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  • 1
    Electronic Resource
    Electronic Resource
    Experimental evidence for interactions between bacterial peptidase and alkaline phosphatase activity in the Baltic Sea (2000)
    Springer
    Aquatic ecology 34 (2000), S. 331-343 
    Details
    ISSN: 1573-5125
    Keywords: alkaline phosphatase activity ; enzyme interaction ; nutrient regeneration ; aminopeptidase activity ; substrate stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From the observed pattern of aminopeptidase and alkaline phosphatase activities in the Baltic Sea, the question arose whether there is an interaction between the activities of both enzymes. In experiments with 0.8 μm filtered seawater, the effects of commercial alkaline phosphatase on bacterial aminopeptidase, the effects of commercial peptidase on bacterial alkaline phosphatase activity (APA), and the effects of proteins, carbohydrates and inorganic nutrients on the activities of both enzymes were investigated. Addition of commercial alkaline phosphatase stimulated bacterial aminopeptidase activity and, similarly, the addition of commercial peptidase increased the APA in bacteria. The proteins, albumin and casein, stimulated aminopeptidase activity and APA simultaneously. Experiments using ammonium and glucose suggested that stimulation of APA by peptidase could be mediated by nitrogen and carbon availability. There were also some indications that stimulation of aminopeptidase activity by alkaline phosphatase functioned by catalysing phosphate release from organic phosphorus compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011482815250
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Variations in the elemental ratio of organic matter in the central Baltic Sea: Part I—Linking primary production to remineralization (2015)
    Elsevier
    In:  Continental Shelf Research, 100 . pp. 25-45.
    Details
    Publication Date: 2019-09-23
    Description: Highlights: • Elemental C:N:P variations of organic matter are simulated at monitoring site BY15. • No N2 fixation needed to explain observed PO4PO4 and pCO2pCO2 levels after spring bloom. • Model features relevance of DOP production and remineralization for N2 fixation. • Model estimates of annual N2 fixation are View the MathML source297±24mmolNm-2a-1. • Model estimates of annual total production are View the MathML source14.16±0.71molCm-2a-1. Abstract: For most marine ecosystems the growth of diazotrophic cyanobacteria and the associated amount of nitrogen fixation are regulated by the availability of phosphorus. The intensity of summer blooms of nitrogen (N2) fixing algae in the Baltic Sea is assumed to be determinable from a surplus of dissolved inorganic phosphorus (DIP) that remains after the spring bloom has ended. But this surplus DIP concentration is observed to continuously decrease at times when no appreciable nitrogen fixation is measured. This peculiarity is currently discussed and has afforded different model interpretations for the Baltic Sea. In our study we propose a dynamical model solution that explains these observations with variations of the elemental carbon-to-nitrogen-to-phosphorus (C:N:P) ratio during distinct periods of organic matter production and remineralization. The biogeochemical model resolves seasonal C, N and P fluxes with depth at the Baltic Sea monitoring site BY15, based on three assumptions: (1) DIP is utilized by algae though not needed for immediate growth, (2) the uptake of dissolved inorganic nitrogen (DIN) is hampered when the algae׳s phosphorus (P) quota is low, and (3) carbon assimilation continues at times of nutrient depletion. Model results describe observed temporal variations of DIN, DIP and chlorophyll-a concentrations along with partial pressure of carbon dioxide (pCO2)(pCO2). In contrast to other model studies, our solution does not require N2 fixation to occur shortly after the spring bloom to explain DIP drawdown and pCO2pCO2 levels. Model estimates of annual N2 fixation are View the MathML source297±24mmolNm-2a-1. Estimates of total production are View the MathML source14200±700mmolCm-2a-1, View the MathML source1400±70mmolNm-2a-1, and View the MathML source114±5mmolPm-2a-1 for the upper 50 m. The models C, N and P fluxes disclose preferential remineralization of P and of organic N that was introduced via N2 fixation. Our results are in support of the idea that P uptake by phytoplankton during the spring bloom contributes to the consecutive availability of labile dissolved organic phosphorus (LDOP). The LDOP is retained within upper layers and its remineralization affects algal growth in summer, during periods of noticeable N2 fixation.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.csr.2014.06.015
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Phosphorus input by upwelling in the eastern Gotland Basin (Baltic Sea) in summer and its effects on filamentous cyanobacteria (2009)
    Elsevier
    In:  Estuarine, Coastal and Shelf Science, 83 (4). pp. 434-442.
