Ribulose bisphosphate carboxylase, protein and nitrogen in Scots pine seedlings cultivated at different nutrient levels

Seedlings of Scots pine (Pinus sylvestris L.) of a northern provenance were cultivated in nutrient solution for 10 weeks in a climate chamber. The nutrient solution (renewed by solution exchange) contained 2.5, 10 or 50 mg N I^?1. All other essential elements were added in optimal proportion to the nitrogen. Seedlings cultivated at 10 and 50 mg N I^?1 were similar with respect to all characteristics studied. Seedlings cultivated at 2.5 mg N I^?1 showed a lower growth rate, especially for the shoot, and an altered morphology, with high root:shoot ratios and long, slender roots. The nitrogen concentrations in shoot and needles as well as in whole seedlings were not significantly affected by the nitrogen supply, while the nitrogen concentrations in the roots were somewhat lower at 2.5 mg N I^?1. Ribulose bisphosphate carboxylase (EC 4.1.1.39) activity and the concentrations of carboxylase, total and soluble protein and of chlorophyll in the needles were consistently much lower for seedlings cultivated at 2.5 mg N I^?1, than for seedlings grown at higher nutrient levels. A close correlation was observed between activity and concentration of the carboxylase (r=0.95). Carboxylase activity and protein were more sensitive to a low nutrient supply than was chlorophyll. The data show how activity and concentration of ribulose bisphosphate carboxylase and the concentrations of soluble and total protein and of chlorophyll in needles of pine seedlings can be negatively affected by the nutrient supply, also when the nitrogen concentrations in the needles are close to those observed at optimal nutrient supply. It is suggested that pine seedlings store assimilated non-protein nitrogen in the needles when protein synthesis is under restraint. The nitrogen concentration in needles and seedlings could not be used as a measure of the physiological state of the seedlings.     

Effect of ammonium nutrition on the activity of nitrate reductase in the roots of apple seedlings

Active extracts of nitrate reductase were prepared from theroots of apple seedlings c.v. Granny Smith which were grownin nutrient solution under controlled enviromental conditions.The nutrient solutions contained various ratios of nitrate andammonium ions but all the treatments contained a total of 112ppm nitrogen. Maximum nitrate reductase activity in the roots was obtainedwhen plants were supplied with nitrate as the sole source ofnitrogen. Roots grown in solution containing only ammonium nitrogenhad little or no activity. When plants were supplied with bothforms of nitrogen in the nutrient solution, the presence ofammonium ions markedly lowered the activity of nitrate reductasein the roots. Plants supplied with 98 ppm nitrate nitrogen plus14 ppm ammonium nitrogen had activities only half those of plantsgrown in nitrate alone. Plants supplied with equal amounts ofammonium and nitrate nitrogen had activities less than one sixththose of plants grown in nitrate alone. (Received June 3, 1972; )     

Response of Chlorella to Scandium and Potassium at Various pH

The response of Chlorella pyrenoidosa cells to moderate potassium deficiency and to the addition of various scandium amounts in the nutrient solution were studied at different pH. The effects on growth, chlorophyll content, oxygen consumption, and the ¹⁴CO₂ incorporation in photosynthesizing cells were measured. Considerable metabolic changes inside the cells were registered under the given nutrient conditions. The separated ¹⁴C-labelled compounds showed, at acid and neutral pH in complete nutrient solution, an increase in the relative content of sugar phosphates and a decrease in the relative content of sucrose, caused by increasing scandium concentrations. Moderate potassium deficiency caused a diminution of the relative content of sugar phosphates. The relative content of amino acids was increased by scandium added to complete nutrient solution, but it decreased under potassium deficiency.     

The relation between nitrogen deficiency and leaf senescence

Because the "mobilization" of nitrogen resulting from nutritional nitrogen deficiency is also prominent during leaf senescence, the characteristics of these two syndromes were compared. Oat plants ( Avena sativa L. cv. Victory) were raised on a nutrient solution, complete except for nitrogen supply (i.e., with only the seed protein as nitrogen source), and the senescence of their leaves was compared with that of controls grown on a full nutrient solution. The N-deficient plants flowered after forming only 4 leaves and each set a single seed. The nitrogen lack affected the content of chlorophyll somewhat more than the content of the amino acids or protein nitrogen. However, spraying the plants with kinetin solution was able to retain 20–30% of the chlorophyll and protein. During senescence, the chlorophyll appears to be less stable in the N-deficient leaves than in the controls, while the protein is somewhat more stable than in the controls. Also, when the detached leaves from N-deficient plants senesced in white light or in darkness, kinetin delayed their senescence almost as effectively as that of control leaves. Most strikingly, the stomata of N-deficient leaves after detachment and floating on water were largely closed in light, just as in senescence, but could be partially induced to open by kinetin treatment. Since stomatal closure has earlier been shown to cause senescence, the characteristic syndrome of foliar nitrogen deficiency is concluded to be partly that of senescence.     

