Isolation and characterization of peculiar aerobic extremely haloalkalidudc archaea from the United Arab Emirates [electronic resource].

Includes references.

Aeroblc, extremely haloalkaliduric archaebacteria are highly spccialized group, which have evolved to overcome the environmental pressures and alkaline pH and high salt concentration. In the present study, four halobacterial isolates were obtained from UAE hyper saline soils located in Shabisi and Um-Annr areas. These isolates exhibited a wide range of unusual morphological, physiological and biochemical properties. Colonies were colorless but extracted lipids were orange to red in color. Isolates were aerobic, pleomorphic, motile, asporgenous and Gram-negative rods. Light microscopy and scanning EM revealed an asymmetrical cell division process, with formation of terminal spherical bodies (-1.0 µm wide) and a cyst-like elliptical structure (0.8-Ll by 1.2S-1.4SJ.lm). Terminal spherical bodies were not stainable by use of endospore stains. All isolates grew at 30% NaCI, and three were able to grow in saturated NaCI medium (3S%) containing low concentration of magnesium ions. Peptone was an excellent energy and carbon source for growth. Growth was obtained over a wide rage of temperature (20-SS'C) and pH (S-l1) with optimum growth at 4S'C and pH 8 - 9. The isolates reduced nitrate to nitrite, fermented several sugars into acids only. Neither hydrogen sulfide nor indole was produced and cell walls were free of muramic acid. The four isolates were sensitive to bacitracin, anisomycin, novobiocin, and nitrofurantion, but resistant to the other eubacteria inhibiting antibiotics. Total lipids accounted 7.1 - 8.0 % w/w) of cell dry weight; polar and non-polar lipids represented 90.5% and 9.S% wlw of total lipids extracted from the cell, respectively. Comparison between the four isolates and four Archaea type strains showed differences that warrant detailed studies at the molecular level to further elucidate their identity.

Summary in Arabic.

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