SILICON METABOLISM IN DIATOMS: IV. GROWTH AND FRUSTULE FORMATION IN NAVIGULA PELLICULOSA

1957 ◽  
Vol 3 (3) ◽  
pp. 427-433 ◽  
Author(s):  
Joyce C. Lewin
Keyword(s):  
Exponential Growth ◽  
Silicon Content ◽  
Dry Weight ◽  
Silicate Solution ◽  
Average Thickness ◽  
Silicon Metabolism ◽  
Doubling Times ◽  
Navicula Pelliculosa

The cells of Navicula pelliculosa (Bréb.) Hilse, when grown in media which contained 3.5, 8.3, and 34.0 mg. Si per liter, reproduced with generation (doubling) times of 20.4, 13.7, and 13.1 hours respectively. The degree of silicification of the cells in each culture initially fell with increasing population. After exponential growth had ceased, this value varied between 0.8 × 10−9 and 2.2 × 10−9 mg. Si per cell, depending on the amount of silicon originally present in the medium and on the age of the culture. When placed in a fresh silicate solution, the cells took up additional silicate with increases in silicon content of 50%, 90%, and 15%, respectively. Silica (SiO2) may represent from 4% to 22% of the dry weight of the cells. The average thickness of the frustules has been calculated to range between 200 and 600 Å.

scholarly journals Large scale laboratory cultures of Ankistrodesmus gracilis (Reisch) Korsikov (Chlorophyta) and Diaphanosoma biergei Korinek, 1981 (Cladocera)

2008 ◽  
Vol 68 (4) ◽  
pp. 875-883 ◽  
Author(s):  
LH. Sipaúba-Tavares ◽  
AML. Pereira
Keyword(s):  
Exponential Growth ◽  
Large Scale ◽  
Light Availability ◽  
Sharp Decrease ◽  
Dry Weight ◽  
Good Alternative ◽  
Production Costs ◽  
Determining Factors ◽  
Weight Protein ◽  
Low Costs

Large-scale lab culture of Ankistrodesmus gracilis and Diaphanososma birgei were evaluated by studying the biology and biochemical composition of the species and production costs. Ankistrodesmus gracilis presented exponential growth until the 6th day, with approximately 144 x 10(4) cells.mL-1, followed by a sharp decrease to 90 x 10(4) cells.mL-1 (8th day). Algae cells tended to increase again from the 11th day and reached a maximum of 135 x 10(4) cells.mL-1 on the 17th day. D. birgei culture showed exponential growth until the 9th day with 140 x 10² individuals.L-1, and increased again as from the 12th day. Algae A. gracilis and zooplankton D. birgei contain 47 to 70% dry weight protein and over 5% dry weight carbohydrates. The most expensive items in the context of variable costs were labor and electricity. Data suggested that temperature, nutrients, light availability and culture management were determining factors on productivity. Results indicate that NPK (20-5-20) may be used directly as a good alternative for mass cultivation when low costs are taken into account, promoting adequate growth and nutritional value for cultured A. gracilis and D. birgei.

Aggressiveness of Spanish isolates of Xylella fastidiosa to almond plants of different cultivars under greenhouse conditions

2021 ◽  
Author(s):  
Aina Baró ◽  
Laura Montesinos ◽  
Esther Badosa ◽  
Emilio Montesinos
Keyword(s):  
Dose Response ◽  
Exponential Growth ◽  
Exponential Growth Phase ◽  
In Planta ◽  
Plant Parts ◽  
Pathogen Dynamics ◽  
Xylem Tissue ◽  
Differential Pattern ◽  
Sequence Types ◽  
Doubling Times

