed in continuous culture. O. oeni grew at a dilution rate range of 0.007 to 0.052 h−1 in a mixture of 5:6 (g l−1) of glucose/fructose at an optimal pH of 4.5, and L. brevis X2 grew at 0.010 to 0.089 h−1 in 10 g l−1 glucose at an optimal pH of 5.5 in a simple and safe medium. The cell dry weight, substrate uptake and product formation
were monitored, as well as growth kinetics, yield parameters and fermentation balances were also evaluated under pH control
conditions. A comparison of growth characteristics of two strains was made, and this showed significantly different performance.
O. oeni has lower maximum specific growth rate (μmax=0.073 h−1), lower maximum cell productivity (Q
x
max=17.6 mg cell l−1 h−1), lower maximum biomass yield (Y
x/s
max=7.93 g cell mol−1 sugar) and higher maintenance coefficient (m
s=0.45 mmol−1 sugar g−1 cell h−1) as compared with L. brevis X2 (μmax=0.110 h−1; Q
x
max=93.2 g−1 cell mol−1 glucose; Y
x/s
max=22.3 g cell mol−1 glucose; m
s=0.21 mmol−1 glucose g−1 cell h−1). These data suggest a possible more productive strategy for their combined use in maturation of cider and wine. 相似文献
7.
D. S. Robson LeRoy Powers N. S. Urquhart 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1967,37(4):205-216
Summary If genetic and environmental effects upon a quantitative phenotype X=G+E are normally and independently distributed then the probability distribution of genetic value G among individuals of fixed phenotypic value X is likewise a normal distribution. The mean of this a posteriori distribution of genetic values is
+h
2 (X−
) and the variance is σ
g
2
(1−h
2), where
is the a priori mean of X, h
2 is the heritability ratio, and σ
g
2
is genetic variance. For any fixed values of h
2 and σ
g
2
the a posteriori probability that the genetic value G associated with a given phenotype X exceeds the population mean by any specified amount can therefore be read directly from the tables of the standard normal
distribution. The expected proportion of these superior genetic deviates among individuals whose phenotypic value exceeds
some specified constant may also be calculated (by numerical analysis) and is presented here in graphical form.
If phenotypic selection is practiced by choosing the best out of N phenotypes then N should be large enough to assure high probability of obtaining a superior genetic deviate. The operating characteristics
of this type of selection are displayed in tabular form, again based upon numerical integration.
Dedicated to Dr. George F. Sprague on the occasion of his 65th birthday.
Cooperative investigations of the Colorado Agricultural Experiment Station, the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Beet Sugar Development Foundation. Approved by the Colorado Agricultural Experiment Station for publication as Scientific Series Article No. 880. Paper No. BU-78, Biometrics Unit, and Paper No. 529, Plant Breeding Department, Cornell University.
Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture; now deceased.
Formerly Research Assistant, Colorado State University; now Assistant Professor of Biological Statistics, Cornell University. 相似文献
Zusammenfassung Wenn genetische und umweltbedingte Effekte auf einen quantitativen Ph?notyp X=G+E von einander unabh?ngig und normal verteilt sind, dann entspricht die Wahrscheinlichkeitsverteilung des genetischen Werts G unter Individuen mit fixiertem ph?notypischem Wert X gleichfalls einer Normalverteilung. Das Mittel dieser a posteriori-Verteilung der genetischen Werte ist +h 2 (X− ) und die Varianz ist σ g 2 (1−h 2); wobei das a priori-Mittel von X, h 2 der Heritabilit?tskoeffizient und σ g 2 die genetische Varianz sind. Für jeden fixierten Wert von h 2 und σ g 2 kann daher die a posteriori-Wahrscheinlichkeit, da? der genetische Wert G das Populationsmittel in Verbindung mit einem gegebenen Ph?notyp X um einen bestimmten Wert übersteigt, direkt aus den Tabellen einer standardisierten Normalverteilung abgelesen werden. Der erwartete Anteil dieser überlegenen, genetisch bedingten Abweichung unter Individuen, deren ph?notypischer Wert einen vorgegebenen Konstantwert übersteigt, kann ebenfalls numerisch errechnet werden. Er wird im vorliegenden Fall graphisch dargestellt. Wenn eine ph?notypische Selektion zur Auswahl der besten Ph?notypen aus N Individuen erfolgt, sollte N gro? genug sein, um mit hoher Wahrscheinlichkeit eine überlegene, genetisch bedingte Abweichung zu erhalten. Die wirksamen Charakteristiken dieses Typs der Selektion werden in tabellierter Form wiedergegeben, die gleichfalls auf numerischer Integration beruht.