Impact of nitrogen limitation on biomass,photosynthesis, and lipid accumulation in <Emphasis Type="Italic">Chlorella sorokiniana</Emphasis>

Induction of oil accumulation in algae for biofuel production is often achieved by withholding nitrogen. However, withholding nitrogen often reduces total biomass yield. In this report, it is demonstrated that Chlorella sorokiniana will not only accumulate substantial quantities of neutral lipids when grown in the absence of nitrogen but will also exhibit unimpeded growth rates for up to 2 weeks. To determine the physiological basis for the observed increase in oil and biomass accumulation, we compared photosynthetic and respiration rates and chlorophyll, lipid, and total energy content under ammonia replete and deplete conditions. Under N-depleted growth conditions, there was a 64 % increase in total energy density and a ～20-fold increase in oil accumulation relative to N-replete growth leading to a 1.6-fold greater total energy yield in N-depleted than in N-replete cultures. We propose that the higher energy accumulation in N-depleted cultures is due to enhanced photosynthetic energy capture and conversion associated with reduced chlorophyll levels and reduced self-shading as well as a shift in metabolism leading to the accumulation of oils.     

谷氨酸对异养培养小球藻生长的影响

在不添加其他氮源的小球藻异养培养基中,谷氨酸可促进小球藻的生长,但基本不增加叶绿素的合成;在以铵盐为氮源时,谷氨酸可明显促进小球藻对铵盐的利用,促进小球藻生物量增加和叶绿素合成;在以硝酸盐为氮源时,谷氨酸可增加小球藻的生物量,对叶绿素含量无明显影响。     

Compaitive Study on Liposoluble Compoands in Autotrophic and Heterotrophic Chlorella protothecoides

Both autotrophically and heterotrophically grown Chlorella protothecoides cells have been obtained in cell cultures. The content of liposoluble compounds in the cells of heterotrophic algae occupied 72% of the total cells in dry weight, which was more than 4 times as high as that in the autotrophic algal cells. There existed remarkbly different distribution patterns of the hydrocarbons in thesetwo kinds of cells. The hydrocarbons in autotrophic cells were characterised by the predominance of C17 normal alkanes, wheraes the heterotrophic cells were rich in normal alkanes of higher molecular weight or longer carbon chain with C25 as the dominant carbon. The structure of the compounds in benzene fraction is not quite clear, but the compounds in autotrophis sample may be related to the degeneration of the pigments. The compounds in heterotrophic sample probably come from lipid acids. The visible--ultraviolet absorption spectrum of the pigment compounds demonstrated the absorption peaks of the acetone extract from the autotrophic cells at 432.5, 451.5, 472.5 and 661.5 nm, reflecting the existence of chlorophyll and carotenoid, both with a rather high concentration. However, the acetone extract from the hetertrophic algal cells only showed absorption peaks at 427.4, 450.8 and 477.5 nm. The absorption peaks of the original green cells completely disappeared at 432.5 and 661.5 nm, reflecting the disappearance of chlorophyll in cells on the whole; the remaining absorption peaks only reflected the existence of carotenoid, but its concentration had already been greatly reduced. The resuls from comparative experiments were of essential significance on the study of physiological metabolism in heterotrophically grown C. protothecoides and on the exploration and application of the lipid compounds in this kind of algae.     

Influence of Potassium Deficiency on Photosynthesis,Chlorophyll Content,and Chloroplast Ultrastructure of Cotton Plants

In cotton (Gossypium hirsutum L.) grown in controlled-environment growth chamber the effects of K deficiency during floral bud development on leaf photosynthesis, contents of chlorophyll (Chl) and nonstructural saccharides, leaf anatomy, chloroplast ultrastructure, and plant dry matter accumulation were studied. After cotton plants received 35-d K-free nutrient solution at the early square stage, net photosynthetic rate (P _N) of the uppermost fully expanded main-stem leaves was only 23 % of the control plants receiving a full K supply. Decreased leaf P _N of K-deficient cotton was mainly associated with dramatically low Chl content, poor chloroplast ultrastructure, and restricted saccharide translocation, rather than limited stomata conductance in K-deficient leaves. Accumulation of sucrose in leaves of K-deficient plants might be associated with reduced entry of sucrose into the transport pool or decreased phloem loading. K deficiency during squaring also dramatically reduced leaf area and dry matter accumulation, and affected assimilate partitioning among plant tissues.     

