Effects of Phytoplankton Growth Phase on Settling Properties of Marine Aggregates

Marine snow aggregates often dominate carbon export from the surface layer to the deep ocean. Therefore, understanding the formation and properties of aggregates is essential to the study of the biological pump. Previous studies have observed a relationship between phytoplankton growth phase and the production of transparent exopolymer particles (TEP), the sticky particles secreted by phytoplankton that act as the glue during aggregate formation. In this experimental study, we aim to determine the effect of phytoplankton growth phase on properties related to aggregate settling. Cultures of the diatom Thalassiosira weissflogii were grown to four different growth phases and incubated in rotating cylindrical tanks to form aggregates. Aggregate excess density and delayed settling time through a sharp density gradient were quantified for the aggregates that were formed, and relative TEP concentration was measured for cultures before aggregate formation. Compared to the first growth phase, later phytoplankton growth phases were found to have higher relative TEP concentration and aggregates with lower excess densities and longer delayed settling times. These findings may suggest that, although particle concentrations are higher at later stages of phytoplankton blooms, aggregates may be less dense and sink slower, thus affecting carbon export.

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Rapid in vitro selection of salt-tolerant genotypes of the potentially medicinal plant Centaurium maritimum (L.) fritsch

Archives of Biological Sciences ◽

10.2298/abs0901057m ◽

2009 ◽

Vol 61 (1) ◽

pp. 57-69 ◽

Cited By ~ 9

Author(s):

Danijela Misic ◽

B. Siler ◽

Biljana Filipovic ◽

Zorica Popovic ◽

Suzana Zivkovic ◽

...

Keyword(s):

Seed Germination ◽

Medicinal Plant ◽

Salinity Tolerance ◽

Growth Phase ◽

In Vitro Selection ◽

Growth Phases ◽

Salt Tolerant ◽

Variable Response ◽

Selection Of

We investigated differences of salinity tolerance between 'salt-tolerant' (ST) and 'salt-sensitive' (SS) genotypes of yellow centaury [Centaurium maritimum (L.) Fritsch] selected during the germination phase. The ability of in vitro cultured C. maritimum to complete the whole ontogenetic cycle in less than 6 months enabled us to deterine salinity tolerance during different growth phases. Based on the physiological attributes measured in this study (growth, morphogenesis, photosynthesis, flowering, seed germination), it can be concluded that C. maritimum genotypes differing in salinity tolerance showed a variable response to elevated salt concentrations during both the vegetative and the generative growth phase.

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Optimizing models of the North Atlantic spring bloom using physical, chemical and bio-optical observations from a Lagrangian float

Biogeosciences Discussions ◽

10.5194/bgd-7-8477-2010 ◽

2010 ◽

Vol 7 (6) ◽

pp. 8477-8520 ◽

Cited By ~ 1

Author(s):

W. Bagniewski ◽

K. Fennel ◽

M. J. Perry ◽

E. A. D'Asaro

Keyword(s):

North Atlantic ◽

Spring Bloom ◽

Deep Ocean ◽

Complex Model ◽

Optical Observations ◽

Model Parameters ◽

Carbon Export ◽

The North ◽

Chemical Measurements ◽

The North Atlantic

Abstract. The North Atlantic spring bloom is one of the main events that lead to carbon export to the deep ocean and drive oceanic uptake of CO2 from the atmosphere. Here we use a suite of physical, bio-optical and chemical measurements made during the 2008 spring bloom to optimize and compare three different models of biological carbon export. The observations are from a Lagrangian float that operated south of Iceland from early April to late June, and were calibrated with ship-based measurements. The simplest model is representative of typical NPZD models used for the North Atlantic, while the most complex model explicitly includes diatoms and the formation of fast sinking diatom aggregates and cysts under silicate limitation. We carried out a variational optimization and error analysis for the biological parameters of all three models, and compared their ability to replicate the observations. The observations were sufficient to constrain most phytoplankton-related model parameters to accuracies of better than 15%. However, the lack of zooplankton observations leads to large uncertainties in model parameters for grazing. The simulated vertical carbon flux at 100 m depth is similar between models and agrees well with available observations, but at 600 m the simulated flux is much larger for the model with diatom aggregation. While none of the models can be formally rejected based on their misfit with the available observations, the model that includes export by diatom aggregation has slightly better fit to the observations and more accurately represents the mechanisms and timing of carbon export based on observations not included in the optimization. Thus models that accurately simulate the upper 100 m do not necessarily accurately simulate export to deeper depths.

