首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Biosurfactant production from synthetic medium and industrial waste, viz. distillery and whey wastes was investigated by using an oily sludge isolate Pseudomonas aeruginosa strain BS2. In synthetic medium separately supplemented with glucose and hexadecane as water-soluble and -insoluble carbon sources, respectively, strain BS2 reduced the surface tension of the fermentation broth from 57 to 27 mN/m. The culture produced biosurfactant during the stationary growth phase and its yield was 0.97 g/l. The culture utilized distillery and whey wastes for its growth, as maximum cell counts reached to 54 × 108 and 64 × 109 c.f.u./ml from an initial inoculum size of 1 × 05 c.f.u./ml, respectively, within 48 h of incubation and in these wastes the yields of biosurfactant obtained were 0.91 and 0.92 g/l, respectively. In synthetic medium, distillery and whey wastes, strain BS2 produced a crystalline biosurfactant which belonged to the category of secondary metabolites and its maximum production occurred after the onset of nitrogen-limiting conditions. After recovering biosurfactant from the fermented waste, the chemical oxygen demand (COD) of distillery and whey wastes was significantly reduced by 81 and 87%, respectively. Total acids, nitrogen and phosphate levels in distillery waste were reduced by 90, 92 and 92%, respectively, while in case of whey waste the concentration of these nutrients was reduced by 88, 95 and 93%, respectively. The isolated biosurfactant possessed potent surface active properties, as it effectively reduced the surface tension of water from 72 to 27 mN/m and formed 100% stable emulsions of a variety of water-insoluble compounds such as hydrocarbons, viz. hexadecane, crude oil, kerosene and oily sludge and pesticides, viz. dichlorodiphenyltrichloroethane (DDT) and benzene hexachloride (BHC). The effectiveness of biosurfactant was also evident from its low critical micellar concentration (CMC) which was 0.028 mg/ml.  相似文献   

2.
Biosurfactant production through a fermentation process involving the biodegradation of soybean oil refining wastes was studied. Pseudomonas aeruginosa MR01 was able to produce extracellular biosurfactant when it was cultured in three soybean oil refinement wastes; acid oil, deodorizer distillate and soapstock, at different carbon to nitrogen ratios. Subsequent fermentation kinetics in the three types of waste culture were also investigated and compared with kinetic behavior in soybean oil medium. Biodegradation of wastes, biosurfactant production, biomass growth, nitrate consumption and the number of colony forming units were detected in four proposed media, at specified time intervals. Unexpectedly, wastes could stimulate the biodegradation activity of MR01 bacterial cells and thus biosurfactant synthesis beyond that of the refined soybean oil. This is evident from higher yields of biodegradation and production, as revealed in the waste cultures (Ydeg|(Soybean oil) = 53.9 % < Ydeg|(wastes) and YP/S|(wastes) > YP/S|(Soybean oil) = 0.31 g g?1, respectively). Although production yields were approximately the same in the three waste cultures (YP/S|(wastes) ? 0.5 g g?1), microbial activity resulted in higher yields of biodegradation (96.5 ± 1.13 %), maximum specific growth rate (μ max  = 0.26 ± 0.02 h?1), and biosurfactant purity (89.6 %) with a productivity of 14.55 ± 1.10 g l?1, during the bioconversion of soapstock into biosurfactant. Consequently, applying soybean oil soapstock as a substrate for the production of biosurfactant with commercial value has the potential to provide a combination of economical production with environmental protection through the biosynthesis of an environmentally friendly (green) compound and reduction of waste load entering the environment. Moreover, this work inferred spectrophotometry as an easy method to detect rhamnolipids in the biosurfactant products.  相似文献   

3.
Wild screening of bacterial strains from compost materials was performed. Several biosurfactant-producer strains were isolated and then cultured in whey as a low-cost medium for biosurfactant production. Two strains, identified as Bacillus sp. and Streptomyces sp., were the best biosurfactant producers and were selected for determination of compost quality enhancing. The effect of cell biomass, cell-free supernatant, and a consortium of these two strains on compost quality were determined and specific parameters of compost were analyzed. The results showed that using these bacteria (or supernatants) in compost processing have slight stimulatory effect on bacterial population (8.08 log10 CFU/g), surface tension reduction (to 42.6 mN/m at 24 h), and heavy metal bioremediation (>50 % in most treatments), speeding up the decomposition rate of organic matter (42.3 % OM at the end of experiment), accelerating the stabilization process by reduction of NH 4 + to NO 3 ? ratio (reduced from 0.2 to 0.026), decreasing the biotoxicity (tested by seed germination and root length of germinated seed), and also reduction of pathogens (reduced from 2100 to 120 MPN/g in fecal coliform).  相似文献   