The aggressiveness of Spanish isolates of X. fastidiosa, representing different sequence types, were studied in almond plants of several cultivars by means of the dynamics of the population levels and symptoms, colonization and spread, and dose-response relationships. Pathogen dynamics in almond plants under greenhouse conditions showed doubling times of 2.1 to 2.5 days during the exponential growth phase, with a maximum population size around 35 dpi. A differential pattern in population dynamics was observed between sap and xylem tissue after the exponential growth, as population levels in the xylem tissue remained stable while viable cells in sap decreased. Population levels were higher in two upwards zones than in downwards zones, with respect to the inoculation area. The first symptoms were observed between 20 and 60 dpi, and disease severity increased over time at doubling times of 30 days, with a maximum observed at 120 dpi. Strains tested showed differences in population levels in the cultivars studied and were able to spread with different intensity from contaminated plant parts to new growing shoots after pruning. Two almond isolates showed a different performance in dose-response relationships when inoculated in Avijor cultivar. While IVIA 5387.2 reached higher population levels but showed high ED50 and MID values, IVIA 5901.2 showed low population levels as well as low ED50 and MID values. This study raises implications for the epidemiology of X. fastidiosa in almond crops, estimating doubling times of the pathogen in planta and of symptoms development, as well as showing differential aggressiveness between strains.

Seasonal Development of Ice Algae and its Prediction from Environmental Factors near Resolute, N.W.T., Canada

1989 ◽  
Vol 46 (10) ◽  
pp. 1793-1804 ◽  
Author(s):  
Harold E. Welch ◽  
Martin A. Bergmann
Keyword(s):  
Algal Biomass ◽  
Algal Growth ◽  
Dry Weight ◽  
Seasonal Development ◽  
Detectable Effect ◽  
Distribution Data ◽  
First Year ◽  
Ice Algae ◽  
Doubling Times ◽  
Snow Thickness

Development of ice algae growing at the bottom of first-year congelation sea ice near Resolute, N.W.T. (75°N) was studied 1984–86. Ice algae moved downwards 1.5 cm∙d−1 as the ice thickened. Biomass increased logarithmically with doubling times on the order of 4–8 d, reaching over 150 mg chlorophyll a∙m−2 in 1985 and over 300 mg∙m−2 in 1986. Algal development was synchronous up to 120 km from the main study site. Snow cover controlled algal growth indirectly by its effect on light. Algal biomass was predictable from snow thickness and date, or snow thickness and light equally well (overall r2 = 0.77 for 1985 and 1986 combined). Ice-associated amphipods were correlated with reduced ice algal biomass, but Si and NO3 concentrations and tidal cycle had little or no detectable effect. Snow depth frequency distribution data are given. Peak ice algal biomass under low snow in 1986 was equal to 0.5 t dry weight and 4.7 kg Si∙ha−1.

scholarly journals Biodegradation of phenanthrene in an anaerobic batch reactor: Growth kinetics

2010 ◽  
Vol 16 (2) ◽  
pp. 157-165 ◽  
Author(s):  
H.S. Nasrollahzadeh ◽  
G.D. Najafpour ◽  
M. Pazouki ◽  
H. Younesi ◽  
A.A. Zinatizadeh ◽  
...  
Keyword(s):  
Microbial Growth ◽  
Microbial Population ◽  
Specific Growth ◽  
Batch Reactor ◽  
Kinetic Studies ◽  
Dry Weight ◽  
Maximum Cell ◽  
High Concentrations ◽  
Specific Growth Rates ◽  
Doubling Times

The purpose of present research was to demonstrate the ability of mixed consortia of microorganisms to degrade high concentrations of phenanthrene (PHE) as the sole carbon source. Batch experiments were carried out by induction of mineral salt medium containing PHE to the seed culture and monitoring PHE biodegradation. The microbial propagation was conducted using PHE concentrations in the range of 20 to 100 mg/l. The microbial growth on PHE was defined based on Monod and modified Logistic rate models. The kinetic studies revealed that maximum specific growth rates (?m) for PHE concentrations of 20, 50 and100 mg/l were 0.12, 0.23 and 0.035 h-1, respectively. The doubling times for microbial population in PHE concentrations of 20, 50 and100 mg/l were 13, 15 and 17.5h, respectively. Also, maximum cell dry weight (xm) of 54.23 mg/l was achieved, while the inhibition coefficient was 0.023 h-1. It was observed that the experimental data were well represented by the proposed models. It was also found that the biodegradation of PHE was successfully performed by the isolated strains.

