Microcystin content ofMicrocystis aeruginosa is modulated by nitrogen uptake rate relative to specific growth rate or carbon fixation rate

2005 ◽  
Vol 20 (3) ◽  
pp. 257-262 ◽  
Author(s):  
T. G. Downing ◽  
C. Meyer ◽  
M. M. Gehringer ◽  
M. van de Venter
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Nitrogen Uptake ◽  
Uptake Rate ◽  
Carbon Fixation ◽  
Specific Growth ◽  
Fixation Rate ◽  
Nitrogen Uptake Rate

scholarly journals Diatom performance in a future ocean: interactions between nitrogen limitation, temperature, and CO2-induced seawater acidification

2018 ◽  
Vol 75 (4) ◽  
pp. 1451-1464 ◽  
Author(s):  
Futian Li ◽  
John Beardall ◽  
Kunshan Gao
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Carbon Fixation ◽  
Specific Growth ◽  
Thalassiosira Pseudonana ◽  
Elevated Pco2 ◽  
Negative Effects ◽  
Seawater Acidification ◽  
Different Temperatures ◽  
Upward Transport

Abstract Phytoplankton cells living in the surface waters of oceans are experiencing alterations in environmental conditions associated with global change. Given their importance in global primary productivity, it is of considerable concern to know how these organisms will perform physiologically under the changing levels of pH, temperatures, and nutrients predicted for future oceanic ecosystems. Here we show that the model diatom, Thalassiosira pseudonana, when grown at different temperatures (20 or 24 °C), pCO2 (400 or 1000 µatm), and nitrate concentrations (2.5 or 102.5 µmol l−1), displayed contrasting performance in its physiology. Elevated pCO2 (and hence seawater acidification) under the nitrate-limited conditions led to decreases in specific growth rate, cell size, pigment content, photochemical quantum yield of PSII, and photosynthetic carbon fixation. Furthermore, increasing the temperature exacerbated the negative effects of the seawater acidification associated with elevated pCO2 on specific growth rate and chlorophyll content under the N-limited conditions. These results imply that a reduced upward transport of nutrients due to enhanced stratification associated with ocean warming might act synergistically to reduce growth and carbon fixation by diatoms under progressive ocean acidification, with important ramifications for ocean productivity and the strength of the biological CO2 pump.

THE KINETICS OF METABOLISM OF GIBBERELLA FUJIKUROI IN STIRRED CULTURE

1964 ◽  
Vol 10 (3) ◽  
pp. 407-444 ◽  
Author(s):  
A. Borrow ◽  
Sheila Brown ◽  
E. G. Jefferys ◽  
R. H. J. Kessell ◽  
Eithne C. Lloyd ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Nitrogen Uptake ◽  
Exponential Growth ◽  
Ammonium Acetate ◽  
Specific Growth ◽  
Dry Weight ◽  
Gibberella Fujikuroi ◽  
Ammonium Tartrate ◽  
Kinetics Of