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Sinking particles promote vertical connectivity in the ocean microbiome

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1802470115 ◽

2018 ◽

Vol 115 (29) ◽

pp. E6799-E6807 ◽

Cited By ~ 48

Author(s):

Mireia Mestre ◽

Clara Ruiz-González ◽

Ramiro Logares ◽

Carlos M. Duarte ◽

Josep M. Gasol ◽

...

Keyword(s):

Surface Waters ◽

Deep Ocean ◽

Rrna Gene ◽

Carbon Export ◽

Size Fractions ◽

Sinking Particles ◽

Prokaryotic Diversity ◽

Compositional Variability ◽

Organic Particles ◽

Community Connectivity

The sinking of organic particles formed in the photic layer is a main vector of carbon export into the deep ocean. Although sinking particles are heavily colonized by microbes, so far it has not been explored whether this process plays a role in transferring prokaryotic diversity from surface to deep oceanic layers. Using Illumina sequencing of the 16S rRNA gene, we explore here the vertical connectivity of the ocean microbiome by characterizing marine prokaryotic communities associated with five different size fractions and examining their compositional variability from surface down to 4,000 m across eight stations sampled in the Atlantic, Pacific, and Indian Oceans during the Malaspina 2010 Expedition. Our results show that the most abundant prokaryotes in the deep ocean are also present in surface waters. This vertical community connectivity seems to occur predominantly through the largest particles because communities in the largest size fractions showed the highest taxonomic similarity throughout the water column, whereas free-living communities were more isolated vertically. Our results further suggest that particle colonization processes occurring in surface waters determine to some extent the composition and biogeography of bathypelagic communities. Overall, we postulate that sinking particles function as vectors that inoculate viable particle-attached surface microbes into the deep-sea realm, determining to a considerable extent the structure, functioning, and biogeography of deep ocean communities.

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Using new observations and Machine Learning to improve organic sinking processes in the PlankTOM global ocean biogeochemical model

10.5194/egusphere-egu21-11356 ◽

2021 ◽

Author(s):

Anna Denvil-Sommer ◽

Corinne Le Quéré ◽

Erik Buitenhuis ◽

Lionel Guidi ◽

Jean-Olivier Irisson

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Deep Ocean ◽

Ecosystem Dynamics ◽

Global Ocean ◽

Biogeochemical Model ◽

Carbon Export ◽

Mixing Depth ◽

Chl A ◽

Biogeochemical Models

A lot of effort has been put in the representation of surface ecosystem processes in global carbon cycle models, in particular through the grouping of organisms into Plankton Functional Types (PFTs) which have specific influences on the carbon cycle. In contrast, the transfer of ecosystem dynamics into carbon export to the deep ocean has received much less attention, so that changes in the representation of the PFTs do not necessarily translate into changes in sinking of particulate matter. Models constrain the air-sea CO2 flux by drawing down carbon into the ocean interior. This export flux is five times as large as the CO2 emitted to the atmosphere by human activities. When carbon is transported from the surface to intermediate and deep ocean, more CO2 can be absorbed at the surface. Therefore, even small variability in sinking organic carbon fluxes can have a large impact on air-sea CO2 fluxes, and on the amount of CO2 emissions that remain in the atmosphere.In this work we focus on the representation of organic matter sinking in global biogeochemical models, using the PlankTOM model in its latest version representing 12 PFTs. We develop and test a methodology that will enable the systematic use of new observations to constrain sinking processes in the model. The approach is based on a Neural Network (NN) and is applied to the PlankTOM model output to test its ability to reconstruction small and large particulate organic carbon with a limited number of observations. We test the information content of geographical variables (location, depth, time of year), physical conditions (temperature, mixing depth, nutrients), and ecosystem information (CHL a, PFTs). These predictors are used in the NN to test their influence on the model-generation of organic particles and the robustness of the results. We show preliminary results using the NN approach with real plankton and particle size distribution observations from the Underwater Vision Profiler (UVP) and plankton diversity data from Tara Oceans expeditions and discuss limitations.