Variations in enzyme activities of Butyrivibrio fibrisolvens and Ruminococcus albus grown in continuous culture

1974 ◽  
Vol 20 (6) ◽  
pp. 861-869 ◽  
Author(s):  
J. P. Kotzé ◽  
A. Kistner
Keyword(s):  
Steady State ◽  
Continuous Culture ◽  
Enzyme Activities ◽  
Dry Weight ◽  
Ruminococcus Albus ◽  
Glucose Limitation ◽  
Butyrivibrio Fibrisolvens ◽  
Cell Counts ◽  
Coefficients Of Variation ◽  
Doubling Times

One strain each of Butyrivibrio fibrisolvens and of Ruminococcus albus were grown in continuous culture under glucose limitation at three dilution rates. The activities of several intermediary enzymes were determined in cell-free extracts. In both organisms, the coefficients of variation of enzyme activities were, with few exceptions, much larger than those of the dry-weight concentration of cells and of glucose uptake from the medium. In B. fibrisolvens, the coefficients of variation of all enzyme activities per milliliter of culture were much greater at a dilution rate (D) of 0.5 h−1 than at D = 0.12 and 0.2 h−1. In R. albus, on the other hand, the coefficients of variation were greater at D = 0.1 h−1 than at D = 0.2 and 0.43 h−1. Cell counts made at short intervals over a period covering three doubling times of a R. albus culture growing under steady-state conditions provided no evidence of synchrony of cell divisions that might account for the fluctuations in enzyme activities. The results indicate the importance of determining the extent of variations in enzyme activities in cells growing at a particular growth rate under steady-state conditions before attempting to compare the effect of different growth rates on enzyme activities. The implications of these findings are discussed in relation to an earlier study on changes in enzyme activities in extracts of the mixed microbial population of an experimental anaerobic digester during adaptation to a synthetic substrate and after prolonged operation on this substrate.

scholarly journals The first month of the COVID-19 outbreak in 46 sub-Saharan African countries. A comparative analysis of growth rates

2020 ◽  
Author(s):  
Martin J. Prince ◽  
Atalay Alem ◽  
Dixon Chibanda ◽  
Lara Fairall ◽  
Abebaw Fekadu ◽  
...  
Keyword(s):  
Critical Care ◽  
Growth Rates ◽  
Exponential Growth ◽  
Linear Growth ◽  
Growth Patterns ◽  
European Countries ◽  
World Health ◽  
African Countries ◽  
Sub Saharan ◽  
Doubling Times

ABSTRACTBackgroundThe COVID-19 outbreak in sub-Saharan African countries started after those in Asia, Europe and North America, on 28th February 2020. The susceptibility to infection of populations in that region has been debated. Outbreaks on the scale of those seen elsewhere would pose substantial challenges. There are reasons for concern that transmission may be high and difficult to control, rapidly exceeding capacity to meet the needs for hospitalization and critical care.MethodsWe obtained data on daily new confirmed cases for all 46 countries from the World Health Organization, and used these to model and visualize growth trajectories using an AutoRegressive Integrated Moving Average (ARIMA) model. We then estimated doubling times from growth rates estimated from Poisson regression models, and by back counting from the most recent observation. We also calculated the time from 1st to 50th case, and the time from 5th to 100th case. These indicators were compared with the same summary indicators of growth at the same stage of the outbreak in highly affected European countries.ResultsKenya was the only country with clear evidence of exponential growth. Nineteen countries had either reported no cases, were in the first few days of the outbreak, or had reported fewer than 10 cases over a period of two or more weeks. For the remaining 27 countries we identified four growth patterns: slow linear growth, more rapid linear growth, variable growth patterns over the course of the outbreak, and early signs of possible exponential growth. For those in the last three groups, doubling times ranged from 3 to 4 days, times from 1st to 50th case from 12 to 29 days, and from 5th to 100th case from eight to 15 days. These early indicators are comparable to those in European countries that have gone on to have substantial outbreaks, and time to 50th case was shorter suggesting lesser effectiveness of contact-tracing and quarantine in the early phase.ConclusionThe 46 sub-Saharan African countries, home to over one billion people, are at a tipping point with clear potential for the outbreak to follow a similar course as in HIC in the global north. Radical population-level physical distancing measures may be required, but their impact on poor, disadvantaged and vulnerable people and communities need mitigating. Health systems in the region need urgent technical and material support, with testing, personal protection, and hospital/ critical care.

