共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
Abstract Dimethyl sulphide (DMS) was degraded by acclimatized activated sludge and by a mixed culture of Thiobacillus thioparus TK-1 and Pseudomonas sp. AK-2. While both these organisms persisted in stable co-culture on DMS, it was found that T. thioparus TK-1 and the derived strain TK-m grew in pure culture on DMS, and oxidized DMS with an apparent K m of 4.5 × 10−5 M. During growth, all the DMS-sulphur was oxidized stoichiometrically to sulphate but no methanol was detected in pure cultures of TK-m. DMS-carbon was probably converted to CO2 , since the fixation of 14 CO2 was progressively diluted during growth of a culture on 14 CO2 and DMS. Growth yields were consistent with autotrophic growth, dependent on the oxidation of the methyl residues to CO2 (probably with formaldehyde as a first intermediate) and the sulphide to sulphate. The organism thus appears to exhibit a mixture, from the one substrate, of chemolithotrophic and methylotrophic energy generation supporting autotrophic growth with CO2 fixation. 相似文献
3.
Elevated CO2 appears to be a significant factor in global warming, which will likely lead to drought conditions in many areas. Few studies have considered the interactive effects of higher CO2 , temperature and drought on plant growth and physiology. We grew canola ( Brassica napus cv. 45H72) plants under lower (22/18°C) and higher (28/24°C) temperature regimes in controlled-environment chambers at ambient (370 μmol mol−1 ) and elevated (740 μmol mol−1 ) CO2 levels. One half of the plants were watered to field capacity and the other half at wilting point. In three separate experiments, we determined growth, various physiological parameters and content of abscisic acid (ABA), indole-3-acetic acid and ethylene. Drought-stressed plants grown under higher temperature at ambient CO2 had decreased stem height and diameter, leaf number and area, dry matter, leaf area ratio, shoot/root weight ratio, net CO2 assimilation and chlorophyll fluorescence. However, these plants had increased specific leaf weight, leaf weight ratio and chlorophyll concentration. Elevated CO2 generally had the opposite effect, and partially reversed the inhibitory effects of higher temperature and drought on leaf dry weight accumulation. This study showed that higher temperature and drought inhibit many processes but elevated CO2 partially mitigate some adverse effects. As expected, drought stress increased ABA but higher temperature inhibited the ability of plants to produce ABA in response to drought. 相似文献
4.
Determination of dissolved carbon dioxide by coulometric titration in modified atmosphere systems 总被引:1,自引:0,他引:1
The solubility of carbon dioxide (CO2 ) in microbiological media at different pH values, water activities ( aw ), temperatures, buffering capacities and ratios of headspace to media volumes was determined by using a coulometer. Buffering capacity and ratio of headspace to media volume were shown to be the major factors influencing the solubility of CO2 in modified atmosphere model systems. The growth inhibitory effects of different dissolved CO2 concentrations (0–50 μmol ml-1 ) were determined for Pseudomonas fragi at 8°C and 22 C. Pseudomonas fragi was shown to be strongly affected by the CO2 concentration in the media. A carbon dioxide concentration of 40 μmol ml-1 was needed to inhibit Ps. fragi at 8°C. The importance of measuring dissolved CO2 concentrations in modified atmosphere packaging applications was shown and the coulometer proved to be an excellent tool for this purpose. 相似文献
5.
