Microbial weeds in hypersaline habitats: The enigma of the weed-like Haloferax mediterranei

Aharon Oren*, John E. Hallsworth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Heterotrophic prokaryotic communities that inhabit saltern crystallizer ponds are typically dominated by two species, the archaeon Haloquadratum walsbyi and the bacterium Salinibacter ruber, regardless of location. These organisms behave as 'microbial weeds' as defined by Cray et al. (Microb Biotechnol 6: 453-492, 2013) that possess the biological traits required to dominate the microbiology of these open habitats. Here, we discuss the enigma of the less abundant Haloferax mediterranei, an archaeon that grows faster than any other, comparable extreme halophile. It has a wide window for salt tolerance, can grow on simple as well as on complex substrates and degrade polymeric substances, has different modes of anaerobic growth, can accumulate storage polymers, produces gas vesicles, and excretes halocins capable of killing other Archaea. Therefore, Hfx. mediterranei is apparently more qualified as a 'microbial weed' than Haloquadratum and Salinibacter. However, the former differs because it produces carotenoid pigments only in the lower salinity range and lacks energy-generating retinal-based, light-driven ion pumps such as bacteriorhodopsin and halorhodopsin. We discuss these observations in relation to microbial weed biology in, and the open-habitat ecology of, hypersaline systems.

Original languageAmerican English
Pages (from-to)134-142
Number of pages9
JournalFEMS Microbiology Letters
Issue number2
StatePublished - 2014

Bibliographical note

Publisher Copyright:
© 2014 Federation of European Microbiological Societies.


  • Archaea
  • Haloferax
  • Halophilic
  • Haloquadratum
  • Salinibacter


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