Dedicated to Dr. George F. Sprague on the occasion of his 65th birthday.
Cooperative investigations of the Colorado Agricultural Experiment Station, the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Beet Sugar Development Foundation. Approved by the Colorado Agricultural Experiment Station for publication as Scientific Series Article No. 880. Paper No. BU-78, Biometrics Unit, and Paper No. 529, Plant Breeding Department, Cornell University.
Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture; now deceased.
Formerly Research Assistant, Colorado State University; now Assistant Professor of Biological Statistics, Cornell University. 相似文献
8.
Sugar cane bagasse hemicellulosic fraction was hydrolysed by treatment with 70 mg of sulphuric acid per gram of dry mass at 125 °C for 2 h. The hydrolysate was used as the substrate to grow Candida langeronii RLJ Y-019 at 42 °C; initial pH 6.0; stirring at 700 rev/min and aeration at 1.0 and 2.0 v/v/min. The utilization of D-xylose, L-arabinose, and acetic acid were delayed due to the presence of D-glucose, but after D-glucose depletion the other carbon sources were utilized. The kinetic parameters calculated for both cultivations at 1.0 and 2.0 v/v/min included: maximum specific growth rate (max) of 0.29 ± 0.01 h–1 and 0.43 ± 0.016 h–1, yields (Y
x/s) of 0.36 ± 0.012 and 0.40 ± 0.012 gx/gs and productivity (Q
x) of 0.81 ± 0.016 and 0.97 ± 0.012 gx/l/h, respectively, and compared favourably with published results obtained with Candida utilis and Geotrichum candidum. Candida langeronii appeared superior to C. utilis for biomass production from hemicellulose hydrolysate, in that it utilized L-arabinose and was capable of growth at higher temperatures. The biomass contained 48.2, 1.4, 5.8 and 23.4% of total protein, DNA, RNA and carbohydrate, respectively and contained essential amino acids for animal feed. 相似文献
9.
Yash Boyjoo Haodong Shi Emilia Olsson Qiong Cai Zhong‐Shuai Wu Jian Liu Gao Qing Lu 《Liver Transplantation》2020,10(20)
Lithium–sulfur batteries (LSBs) are a class of new‐generation rechargeable high‐energy‐density batteries. However, the persisting issue of lithium polysulfides (LiPs) dissolution and the shuttling effect that impedes the efficiency of LSBs are challenging to resolve. Herein a general synthesis of highly dispersed pyrrhotite Fe1?xS nanoparticles embedded in hierarchically porous nitrogen‐doped carbon spheres (Fe1?xS‐NC) is proposed. Fe1?xS‐NC has a high specific surface area (627 m2 g?1), large pore volume (0.41 cm3 g?1), and enhanced adsorption and electrocatalytic transition toward LiPs. Furthermore, in situ generated large mesoporous pores within carbon spheres can accommodate high sulfur loading of up to 75%, and sustain volume variations during charge/discharge cycles as well as improve ionic/mass transfer. The exceptional adsorption properties of Fe1?xS‐NC for LiPs are predicted theoretically and confirmed experimentally. Subsequently, the electrocatalytic activity of Fe1?xS‐NC is thoroughly verified. The results confirm Fe1?xS‐NC is a highly efficient nanoreactor for sulfur loading. Consequently, the Fe1?xS‐NC nanoreactor performs extremely well as a cathodic material for LSBs, exhibiting a high initial capacity of 1070 mAh g?1 with nearly no capacity loss after 200 cycles at 0.5 C. Furthermore, the resulting LSBs display remarkably enhanced rate capability and cyclability even at a high sulfur loading of 8.14 mg cm?2. 相似文献
10.