    Details
    Publication Date: 2015-09-25
    Description: In July 2007, phosphorus input by an upwelling event along the east coast of Gotland Island and the response of filamentous cyanobacteria were studied to determine whether introduced phosphorus can intensify cyanobacterial bloom formation in the eastern Gotland Basin. Surface temperature, nutrient concentrations, phytoplankton biomass and its stoichiometry, as well as phosphate uptake rates were determined in two transects between the coasts of Gotland and Latvia and in a short grid offshore of Gotland. In the upwelling area, surface temperatures of 11–12 °C and average dissolved inorganic phosphorus (DIP) concentrations of 0.26 μM were measured. Outside the upwelling, surface temperatures were higher (15.5–16.6 °C) and DIP supplies in the upper 10 m layer were exhausted. Nitrite and nitrate concentrations (0.01–0.22 μM) were very low within and outside the upwelling region. Abundances of filamentous cyanobacteria were highly reduced in the upwelling area, accounting for only 1.4–6.0% of the total phytoplankton biomass, in contrast to 18–20% outside the upwelling. The C:P ratio of filamentous cyanobacteria varied between 32.8 and 310 in the upwelling region, most likely due to the introduction of phosphorus-depleted organisms into the upwelling water. These organisms accumulate DIP in upwelling water and have lower C:P ratios as long as they remain in DIP-rich water. Thus, diazotrophic cyanobacteria benefit from phosphorus input directly in the upwelling region. Outside the upwelling region, the C:P ratios of filamentous cyanobacteria varied widely, between 240 and 463, whereas those of particulate material in the water ranged only between 96 and 224. To reduce their C:P ratio from 300 to 35, cyanobacteria in the upwelling region had to take up 0.05 mmol m−3 DIP, which is about 20% of the available DIP. Thus, a larger biomass of filamentous cyanobacteria may be able to benefit from a given DIP input. As determined from the DIP uptake rates measured in upwelling cells, the time needed to reduce the C:P ratio from 300 to 35 was too long to explain the huge bloom formations that typically occur in summer. However, phosphorus uptake rates increased significantly with increasing C:P ratios, allowing phosphorus accumulation within 4–5 days, a span of time suitable for bloom formation in July and August.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.ecss.2009.04.031
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Phosphorus transformation by Nodularia spumigena and by heterotrophic bacteria under different pCO2 levels first results (2010)
    In:  [Poster] In: BIOACID / EPOCA / UKOARP Meeting Bremerhaven , 27.-20.09.2010, Bremerhaven, Germany .
    Details
    Publication Date: 2018-01-18
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 5
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    Response of the filamentous cyanobacterium Nodularia spumigena to pCO2 - Exudation and extracellular enzymes (2015)
    In:  [Talk] In: International Workshop „Marine research and management“, 12.06.2015, University of Riga, Latvia .
    Details
    Publication Date: 2019-09-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 6
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    Concentrations and Uptake of Dissolved Organic Phosphorus Compounds in the Baltic Sea (2018)
    Frontiers
    Details
    Publication Date: 2023-09-19
    Description: The dissolved organic phosphorus (DOP) pool in marine waters contains a variety of different compounds. Knowledge of the distribution and utilization of DOP by phyto- and bacterioplankton is limited, but critical to our understanding of the marine phosphorus cycle. In the Baltic Sea, detailed information about the composition of DOP and its turnover is lacking. This study reports the concentrations and uptake rates of DOP compounds, namely, adenosine triphosphate (dATP), deoxyribonucleic acid (dDNA), and phospholipids (dPL), in the Baltic Proper and in Finnish coastal waters in the summers of 2011 and 2012. Both areas differed in their dissolved inorganic phosphorus (DIP) concentrations (0.16 and 0.02–0.04 μM), in the C:P (123–178) and N:P (18–27) ratios, and in abundances of filamentous cyanobacteria and of autotrophic and heterotrophic picoplankton. The mean concentrations of dATP-P, dDNA-P, and dPL-P were 4.3–6.4, 0.05–0.12, and 1.9–6.8 nM, respectively, together contributing between 2.4 and 5.2% of the total DOP concentration. The concentrations of the compounds varied between and within the investigated regions and the distribution patterns of the individual components are not linked to each other. DIP was taken up at rates of 10.1–380.8 nM d-1. dATP-P and dDNA-P were consumed simultaneously with DIP at rates of 6.9–24.1 and 0.09–0.19 nM d-1, respectively, with the main proportion taken up by the size fraction 〈3 μm and with DIP to be the dominant source. Groups of hydrographical and biological parameters were identified in the multiple regression analysis to impact the concentrations and uptake rates. It points to the complexity of the regulation. Our results indicate that the investigated DOP compounds, particularly dATP-P, can make significant contributions to the P nutrition of microorganisms and their use seems to be not intertwined. Therefore, more detailed knowledge of all DOP components including variation of concentrations and the utilization is required to understand the roles of DOP in marine ecosystems.