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Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

Biogeosciences ◽

10.5194/bg-14-1493-2017 ◽

2017 ◽

Vol 14 (6) ◽

pp. 1493-1509 ◽

Cited By ~ 13

Author(s):

Rosie M. Sheward ◽

Alex J. Poulton ◽

Samantha J. Gibbs ◽

Chris J. Daniels ◽

Paul R. Bown

Keyword(s):

Cell Division ◽

Environmental Change ◽

Growth Phase ◽

Fossil Record ◽

Phase Shifts ◽

Cell Physiology ◽

Nutrient Depletion ◽

Growth Responses ◽

Growth Phases ◽

Phytoplankton Group

Abstract. Coccolithophores are an abundant phytoplankton group that exhibit remarkable diversity in their biology, ecology and calcitic exoskeletons (coccospheres). Their extensive fossil record is a testament to their important biogeochemical role and is a valuable archive of biotic responses to environmental change stretching back over 200 million years. However, to realise the full potential of this archive for (palaeo-)biology and biogeochemistry requires an understanding of the physiological processes that underpin coccosphere architecture. Using culturing experiments on four modern coccolithophore species (Calcidiscus leptoporus, Calcidiscus quadriperforatus, Helicosphaera carteri and Coccolithus braarudii) from three long-lived families, we investigate how coccosphere architecture responds to shifts from exponential (rapid cell division) to stationary (slowed cell division) growth phases as cell physiology reacts to nutrient depletion. These experiments reveal statistical differences in coccosphere size and the number of coccoliths per cell between these two growth phases, specifically that cells in exponential-phase growth are typically smaller with fewer coccoliths, whereas cells experiencing growth-limiting nutrient depletion have larger coccosphere sizes and greater numbers of coccoliths per cell. Although the exact numbers are species-specific, these growth-phase shifts in coccosphere geometry demonstrate that the core physiological responses of cells to nutrient depletion result in increased coccosphere sizes and coccoliths per cell across four different coccolithophore families (Calcidiscaceae, Coccolithaceae, Isochrysidaceae and Helicosphaeraceae), a representative diversity of this phytoplankton group. Building on this, the direct comparison of coccosphere geometries in modern and fossil coccolithophores enables a proxy for growth phase to be developed that can be used to investigate growth responses to environmental change throughout their long evolutionary history. Our data also show that changes in growth rate and coccoliths per cell associated with growth-phase shifts can substantially alter cellular calcite production. Coccosphere geometry is therefore a valuable tool for accessing growth information in the fossil record, providing unprecedented insights into the response of species to environmental change and the potential biogeochemical consequences.

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EFFECTIVENESS OF A JAVANESE TURMERIC ETHANOL EXTRACT FOR ERADICATING STREPTOCOCCUS MUTANS AND PORPHYROMONAS GINGIVALIS BIOFILMS

International Journal of Applied Pharmaceutics ◽

10.22159/ijap.2019.v11s1.ar157 ◽

2019 ◽

pp. 27-31

Author(s):

DEWI FATMA SUNIARTI ◽

AGOENG TJAHAJANI SARWONO ◽

MARINA ROSYANA

Keyword(s):

Streptococcus Mutans ◽

Porphyromonas Gingivalis ◽

Growth Phase ◽

Ethanolic Extract ◽

Ethanol Extract ◽

Growth Phases

Objective: We aimed to determine the effectiveness of an identified Javanese turmeric ethanolic extract (IIJTEE) for eradicating biofilms formed byStreptococcus mutans, Porphyromonas gingivalis, or both.Methods: Such biofilms during different growth phases were exposed to various concentrations of an IJTEE to determine its effects on bacterialproliferation.Results: The effectiveness of the IJTEE in eradicating the S. mutans biofilm was concentration-dependent but not when used to treat P. gingivalis andS. mutans - P. gingivalis biofilms.Conclusion: The effectiveness of the IJTEE for eradicating biofilms formed by S. mutans, P. gingivalis, and S. mutans plus P. gingivalis biofilms dependedon the growth phase of the biofilm. Thus, IJTEE eradicated biofilms formed by S. mutans, P. gingivalis, or both.