The estimator ?0(x) of the regression r(x) = E (Y | × = x) from measured points (xi, yi), i = 1(1) n, of a continuous two-dimensional random variable (X, Y) with unknown continuous density function f(x, y) and with moments up to the second order can be made with the help of a density estimation f?0(x, y) (see e.g. SCHMERLING and PEIL, 1980). Here f?0(x, y) still contains free parameters (so-called band-width-parameters), the values of which have to be optimally fixed in the concrete case. This fixing can be done by using a modification of the maximum-likelihood principle including jackknife techniques. The parameter values can be also found from the estimators for r(x). Here the cross-validation principle can be applied. Some numerical aspects of these possibilities for optimally fixing the bandwidth-parameter are discussed by means of examples. If ?0(x) is used as a smoothing operator for time series the optimal choice of the parameter values is dependent on the purpose of application of the smoothed time series. The fixing will then be done by considering the so-called filter-characteristic of ?C0(x). 相似文献
11.
The αII-helix (? = ?70.47°, ψ = ?35.75°) is a structure having the same n and h as the (standard) αI-helix (? = ?57.37°, ψ = ?47.49°). Its conformational angles are commonly found in proteins. Using an improved α-helix force field, we have compared the vibrational frequencies of these two structures. Despite the small conformational differences, there are significant predicted differences in frequencies, particularly in the amide A, amide I, and amide II bands, and in the conformation-sensitive region below 900 cm?1. This analysis indicates that αII-helices are likely to be present in bacteriorhodopsin [Krimm, S. & Dwivedi, A. M. (1982) Science 216 , 407–408]. 相似文献
12.
Summary The study of 249 serum samples from blood donors of Berne, previously typed with respect to the Ag(x,y,a1,d,c,g) factors has given preliminary evidence that the genes Ag
a
1 and Ag
d, and Ag
c and Ag
g respectively are two pairs of co-dominant alleles. The locus Ag
c/g appears to be closely linked with loci Ag
x/y and Ag
11/d . 相似文献
13.
R. Schweitzer-Stenner W. Dreybrodt D. Wedekind S. el Naggar 《European biophysics journal : EBJ》1984,11(1):61-76
The depolarisation ratio and the excitation profiles of some prominent Raman lines of the oxyhaemoglobin spectrum (1,375 cm-1, 1,583 cm-1, 1,638 cm-1) have been measured as functions of the exciting laser frequency. The depolarisation ratio shows a complicated minimum-maximum structure in the preresonant region between Soret- and -band of the optical spectrum, which depends on the pH-value of the solution. These dispersion curves are interpreted by fifth-order Loudon theory of the polarisability tensor including static distortions of the haem group, which lower its symmetry from the ideal D
4h-symmetry, and enhancement by a second, non-Raman-active phonon. The fitting constants needed to fit the experimental data are related to static distortions of A
1g, B
1g, B
2g, and A
2g` symmetry types and thus give information on the symmetry lowering from D
4h. The variation of the fitting constants with the pH-value of the solution is interpreted to be caused by protonation/deprotonation processes of titrable amino acid groups contributing to the alkaline and acid Bohr effect. The protonation changes the electrostatic interaction energies in the globular protein and destabilises the salt bridge between His(HC3) and Asp(FG1) in the R-state. These processes induce distortions of the haem group via haem-apoprotein interactions. Our results give no indication for a dominant role of the covalent Fe2+-N[His(F8)] bond in this process. They are in agreement, however, with the allosteric model of Hopfield, which assumes all interactions to be evenly distributed all over the protein molecule.List of abbreviations DPR
depolarisation ratio
- EP
excitation profile
- oxyHb
oxyhaemoglobin
- deoxyHb
deoxyhaemoglobin
- HbA
human adult haemoglobin
- metMbCN
metmyoglobincyanide
- metHbCN
methaemoglobincyanide
- BME
bis(N-maleimidomethyl)ether 相似文献
14.
Smart construction of ultraflexible electrodes with superior gravimetric and volumetric capacities is still challenging yet significant for sodium ion batteries (SIBs) toward wearable electronic devices. Herein, a hybrid film made of hierarchical Fe1?xS‐filled porous carbon nanowires/reduced graphene oxide (Fe1?xS@PCNWs/rGO) is synthesized through a facile assembly and sulfuration strategy. The resultant hybrid paper exhibits high flexibility and structural stability. The multidimensional paper architecture possesses several advantages, including rendering an efficient electron/ion transport network, buffering the volume expansion of Fe1?xS nanoparticles, mitigating the dissolution of polysulfides, and enabling superior kinetics toward efficient sodium storage. When evaluated as a self‐supporting anode for SIBs, the Fe1?xS@PCNWs/rGO paper electrode exhibits remarkable reversible capacities of 573–89 mAh g?1 over 100 consecutive cycles at 0.1 A g?1 with areal mass loadings of 0.9–11.2 mg cm?2 and high volumetric capacities of 424–180 mAh cm?3 in the current density range of 0.2–5 A g?1. More competitively, a SIB based on this flexible Fe1?xS@PCNWs/rGO anode demonstrates outstanding electrochemical properties, thus highlighting its enormous potential in versatile flexible and wearable applications. 相似文献
15.
