Halobacterium mediterranei spec, nov., a New Carbohydrate-Utilizing Extreme Halophile

The extremely halophilic rod-shaped bacterium, strain R-4, has features very different from other known Halobacterium species. As do all other extreme halophiles, the organism possesses a high excess of acidic over basic amino acids in its proteins, a cell wall lacking peptidoglycan, and ether-linked diphytanyl lipids. It differs from the "classic" halobacteria in several important ways: it can use many different compounds as sole sources of carbon and energy. It is strongly amylolytic and lipolytic (against different Tweens), and does not produce H(2)S. The cell envelope of R-4 is much thicker than that of other halobacteria. The proportions of polar lipids in the envelope are different, and a new glycolipid sulfate is present in this strain. The envelope has a relatively low protein content, although a glycoprotein similar to the one of Halobacterium salinarium was detected. The G + C content (60%) is lower than that of other halobacteria. It is suggested that R-4 be designated a new species, Halobacterium mediterranei.