Zur mixotrophen Kultivation von Chlorella vulgaris in homokontinuerlicher Chemostatkultur

Cells of Chlorella vulgaris, BEIJ. Greifswald 9, were grown on autotrophic and mixotrophic conditions using glucose and acetate as organic substrates. It was shown that these C-sources applicated in a suitable range of concentrations increase the growth rate and the productivity of the algal cultures. The cells grown on mixotrophic conditions have a higher total pigment content and exhibit variations in the ratio chlorophyll a/chlorophyll b. In addition the contents of proteins, lipids, carbohydrates, and nucleic acids of the biomass were shown to be dependent on the kind of the organic substrate used.     

PHYSIOLOGICAL AND ULTRASTRUCTURAL RESPONSES OF CYCLOTELLA MENEGHINIANA (BACILLARIOPHYTA) TO LIGHT INTENSITY AND NUTRIENT LIMITATION1

Photosynthetic characteristics and chloroplast ultrastructure of Cyclotella meneghiniana Kütz. were quantified while the organism was simultaneously adjusting to light and nutrient stress. Cells were grown in batch culture at either low or high light intensity on medium with a nitrogen/phosphorus molar ratio of 2:1 as a control, or with nitrogen or phosphorus deleted from the medium to create nutrient deficiencies. Analysis of variance indicated that light intensity, nutrient deficiency and duration of nutrient deficiency all had significant effects on cell growth, chlorophyll (Chl) concentration/cell, cellular fluorescence capacity (CFC), chloroplast volume and thylakoid surface density. Because interactions existed among nutrient deficiency, extent of nutrient deficiency, and light intensity, all three must be considered together in order to describe accurately the physiology and chloroplast ultrastructure of the diatom. Significant correlations were found between the Chl/cell or CFC/cell and chloroplast volume and thylakoid surface density. Through an increase in Chi concentration, chloroplast volume and thylakoid surface density, the cells successfully adapted to the conditions of low light intensity even while under nutrient stress. In contrast, less Chl/cell, smaller chloroplast volume and less thylakoid surface density were found at high light intensity.     

Inorganic Carbon Limitation and Chemical Composition of Two Freshwater Green Microalgae

Two freshwater chlorophytes, Chlorella vulgaris and Scenedesmus obliquus, were grown in inorganic carbon-limited continuous cultures in which HCO₃⁻ was the sole source of inorganic carbon. The response of the steady-state growth rate to the external total inorganic carbon concentration was reasonably well described by the Monod equation; however, the response to the internal nutrient concentration was only moderately well represented by the Droop equation when the internal carbon concentration was defined on a cellular basis. The Droop equation was totally inapplicable when total biomass (dry weight) was used to define internal carbon because the ratio of carbon to dry weight did not vary over the entire growth rate spectrum. In batch cultures, maximum growth rates were achieved at the CO₂ levels present in atmospheric air and at HCO₃⁻ concentrations of 3 mM. No growth was observed at 100% CO₂. Both nitrogen uptake and chlorophyll synthesis were tightly coupled to carbon assimilation, as indicated by the constant C/N and C/chlorophyll ratios found at all growth rates. The main influence of inorganic carbon limitation appears to be not on the chemical structure of the biomass, but rather on cell size; higher steady-state growth rates lead to bigger cells.     

Properties of Chlorella cells grown under various photo-heterotrophic conditions

1. Chlorella ellipsoidea was cultured under photo-heterotrophicconditions. Cells showed most favorable growth when 0.2% glucosewas added at the start to the inorganic nutrient medium. 2. Treatment with a mixed solvent, methanol/hexane: 4/3, gavehighly decolorized cells. Molasses alone and pyruvate in combinationwith glucose or with molasses and glucose were effective inobtaining a high yield of chlorophyll and carotenoid pigments. 3. The nitrogen content was lower in bleached cells than innormal cells. Protein yield obtained by the urea soaking methodwas higher with bleached cells than with normal cells. 4. Electron microscopic studies revealed that the outer partof normal cells consists of two layers, an electron-dense innerlayer and an electron-lucent outer layer, whereas, that of bleachedcells consists of only an electron-dense layer. (Received August 28, 1969; )     

Efficacy of Chlorella pyrenoidosa and Scenedesmus abundans for Nutrient Removal in Rice Mill Effluent (Paddy Soaked Water)