4.
The fermentation characteristics of 24 strains of Saccharomyces cerevisiae and one strain of Candida apicola, C. famata, C. guilliermondii, Hanseniospora occidentalis, Pichia subpelicullosa and Schizosaccharomyces pombe were evaluated for the production of cachaça. They were isolated from small cachaça distilleries (27), industrial cachaça distilleries (2) and one sugarcane alcohol distillery. The yeasts showed significant differences in ethanol yield, substrate conversion, efficiency, conversion factors of substrate into ethanol (Y p/s), cells (Y x/s), organic acids (Y ac/s) and glycerol (Y g/s), and maximum specific growth rate ( max). In general the S. cerevisiae strains showed better fermentation potential, with yields between 83 and 91% and max between 0.450 and 0.640 h–1, several of them being comparable with the high performance yeast used in the industrial production of ethanol, which was adopted as a reference. The non-Saccharomyces strains showed high efficiency, very low ethanol yield and very high Y ac/s and Y g/s values, except Pichia subpelliculosa, which behaved very similarly to the S. cerevisiae strains. Hierarchical Cluster Analysis and Principal Component Analysis showed the fermentation yield (or substrate conversion) as being the variable which contributed most to the separation of the strains into different groups.  相似文献   

5.
Anaerobic co-digestion is effective and environmentally attractive technology for energy recovery from organic waste. Organic, agricultural and industrial wastes are good substrates for anaerobic co-digestion because they contain high levels of easily biodegradable materials. In this paper enhancement of biogas production from codigestion of whey and cow manure was investigated in a series of batch experiments. The influence of whey ratio on specific biogas production in a mixture with cow manure was analyzed at 35 and 55°C, for different initial pH values and for different concentrations of supplemental bicarbonate in experiments carried out over 12 days. Good biogas production (6.6 dm3/dm3), methane content (79.4%) in a biogas mixture and removal efficiencies for total solids (16%) were achieved at optimum process conditions (temperature of 55°C, 10% v/v of whey and 5 g/dm3 NaHCO3 in the initial mixture). In order to validate optimized conditions for co-digestion of whey and cow manure in the one-stage batch process, the experiments were performed within 45 days. The high biogas production (21.8 dm3/dm3), a good methane content (78.7%) in a biogas mixture as well as maximum removal efficiencies for total solids (32.3%), and chemical oxygen demand (56.3%), respectively indicate that whey could be efficiently degraded to biogas in a onestage batch process when co-digested with cow manure.  相似文献   

6.
Summary Lipid production of the oleaginous yeastApiotrichum curvatum was studied in wheypermeate to determine optimum operation conditions in this medium. Studies on the influence of the carbon to nitrogen ratio (C/N-ratio) of the growth medium on lipid production in continuous cultures demonstrated that cellular lipid content in wheypermeate remained constant at 22% of the cell dry weight up to a C/N-ratio of about 25. The maximal dilution rate at which all lactose is consumed in wheypermeate with excess nitrogen was found to be 0.073 h-1. At C/N-ratios higher than 25–30 lipid content gradually increased to nearly 50% at C/N=70 and the maximal obtainable dilution rate decreased to 0.02 h-1 at C/N=70. From these studies it could be derived that maximal lipid production rates can be obtained at C/N-ratios of 30–35 in wheypermeate. Since the C/N-ratio of wheypermeate normally has a value between 70 and 101, some additional nitrogen is required to optimize the lipid production rate. Lipid production rates ofA. curvatum in wheypermeate were compared in four different culture modes: batch, fed-batch, continuous and partial recycling cultures. Highest lipid production rates were achieved in culture modes with high cell densities. A lipid production rate of nearly 1 g/l/h was reached in a partial recycling culture. It was calculated that by using this cultivation technique lipid production rates of even 2.9 g/l/h may be reached when the supply of oxygen can be optimized.Nomenclature C/N-ratio carbon to nitrogen ratio of the growth medium (g/g) - C/Ncrit C/N-ratio at which there is just enough nitrogen to allow all carbon source to be converted to biomass - D dilution rate=volume of incoming medium per unit time/volume of medium in the culture vessel (h-1) - Dmax maximum dilution rate (h-1) - DW cell dry weight - L lipid yield (g storage lipid/g carbon source) - specific growth rate (h-1) - max maximum specific growth rate (h-1) - QL lipid production rate (g/l/h) - Yi molecular fraction of carbon substrate that is converted to storage carbohydrate (C-mol/C-mol) - Yls maximal amount of storage lipid that can be produced per mol carbon source (C-mol/C-mol)  相似文献   