Elevated atmospheric CO2 lowers leaf litter nutritional quality for stream ecosystem food webs 总被引:1,自引:0,他引:1
Nancy C. Tuchman† Robert G. Wetzel‡ Steven T. Rier† Kirk A. Wahtera† James A. Teeri† 《Global Change Biology》2002,8(2):163-170
Up to 99% of the carbon fuelling the food webs of temperate woodland streams is derived from inputs of terrestrial leaf litter. Aquatic bacteria, fungi, and detritivore invertebrates directly utilize these inputs, transferring this energy to other components of the food web. Increases in atmospheric CO2 could indirectly impact woodland stream food webs by chemically altering leaf litter. This study evaluated CO2 -induced chemical changes in aspen ( Populus tremuloides ) leaf litter, and the corresponding effects on stream bacteria, fungi and leaf-shredding cranefly larvae ( Tipula abdominalis : Diptera). Leaf litter from plants grown under elevated CO2 had decreased nutritional value to aquatic decomposers and detritivores because of higher levels of structural compounds and lower nitrogen content. Consequently, elevated CO2 -grown leaf litter supported 59% lower bacterial production in a stream than litter grown at ambient CO2 levels, while not affecting fungal biomass. Larval craneflies fed elevated CO2 -grown microbially colonized leaves consumed less, assimilated less, and grew 12 times slower than their ambient fed counterparts. 相似文献
6.
A relationship between carbon dioxide, photosynthetic efficiency and shade tolerance 总被引:2,自引:0,他引:2
Net photosynthesis and transpiration of seedlings from shade tolerant, moderately tolerant and intolerant tree species were measured in ambient carbon dioxide (CO2 ) concentrations ranging from 312 to 734 ppm. The species used, Fagus grandifolia Ehrh. (tolerant), Quercus alba L., Q. rubra L., Liriodendron tulipifera L. (moderately tolerant), Liquidambar styraciflua L. and Pinus taeda L. (intolerant), are found co-occurring in the mixed pine-hardwood forests of the Piedmont region of the southeastern United States. When seedlings were grown in shaded conditions, photosynthetic CO2 efficiency was significantly different in all species with the highest efficiency in the most shade tolerant species, Fagus grandifolia , and progressively lower efficiencies in moderately tolerant and intolerant species. Photosynthetic CO2 efficiency was defined as the rate of increase in net photosynthesis with increase in ambient CO2 concentration. When plants which had grown in a high light environment were tested, the moderately tolerant and intolerant deciduous species had the highest photosynthetic CO2 efficiencies but this capacity was reduced when these species grew in low light. The lowest CO2 efficiency and apparent quantum yield occurred in Pinus taeda in all cases. Water use efficiency was higher for all species in enriched CO2 environments but transpiration rate and leaf conductance were not affected by CO2 concentration. High photosynthetic CO2 efficiency may be advantageous for maintaining a positive carbon balance in the low light environment under a forest canopy. 相似文献
7.
Abstract In cell suspensions of the methanogenic bacterium strain Gö1 or Methanosarcina barkeri H2 formation from methanol in the presence of 2-bromoethanesulfonic acid (BES) was strictly dependent on sodium ions; apparent K S for Na+ , 1.3±0.3 mM.H2 formation was inhibited by the uncoupler tetrachlorosalicylanilide (TCS), but this inhibition could be temporarily overcome, when a sodium pulse (100 mM) was given to the cell suspension. On the other hand, H2 formation from formaldehyde in the presence of BES (rate: 300 nmol H2 /h·mg protein as compared to 25 nmol H2 /h·mg protein from methanol) was not sodium-dependent, not TCS-sensitive and not inhibited by addition of monensin. H2 formation was accompanied by CO2 formation in stoichiometric amounts, 3 H2 :1 CO2 for methanol and 2 H2 :1 CO2 for formaldehyde oxidation. 相似文献
8.
In the CAM plants, Kalanchoë tubiflora (Harvey) Hasset, Sedum morganianum E. Walth and Sedum rubrotinctum R. T. Clausen, the effects of CO2 concentrations on the light-dependent 14 C transfer from the nocturnally synthetized [14C]-malic acid to starch have been studied. CO2 concentrations up to 5 × 103 μ1 1–1 did not inhibit this carbon transfer. Higher CO2 concentrations, however, were increasingly inhibitory. At 104 μl 1–1 CO2 , the carbon transfer was practically prevented.