Microalgae are product of sustainable development owing to its ability to treat variety of wastewater effluents and thus produced biomass can serve as value added product for various commercial applications. This paper deals with the cultivation of microalgae species namely Chlorella pyrenoidosa and Scenedesmus abundans in rice mill effluent (i.e., paddy soaked water) for nutrient removal. In order to investigate the nutrient removal capability, microalgae are subjected to cultivation in both raw and autoclaved samples. The maximum phosphate removal by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 98.3% and 97.6%, respectively, whereas, the removal of ammoniacal nitrogen by Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 92% and 90.3%, respectively. The growth (measured in terms of chlorophyll content) of Scenedesmus abundans and Chlorella pyrenoidosa in raw sample was 3.88 mg/l and 5.55 mg/l, respectively. The results indicate the suitability of microalgae cultivation in rice mill effluent treatment for nutrient removal.     

Properties ofChlorella vulgaris strain adapted to high concentration of ammonium nitrogen.

Chlorella vulgaris is very sensitive to high concentrations of ammonium nitrogen. In medium containing 0.33 g NH4-N/1 its growth is inhibited by 50%. Prolonged incubation of the strain in media inhibiting any increase in cell number enabled the isolation of a strain with enhanced tolerance to high ammonium nitrogen concentration. The strain has been designated Chlorella vulgaris/AA. The concentration of nitrogen inhibiting the growth of the strain by 50% was 195 g NH4-N/1. The acquired character proved stable. The isolated strain also demonstrated increased tolerance to high concentration of urea nitrogen. Chl. vulgaris/AA cells were larger than the cells of the parental strain.     

Effects of water stress on the chlorophyll content,nitrogen level and photosynthesis of leaves of two maize genotypes

The dynamics of leaf chlorophyll level, nitrogen content, photosynthesis and stomatal conductance were followed in detail in two cultivars of maize (Zea mays) during a short period of water stress, applied at tasseling, and during the subsequent recovery phase. Plants used in the experiment were grown in sand-nutrient solution culture under field weather conditions. Water stress reduced chlorophyll levels, stomatal conductance and photosynthesis, but the nitrogen content of the leaves was not affected. It is concluded that the stress-induced loss of chlorophyll is not mediated by a lack of nitrogen. Considerable differences were observed between genotypes in the rate of post-stress recovery of chlorophyll level. Recovery, upon rewatering, of stomatal conductance and photosynthesis preceded that of chlorophyll level. Losses of up to 40% of leaf chlorophyll content were insufficient to affect rates of photosynthesis measured at mid-day.     

2种小球藻在鱼糜加工废水处理过程中的生长和油脂积累规律

以小球藻Chlorella pyrenoidsa F-9和C.vulgaris HYS-2为材料,研究小球藻在鱼糜加工废水中的生长速率、脂类积累规律和对氮磷营养的消除效果。结果表明,2种小球藻在鱼糜加工废水中快速生长,最高生物量达到0.293 g/L和0.276 g/L,分别是f/2对照培养基的2.4和1.6倍。小球藻HYS-2在鱼糜加工废水中油脂百分含量最高达到36.22%,为对照培养基的1.27倍,小球藻F-9在鱼糜加工废水中的油脂含量达到17.89%,为f/2培养基中的0.89倍。培养15 d后,2种小球藻对鱼糜加工废水中氮磷去除率均达90%以上。以上研究表明,用未经任何化学处理的鱼糜加工废水养殖小球藻在生长速率上远远大于f/2培养基,说明其具有较好地发展潜力,可以实现微藻的低成本养殖。     

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

The research aimed to verify the important physiological effect of nitrogen (N) on plants exposed to cadmium (Cd). The poplar plants were grown in a Hoagland nutrient solution and treated with extra N, Cd, and N + Cd. After treatment, plant growth and chlorophyll content were recorded. The oxidative stress, the activity of antioxidant enzymes, and the expression of related genes were also examined. The results indicated the plants treated with sole Cd presented obvious toxicity symptoms, i.e. growth inhibition, reactive oxygen species accumulation, and chlorophyll content decrement. However, when N was added to the plants under Cd stress, plant growth was enhanced, chlorophyll synthesis was promoted, and the oxidative stress was alleviated. Further, the expression of antioxidant enzymes genes was upregulated by N. The results indicated that N partially reversed the toxic effect of Cd on poplar plants, which can provide new methodology to enhance the phytoremediation technology for heavy metal pollution soil.     

