Mycosporine-like amino acids as osmotic solutes in a community of halophilic cyanobacteria

Aharon Oren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

158 Scopus citations

Abstract

Large concentrations of mycosporine-like amino acids (MAAs) were found in a community of unicellular cyanobacteria inhabiting a gypsum crust developing on the bottom of a hypersaline saltern pond in Eilat, Israel. This is the first report of the occurrence of MAAs in a halophilic cyanobacterial community. Two MAAs were detected, one with an absorption maximum at 332 nm, and one at 362 nm. Intracellular MAA concentrations in the cyanobacterial community were estimated to be at least 98 mM, and this already high value is probably an underestimation. With an average molecular weight of around 300, MAAs should contribute at least 3% of the cell wet weight. While MAAs have been shown to absorb ultraviolet (UV) radiation, protecting the cells against solar radiation, they may also have an osmotic function in cyanobacterial communities inhabiting hypersaline environments, and help the cells to cope with the high salt concentrations in their environment. When the upper layer of the gypsum crust was subjected to dilution with distilled water, MAAs rapidly appeared in the outer medium, with the extent of loss of intracellular MAAs being approximately proportional to the extent of the dilution stress applied. No uptake of MAAs was observed in response to a subsequent increase in medium salinity.

Original languageAmerican English
Pages (from-to)231-240
Number of pages10
JournalGeomicrobiology Journal
Volume14
Issue number3
DOIs
StatePublished - 1997

Bibliographical note

Funding Information:
I thank the Israel Salt Company for allowing access to the Eilat saltern ponds, the staff of the Interuniversity Institute of Eilat for logistic support, F. Garcia-Pichel (Max-Planck Institut für marine Mikrobiologie, Bremen) for invaluable discussions, and I. Giladi for his participation in the work. This work was supported by the Israel Science Foundation administred by the Israel Academy of Sciences and Humanities, and by the Moshe Shilo Center for Marine Biogeochemistry, BMFT-Minerva Gesellschaft für Forschung, München, Germany.

Keywords

  • Cyanobacterium
  • Gypsum
  • Mycosporine-like amino acids
  • Osmotic solutes
  • Salterns
  • Ultraviolet radiation

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