LONG-TERM AND SHORT-TERM CHANGES IN THE MICROBIAL COMMUNITIES IN THE DEAD SEA Aharon Oren, Ittai Gavrieli, Jonah Gavrieli, and Joseph Lati ISSEEQ – Rehovot – June 1, 2005 The Dead Sea – a terminal desert lake LANDSAT view of the Dead Sea (January 1987) Bathymetric map of the Dead Sea Flow through the Jordan river in the past: around 1000 x 106 m3/year Presently: around 150 x 106 m3/year Dead Sea water levels – 1800-2002 The ionic composition of the Dead Sea (1996): Mg2+ 1.89 M 45.9 g/l Na+ 1.59 M 36.6 g/l Ca2+ 0.44 M 17.6 g/l K+ 0.20 M 7.8 g/l Cl- 6.34 M 224.8 g/l Br- 0.07 M 5.6 g/l Total dissolved salts: about 340 g/l pH: about 6.0 The lake is supersaturated with respect to sodium, and massive amounts of NaCl precipitate to the bottom Life in the Dead Sea Benjamin Elazari-Volcani (Wilkansky), 1936 Dunaliella from the Dead Sea Halophilic Archaea in the Dead Sea (1992) Halophilic Archaea isolated from the Dead Sea Haloferax volcanii Halorubrum sodomense These halophilic Archaea are colored brightly red by: - C-50 carotenoids (bacterioruberins) - Bacteriorhodopsin (in some species only, under suitable growth conditions) The dynamics of the microbial communities in the Dead Sea - 1980 to present The 1980 archaeal bloom in the Dead Sea In the summer of 1980 the water was red! An early record of a “red” Dead Sea? (2 מלכים ב: 2222---2323))) And when they rose early in the morning, and the sun shone upon the water, the Moabites saw the water opposite them as red as blood. And they said: “This is blood …” (2 Kings 3: 22-23) This archaeal bloom developed concomitant with a bloom of Dunaliella, the primary producer in the lake Phosphate is the limiting inorganic nutrient in the Dead Sea Nitrogen is abundantly available in the Dead + Sea – around 2 mM NH4 Effect of dilution and phosphate on the growth rate and growth yield of Dunaliella in Dead Sea water An even denser algal and archaeal bloom developed in the Dead Sea in 1992, once more coloring the waters red Dead Sea chemical parameters 1980-1996 Comparison of the 1980 and 1992 microbial blooms in the Dead Sea The 1992 Dunaliella bloom in the Dead Sea The 1992 archaeal bloom in the Dead Sea The polar lipid pattern of the biomass during the 1992 bloom was consistent with the genera Halobaculum and/or Haloferax . !!!!!!!!!!!!!!!!!!!!!!!!! Polar lipids in the 1992 archaeal bloom in the Dead Sea PG Me-PGP One of the factors responsible for the decline of the archaeal community in the Dead Sea following a bloom may be halophilic bacteriophages (“halophages”) Bacteriophages in the Dead Sea (1994) The biology of the Dead Sea – 1980-present One of the factors responsible for the decline of the archaeal community in the Dead Sea following a bloom may be halophilic bacteriophages (“halophages”) Unexpected observations during a search for the biblical Sodom and Gomorrah (1999) …. Michael Sanders (Irvine, California) www.biblemysteries.com/Expeditiontrips/sgalbum.htm (Pictures below: courtesy of Zvi Ben-Avraham and Michael Lazar – Tel Aviv University) The future of the Dead Sea and its biota? Dead Sea water levels – 1800-2002 The “Peace Conduit” (the “Red-Dead” canal) The Johannesburg Summit – September 2002 REUTERS – 1/9/02 BBC NEWS – 2/9/02 CNN – 1/9/02 The proposed “Peace Conduit” Flow: between 1.2 and 2.5x109 m3/year The experimental ponds at Sedom After three months: 100% Dead Sea water … 85% Dead Sea water, 15% Red Sea water … No phosphate With 10 µM phosphate With 1 µM phosphate 70% Dead Sea water, 30% Red Sea water … The same with 1 µM phosphate … … and 10 µM phosphate Polar lipids of the microbial community Phosphate Orcinol stain α-Naphthol stain 70 Dead Sea stain water – 30 Red Sea water + 10 µM phosphate PG 1. Pond sample 2. Haloferax Me-PGP denitrificans 3. Haloarcula vallismortis PGS 4. Halobacterium salinarum S-DGD-1 5. Halorubrum distributum 2 1 3 4 2 1 3 5 4 2 1 3 5 Will density stratification lead to the accumulation of sulfide in the hypolimnion of the Dead Sea? Evidence for sulfate reduction in the Dead Sea in the past (Nissenbaum and Kaplan, 1976) Are sulfate reducers active in the Dead Sea sediments? Some indications have been obtained that sulfate reduction does occur in the sediments of the Dead Sea, Attempts to grow the organisms involved are under way Earlier attempts have led discovery of a range of other interesting anaerobes: Some anaerobic halophilic Bacteria isolated from Dead Sea sediments Halobacteroides halobius Sporohalobacter lortetii Orenia marismortui Selenihalanaerobacter shriftii How much “alive” will the Dead Sea eventually become? And he said to me, “This water flows toward the eastern region and goes down into the Arabah; and when it enters the stagnant waters of the sea, the water will become fresh. And wherever the river goes every living creature which swarms will live, and there will be very many fish, for this water goes there, that the waters of the sea may become fresh; so everything will live where the water (((יחזקאל מ"ז: goes. Fishermen will stand beside (((88--12 the sea; from Ein-ge’di to En-egla’im it will be a place for spreading of nets; its fish will be of very many kinds, like the fish of the Great Sea. …. But its swamps and marshes will not become fresh; they are to be left (Ezekiel 47: 8-11) for salt..