Characterization of the endoevaporitic microbial communities in a hypersaline gypsum crust by fatty acid analysis

Danny Ionescu, André Lipski, Karlheinz Altendorf, Aharon Oren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

We have used fatty acid analyses to study the community structure of a layered endoevaporitic microbial community within a gypsum crust that covers the bottom of a saltern evaporation pond in Eilat, Israel. This community, living at a salinity of 218-238 g l-1 total dissolved salts, consists of an upper brown layer dominated by unicellular cyanobacteria, a green layer with filamentous cyanobacteria, a red-purple layer with both Chromatium and Ectothiorhodospira/Halorhodospira type of purple sulfur bacteria, and a black layer in which dissimilatory sulfate reduction occurs. An olive-green layer is sometimes present below the red-purple layer. Analysis by gas chromatography/mass spectrometry of the fatty acid methyl esters prepared from the different fractions showed characteristic patterns in each layer, and these could be related to fatty acid composition data from the literature and to fatty acid analyses of representative halophilic microorganisms isolated from the site. The nature of the fatty acids in the green layer suggests that the cyanobacteria present there use the oxygen-independent pathway for production of unsaturated fatty acids, a pathway only occasionally encountered in filamentous cyanobacteria. The facultative anaerobic nature of the cyanobacteria in the green layer was confirmed by their ability to perform anoxygenic photosynthesis with sulfide as electron donor. Specific signature fatty acids identified for each layer corresponded well with the microscopic and functional analysis of the biota present.

Original languageAmerican English
Pages (from-to)15-26
Number of pages12
JournalHydrobiologia
Volume576
Issue number1
DOIs
StatePublished - Feb 2007

Bibliographical note

Funding Information:
Acknowledgements We thank the Israel Salt Company in Eilat, Israel for allowing access to the salterns, and the staff of the Interuniversity Institute for Marine Sciences of Eilat for logistic support. We are further grateful to Ilia Belotserkovsky, Noa Eden, and Nina Kamennaya who contributed data on CO2 photoassimilation, and to Prof. Zeev Aizenshtat and to Irena Miloslavski for their assis- tance with the operation of the GC/MS in Jerusalem. This joint research project was financially supported by the State of Lower-Saxony and the Volkswagen Foundation, Hannover, Germany.

Keywords

  • Cyanobacteria
  • Gypsum
  • Halophilic
  • Hypersaline
  • Purple bacteria
  • Salterns
  • Sulfate reduction

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