Bacillus mycoides strain RIJ B-017, a growth-associated poly-3-hydroxybutyrate (PHB) producer was grown on sucrose-containing media. PHB accumulated
in cells up to 72% of dry cell mass. The overall maximum value of PHB yield (Y
p/s) and productivities (Q
p andq
p) 250 mgp/gs, 120 mgp L−1 h−1 and 30 mgp gx
−1 h−1, respectively, were obtained at 15 g/L sucrose. Differential scanning calorimeter heating curve showed two peaks, one at
95.9 °C and another at 165.4°C with a shoulder around 154.6 °C. The viscosity-average molar mass in chloroform at 27°C was
505 kDa. The carbon content of PHB was 55.4% of the mass. 相似文献
16.
Rengesh Balakrishnan Subbi Rami Reddy Tadi Naresh Mohan 《Preparative biochemistry & biotechnology》2020,50(4):365-378
AbstractA low-cost Kodo millet bran residue was utilized as feedstock for the production of D (?) lactic acid (DLA) using Lactobacillus delbrueckii NBRC3202 under anaerobic condition. Data culled from a series of batch fermentation processes with different initial Kodo millet bran residue hydrolysate (KMBRH) and DLA concentrations were used for kinetic model development. Both simulated and experimental data were in good agreement for cell growth, KMBRH utilization, and DLA formation. The values of kinetic constants specific growth rate, (μm = 0.17?h?1); growth (αP = 0.96?g.g?1) and non-growth (βP = 1.19?g.g?1.h?1) associated constant for DLA production and the maximum specific KMBRH utilization rate, (qG, max = 1.18?g.g?1.h?1) were in good agreement with the literature reports. Kinetic analysis elucidated that L. delbrueckii growth was predominantly influenced by KMBRH limitation and highly sensitive to DLA inhibition. Fed-batch fermentation studies demonstrated the existence of substrate and product inhibition paving the scope for process intensification. 相似文献
17.
Leaf tensity: a method for rapid determination of water requirement information in Brassica napus L.
Deke Xing Xiaojian Xu Yujing Liu Yansheng Wu Jiheng Ni 《Journal of Plant Interactions》2018,13(1):380-387
Water regulation caused by enzymes, such as carbonic anhydrase (CA), changes the water status, making it difficult to diagnose water deficit using leaf water potential (ψL) or stomatal conductance (gs). Therefore, new methods for timely and accurately determining plant water status should be established. In this study, CA activity, ψL, leaf tensity (Td), photosynthetic characteristics and plant growth of Brassica napus L. seedlings under drought and subsequent rewatering were analysed. Results indicated that Td could reflect the plant water status better than ψL or gs and played an important role in the photosynthesis of B. napus. B. napus exhibited good restorability at the 40?g?L?1 polyethylene glycol level. The rewatering strategy for B. napus was excellent at 40?g?L?1 (?0.15?MPa) →20?g?L?1 (?0.11?MPa). Td could be used for the rapid determination of water requirement information in B. napus during winter drought period. 相似文献
18.
