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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 267 (1977), S. 696-698 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Although the particulate ATP content of marine seston (suspended particles) has been used extensively as a sensitive indicator of microbial biomass in oceans and lakes4, the presence of DATP in seawater had not been demonstrated conclusively9. This has been due, in part, to the absence of a ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 2 (1969), S. 333-335 
    ISSN: 0014-5793
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Soil Biology and Biochemistry 25 (1993), S. 1787-1792 
    ISSN: 0038-0717
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Soil Biology and Biochemistry 25 (1993), S. 1637-1638 
    ISSN: 0038-0717
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 12 (1993), S. 0 
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The incorporation of 32P-phosphorus into marine bacteriophage nucleic acid was studied in culture experiments to investigate the source of nucleotides used by the phage. We consistently found that the 32P-specific activity in the phage genome increased during the 11 h incubation and was low relative to the specific activity in the medium, averaging 21% (±SD 5.9) for the three phage isolates. This was in accordance with a mathematical model where most of the nucleotides for phage DNA synthesis were derived from the host cell nucleic acid rather than de novo synthesis. We propose that this metabolic strategy may be common among marine phages, as an adaptation to a nutrient poor environment. Consequently, the contribution of free DNA to the dissolved fraction through phage lysis of bacteria, may be less that previously thought. Also during radiolabelling of bacteriophages in natural water samples, isotope dilution may be dependent on the specific growth rate of the bacterial host.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To assess bacterioplankton production in the sea, we have developed a procedure for measuring growth based on incorporation of tritiated thymidine into DNA; the accuracy of this procedure was tested under a variety of laboratory and field conditions. By autoradiography, we have found that for all practical purposes our technique is specific for the nonphotosynthetic bacteria and that virtually all of the “active” bacteria (one-third or more of the total countable bacteria) take up thymidine. We also measured (1) the intracellular isotope dilution of thymidine assessed by parallel experiments with labeled phosphorus, and (2) DNA content of natural marine bacteria (0.2 to 0.6 μm size fraction); a conversion factor derived from these data permitted estimation of production from thymidine incorporation results. A very similar conversion factor was independently derived from the empirical relationship between thymidine incorporation and growth of natural bacterioplankton under controlled conditions. Combined results show that this technique, which can be performed rapidly and easily at sea, provides good estimates of production. Data from Southern California Bight waters, which contain oligotrophic as well as moderately eutrophic regions, show that average bacterioplankton doubling times, like those of the phytoplankton, are on the order of a few days, with fastest growth at depths just below those of greatest phytoplankton abundance. Offshore bacterial production is roughly 5 to 25% of the primary production; thus, at a 50% assimilation efficiency, the bacterioplankton would consume 10 to 50% of the total fixed carbon.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 23 (1973), S. 191-196 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An improved method is described for the study of heterotrophic utilization of dissolved organic substances by marine microorganisms. The method is based on the use of 3H-labelled organic substrates of very high specific activity, rather than the conventionally used 14C-labelled substrates. Direct measurement of the rate of tracer uptake at near ambient concentration can thus be made instead of extrapolation using the Michaelis-Menten equation. The method also permits comparison between the rates of tracer uptake in sub-samples exposed to different physico-chemical conditions (temperature, light, pollutants, etc.) without the necessity of determining the ambient substrate concentration. The method was applied to the determination of D-glucose uptake by nearshore and pelagic natural microbial populations, and was found to be sensitive and convenient.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 34 (1976), S. 143-149 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple technique is described for de-salting and concentrating adenosine triphosphate (ATP) extracted from seawater or marine sediment samples prior to assays with the standard luciferin-luciferase procedure. The technique involves chromatography of H2SO4 extracts on columns of activated carbon. The efficiency of ATP recovery from marine sediments using this pre-treatment was superior to that attained with either boiling “Tris” extraction or with H2SO4 extraction without subsequent purification. All ions which interfere with the luciferase reaction or precipitate ATP upon neutralization of acid extracts are removed with this procedure, thus eliminating the 50- to 100-fold dilutions required with other acid-extraction procedures. In addition, the purified ATP extracts may be concentrated up to 100-fold, thus greatly improving the sensitivity of ATP measurement in samples containing very low biomass. This procedure has been applied to ATP determination in marine sediments in the upwelling area off northwest Africa. The average ATP concentrations in the upper 6 cm of sediment from 1000 and 200 m were 195 and 545 ng per ml wet sediment, respectively.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution and activity of bacterioplankton, and the turnover of dissolved organic matter (DOM) were examined in McMurdo Sound, Antarctica. On the eastern side of the Sound, bacteria averaged 6.5×108 l-1, and turnover rates of dissolved adenosine triphosphate, D-glucose and l-leucine averaged 16, 116 and 124 h, respecitvely. These molecules as well as thymidine were taken up maximally from 0° to 5°C and near-maximally from -1.5° to 0°C, indicating bacterial adaptation to rapid turnover of dissolved organic matter at the ambient temperature. On the west side of the Sound, bacteria averaged only 0.65×108 l-1, and turnover times for adenosine triphosphate, D-glucose and lleucine averaged 59, 20454, and 3070 h, respectively. Total microbial adenosine triphosphate (an indicator of total microbial biomass) and chlorophyll a were also much lower at the western than at the eastern side stations. Moreover, no primary production could be detected at one western side station (New Harbor). Thus, in McMurdo Sound, the western side is highly oligotrophic, but the eastern side has an abundant active bacterioplankton, comparable to that of temperate coastal waters.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 2 (1986), S. 157-163 
    ISSN: 1432-0789
    Keywords: Available N ; Fumigation method ; N immobilization-remineralization ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The chloroform fumigation-incubation method (CFIM) was used to measure the microbial biomass of 17 agricultural soils from Punjab Pakistan which represented different agricultural soil series. The biomass C was used to calculate biomass N and the changes occurring in NH4 +-N and NO3 −-N content of soils were studied during the turnover of microbial biomass or added C source. Mineral N released in fumigated-incubated soils and biomass N calculated from biomass C was correlated with some N availability indexes. The soils contained 427–1240 kg C as biomass which represented 1.2%–6.9% of the total organic C in the soils studied. Calculations based on biomass C showed that the soils contained 64–186 kg N ha−1 as microbial biomass. Immobilization of NCO3 −-N was observed in different soils during the turnover of microbial biomass and any net increase in mineral N content of fumigated incubated soils was attributed entirely to NH4 +-N. Biomass N calculated from biomass C showed non-significant correlation with different N availability indexes whereas mineral N accumulated in fumigated-incubated soils showed highly significant correlations with other indexes including N uptake by plants.
    Type of Medium: Electronic Resource
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