7.
This report presents results on relationships between the kinetics (Vmax and Km) of -glucosidase (GLCase) and aminopeptidase (AMPase) activity, and dissolved organic carbon (DOC) and bacterial secondary production in freshwater mesocosms of differing degrees of eutrophication. These relationships varied in different mesocosms and depended on the trophic status of water and the exudation rates of organic carbon (EOC) by phytoplankton. Close coupling of bacterial production to Vmax of GLCase activity was observed only in nutrient-enriched mesocosms. The relationship between GLCase and DOC content was also significant in enriched water. There was no correlation between the Vmax, of GLCase and DOC and bacterial production in nutrient-impoverished and control (mesotrophic) enclosures. However, the Vmax of AMPase correlated well to DOC and bacterial production in these mesocosms. AMPase activity did not correlate with DOC and bacterial production in nutrient-impoverished mesocosms. There was no relationship between bacterial biomass and enzyme activity in all studied mesocosms. Comparison of the rates of phytoplankton production of EOC and rates of the bacterial organic carbon demand (BOCD) in nutrient-impoverished mesocosms showed that EOC flux constituted, on average, 90% of BOCD. However, in nutrient-enriched mesocosms EOC contributed only, on average, 27% to the BOCD; thus, in these mesocosms, bacteria were probably organic-carbon limited. It is hypothesized that to bypass substrate limitation, bacteria produced GLCase and AMPase. These enzymes had a high specific activity and high affinity to their substrates and efficiently hydrolyzed polysaccharides and proteins, thereby supplying microorganisms with readily utilizable products of enzyme catalysis. Offprint requests to: R.J. Chróst.  相似文献   

8.
Summary Thermoanaerobium brockii was grown in batch and continuous culture at supraoptimal temperatures (>65° C). Specific growth rates were lower in batch (max>1.0 h-1) than in continuous cultures (max1.2–1.4 h-1). Acetone addition to the medium did not increase critical dilution rate significantly. The media used contained significantly less organic material and sulfide than previously reported media; however, yeast extract requirements were shown to be exceptionally high (60% of the glucose concentration used). Organic substrates inhibited growth and product formation in chemostat cultures whereas the slow formation of acetic acid was observed in batch cultures, but also with virtually no growth. The inhibiting concentration was found to be approximately 15 g organic carbon·l-1. The maintenance requirements of T. brockii were in the same range as expected of aerobic extreme thermophiles (ms0.5 g·g-1·h-1) and could be met only by glucose and not by yeast extract. Maintenance was obviously not independent of specific growth rate. Production of the stereospecific alcohol-aldehyde/ketone oxidore-ductase was strictly growth associated and its formation was not affected by acetone added to medium.  相似文献   

9.
The relationship between growth and interferon- (IFN-) production in the recombinant cell line CHO 320 was studied by varying the foetal calf serum (FCS) concentration. The specific growth rate varied with the initial FCS concentration in a manner which could be well fitted by the Monod model. TheK s and max values were found to be 0.771% (v/v) serum and 0.031 h–1 respectively. The average specific IFN- production rates during the exponential phase increased with increasing FCS concentration. A good correlation between specific production rate and specific growth rate was found in all phases of the culture except the lag phase and it was clearly demonstrated that IFN- production was growth associated. Specific glucose and glutamine utilisation rates were inversely related to specific growth rates.  相似文献   