scholarly journals SILICON METABOLISM IN DIATOMS

1954 ◽  
Vol 37 (5) ◽  
pp. 589-599 ◽  
Author(s):  
Joyce C. Lewin
Keyword(s):  
Ascorbic Acid ◽  
Cell Membrane ◽  
Sodium Arsenite ◽  
Silicate Solution ◽  
Distilled Water ◽  
Silicon Uptake ◽  
Aerobic Process ◽  
Silicon Metabolism ◽  
Growing Conditions ◽  
Silica Frustules

1. Cells of the fresh water diatom Navicula pelliculosa may be grown in a mineral medium containing a low concentration of silicon. When transferred to a fresh silicate solution and incubated under non-growing conditions such deficient cells rapidly take up silicon from the medium. 2. The utilization of silicon is an aerobic process. 3. When deficient cells are washed with distilled water or saline, their ability to utilize silicon is impaired whereas respiration is unaffected. 4. The ability of washed cells to take up silicon can be partially restored with sulfate or ascorbic acid, and is completely restored by Na2S, Na2S2O3, glutathione, l-cysteine, dl-methionine, or ascorbic acid plus sulfate. 5. The sulfhydryl reagent, CdCl2, inhibits silicon utilization of unwashed cells at concentrations which do not affect respiration. This inhibition similarly is reversed by glutathione or cysteine. 6. However, sodium iodoacetate or sodium arsenite inhibits respiration and silicon utilization at the same concentrations. 7. The silicon taken up by deficient cells is deposited at the cell surface as a thickening of the existing silica frustules. 8. Sulfhydryl groups in the cell membrane may be involved in silicon uptake by diatoms.

scholarly journals Growth Characteristics ofMethanomassiliicoccus luminyensisand Expression of Methyltransferase Encoding Genes

Archaea ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Lena Kröninger ◽  
Jacqueline Gottschling ◽  
Uwe Deppenmeier
Keyword(s):  
Growth Yield ◽  
Dry Weight ◽  
Transcript Level ◽  
Resting Cells ◽  
Growth Substrate ◽  
Human Gut ◽  
Genes Encoding ◽  
Seventh Order ◽  
Encoding Genes ◽  
Doubling Times

DNA sequence analysis of the human gut revealed the presence a seventh order of methanogens referred to as Methanomassiliicoccales.Methanomassiliicoccus luminyensisis the only member of this order that grows in pure culture. Here, we show that the organism has a doubling time of 1.8 d with methanol + H2and a growth yield of 2.4 g dry weight/mol CH4.M. luminyensisalso uses methylamines + H2(monomethylamine, dimethylamine, and trimethylamine) with doubling times of 2.1–2.3 d. Similar cell yields were obtained with equimolar concentrations of methanol and methylamines with respect to their methyl group contents. The transcript levels of genes encoding proteins involved in substrate utilization indicated increased amounts of mRNA from themtaBC2gene cluster in methanol-grown cells. When methylamines were used as substrates, mRNA of themtb/mttoperon and of themtmBC1cluster were found in high abundance. The transcript level ofmtaC2was almost identical in methanol- and methylamine-grown cells, indicating that genes for methanol utilization were constitutively expressed in high amounts. The same observation was made with resting cells where methanol always yielded the highest CH4production rate independently from the growth substrate. Hence,M. luminyensisis adapted to habitats that provide methanol + H2as substrates.

