Biomass Reduction and Mineralization Increase Due to the Ciliate Tetrahymena pyriformis Grazing on the Bacterium Pseudomonas fluorescens

1994 ◽  
Vol 29 (7) ◽  
pp. 119-128 ◽  
Author(s):  
C. H. Ratsak ◽  
B. W. Kooi ◽  
H. W. van Verseveld
Keyword(s):  
Growth Rates ◽  
Growth Parameters ◽  
Waste Water Treatment ◽  
High Growth ◽  
Tetrahymena Pyriformis ◽  
Lower Growth ◽  
Purification Efficiency ◽  
High Purification ◽  
Biomass Reduction ◽  
Sludge Production

The currently high sludge production and increasing processing costs call for waste-water treatment plants with high purification efficiency and low biomass production. We studied the latter issue through two-stage chemostat cascades to assess the overall biomass reduction due to ciliate grazing. The bacteria were cultured in the first chemostat whereas the ciliates, grazing on the bacteria from the first chemostat, were cultured in the second chemostat. Mathematical modelling was used to describe the bacteria/ciliate dynamics and some of the growth parameters were fitted. In the second chemostat 22-44% of the carbon originating from the first chemostat was mineralized to CO2. An extra biomass reduction of 12-43% was possible due to grazing by the ciliates. At lower growth rates of the ciliates the extra biomass reduction was higher than at high growth rates. This finding is auspicious, suggesting that predator organisms indeed can reduce sludge production.

scholarly journals No selection for greater size in an introduced grass invading semiarid grassland

Botany ◽  
2016 ◽  
Vol 94 (10) ◽  
pp. 957-966 ◽  
Author(s):  
Malin J. Hansen ◽  
Scott D. Wilson
Keyword(s):  
Great Plains ◽  
Artificial Selection ◽  
Growth Rates ◽  
Native Species ◽  
High Growth ◽  
Tiller Number ◽  
Lower Growth ◽  
Semiarid Grassland ◽  
Growing Seasons ◽  
Common Gardens

Exotic species are often planted for restoration or to enhance production. Populations that expand from plantings may undergo selection in directions that differ from those produced by artificial selection prior to planting. Here, we test whether a highly productive grass, Agropyron cristatum (L.) Gaertn., introduced to the semiarid Great Plains of North America, evolves during invasion from seeded fields into native grassland. We grew individuals of A. cristatum from six seeded populations and 12 invading populations in 12 common gardens separated by 0.5–12 km for two growing seasons. Contrary to expectations, individuals from invading populations did not have significantly greater tiller number or growth (increase in tiller number) than did individuals from seeded populations, suggesting that they have not undergone evolution towards increased invasion ability through increased size or growth. Instead, there was a general trend for individuals from invading populations to have lower growth rates and fewer tillers when grown without neighbours. Large size or high growth rates arising from artificial selection prior to introduction may be disadvantageous to populations invading semiarid grassland on dry, nutrient-poor soils. In this case, evolution may have resulted in convergence between the relatively large planted species and the smaller native species.

scholarly journals Growth Rate-Dependent Control in Enterococcus faecalis: Effects on the Transcriptome and Proteome, and Strong Regulation of Lactate Dehydrogenase

2011 ◽  
Vol 78 (1) ◽  
pp. 170-176 ◽  
Author(s):  
Ibrahim Mehmeti ◽  
Ellen M. Faergestad ◽  
Martijn Bekker ◽  
Lars Snipen ◽  
Ingolf F. Nes ◽  
...  
Keyword(s):  
Growth Rate ◽  
Lactate Dehydrogenase ◽  
Enterococcus Faecalis ◽  
Growth Rates ◽  
Posttranscriptional Regulation ◽  
High Growth ◽  
Regulation Of Expression ◽  
Lower Growth ◽  
Content Type ◽  
Rate Dependent

ABSTRACTEnterococcus faecalisV583 was grown in a glucose-limited chemostat at three different growth rates (0.05, 0.15, and 0.4 h−1). The fermentation pattern changed with growth rate, from a mostly homolactic profile at a high growth rate to a fermentation dominated by formate, acetate, and ethanol production at a low growth rate. A number of amino acids were consumed at the lower growth rates but not by fast-growing cells. The change in metabolic profile was caused mainly by decreased flux through lactate dehydrogenase. The transcription ofldh-1, encoding the principal lactate dehydrogenase, showed very strong growth rate dependence and differed by three orders of magnitude between the highest and the lowest growth rates. Despite the increase inldh-1 transcript, the content of the Ldh-1 protein was the same under all conditions. Using microarrays and quantitative PCR, the levels of 227 gene transcripts were found to be affected by the growth rate, and 56 differentially expressed proteins were found by proteomic analyses. Few genes or proteins showed a growth rate-dependent increase or decrease in expression across the whole range of conditions, and many showed a maximum or minimum at the middle growth rate (i.e., 0.15 h−1). For many gene products, a discrepancy between transcriptomic and proteomic data were seen, indicating posttranscriptional regulation of expression.