10.
A strain of broad-spectrum, mercury-resistant Pseudomonas putida FB1 was used to remove mercury as the gaseous element (Hg(0)) from a continuous axenic culture, fed with a synthetic medium containing 1 mg Hg l-1 as HgCl2. Mercury determinations were performed in steady-state cultures using various culture fractions [whole culture, filtered supernatant, bacterial cells (dry wt), recovery trap liquid] in order to determine the removal efficiency at different dilution rates (from 0.1 to 3.0 day-1). The removal efficiency ranged from 99.2% to 99.8%, and the residual Hg was maintained below 5 l-1 (the maximum allowable concentration of Hg in liquid wastes according to Italian law) at a dilution rate of 1.0 day-1, corresponding to a Hg flux of 40 g l-1 h-1. Hg accumulation by cell biomass was negligible for dilution rates under 1.0 day-1. A progressive accumulation of Hg, both in the liquid phase and in cells, occurred at a higher dilution rate (3.0 day-1; close to washout), corresponding to a Hg concentration of 25 g g-1 (dry wt). The estimated Km and Vmax for Hg reduction were 0.241 mg l-1 and 9.5 mg g-1 h-1, respectively. In batch experiments maximum Hg removal occurred at the optimum growth temperature (28°C) of P. putida. The maximum recovery of Hg in the liquid trap was 78%.  相似文献   

11.
Summary In order to obtain a better understanding of the behaviour ofPediococcus pentosaceus in food products as well to facilitate the designing of industrial production processes for the organism, the growth and lactic acid production ofPediococcus pentosaceus in a complex glucose medium was followed in batch cultures at different gas environments (CO2, air, N2 and static cultures without gasflow), temperatures (10–50°C), pH (4.3–7.3) and nitrite concentrations (0–700 ppm). Optimal growth was obtained in CO2 at 40°C and pH 6.3 and resulted in a maximum specific growth rate ( max) of 1.27 h–1. In static culture at 40°C and pH 6.3 the max was 1.21 h–1. The max was, compared with static culture, reduced in air (12%) and nitrogen (26%). At 10°C the max was reduced by 99% and at 50°C by 88%. The reduction at pH 4.3 and 7.3 was 65% and 57%, respectively. Nitrite did not affect the max at any pH but increased the lag phase at pH 4.3 by a factor of 12. The lactic acid production was linked to the growth. The total amount of lactic acid produced was the same in all the tested gases and nitrite concentrations and also within the wide temperature range (15–45°C) and pH range (5.3–7.3). Mainly L(+)-lactic acid was produced during the exponential growth phase, but after this growth declined about 30% of the L(+)-lactic acid was converted to D(–)-lactic acid. The lactic acid product yield and the cellmass yied were both affected by the temperature but not by the pH.  相似文献   

12.
Three differently metabolically engineered strains, 2 single PHA- and Hup- mutants and one double PHA-/Hup- mutant, of the purple nonsulfur photosynthetic bacterium Rhodobacter sphaeroides RV, were constructed to improve a light-driven biohydrogen production process combined with the disposal of solid food wastes. These phenotypes were designed to abolish, singly or in combination, the competition of H2 photoproduction with polyhydroxyalkanoate (PHA) accumulation by inactivating PHA synthase activity, and with H2 recycling by abolishing the uptake hydrogenase enzyme. The performance of these mutants was compared with that of the wild-type strain in laboratory tests carried out in continuously fed photobioreactors using as substrates both synthetic media containing lactic acid and media from the acidogenic fermentation of actual fruit and vegetable wastes, containing mainly lactic acid, smaller amounts of acetic acia, and traces of higher volatile acids. With the lactic acid-based synthetic medium, the single Hup- and the double PHA-/Hup- mutants, but not the single PHA- mutant, exhibited increased rates of H2 photoproduction, about one third higher than that of the wild-type strain. With the food-waste-derived growth medium, only the single Hup- mutant showed higher rates of H2 production, but all 3 mutants sustained a longer-term H2 photoproduction phase than the wild-type strain, with the double mutant exhibiting overall the largest amount of H2 evolved. This work demonstrates the feasibility of single and multiple gene engineering of microorganisms to redirect their metabolism for improving H2 photoproduction using actual waste-derived substrates.  相似文献   