The basic theoretical groundwork for the use of derivative binding isotherms in the analysis of ligand binding is presented. The derivative binding isotherm is defined as Γ (Y) = df/dy where f = fractional degree of saturation and y = natural logarithm of the free ligand concentration. Since Γ (y) is a positive function, which goes to zero as y → ±∞, the mean value of y, 〈y〉, and the second and third moments, μ2 and μ3 about 〈y〉 are well defined. For a macromolecular system consisting of N equivalent and independent binding sites, Γ (y) is a symmetrical bell-shaped function with one maximum. The maximum occurs when y = ?ln Kassoc; μ2 = π2/3, and μ3 = 0. For multiple sets of independent binding sites, Γ (y) is a superposition of Γ-type functions. If the sets are sufficiently well separated in binding free energy, multiple extrema may be seen at positions corresponding to the logarithms of the dissociation constants for the individual sets. In any case, 〈y〉 is equal to the mean value of the logarithms of the dissociation constants for the sets; μ2 > π2/3 and equal to π2/3 plus the variance of the logarithms of the dissociation constants about their mean value; and μ3 is, except by coincidence, not equal to zero and equals the third moment of the distribution of logarithms of the dissociation constants about their mean value. Analysis of Γ(y) for the case of cooperative interactions within a set of binding sites was investigated by examining (1) the Hill model (whose mathematical representation is equivalent to that used to describe antibody heterogeneity except that in the latter case the parameter a, the Sips, constant, is constrained (0 < a ≤1);(2) a common model for cooperativity in which the cooperative free energy is a linear function of the fraction bound; and (3) a general representation of cooperative interactions within a set of sites in terms of ?(f), a smooth function that gives the interaction free energy in units of RT. For the Hill model (or Sips model) Γ(y) is a symmetrical function with one maximum at y = (?1)/a)lnK, μ2 = π2/3a2; and μ3 = 0. For the case in which the cooperative free energy is a linear function of f [?(f) = cf], 〈y〉 = ?ln K0 + (c/2); μ2 = (π2/3) + c[(c/12) + 1] where c > ?4; and μ3 = 0. General expressions for the moments in terms of ?(f) are derived. In general, μ2 < (π2/3) for positive cooperativity and μ2 > (π2/3) for negative for negative cooperativity. Γ(y) will be symmetrical if and only if the cooperative free energy is introduced symmetrically about f = 0.5. 相似文献
19.
C. Wiencke J. Rahmel U. Karsten G. Weykam G. O. Kirst 《Plant biology (Stuttgart, Germany)》1993,106(1):78-87
The photosynthetic performance of macroalgae isolated in Antarctica was studied in the laboratory. Species investigated were the brown algae Himantothallus grandifolius, Desmarestia anceps, Ascoseira mirabilis, the red algae Palmaria decipiens, Iridaea cordata, Gigartina skottsbergii, and the green algae Enteromorpha bulbosa, Acrosiphonia arcta, Ulothrix subflaccida and U. implexa. Unialgal cultures of the brown and red algae were maintained at 0°C, the green algae were cultivated at 10°C. IK values were between 18 and 53 μmol m?2 s?1 characteristic or low light adapted algae. Only the two Ulothrix species showed higher IK values between 70 and 74 μmol m?2 s?1. Photosynthesis compensated dark respiration at very low photon fluence rates between 1.6 and 10.6 μmol m?2 s?1. Values of α were high: between 0.4 and 1.1 μmol O2 g?1 FW h?1 (μmol m?2 s?1)?1 in the brown and red algae and between 2.1 and 4.9 μmol O2 g?1 FW h?1 (μmol m?2 s?1)?1 in the green algal species. At 0°C Pmax values of the brown and red algae ranged from 6.8 to 19.1 μmol O2 g?1 FW h?1 and were similarly high or higher than those of comparable Arctic-cold temperate species. Optimum temperatures for photosynthesis were 5 to 10°C in A. mirabilis, 10°C in H. grandifolius, 15°C in G. skottsbergii and 20°C or higher in D. anceps and I. cordata. P: R ratios strongly decreased in most brown and red algae with increasing temperatures due to different Q10 values for photosynthesis (1.4 to 2.5) and dark respiration (2.5 to 4.1). These features indicate considerable physiological adaptation to the prevailing low light conditions and temperatures of Antarctic waters. In this respect the lower depth distribution limits and the northern distribution boundaries of these species partly depend on the physiological properties described here. 相似文献
20.
Xylanase was produced by solid-state fermentation using Thermoascus aurantiacus. Maximum production (500 U g–1 bagasse) was achieved on the sixth day of cultivation on solid sugarcane bagasse medium supplemented with 15% (v/w) rice bran extract. The fungal biomass, determined from its glucosamine content, reached 28 mg g–1 on the 8th day of cultivation. The cell yield against O2 (Y
x/o
=0.18g
cell/gO2) and maintenance coefficient (m
0=0.013g
O2/g
cell
h) were determined with the low Y
x/o
value for T. aurantiacus agreeing with the calculated value. 相似文献