    Type: Article , PeerReviewed
    Format: text
    Format: image
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Oceans turning sour - will it directly affect growth and production of heterotrophic bacteria? - What we have learned so far from laboratory to mesocosm experiments (2011)
    In:  EPIC32nd annual BIOACID meeting, Universität Bremen, 2011-09-26-2011-09-28
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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    PAPER (OA)
  • 8
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    Effect of ocean acidification on microbial degradation of organic matter derived from a Thalassiosira weissflogii chemostat culture (2011)
    In:  EPIC3YOUMARES 2.0 - Ocean amidst science, innovation and society, Bremerhaven, 2011-09-07-2011-09-09
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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    PAPER (OA)
  • 9
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    Impact of ocean acidification on microbial degradation of organic matter (2011)
    In:  EPIC32nd annual BIOACID meeting, Universität Bremen, 2011-09-26-2011-09-28
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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    PAPER (OA)
  • 10
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    Response of Nodularia spumigena to pCO2 (2013)
    PANGAEA
    In:  Supplement to: Endres, Sonja; Unger, Juliane; Wannicke, Nicola; Nausch, Monika; Voss, Maren; Engel, Anja (2013): Response of Nodularia spumigena to pCO2; Part 2: Exudation and extracellular enzyme activities. Biogeosciences, 10(1), 567-582, https://doi.org/10.5194/bg-10-567-2013
    Details
    Publication Date: 2024-03-15
    Description: The filamentous and diazotrophic cyanobacterium Nodularia spumigena plays a major role in the productivity of the Baltic Sea as it forms extensive blooms regularly. Under phosphorus limiting conditions Nodularia spumigena has a high enzyme affinity for dissolved organic phosphorus (DOP) by production and release of alkaline phosphatase. Additionally, it is able to degrade proteinaceous compounds by expressing the extracellular enzyme leucine aminopeptidase. As atmospheric CO2 concentrations are increasing, we expect marine phytoplankton to experience changes in several environmental parameters including pH, temperature, and nutrient availability. The aim of this study was to investigate the combined effect of CO2-induced changes in seawater carbonate chemistry and of phosphate deficiency on the exudation of organic matter, and its subsequent recycling by extracellular enzymes in a Nodularia spumigena culture. Batch cultures of Nodularia spumigena were grown for 15 days aerated with three different pCO2 levels corresponding to values from glacial periods to future values projected for the year 2100. Extracellular enzyme activities as well as changes in organic and inorganic compound concentrations were monitored. CO2 treatment-related effects were identified for cyanobacterial growth, which in turn was influencing exudation and recycling of organic matter by extracellular enzymes. Biomass production was increased by 56.5% and 90.7% in the medium and high pCO2 treatment, respectively, compared to the low pCO2 treatment and simultaneously increasing exudation. During the growth phase significantly more mucinous substances accumulated in the high pCO2 treatment reaching 363 µg Gum Xanthan eq /l compared to 269 µg Gum Xanthan eq /l in the low pCO2 treatment. However, cell-specific rates did not change. After phosphate depletion, the acquisition of P from DOP by alkaline phosphatase was significantly enhanced. Alkaline phosphatase activities were increased by factor 1.64 and 2.25, respectively, in the medium and high compared to the low pCO2 treatment. In conclusion, our results suggest that Nodularia spumigena can grow faster under elevated pCO2 by enhancing the recycling of organic matter to acquire nutrients.
    Keywords: Alkaline phosphatase, Km value; Alkaline phosphatase activity; Alkalinity, total; Alkalinity, total, standard deviation; alpha-glucosidase activity; Aragonite saturation state; Bacteria, abundance; Bacteria, abundance, standard deviation; beta-glucosidase activity; Bicarbonate ion; BIOACID; Biological Impacts of Ocean Acidification; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, dissolved; Carbon, organic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chlorophyll a; Chlorophyll a, standard deviation; Coomassie stainable particles; Coomassie stainable particles, abundance; Coomassie stainable particles, equivalent spherical diameter; DATE/TIME; Flow cytometry; Fluorometry; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Incubation duration; Leucine aminopeptidase activity; Microscopy; Mucinous substances; Nitrogen, inorganic, dissolved; Nitrogen, inorganic, dissolved, standard deviation; Nitrogen, organic, dissolved; Nodularia spumigena; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Phosphate; Phosphate, organic, dissolved; Phosphate, standard deviation; Salinity; SPEC; Species; Spectrophotometer; Spectrophotometer Hitachi U-2000; Standard deviation; Temperature, water; TOC analyzer (Shimadzu); Treatment; UV/VIS Spectrometer
    Type: Dataset
    Format: text/tab-separated-values, 660 data points
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    DATA PANGAEA
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