13.
Phenol, a major pollutant in several industrial waste waters is often used as a model compound for studies on biodegradation. This study investigated the anoxic degradation of phenol and other phenolic compounds by a defined mixed culture of Alcaligenes faecalis and Enterobacter species. The culture was capable of degrading high concentrations of phenol (up to 600 mg/l) under anoxic conditions in a simple minimal mineral medium at an initial cell mass of 8 mg/l. However, the lag phase in growth and phenol removal increased with increase in phenol concentration. Dissolved CO2 was an absolute requirement for phenol degradation. In addition to nitrate, nitrite and oxygen could be used as electron acceptors. The kinetic constants, maximum specific growth rate max; inhibition constant, K i and saturation constant, K s were determined to be 0.206 h–1, 113 and 15 mg phenol/l respectively. p-Hydroxybenzoic acid was identified as an intermediate during phenol degradation. Apart from phenol, the culture utilized few other monocyclic aromatic compounds as growth substrates. The defined culture has remained stable with consistent phenol-degrading ability for more than 3 years and thus shows promise for its application in anoxic treatment of industrial waste waters containing phenolic compounds.  相似文献   

14.
The abilities of organisms to sequester substrate are described by the two kinetic constants specific affinity, a°, and maximal velocity Vmax. Specific affinity is derived from the frequency of substrate-molecule collisions with permease sites on the cell surface at subsaturating concentrations of substrates. Vmax is derived from the number of permeases and the effective residence time, τ, of the transported molecule on the permease. The results may be analyzed with affinity plots (v/S versus v, where v is the rate of substrate uptake), which extrapolate to the specific affinity and are usually concave up. A third derived parameter, the affinity constant KA, is similar to KM but is compared to the specific affinity rather than Vmax and is defined as the concentration of substrate necessary to reduce the specific affinity by half. It can be determined in the absence of a maximal velocity measurement and is equal to the Michaelis constant for a system with hyperbolic kinetics. Both are taken as a measure of τ, with departure of KM from KA being affected by permease/enzyme ratios. Compilation of kinetic data indicates a 108-fold range in specific affinities and a smaller (103-fold) range in Vmax values. Data suggest that both specific affinities and maximal velocities can be underestimated by protocols which interrupt nutrient flow prior to kinetic analysis. A previously reported inverse relationship between specific affinity and saturation constants was confirmed. Comparisons of affinities with ambient concentrations of substrates indicated that only the largest a°S values are compatible with growth in natural systems.  相似文献   

15.
Biosurfactants are amphiphilic compounds produced by several microorganisms that reduce the surface tension. Low toxicity, optimal activity in extreme conditions, biodegradability and production from several wastes are main advantages of biosurfactants as compared to synthetic surfactants. Production of biosurfactant by a white rot fungus Pleurotus djamor on sunflower seed shell in solid-state fermentation was determined by emulsification indexes, oil spreading activity and surface tension (28.82 ± 0.3mN/m) measurement. The critical micelle concentration was detected as 0.964 ± 0.09 mg/mL. Also, the chemical and physicochemical properties of the biosurfactant produced were investigated. Considering the results of the chemical contents analysis, HPLC, FT-IR and 1H-NMR, it can be concluded that the produced biosurfactant has a complex structure. Besides, resistance of its activity to environmental factors such as temperature, pH and salt concentration, as well as its thermal stability, were investigated. Additionally, the produced biosurfactant formed stabile emulsions with different hydrocarbons. Lastly, the performance of removing waste frying oil from contaminated sand of produced biosurfactant was detected as 76.57 ± 6%. Owing to its high emulsification capacity, low surface tension and critical micelle concentration, the biosurfactant, shows great potential for use in hydrocarbon removal applications.  相似文献   

16.
An efficient biosurfactant-producing strain was isolated and cultured from Dagang oil field (China) using crude oil as sole source of carbon. Based on partial sequenced 16S rDNA analysis, the isolated strain was identified as Pseudomonas aeruginosa SNP0614. The bacterium P. aeruginosa SNP0614 produced a type of biosurfactant with excessive foam-forming properties. After microbial cultivation at 37°C and 150 rpm for 12 h, the produced biosurfactant was found to reduce the surface tension to 25.4 mN/m with critical micelle concentration (CMC) of 45.0 mg/L. After 20 days of incubation, the biosurfactant exhibited 90% emulsification activity (E24) on crude oil. FTIR spectroscopy of extracted biosurfactant indicated the biosurfactant as lipopeptide. The significant synergistic effect between P. aeruginosa SNP0614 and the mixed oildegrading bacteria resulted in increasing n-alkanes degradation rate by 30%. The strain P. aeruginosa SNP0614 represented as a promising biosurfactant producer and could be applied in a variety of biotechnological and industrial processes, particularly in microbial enhanced oil recovery and the bioremediation of oil pollution.  相似文献   