The malic acid consumption in the light showed the same response to CO2 concentrations as the [l4 C]-transfer. Photosynthesis itself was not inhibited by the CO2 concentrations applied. It is assumed that, during phase III of CAM, light controls the internal CO2 concentration via photosynthesis; and that the internal CO2 concentration then controls the rate of malate decarboxylation. 相似文献
The malic acid consumption in the light showed the same response to CO
9.
Hydrogen cycling in a three-tiered food web growing on the methanogenic conversion of 3-chlorobenzoate 总被引:4,自引:0,他引:4
Abstract A defined 3-chlorobenzoate-degrading methanogenic consortium was constructed by recombining key organisms isolated from a 3-chlorobenzoate-degrading methanogenic sludge enrichment. The organisms comprise a three-tiered food chain which includes: (1) reductive dechlorination of 3-chlorobenzoate; (2) oxidation of benzoate to acetate, H2 and CO2 ; (3) removal of H2 plus CO2 by conversion into methane. The defined consortium, consisting of a dechlorinating organism (DCB-1), a benzoate degrader (BZ-1) and a lithotrophic methanogen ( Methanospirillum strain PM-1) grew well in a basal salts medium supplemented with 3-chlorobenzoate (3.2 mM) as the sole energy source. The chlorine released from the aromatic ringe was recovered in stoichiometric amounts as the chloride ion. The reducing power required for reductive dechlorination was obtained from the hydrogen produced in the acetogenic oxidation of benzoate. One-third of the benzoate-derived hydrogen was recycled via the reductive dechlorination of 3-chlorobenzoate, indicating that the consortium operated as a food web rather than a food chain. 相似文献
10.
To investigate the diurnal variation of stomatal sensitivity to CO2 , stomatal response to a 30 min pulse of low CO2 was measured four times during a 24 h time-course in two Crassulacean acid metabolism (CAM) species Kalanchoe daigremontiana and Kalanchoe pinnata , which vary in the degree of succulence, and hence, expression and commitment to CAM. In both species, stomata opened in response to a reduction in p CO2 in the dark and in the latter half of the light period, and thus in CAM species, chloroplast photosynthesis is not required for the stomatal response to low p CO2 . Stomata did not respond to a decreased p CO2 in K. daigremontiana in the light when stomata were closed, even when the supply of internal CO2 was experimentally reduced. We conclude that stomatal closure during phase III is not solely mediated by high internal p CO2 , and suggest that in CAM species the diurnal variability in the responsiveness of stomata to p CO2 could be explained by hypothesizing the existence of a single CO2 sensor which interacts with other signalling pathways. When not perturbed by low p CO2 , CO2 assimilation rate and stomatal conductance were correlated both in the light and in the dark in both species. 相似文献
11.
KAY-MAY MIYAGI TOSHIHIKO KINUGASA KOUKI HIKOSAKA TADAKI HIROSE 《Global Change Biology》2007,13(10):2161-2170
Elevated atmospheric CO2 concentration ([CO2 ]) stimulates seed mass production in many species, but the extent of stimulation shows large variation among species. We examined (1) whether seed production is enhanced more in species with lower seed nitrogen concentrations, and (2) whether seed production is enhanced by elevated [CO2 ] when the plant uses more N for seed production. We grew 11 annuals in open top chambers that have different [CO2 ] conditions (ambient: 370 μmol mol−1 , elevated: 700 μmol mol−1 ). Elevated [CO2 ] significantly increased seed production in six out of 11 species with a large interspecific variation (0.84–2.12, elevated/ambient [CO2 ]). Seed nitrogen concentration was not correlated with the enhancement of seed production by elevated [CO2 ]. The enhancement of seed production was strongly correlated with the enhancement of seed nitrogen per plant caused by increased N acquisition during the reproductive period. In particular, legume species tended to acquire more N and produced more seeds at elevated [CO2 ] than non-nitrogen fixing species. Elevated [CO2 ] little affected seed [N] in all species. We conclude that seed production is limited primarily by nitrogen availability and will be enhanced by elevated [CO2 ] only when the plant is able to increase nitrogen acquisition. 相似文献
12.