氮磷营养限制影响三角褐指藻光合无机碳利用和碳酸酐酶活性

以海洋硅藻三角褐指藻为实验材料, 研究了不同氮磷比培养对其光合无机碳利用和碳酸酐酶活性的影响, 结果显示三角褐指藻生长速率在N:P=16:1时最大, 高于或低于16:1时明显下降, 表明其最适生长受到氮磷的限制。氮限制(N:P=4:1或1:1)导致叶绿素a含量分别下降30.1% 和47.6%, 磷限制(N:P=64:1或256:1)下降39.1%和52.4%, 但氮或磷限制对叶绿素c含量并没有明显影响。不同营养水平培养对光饱和光合速率具有明显的影响, 与营养充足培养相比, 在严重氮磷限制(N:P=1:1或256:1)培养下光饱和光合速率分别下降39.7%和48.0%, 光合效率与暗呼吸速率也明显下降。在氮磷限制培养下藻细胞pH补偿点明显下降; K0.5CO2值在磷限制下降低30%, 表明磷限制有助于提高细胞对CO2的亲和力, 但氮限制并没有明显影响。在氮磷限制培养的细胞反应液中Fe (CN)63-浓度下降速率较慢, 表明在氮磷限制环境中生长的细胞质膜氧化还原能力明显低于营养充足条件下生长的细胞。氮磷限制也导致胞内、外碳酸酐酶活性明显下降, 其中在氮限制下胞外碳酸酐酶活性分别下降50%和37.5%, 在磷限制下下降22.3%和42.1%。严重的氮(N:P=1:1)或磷(N:P=256:1)限制导致胞内碳酸酐酶活性下降36.5%和42.9%。研究结果表明, 三角褐指藻细胞在氮磷营养限制的环境中, 可以通过调节叶绿素含量、无机碳的利用方式和碳酸酐酶的活性以维持适度的生长。       

Effects of phosphorous, nitrogen, and carbon limitation on biomass composition in batch and continuous flow cultures of the heterotrophic dinoflagellate Crypthecodinium cohnii

We have used phosphate, nitrogen, or carbon limited batch and continuous flow cultures to study how growth and biochemical composition of the dinoflagellate Crypthecodinium cohnii CCMP 316 is affected by nutrient limitation. Specific contents of phosphorous, proteins, and starch were differently affected by nutrient limitation. The specific phosphorous content in C. cohnii varied 10-20 times depending on phosphate availability in the medium. When phosphate was available it was taken up in excess and stored to be re-utilized during phosphate limitation. The specific protein content varied twofold. At most conditions, proteins made up 12-15% of the biomass dry weight but when cells were nitrogen limited, the specific protein content was only half this value. Floridean starch was the major cell constituent of C. cohnii accounting for 40-50% of the biomass dry weight. Only during carbon limitation did the specific starch content decrease. In contrast was the specific lipid content almost unaffected by nutrient availability and lipids accounted for 12-15% of the biomass dry weight irrespectively of which nutrient that was limiting. Lipid production does therefore not depend on nutrient limitation in C. cohnii and lipids are produced even by carbon limited cells. Cultures grown under phosphate limitation resulted in formation of cells with maximal specific contents of all the three major cell constituents; starch, lipid, and protein.     

Effects of carbon and nitrogen sources on fatty acid contents and composition in the green microalga, Chlorella sp. 227

In order to investigate and generalize the effects of carbon and nitrogen sources on the growth of and lipid production in Chlorella sp. 227, several nutritional combinations consisting of different carbon and nitrogen sources and concentrations were given to the media for cultivation of Chlorella sp. 227, respectively. The growth rate and lipid content were affected largely by concentration rather than by sources. The maximum specific growth was negatively affected by low concentrations of carbon and nitrogen. There is a maximum allowable inorganic carbon concentration (less than 500~1,000 mM bicarbonate) in autotrophic culture, but the maximum lipid content per gram dry cell weight (g DCW) was little affected by the concentration of inorganic carbon within the concentration. The lipid content per g DCW was increased when the microalga was cultured with the addition of glucose and bicarbonate (mixotrophic) at a fixed nitrogen concentration and with the lowest nitrogen concentration (0.2 mM), relatively. Considering that lipid contents per g DCW increased in those conditions, it suggests that a high ratio of carbon to nitrogen in culture media promotes lipid accumulation in the cells. Interestingly, a significant increase of the oleic acid amount to total fatty acids was observed in those conditions. These results showed the possibility to induce lipid production of high quality and content per g DCW by modifying the cultivation conditions.