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Protein Aggregation is Associated with Acinetobacter baumannii Desiccation Tolerance

Microorganisms ◽

10.3390/microorganisms8030343 ◽

2020 ◽

Vol 8 (3) ◽

pp. 343 ◽

Cited By ~ 1

Author(s):

Xun Wang ◽

Cody G. Cole ◽

Cory D. DuPai ◽

Bryan W. Davies

Keyword(s):

Acinetobacter Baumannii ◽

Desiccation Tolerance ◽

Bacterial Pathogen ◽

Protein Aggregates ◽

Cellular Protein ◽

Aggregate Formation ◽

Growth Phases ◽

Protein Aggregate ◽

Factors Influencing ◽

Cellular Aggregates

Desiccation tolerance has been implicated as an important characteristic that potentiates the spread of the bacterial pathogen Acinetobacter baumannii on dry surfaces. Here we explore several factors influencing desiccation survival of A. baumannii. At the macroscale level, we find that desiccation tolerance is influenced by cell density and growth phase. A transcriptome analysis indicates that desiccation represents a unique state for A. baumannii compared to commonly studied growth phases and strongly influences pathways responsible for proteostasis. Remarkably, we find that an increase in total cellular protein aggregates, which is often considered deleterious, correlates positively with the ability of A. baumannii to survive desiccation. We show that inducing protein aggregate formation prior to desiccation increases survival and, importantly, that proteins incorporated into cellular aggregates can retain activity. Our results suggest that protein aggregates may promote desiccation tolerance in A. baumannii through preserving and protecting proteins from damage during desiccation until rehydration occurs.

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Duration of the growth phase in cases of ice deposits of category SHP (spontaneous) in the territory of Ukraine in the months of the cold period of the year during 1991–2016

Physical Geography and Geomorphology ◽

10.17721/phgg.2019.4-6.05 ◽

2019 ◽

Vol 96 (4-6) ◽

pp. 43-53

Author(s):

Svitlana Pyasetska

Keyword(s):

Growth Phase ◽

Winter Season ◽

Cold Period ◽

Time Range ◽

Growth Phases ◽

Emergency Situations ◽

Ice Storms ◽

Long Duration

The data on the duration of the growth phase of cases of ice storms of the category of SHР in the territory of Ukraine for certain periods of time during 1991–2016 in the month of the cold period of the year and the separate months of the transitional seasons are considered. It has been established that the duration of the growth phase varies from a few hours to several dozen and sometimes hundreds of hours in a row. It was found that, for the most part, slight duration of the growth phase of icing of the category of SHP is predominant. They are usually calculated several dozens of hours, but there are longer ones. The most prolonged were the growth phases in the cases of ice deposits in the category of SHP in the winter months. You can make a number of conclusions from the conducted research, such as: – The duration of the growth phase of ice-oily deposits in the category of SHP is within a fairly wide time range from several hours to tens or hundreds of hours, depending on the current conditions. – It has been established that for the most part, the duration of the growth phase of ice deposits is insignificant and lasts from several hours to several dozens of hours, regardless of the place where the sediment was formed. - Most often, longer phases of growth are observed in the months of the winter season, especially in January and December, as well as in November. This refers to the 1991–2000 and 2001–2010 periods. - The most prolonged phases of the accumulation of ice deposits of the CSF category, which exceeded 48 hours in a row, were observed during 1991-2000 in February 1995 at MS Play, November 1991 and 2000 in Lyubashivka, 1999 in Mariupol, November 2000, in Razdelna and Nova Ushytsia, December 1992 in Lyubashitsa, December 1997 in Pomechna, Kryvyi Rih and Loshkarovka. During 2001–2010, the longest phases of the increase in ice deposits of the CSF category were observed in January and December 2007 at MS Play, December 2007 in Debaltseve, 2008 in Ovruch, Vinnytsia. During 2011-2016, cases of ice deposition with such prolonged phases of an increase in ice of the SНР category were observed in Poltava in January 2013. – For cases where the duration of the growth phase of ice deposits was negligible, it would have a long duration of the preservation and destruction phase. Because due to the considerable duration of this phase, the danger of emergency situations in the ice-and-frost deposits depending on the sectors of the economy will increase.

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Evaluation of Anabaena flos-aquae as a precursor for trihalomethane and haloacetic acid formation

Water Science & Technology Water Supply ◽

10.2166/ws.2008.151 ◽

2008 ◽

Vol 8 (6) ◽

pp. 653-662 ◽

Cited By ~ 7

Author(s):

J. Huang ◽

N. Graham ◽

M. R. Templeton ◽

Y. Zhang ◽

C. Collins ◽

...