Sporulation of Streptomyces antibioticus ETHZ 7451 in submerged culture

1992 ◽  
Vol 38 (8) ◽  
pp. 769-773 ◽  
Author(s):  
Isabel S. Novella ◽  
Covadonga Barbés ◽  
Jesús Sánchez
Keyword(s):  
Growth Rates ◽  
Submerged Culture ◽  
Carbon Sources ◽  
High Growth ◽  
Nitrogen Sources ◽  
Lower Growth ◽  
Streptomyces Antibioticus ◽  
Sporulation Efficiency ◽  
Repressive Effect ◽  
Casamino Acids

Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual for Streptomyces spores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions. Key words: Streptomyces antibioticus, sporulation.

The Influence of Hydrogen Dilution and Substrate Temperature in Hot-Wire Deposition of Amorphous and Microcrystalline Silicon With Filament Temperatures Between 1900 And 2500 °C

1996 ◽  
Vol 420 ◽  
Author(s):  
J. P. Conde ◽  
P. Brogueira ◽  
R. Castanha ◽  
V. Chu
Keyword(s):  
Substrate Temperature ◽  
Growth Rates ◽  
Chemical Vapor ◽  
High Growth ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Crystalline Fraction ◽  
Lower Growth ◽  
Filament Temperature ◽  
Hydrogen Dilution

AbstractThe effect of hydrogen dilution and substrate temperature on the optoelectronic and structural properties of thin films deposited by hot-wire chemical vapor deposition with filament temperatures between 1900 and 2500 °C from silane and hydrogen are studied. Amorphous silicon films are obtained at high deposition rates for hydrogen dilutions below 90%. The deposition rate scales approximately linearly with the filament temperature in this regime. Microcrystalline films are obtained for hydrogen dilution above 90%, independently of the filament temperature and substrate temperature, with much lower growth rates. The Raman spectrum of these films shows high crystalline fraction and small grain size. High conductivity films, typical of microcrystalline silicon, with high growth rates were achieved by either increasing the substrate temperature at low hydrogen dilution, or by using a hydrogen dilution just at the amorphous to microcrystalline transition point.

The Importance of Comparative Growth Rates in Determining the Canopy Composition of Tasmanian Rainforest

1995 ◽  
Vol 43 (3) ◽  
pp. 243 ◽  
Author(s):  
J Read
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
High Growth ◽  
Forest Stands ◽  
Lower Growth ◽  
Naturally Occurring ◽  
Significant Difference ◽  
Pot Trials ◽  
Canopy Composition ◽  
Study Sites

Growth rates of the rainforest canopy species Atherosperma moschatum Labill., Eucryphia lucida (Labill.) Baill., Nothofagus cunninghamii (Hook.) Oerst., Athrotaxis selaginoides D.Don and Phyllocladus aspleniifolius (Labill.) Hook.f. were measured in naturally-occurring seedlings and in seedlings grown in glasshouse pot trials. The highest field growth rates were recorded in N. cunninghamii on lowland sites on fertile, well-drained soils. On poorer soils, growth rates of N. cunninghamii were lower and there was little difference in growth rates between species. On the most acidic and probably infertile soil, the growth rate of P. aspleniifolius was 1.4 times higher than that of N. cunninghamii, although not significantly different at the 95% level. Similar trends in growth rates were recorded in pot trials. High growth rates were recorded in N. cunninghamii and E. lucida on fertile, well-drained soils, with generally lower growth rates in A. moschatum, P. aspleniifolius and A. selaginoides. No significant difference in growth rate was recorded among N. cunninghamii, E. lucida, A. moschatum and P. aspleniifolius when grown in poor soils or in low nutrient treatments. The trends in comparative growth rates correlate with the measured canopy composition of the study sites. Nothofagus cunninghamii dominates forest stands on sites where it has a clearly superior growth rate compared with co-occurring light-demanding species. Mixed canopies occur on sites where there is little or no difference between species' growth rates. However, not all patterns of canopy dominance can be explained by comparative growth rates alone. For example, P. aspleniifolius commonly dominates forest stands at low to mid-altitude where growth rates of all species are very low, but without necessarily a higher growth rate in P. aspleniifolius than in co-occurring species. The results of the growth rate studies are integrated with some other aspects of the biology of these species in a discussion of the mechanisms determining canopy composition of Tasmanian rainforests.

