No abstract

Haloarcula mukohataei, previously isolated from soils of salt flats in Argentina, was originally placed in the genus Haloarcula on the basis of 16S rRNA gene sequence comparison. However, its morphology and polar lipid composition differs from that of the other Haloarcula species. In addition, its phylogenetic distance from other Haloarcula species is rather large, and the 16S rDNA sequence does not contain many of the signature bases characteristic of the genus. Transfer of the species to a new genus was therefore recommended by the International Committee on Systematic Bacteriology Subcommittee on the taxonomy of Halobacteriaceae. A full description of the isolate, proposed as a member of a new genus, Halomicrobium, as Halomicrobium mukohataei comb. nov., is presented. The type strain is strain arg-2T (= JCM 9738T = DSM 12286T = ATCC 700874T = NCIMB 13541T).

Growth of Salinibacter ruber, a red, extremely halophilic bacterium phylogenetically affiliated with the Flavobacterium/Cytophaga branch of the domain Bacteria, is stimulated by glycerol. In contrast to glucose consumption, which starts only after more easily degradable substrates present in yeast extract have been depleted, glycerol is consumed during the earliest growth phases. When U-14 Clabeled glycerol was added to the culture, up to 25% of the radioactivity was incorporated by the cells. Glycerol kinase activity was detected only in cells grown in the presence of glycerol (up to 90 nmol mg protein 31 min 31 ). This enzyme functioned over salt concentrations from 0.6 to 2.8 M KCl. No significant activity of NAD-dependent glycerol dehydrogenase was found. It is suggested that Salinibacter may use glycerol as one of its principal substrates in its habitat, the saltern crystallizer ponds.