Sensing of atmospheric CO2 by plants 总被引:15,自引:12,他引:3
K. A. MOTT 《Plant, cell & environment》1990,13(7):731-737
Abstract. Despite recent interest in the effects of high CO2 on plant growth and physiology, very little is known about the mechanisms by which plants sense changes in the concentration of this gas. Because atmospheric CO2 concentration is relatively constant and because the conductance of the cuticle to CO2 is low, sensory mechanisms are likely to exist only for intercellular CO2 concentration. Therefore, responses of plants to changes in atmospheric CO2 will depend on the effect of these changes on intercellular CO2 concentration. Although a variety of plant responses to atmospheric CO2 concentration have been reported, most of these can be attributed to the effects of intercellular CO2 on photosynthesis or stomatal conductance. Short-term and long-term effects of CO2 on photosynthesis and stomatal conductance are discussed as sensory mechanisms for responses of plants to atmospheric CO2 . Available data suggest that plants do not fully realize the potential increases in productivity associated with increased atmospheric CO2 . This may be because of genetic and environmental limitations to productivity or because plant responses to CO2 have evolved to cope with variations in intercellular CO2 caused by factors other than changes in atmospheric CO2 . 相似文献
13.
1. We grew the submersed freshwater macrophyte Vallisneria americana under controlled conditions at low and high [CO2 ] to produce litter with high and low tissue nitrogen concentration ([N]), respectively. We then followed mass and nitrogen dynamics in situ in this litter to test the indirect effect of [CO2 ] on its subsequent decomposition and colonisation by macroinvertebrates.
2. Litter from plants grown in high CO2 initially lost mass and N at a significantly lower rate but, by day 30, both litter types had lost about 90% of mass and N. Litter [N] did not appear to govern decay rate.
3. There was no effect of CO2 on the pattern of macroinvertebrate colonisation.
4. The potential exists for high [CO2 ] to increase rates of C and N cycling and, thereby, to increase internal N loading in macrophyte-dominated shallow water ecosystems. 相似文献
2. Litter from plants grown in high CO
3. There was no effect of CO
4. The potential exists for high [CO
14.
In July of 1987, we planted eight 30-cm-tall sour orange tree seedlings in a field of Avondale loam at Phoenix, Arizona and enclosed them in pairs in clear-plastic-wall open-top chambers. Since 18 November of that year, we have continuously pumped ambient air of ≈400 ppmv [CO2 ] through two of these enclosures, while through the other two we have continuously pumped air of ≈700 ppmv [CO2 ]. By the end of the second year of the study, the trunk plus branch volume of the [CO2 ]-enriched trees was ≈2.75 times greater than that of the ambient-treatment trees. Three years later, this factor had dropped to ≈2.0; but the decline in the [CO2 ]-enriched/ambient-treatment ratio of trunk plus branch volume was nearly perfectly offset by the relative fruit production advantage enjoyed by the [CO2 ]-enriched trees over that period. In Years 6, 7 and 8, however, there was a moderate drop in total productivity enhancement. This decline may be a delayed acclimation response, or it could be due to enhanced self-shading in the [CO2 ]-enriched trees or to the fact that, starting early in Year 6, many branches of the [CO2 ]-enriched trees grew all the way to the walls of their enclosures, so that many blossoms and young fruit were destroyed by intermittent physical trauma produced by the action of wind against the taut plastic in that year and in all succeeding years. Hence, we will have to maintain our experiment for several more years for this lateral growth obstruction to occur to the same degree in the ambient-air chambers as it has in the [CO2 ]-enriched chambers, in order to determine the long-term equilibrium effects of atmospheric [CO2 ] enrichment in a spatially confined environment. 相似文献
15.