GROWTH OF PIKE-PERCH SANDER LUCIOPERCA (L., 1758) (PERCIDAE) IN RESERVOIRS OF K. SATPAYEV’S CHANNEL

2018 ◽  
pp. 59-68
Author(s):  
Saule Zhangirovna Asylbekova ◽  
Kuanysh Baibulatovich Isbekov ◽  
Vladimir Nickolaevich Krainyuk
Keyword(s):  
Growth Rates ◽  
Growth Dynamics ◽  
High Growth ◽  
Water Bodies ◽  
Volga River ◽  
Trophic Resources ◽  
Pike Perch ◽  
The Amur River ◽  
Back Calculation ◽  
Abiotic And Biotic Factors

Pike-perch is an invader for the water basins of Central Kazakhstan. These species have stable self-reproductive populations in the regional waters. Back calculation method was used to investigate pike-perch growth rates in reservoirs of K. Satpayev’s channel. For comparison, the data from the other water bodies (Vyacheslavsky and Sherubay-Nurinsky water reservoirs) were used, as well as literature data. Pike-perch species from the investigated waters don’t show high growth rates. The populations from the reservoirs of K. Satpayev’s channel have quite similar growth rates with populations from the Amur river, from a number of reservoirs in the Volga river basin and from the reservoir in Spain. Sexual differences in growth have not been observed. Evaluating possible influence of various abiotic and biotic factors on the growth rate of pike-perch in the reservoirs of K. Satpayev’s channel was carried out. It has been stated that the availability of trophic resources cannot play a key role in growth dynamics because of their high abundance. Morphology of water bodies also does not play a role, as well as chromaticity, turbidity and other optical water indicators. It can be supposed that the main factor influencing growth of pike perch is the habitat’s temperature. This factor hardly ever approaches optimal values for the species in reservoirs of K. Satpaev’s channel. The possible influence of fishing selectivity on pike-perch growth rates was also evaluated. Currently, there has been imposed a moratorium on pike-perch catch. However, pike-perch is found in by-catches and in catches of amateur fishermen. It should be said that such seizures have an insignificant role in the dynamics of growth rates.

Biology of Gadus morhua in Ogac Lake, a Landlocked Fiord on Baffin Island

1967 ◽  
Vol 24 (12) ◽  
pp. 2573-2594 ◽  
Author(s):  
David G. Patriquin
Keyword(s):  
Growth Rates ◽  
Gadus Morhua ◽  
Environmental Variability ◽  
Sea Urchins ◽  
High Growth ◽  
Baffin Island ◽  
Meristic Characters ◽  
Large Size ◽  
Fin Ray ◽  
High Length

Gadus morhua L. occurs in Ogac Lake, a salt, meromictic lake on Baffin Island that receives influxes of seawater only during the highest summer tides. Cod of the order of 10,000 of lengths 25 cm and greater and 500 of lengths greater than 60 cm were present. The size ranges for various ages far exceeded those of oceanic populations. Feeding conditions were poor, and sea urchins predominated in the diet. Large cod (greater than 50 cm) were highly cannibalistic, and it was estimated that they consume of the order of 3500 fish of 20–40 cm annually. Maturation occurred at the unusually large size of 85 cm in females, and at about 65 cm in males. Apparently many of the cod never reach these sizes. Spawning was from late May to early July in 1962, and initiation of spawning appeared to be related to light. The hatching of cod larvae coincided with the appearance of the nauplii of the dominant copepod in the lake. Egg size was highly variable and exhibited a curious bimodalism. Variation in vertebral and fin-ray counts was slight in spite of high environmental variability, and thus appears largely genetically controlled. Possibly the first inhabitants came from Greenland stocks, which have high growth rates similar to the faster growing cod in the lake, and similar high length at maturity. Meristic characters also suggest affinity with Greenland rather than Labrador cod. The hydrography of the area and the possibilities of larval drift or adult migration into the lake are discussed. Cannibalism must exert continuing selection for high growth rates, but very poor feeding conditions and hierarchial dominance effects probably prevent general attainment of high growth rates.

Growth and movement of the South African abalone Haliotis midae: A reassessment

1995 ◽  
Vol 46 (3) ◽  
pp. 583 ◽  
Author(s):  
RJQ Tarr
Keyword(s):  
South African ◽  
Growth Rates ◽  
Growth Parameters ◽  
Eastern Coast ◽  
Island Population ◽  
Western Coast ◽  
Eastern Cape ◽  
The South ◽  
Significant Difference ◽  
Haliotis Midae

Growth rates of a number of Haliotis midae populations around the South African coast were studied by means of tagging. These populations ranged from the cool waters of the western coast to the more temperate environment of the eastern Cape. Standard von Bertalanffy growth curves were fitted and growth parameters derived. These ranged from 0.19 to 0.25 for K, the average rate at which L∞ is approached, and from 156 to 173 for L∞, the average theoretical maximum length. These indicate far higher growth rates than were previously published for this commercially fished species, and the reasons for this difference are discussed. The expectation that growth rates would be fastest in the warmer eastern Cape waters was not realized, there being no significant difference in growth between the Bird Island population on the eastern coast and the Robben Island population on the western coast. These new growth parameters indicate that H. midae in the commercial fishery grounds is attaining sexual maturity some four years earlier, and the minimum legal size some five years earlier, than previously considered. This has considerable significance for modelling studies presently underway. Movement of a small population of adult H. midae was studied over a three-year period, after which 47% of the original abalone were still present on the study site. Of these, 81.5% still occupied exactly the same position on the rocks. This indicates that H. midae that have located an optimum habitat, and that are not disturbed, tend not to move.

Sign in / Sign up

Export Citation Format

Share Document