Some aspects are described of the kinetics of the growth of Gibberella fujikuroi in nitrogen-limited media containing either ammonium nitrate, ammonium acetate, ammonium tartrate, urea, or glycine. Also varied were inoculum size, agitation rate, pH, and initial concentrations of glucose and nitrogen source. The significance of kinetic parameters used in this, and published studies, is discussed.A lag phase was only found on ammonium acetate media or when high concentrations of glucose were present. Early growth was exponential on all nitrogen sources. On ammonium acetate the specific growth rate decreased at a dry weight of ca. 1 mg/g WS (Whole unfiltered Sample). On ammonium nitrate, early exponential growth utilized more NH3-nitrogen than NO3-nitrogen with a concomitant decrease in pH. In the range pH 3.0–2.8 NH3-nitrogen uptake and dry weight increase ceased, but NO3-nitrogen uptake continued, and the pH increased until growth and NH3-nitrogen uptake restarted. This pattern could be repeated. Finally, exponential growth was resumed at a low specific growth rate. On glycine, urea, and ammonium tartrate media, exponential growth continued to a dry weight of about 7 mg/g WS. During this period the uptakes relative to dry weight (contributions) of glucose, nitrogen, phosphate, and magnesium remained constant and were unaffected by the rate of agitation, as also was the specific growth rate, but the latter decreased with increasing glucose concentration.A period of linear growth could follow the exponential period. The contribution of glucose was greater, and that of phosphate and magnesium less, than during exponential growth. The dry weight at which exponential growth changed to linear growth was greater the higher the rate of agitation, and this change may be a response to oxygen restriction.After nitrogen exhaustion, fat and carbohydrate accumulation in the cells largely accounted for the increase in dry weight. The specific rates of dry weight increase and glucose uptake remained constant over the lower range of initial nitrogen concentrations. Both rates decreased with increasing nitrogen over the higher range.Gibberellic acid production began at, or soon after, nitrogen exhaustion. The amount present increased linearly with time. The productivity decreased with increasing glucose concentration, and first increased and then decreased with increasing initial nitrogen. The maximum amount produced was proportional to the initial nitrogen provided. Some published results are discussed in the light of these relations.

The growth and development of some barley varieties in response to irrigation and nitrogen fertilizer

1969 ◽  
Vol 72 (3) ◽  
pp. 467-474 ◽  
Author(s):  
E. J. M. Kirby
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Leaf Area ◽  
Nitrogen Uptake ◽  
Nitrogen Fertilizer ◽  
Specific Growth ◽  
Leaf Growth ◽  
Specific Rate ◽  
High Fertility ◽  
Area Index

SUMMARYIn an experiment to investigate growth in relation to nitrogen concentration and nitrogen uptake, Proctor was compared with four other varieties of barley at two levels of irrigation and two levels of nitrogen fertilizer by means of weekly samples throughout the growing season. The varieties were Deba Abed, a new variety recommended for high fertility conditions where feeding quality grain is required, and three exotic varieties, chosen for their high concentration of nitrogen in the grain.Irrigation stimulated tillering, although certain varieties responded more strongly than others; irrigation also led to a higher specific growth rate. Certain of the exotic varieties had high growth rates early in the season but growth fell off earlier due to earlier ear emergence. Maximum leaf area index was greater in the irrigated treatment at the high nitrogen fertilizer level. The adapted varieties had higher maximum leaf area indices than the exotic varieties, although some of the exotics had higher rates of leaf area growth early in the season; there were also differences in the way in which the varieties responded to irrigation. Irrigation and variety both affected the rate at which the percentage nitrogen in the shoot fell with time.Analysis of these data indicates that nitrogen uptake early in the season was an important factor determining the total amount of nitrogen taken up by the plant. It was also shown that the relative rate of decline of the specific growth rate and the specific rate of nitrogen uptake differed between varieties. Analysis of the specific growth rate indicated that differences in leaf growth, rather than net assimilation rate, led to the varietal differences. The differential response to irrigation is discussed with reference to drought resistance.

scholarly journals Feed demand behavior in sea bass juveniles: Effects on individual specific growth rate variation and health (inter-individual and inter-group variation)

Aquaculture ◽  
2008 ◽  
Vol 274 (1) ◽  
pp. 87-95 ◽  
Author(s):  
S. Millot ◽  
M.-L. Bégout ◽  
J. Person-Le Ruyet ◽  
G. Breuil ◽  
C. Di-Poï ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Sea Bass ◽  
Rate Variation ◽  
Group Variation

scholarly journals Control of the specific growth rate of Bacillus subtilis for the production of biosurfactant lipopeptides in bioreactors with foam overflow

2010 ◽  
Vol 45 (11) ◽  
pp. 1800-1807 ◽  
Author(s):  
S. Chenikher ◽  
J.S. Guez ◽  
F. Coutte ◽  
M. Pekpe ◽  
P. Jacques ◽  
...  
Keyword(s):  
Growth Rate ◽  
Bacillus Subtilis ◽  
Specific Growth Rate ◽  
Specific Growth
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