17.
Pseudomonas oxalaticus was grown in carbon- and energy-limited continuous cultures either with oxalte or formate or with mixtures of these substrates. During growth on the mixtures, simultaneous utilization of the two substrates occurred at all dilution rates tested. Under these conditions oxalate repressed the synthesis of ribulosebisphosphate carboxylase. The degree of this repression was dependent on the dilution rate and the ratio of oxalate and formate in the medium reservoir. At a fixed oxalate/formate ratio repression was greatest at intermediate dilution rates, whereas derepression occurred at both low and high dilution rates. Progressive depression of ribulosebisphosphate carboxylase synthesis and of autotrophic CO2 fixation at low dilution rates was attributed to the decreasing concentration of intracellular repressor molecule(s), parallel to the decreasing concentration of the growth-limiting substrates in the culture. To account for the derepression at higher dilution rates, it is proposed that the rate of oxalyl-CoA production from oxalate limits the supply of metabolic intermediates and that additional energy and reducing power generated from formate drains the pools of metabolic intermediates sufficiently to lower the intracellular concentration of the repressor(s). During growth of Pseudomonas oxalaticus on the heterotrophic substrate oxalate alone, at dilution rates below 10% of the maximum specific growth rate, derepression of ribulosebisphosphate carboxylase synthesis and of autotrophic CO2 fixation was observed to a level which was 50% of that observed during growth on formate alone at the same dilution rate. It is concluded that in Pseudomonas oxalaticus the synthesis of enzymes involved in autotrophic CO2 fixation via the Calvin cycle is regulated by a repression/derepression mechanism and that the contribution of autotrophic CO2 fixation to the biosynthesis of cell material in this organism is mainly controlled via the synthesis of these enzymes.Abbreviations RuBPCase ribulosebisphosphate carboxylase - PMS phenazine methosulphate - DCPIP 2,6-dichlorophenolindophenol - FDH formate dehydrogenase - SR concentration of growth-limiting substrate in reservoir  相似文献   

18.
To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P50 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P50 566 nm) photic regime exhibited sensitivity to medium (max 540–560) and long (max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P50 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (max 560 nm) and long (max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.  相似文献   

19.
Summary The effect of nutritional factors in a new culture medium (BW3) is described for the cyanobacterium Nostoc sp. The growth of Nostoc sp. was higher in BW3 than in control media currently used for cyanobacteria. With medium BW3 the content of the pigment c-phycocyanin depended on the culture conditions employed, particularly the nature of the nitrogen and carbon sources. Higher amounts of c-phycocyanin amounting to 20.1% on a dry-weight basis were accumulated when both sources were supplied in the gas phase of the culture. The phycobiliproteins of Nostoc sp. were resolved into two components: c-phycocyanin (max = 614 nm) and allophycocyanin (max = 652 nm). The phycobiliprotein composition was 30% allophycocyanin and 70% c-phycocyanin. The culture of Nostoc sp. in BW3 medium seems promising as a source of biomass for the production of natural dyes.  相似文献   

20.
Y. Jia  V. M. Gray 《Photosynthetica》2004,42(4):535-542
The influence of phosphorus (P) and nitrogen (N) supply on biomass, leaf area, photon saturated photosynthetic rate (Pmax), quantum yield efficiency (), intercellular CO2 concentration (Ci), and carboxylation efficiency (CE) was investigated in Vicia faba. The influence of P on N accumulation, biomass, and leaf area production was also investigated. An increase in P supply was consistently associated with an increase in N accumulation and N productivity in terms of biomass and leaf area production. Furthermore, P increased the photosynthetic N use efficiency (NUE) in terms of Pmax and . An increase in P supply was also associated with an increase in CE and a decrease in Ci. Under variable daily meteorological conditions specific leaf nitrogen content (NL), specific leaf phosphorus content (PL), specific leaf area (L), root mass fraction (Rf), Pmax, and remained constant for a given N and P supply. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. L increased with increasing N supply or with increasing NL. We tested also the hypothesis that P supply positively affects both N demand and photosynthetic NUE by influencing the upper limit of the asymptotic values for Pmax and CE, and the lower limit for Ci in response to increasing N.This revised version was published online in March 2005 with corrections to the page numbers.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号