Plantago lanceolata L. and Trifolium repens L. were grown for 16 wk in ambient (360 μmol mol−1 ) and elevated (610 μmol mol−1 ) atmospheric CO2 . Plants were inoculated with the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe and given a phosphorus supply in the form of bonemeal, which would not be immediately available to the plants. Seven sequential harvests were taken to determine whether the effect of elevated CO2 on mycorrhizal colonization was independent of the effect of CO2 on plant growth. Plant growth analysis showed that both species grew faster in elevated CO2 and that P. lanceolata had increased carbon allocation towards the roots. Elevated CO2 did not affect the percentage of root length colonized (RLC); although total colonized root length was greater, when plant size was taken into account this effect disappeared. This finding was also true for root length colonized by arbuscules. No CO2 effect was found on hyphal density (colonization intensity) in roots. The P content of plants was increased at elevated CO2 , although both shoot and root tissue P concentration were unchanged. This was again as a result of bigger plants at elevated CO2 . Phosphorus inflow was unaffected by CO2 concentrations. It is concluded that there is no direct permanent effect of elevated CO2 on mycorrhizal functioning, as internal mycorrhizal development and the mycorrhizal P uptake mechanism are unaffected. The importance of sequential harvests in experiments is discussed. The direction for future research is highlighted, especially in relation to C storage in the soil. 相似文献
16.
KRISTINA A. STINSON † JIMMY H. TRAN‡ JENNIFER L. PETZOLD§ F. A. BAZZAZ 《Global Change Biology》2006,12(9):1680-1689
Testing whether and how subordinate individuals differ from dominants in the utilization of enriched CO2 atmospheres is important for understanding future stand and community structure. We hypothesized that subordinate and dominant Ambrosia artemisiifolia L. (Asteraceae) (common ragweed) plants growing in dense stands would not equally acquire or utilize carbon gains from CO2 -enrichment, and that the resulting disproportionate growth gains to subordinates would reduce size inequalities in competing stands. We grew experimental stands of A. artemisiifolia in either ambient (360 μL L−1 ) or twice ambient (720 μL L−1 ) levels of atmospheric CO2 . We compared the relative growth, photosynthetic capacity, and architecture of subordinate and dominant plants in each treatment, and assessed size inequalities using the stand-level coefficient of variation (CV). In elevated CO2 , plants grew larger, but subordinate plants shifted more mass to upper stem allocation than dominants. Dominant plants demonstrated reduced leaf-level photosynthetic gains in elevated CO2 compared with subordinate plants. Reduced CVs in plant size reflected smaller proportional growth gains by dominants over subordinates in elevated vs. ambient stands. We conclude that differences in the architectural and physiological responses of subordinate and dominant ragweed plants reduce competition and allow subordinate plants to catch up to dominants in elevated CO2 conditions. 相似文献
17.
Elly Spijkerman 《Physiologia plantarum》2008,133(1):41-48
Chlamydomonas acidophila Negoro is a green algal species abundant in acidic waters (pH 2–3.5), in which inorganic carbon is present only as CO2 . Previous studies have shown that aeration with CO2 increased its maximum growth rate, suggesting CO2 limitation under natural conditions. To unravel the underlying physiological mechanisms at high CO2 conditions that enables increased growth, several physiological characteristics from high- and low-CO2 -acclimated cells were studied: maximum quantum yield, photosynthetic O2 evolution (Pmax ), affinity constant for CO2 by photosynthesis (K0.5,p ), a CO2 -concentrating mechanism (CCM), cellular Rubisco content and the affinity constant of Rubisco for CO2 (K0.5,r ). The results show that at high CO2 concentrations, C. acidophila had a higher K0.5,p , Pmax , maximum quantum yield, switched off its CCM and had a lower Rubisco content than at low CO2 conditions. In contrast, the K0.5,r was comparable under high and low CO2 conditions. It is calculated that the higher Pmax can already explain the increased growth rate in a high CO2 environment. From an ecophysiological point of view, the increased maximum growth rate at high CO2 will likely not be realised in the field because of other population regulating factors and should be seen as an acclimation to CO2 and not as proof for a CO2 limitation. 相似文献
18.
