Occurrence of virus-like particles in the Dead Sea.
Electron-microscopic examination of water samples from the hypersaline Dead Sea showed the presence of high numbers of virus-like particles. Between 0.9 and 7.3 x 10(7) virus-like particles ml(-1) were enumerated in October 1994 in the upper 20 m of the water column during the decline of a bloom of halophilic Archaea. Virus-like particles outnumbered bacteria by a factor of 0.9-9.5 (average 4.4). A variety of viral morphologies were detected, the most often encountered being spindle-shaped, followed by polyhedral and tailed phages. In addition, other types of particles were frequently found, such as unidentified algal scales, and virus-sized star-shaped particles. Water samples collected during 1995 contained low numbers of both bacteria and virus-like particles (1.9-2.6 x 10(6) and 0.8-4.6 x 10(7) ml(-1) in April 1995), with viral numbers sharply declining afterwards (less than 10(4) ml(-1) in November 1995-January 1996). It is suggested that viruses may play a major role in the decline of halophilic archaeal communities in the Dead Sea. an environment in which protozoa and other predators are absent.
The Alexander Silverman Institute of Life Sciences and The Moshe Shilo Minerva Center for Marine Biogeochemistry, The Hebrew University of Jerusalem, Israel. orena@shum.cc.huji.ac.il
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D008877:Middle East; D009792:Oceans and Seas; D014780:Viruses / Q000302:isolation & purification* / Q000648:ultrastructure; D014871:Water Microbiology