1887

Abstract

Summary

Growth of PCC 6803 in BG-11 medium supplemented with 1 mM-CsCl resulted in intracellular accumulation of Cs to a final level of approximately 510 nmol (10 cells) after incubation for 10 d. The doubling time was increased by 64% and the final cell yield was decreased by 70% during growth in the presence of Cs as compared to growth in control BG-11 medium. When the total monovalent cation concentration of the medium was doubled by adding either K or Na, levels of accumulated Cs were decreased by approximately 50% to 220 and 270 nmol (10 cells), respectively, after 28 d with little inhibition of growth being apparent. Short-term experiments revealed that extracellular K and Na inhibited Cs accumulation to a similar extent, with 90% inhibition of Cs accumulation occurring at the highest concentrations used (50 mM-K or Na; 1 mM-Cs). In all experiments, Cs accumulation resulted in a reduction in intracellular K, except when cells were grown in K-depleted medium, although a stoichiometric relationship was not apparent, the amount of Cs accumulated generally being greater than the amount of K released. Cs accumulation had no discernible effect on intracellular Na. When K, Na, Rb, Li or Tl were supplied at equimolar (1 mM) concentrations to Cs, only Tl significantly reduced Cs accumulation. However, an approximately 50% inhibition of Cs accumulation resulted when concentrations of K, Na, Rb or Li were increased to 10 mM, which suggests that Cs may have a higher affinity for the monovalent cation transport system than K, Rb and TI also caused a decrease in intracellular K, whereas Na and Li stimulated K uptake. Cs accumulation was dependent on the external Cs concentration and showed a linear relationship to external Cs concentrations≤2 mM over 12 h incubation. However, prolonged incubation in external Cs concentrations≥ 0·8 mM resulted in Cs release from the cells and after 48 h, similar amounts of Cs and K were present in cells incubated at these higher concentrations. Cs accumulation was energy- and pH-dependent. Incubation in the light at 4 °C, or in the presence of 3(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), or at 22 °C in the dark resulted in decreased Cs accumulation and decreased K release from the cells. Increased amounts of Cs were accumulated as the pH of the external medium was increased, with maximal accumulation [approximately 1330 nmol Cs (10 cells) after 24 h incubation] occurring at pH 10, the highest pH value used. It is suggested that an important mechanism of Cs toxicity in PCC 6803 arises through replacement of cellular K by Cs. The possible role of primary producers such as cyanobacteria in the mobilization of this radionuclide in aquatic habitats is discussed.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-137-2-405
1991-02-01
2024-04-16
Loading full text...

Full text loading...

/deliver/fulltext/micro/137/2/mic-137-2-405.html?itemId=/content/journal/micro/10.1099/00221287-137-2-405&mimeType=html&fmt=ahah

