Gracilibacillus gen. nov., with description of Gracilibacillus halotolerans gen. nov., sp. nov.; transfer of Bacillus dipsosauri to Gracilibacillus dipsosauri comb. nov., and Bacillus salexigens to the genus Salibacillus gen. nov., as Salibacillus salexigens comb. nov.

A Gram-positive, extremely halotolerant bacterium was isolated from the Gre at Salt Lake, Utah, USA. The strain, designated NNT (= DSM 11805(T)), was s trictly aerobic, rod-shaped, motile by peritrichous flagella and spore-form ing. Strain NNT grew at salinities of 0-20% (w/v) NaCl. A distinctive featu re of strain NNT was its optimal growth in salt-free medium. The polar lipi d pattern of strain NNT consisted of phosphatidyl glycerol, diphosphatidyl glycerol and two phospholipids of unknown structure. The G+C content of its DNA was 38 mol%. The morphological, physiological and, particularly, the 1 6S rDNA sequence data, showed that strain NNT was associated with 'Bacillus group 1'. However, the organisms showing the greatest degree of sequence s imilarity to strain NNT were members of the genus Halobacillus and the spec ies Marinococcus albus, Virgibacillus pantothenticus, Bacillus salexigens a nd Bacillus dipsosauri. On the basis of chemotaxonomic data, strain NNT was shown to be chemically most similar to B. salexigens and B. dipsosauri, wi th the greatest degree of similarity being shown to the latter organism. Th is was consistent with the 16S rDNA sequence data. Members of the genus Hal obacillus comprise a chemically distinct group and can easily be distinguis hed from all other organisms of 'Bacillus group 1'. On the basis of the 16S rDNA data, chemotaxonomy and the physiology of strain NNT, it is proposed that this organism is a member of a new species, within a new genus, for wh ich the name Gracilibacillus halotolerans is proposed. It is also proposed that B. dipsosauri be transferred to this genus as Gracilibacillus dipsosau ri comb, nov. and that B. salexigens be transferred to the genus Salibacill us gen. nov., as Salibacillus salexigens comb. nov. Finally, additional dat a is provided to support the transfer of Bacillus pantothenticus to the gen us Virgibacillus, as Virgibacillus pantothenticus Heyndrickx et al. (1998).