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.

scholarly journals DRY WEIGHT, CARBON, C/N RATIO, HYDROGEN, AND CHLOROPHYLL VARIATION DURING EXPONENTIAL GROWTH OF SELECTED MICROALGAE SPECIES USED IN AQUACULTURE

2015 ◽  
Vol 30 (1) ◽  
pp. 33
Author(s):  
A. Pérez -Morales ◽  
A. Martínez -López ◽  
J. M. Camalich -Carpizo
Keyword(s):  
Growth Rate ◽  
Exponential Growth ◽  
Food Source ◽  
Culture Medium ◽  
Isochrysis Galbana ◽  
Dry Weight ◽  
Dunaliella Tertiolecta ◽  
Physiological Indicators ◽  
Nutrients Uptake ◽  
Chaetoceros Calcitrans

Microalgae are commonly used as food source in aquaculture, mainly for shellfish and larvae of crustacean and fish. All hatcheries need an excellent inoculum to produce high-quality microalgae when cultured outdoor in extensive systems, and this depends largely on the health of the microalgae cultured under laboratory conditions as a primary step. Therefore, the aim of this work was to assess variations of dry weight, carbon, C/N ratio, hydrogen and chlorophylls as physiological indicators of nutrients uptake and growth rate during exponential growth of Isochrysis galbana, Chaetoceros calcitrans and Dunaliella tertiolecta, using f/2 as culture medium. Chaetoceros calcitrans and D. tertiolecta had higher carbon content (~30 pg cell-1). The C/N ratio varied widely, gradually decreasing on I. galbana. Chlorophyll a varied among the three microalgae tested, ranging from 0.25 pg cell-1. Growth rate was higher in I. galbana (K’ 0.83) followed by D. tertiolecta and C. calcitrans. Results showed that nutrient incorporation by cell change when cell density increases; this information provides new insights in the physiology of marine microalgae and confirms that nutrient uptake dynamics is different in each microalga species. Finally, this study indicates that using one culture medium is not equally efficient for all microalgae used in aquaculture since each species has specific nutritional requirements. Variación de peso seco, carbono, relación C/N, hidrógeno y clorofilas durante el crecimiento exponencial de especies selectas de microalgas utilizadas en acuacultura Las microalgas son comúnmente utilizadas como fuente de alimento en acuacultura, principalmente para cultivo de moluscos y para las fases larvarias de crustáceos y peces. Los criaderos de larvas necesitan un excelente inóculo para producir microalgas de alta calidad cuando se cultivan al exterior en sistemas extensivos; esto depende principalmente de la salud de las microalgas cultivadas bajo condiciones de laboratorio como primer paso. Por lo tanto, el objetivo de este trabajo fue evaluar variaciones de peso seco, carbono, relación C/N, hidrógeno y clorofilas como indicadores fisiológicos de la asimilación de nutrientes y tasa de crecimiento durante el crecimiento exponencial de Isochrysis galbana, Chaetoceros calcitrans y Dunaliella tertiolecta, usando f/2 como medio de cultivo. Chaetoceros calcitrans y D. tertiolecta presentaron el mayor contenido de carbono (~30 pg cél-1). La relación C/N varió ampliamente, decreciendo gradualmente en I. galbana. La clorofila a fue la que más varió entre las tres microalgas evaluadas, en el intervalo de 0.25 pg cél-1. La tasa de crecimiento fue mayor en I. galbana (K’ 0.83) seguido por D. tertiolecta y C. calcitrans. Los resultados mostraron que la incorporación de nutrientes por célula cambia cuando la densidad celular se incrementa; esta información provee nuevo conocimiento sobre la fisiología de microalgas marinas y confirma que la dinámica de incorporación de nutrientes es diferente en cada especie de microalga. Por último, este estudio indicó que el uso de un solo medio de cultivo no es igualmente eficiente para todas las microalgas usadas en acuacultura, debido a que necesitan requerimientos nutricionales específicos.

Sign in / Sign up

Export Citation Format

Share Document