References

  1. Bakker E. P. 1983; pH-dependent transport of rubidium by the constitutive potassium uptake system TrkA of Escherichia coli K-12. FEMS Microbiology Letters 16:229–233
    [Google Scholar]
  2. Booth I. R. 1985; Regulation of cytoplasmic pH in bacteria. Microbiological Reviews 49:359–378
    [Google Scholar]
  3. Borst-Pauwels G. W. F. H. 1981; Ion transport in yeast. Biochimica et Biophysica Acta 650:88–127
    [Google Scholar]
  4. Bossemeyer D., Schlösser A., Barker E. P. 1989; Specific cesium transport via the Escherichia coli Kup (TrkD) K+ uptake system. Journal of Bacteriology 171:2219–2221
    [Google Scholar]
  5. Damper P. D., Epstein W., Rosen B. P., Sorensen E. N. 1979; Thallous ion is accumulated by potassium transport systems in Escherichia coli . Biochemistry 18:4165–4169
    [Google Scholar]
  6. Dighton J., Horrill A. 1988; Radiocaesium accumulation in the mycorrhizal fungi Lactarius rufus and Inocybe longicystis, in upland Britain, following the Chernobyl accident. Transactions of the British Mycological Society 91:335–337
    [Google Scholar]
  7. Elstner E. F., Fink R., Höll W., Lengfelder E., Ziegler H. 1987; Natural and Chernobyl-caused radioactivity in mushrooms, mosses and soil samples of defined biotopes in SW Bavaria. Oecologia (Berlin) 73:553–558
    [Google Scholar]
  8. Fisher N. S. 1985; Accumulation of metals by marine picoplankton. Marine Biology 87:137–142
    [Google Scholar]
  9. Gadd G. M. 1988; Accumulation of metals by microorganisms and algae. In Biotechnology 6b Special Microbial Processes401–433 Rehm H.-J. VCH Verlagsgesellschaft; Weinheim:
    [Google Scholar]
  10. Gadd G. M. 1990; Metal tolerance. In Microbiology of Extreme Environments178–210 Edwards C. Open University Press; Milton Keynes:
    [Google Scholar]
  11. Greenwood N. N., Earnshaw A. 1984 Chemistry of the Elements Pergamon Press; Oxford:
    [Google Scholar]
  12. Harvey R. S., Patrick R. 1967; Concentration of 137Cs, 65Zn and 85Sr by freshwater algae. Biotechnology and Bioengineering 9:449–456
    [Google Scholar]
  13. Haselwandter K., Berreck M., Brunner P. 1988; Fungi as bioindicators of radiocaesium contamination: pre- and post-Chernobyl activities. Transactions of the British Mycological Society 90:171–174
    [Google Scholar]
  14. HUGHES M. N., Poole R. K. 1989 Metals and Micro-organisms Chapman & Hall; London:
    [Google Scholar]
  15. Jasper P. 1978; Potassium transport in Rhodopseudomonas capsulata . Journal of Bacteriology 133:13 14–1 322
    [Google Scholar]
  16. Kellar P. E., Paerl H. W. 1980; Physiological daptations in response to environmental stress during an N2fixing Anabaena bloom. Applied and Environmental Microbiology 40:587–595
    [Google Scholar]
  17. Kirk G. J. D., Staunton S. 1989; On predicting the fate of radioactive caesium in soil beneath grassland. Journal of Soil Science 40:71–84
    [Google Scholar]
  18. Korky J. K., Kowalski L. 1989; Radioactive cesium in edible mushrooms. Journal of Agricultural and Food Chemistry 37:568–569
    [Google Scholar]
  19. Nakamura T., Tokuda H., Unemoto T. 1982; Effects of pH and monovalent cations on the potassium ion exit from the marine bacterium, Vibrio alginolyticus, and the manipulation of cellular cation contents. Biochimica et Biophysica Acta 692:389–396
    [Google Scholar]
  20. Norris P., Kee Man W., Hughes M. N., Kelly D. P. 1976; Toxicity and accumulation of thallium in bacteria and yeast. Archives of Microbiology 110:279–286
    [Google Scholar]
  21. Padan E., Vitterbo A. 1988; Cation transport in cyanobacteria. Methods in Enzymology 167:561–577
    [Google Scholar]
  22. Paerl H. W., Ustach J. F. 1982; Blue-green algal scums: an explanation for their occurrence during freshwater blooms. Limnology and Oceanography 27:2 12–2 17
    [Google Scholar]
  23. Paschinger H. 1977; DCCD induced sodium uptake by Anacystis nidulans . Archives of Microbiology 113:285–291
    [Google Scholar]
  24. Raven J. A. 1980; Nutrient transport in microalgae. Advances in Microbial Physiology 21:47–226
    [Google Scholar]
  25. Reed R. H. 1986; Halotolerant and halophilic microbes. In Microbes in Extreme Environments55–81 Herbert R. A., Codd G. A. Academic Press; London:
    [Google Scholar]
  26. Reed R. H., Gadd G. M. 1990; Metal tolerance in eukaryotic and prokaryotic algae. In Heavy Metal Tolerance in Plants: Evolutionary Aspects105–108 Shaw. Boca Raton A. J. CRC press; London:
    [Google Scholar]
  27. Reed R. H., Rowell P., Stewart W. D. P. 1981a; Characterization of the transport of potassium ions in the cyanobacterium Anabaena variabilis Kiitz. European Journal of Biochemistry 116:323–330
    [Google Scholar]
  28. Reed R. H., Rowell P., Stewart W. D. P. 1981b; Uptake of potassium and rubidium ions by the cyanobacterium Anabaena variabilis . FEMS Microbiology Letters 11:233–236
    [Google Scholar]
  29. Rhoads D. B., Woo A., Epstein W. 1977; Discrimination between Rb+ and K+ by Escherichia coli . Biochimica et Biophysica Acta 469:45–51
    [Google Scholar]
  30. Richardson D. L., Reed R. H., Stewart W. D. P. 1983; Synechocystis PCC 6803 : a euryhaline cyanobacterium. FEMS Microbiology Letters 18:99–102
    [Google Scholar]
  31. Rothstein A., Bruce M. 1958; The potassium efflux and influx in yeast at different potassium concentrations. Journal of Cellular and Comparative Physiology 51:145–159
    [Google Scholar]
  32. Stanier R. Y., Kunisawa R., Mandel M., Cohen-Bazire G. 1971; Purification and properties of unicellular blue-green algae (order Chroococcales) . Bacteriological Reviews 32:171–205
    [Google Scholar]
  33. Walderhaug M. O., Dosch D. C., Epstein W. 1987; Potassium transport in bacteria. In Ion Transport in Prokaryotes85–130 Rosen B. P., Silver S. Academic Press; New York:
    [Google Scholar]
  34. White C., Gadd G. M. 1987; Inhibition of H+ efflux and K+ uptake, and induction of K+ efflux in yeast by heavy metals. Toxicity Assessment 2:437–447
    [Google Scholar]
  35. Williams L. G. 1960; Uptake of cesium137 by cells and detritus of Euglena and Chlorella . Limnology and Oceanography 5:301–311
    [Google Scholar]
  36. Williams L. G. 1970; Concentration of 85strontium and 137cesium from water solutions by Cladophora and Pithophora . Journal of Phycology 6:314–316
    [Google Scholar]
  37. Williams L. G., Swanson H. D. 1958; Concentration of cesium-137 by algae. Science 127:187–188
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-137-2-405
Loading
/content/journal/micro/10.1099/00221287-137-2-405
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error