Sambhar Salt Lake.

The saline and alkaline brines from the Sambhar Salt Lake (SSL), both from the main lake and from the solar evaporation pans at Sambhar Salt Limited, Sambhar, Rajasthan, India, were studied with respect to their chemical composition and presence of red, extremely haloalkaliphilic archaebacteria. The brines had pH values of 9.5±0.2 and a total salt content ranging from 7% (w/v) to more than 30% (w/v). Sodium chloride, sodium carbonate, sodium bicarbonate and sodium sulphate were the principal salts present in these brines which lacked divalent cations (calcium and magnesium). Six strains of red, extremely haloalkaliphilic bacteria, designated SSL 1 to SSL 6, were isolated. All the isolates showed obligate requirements for sodium chloride (>15%, w/v) and high pH (>9.0). Magnesium ions were required in traces for maintaining morphological structure and pigmentation. All these strains possessed the diether core lipids, phosphatidylglycerol (PG), phosphatidylglycerophosphate (PGP), and bacterioruberins characteristic of halophilic archaebacteria. The strains were assigned to the newly proposed genus Natronobacterium. [ABSTRACT FROM AUTHOR]