Keyword(s):

Growth Phase ◽

Stationary Phases ◽

Fulvic Acids ◽

Growth Phases ◽

Haloacetic Acid ◽

Humic And Fulvic Acids ◽

Blue Green Algae ◽

Disinfection Byproduct ◽

Extracellular Organic Matter ◽

Axenic Conditions

This paper summarizes an investigation of a common blue–green algae species, Anabaena flos-aquae, as a precursor substrate in the formation of trihalomethane (THM) and haloacetic acid (HAA) compounds during chlorination. The algae were cultured under controlled and axenic conditions throughout all four growth phases and samples taken during these phases were subjected to chlorination to determine disinfection byproduct (DBP) formation potentials. Algal cells and extracted extracellular organic matter (EOM) of Anabaena showed a comparable ability to form THM and HAA compounds as humic and fulvic acids. Overall yields of total THM (4) and HAA (9) compounds were closely related to the growth phase, with peak formation in the late exponential-stationary phases. Specific (normalized) DBP yields (yield/unit C) were in the range of 2–11 μmol/mmol C for TTHM and 2–17 μmol/mmol C for THAA. The presence of bromide appeared to increase TTHM formation and decrease THAA formation, thereby leading to a shift in the DBP species from HAA to THM compounds. The distribution of HAA species varied with growth phase. Monochloroacetic acid was found to be the dominant HAA species during the lag and early exponential phases, and a prominent compound in the later growth phases.

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Variability of neuD transcription levels and capsular sialic acid expression among serotype III group B Streptococcus strains

Microbiology ◽

10.1099/mic.0.050013-0 ◽

2011 ◽

Vol 157 (12) ◽

pp. 3282-3291 ◽

Cited By ~ 2

Author(s):

Marie-Frédérique Lartigue ◽

Agnès Fribourg Poulard ◽

Rim Al Safadi ◽

Hélène Pailhories ◽

Anne-Sophie Domelier-Valentin ◽

...

Keyword(s):

Genetic Diversity ◽

Sialic Acid ◽

Growth Phase ◽

Exponential Growth ◽

Bacterial Species ◽

Group B Streptococcus ◽

Neonatal Meningitis ◽

Exponential Growth Phase ◽

Growth Phases ◽

Group B

Serotype III group B Streptococcus (GBS) is the major cause of neonatal meningitis, but the risk of infection in the colonized neonates is variable. Capsular sialic acid (Sia), whose synthesis is encoded by neu genes, appears to be a major virulence factor in several bacterial species able to reach the cerebrospinal fluid. Therefore, variations of Sia expression related to the genetic diversity of strains may have an impact on the risk of meningitis in colonized neonates. We characterized by MLST the phylogenetic diversity of 64 serotype III GBS strains isolated from vaginal flora and randomly selected. These strains mostly belonged to three major sequence types (STs): ST1 (11 %), ST17 (39 %) and ST19 (31 %). The genetic diversity of strains of these lineages, characterized by PFGE, allowed the selection of 17 representative strains, three ST1, six ST17 and eight ST19, with NEM316 as reference, in order to evaluate (i) by quantitative RT-PCR, the level of transcription of the neuD gene as a marker for the transcription of neu genes and (ii) by enzymological analysis, the expression of Sia. The mean transcription level of neuD was higher for ST17 strains than for ST1 and ST19 strains in the early, mid- and late exponential growth phases, and was maximum in the early exponential growth phase for ST17 strains and in the mid-exponential growth phase for ST1 and ST19 strains. Mean Sia concentration was higher for ST17 than for ST1 and ST9 strains in all three growth phases. For the total population, Sia concentration varied notably in the stationary phase, from 0.38 to 9.30 nmol per 108 viable bacteria, with a median value of 2.99 nmol per 108 bacteria. All ST17 strains, only one-third of the ST19 strains and none of the ST1 strains had Sia concentrations higher than the median Sia concentration. Therefore, differences in the level of expression of Sia by strains of the major serotype III GBS phylogenetic lineages might be one of the factors that explain the leading role of ST17 strains in neonatal meningitis.

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