Abstract. The anthropophilic malaria mosquito Anopheles gambiae sensu stricto responds to CO2 and human skin emanations. How these odorants affect the behaviour of this mosquito species is studied in an olfactometer. Carbon dioxide is released either as an homogeneous plume or in a turbulent fashion at two different positions from the trap entrance. Anopheles gambiae is deterred from entering a trap with CO2 as the only kairomone, when presented as an homogeneous or turbulent plume. This effect is completely overcome by the addition of skin emanations to the CO2 plume, with a high proportion of mosquitoes found in the trap with skin emanations. Rearrangement of the position of the turbulent CO2 source so that it is 5 cm downwind of the trap entrance overcomes the deterrent effect of CO2 . Carbon dioxide alone, however, does not elicit higher proportions caught compared with clean air. Further studies with the CO2 source positioned 5 cm downwind of the trap entrance show that skin emanations alone result in fewer mosquitoes entering the trap than CO2 + skin emanations. Skin emanations induce more mosquitoes to fly into a trap than a synthetic blend of NH3 + l-lactic acid when both are combined with CO2 . It is concluded that CO2 is a poor kairomone when offered alone and that its presence in the plume at the trap entrance deters mosquitoes from entering. By contrast, when positioned just downwind of the trap entrance, CO2 appears to guide mosquitoes to the vicinity of the trap, where skin emanations then become the principle attractant, causing the mosquito trap entry response. The results of the study have implications for the design of odour-baited traps for this mosquito species. 相似文献
19.
Heterotrophic (Dark) CO2 Fixation by Euglena gracilis. Possible regulation by tricarboxylic acid cycle intermediates 总被引:1,自引:0,他引:1
SYNOPSIS. Heterotrophic (dark) CO2 fixation by Euglena gracilis strain Z varies with phase of batch culture and mode of nutrition. Dark CO2 fixation increased transiently during the growth of cells under photoautotrophic (CO2 , light) and heterotrophic (glucose, dark) conditions. Cells grown heterotrophically with acetate or ethanol had no transient increase in fixation. The addition of acetate to a heterotrophically growing culture during the period of increasing dark CO2 fixation resulted in rapid elimination of this fixation. The results suggest that dark CO2 fixation in Euglena functions in anaplerotic feeding of the tricarboxylic acid cycle, drained by biosyntheses during growth. Induction of the glyoxylate cycle by acetate may provide an alternate source of tricarboxylic cycle intermediates, obviating the requirement for dark CO2 fixation as a source of the intermediates. 相似文献
20.
1. Ten herbaceous species were grown over a 4-month period under ambient (360 μmol mol–1 ) and elevated (610 μmol mol–1 ) atmospheric CO2 conditions. Plants were inoculated with the arbuscular mycorrhizal (AM) fungus Glomus mosseae and given a phosphorus (P) supply which was not immediately available to the plants.
2. Multiple harvests were taken in order to determine whether the effect of elevated CO2 on mycorrhizal colonization and phosphorus inflow was independent of its effect on plant growth.
3. All species grew faster under elevated CO2 and carbon partitioning was altered, generally in favour of the shoots. All species responded similarly to elevated CO2 .
4. Elevated CO2 did not affect the percentage of root length colonized by AM fungi, but the total amount of colonized root length was increased, because the plants were bigger.
5. Elevated CO2 increased total P content, but had little or no effect on P concentration. At a given age, P inflow was stimulated by elevated CO2 , but when root length was taken into account the CO2 effect disappeared.
6. In these host species there is no evidence for a direct effect of elevated CO2 on mycorrhizal functioning, because both internal mycorrhizal colonization and P inflow are unaffected.
7. Future research should concentrate on the potential for carbon flow to the soil via the external mycelial network. 相似文献
2. Multiple harvests were taken in order to determine whether the effect of elevated CO
3. All species grew faster under elevated CO
4. Elevated CO
5. Elevated CO
6. In these host species there is no evidence for a direct effect of elevated CO
7. Future research should concentrate on the potential for carbon flow to the soil via the external mycelial network. 相似文献