International Journal of Systematic and Evolutionary Microbiology (2000), 50, 1501–1503 Printed in Great Britain NOTE Reclassification of Bacillus marismortui as Salibacillus marismortui comb. nov. David R. Arahal, 1 M. Carmen Ma  rquez, 1 Benjamin E. Volcani, 2 § Karl H. Schleifer 3 and Antonio Ventosa 1 Author for correspondence : Antonio Ventosa. Tel : 34 954 556 765. Fax: 34 954 628 162. e-mail : ventosacica.es 1 Departamento de Microbiologı  ay Parasitologı  a, Facultad de Farmacia, Universidad de Sevilla, Seville, Spain 2 Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 920933-0202, USA 3 Lehrstuhl fu  r Mikrobiologie, Technische Universita  t Mu  nchen, Freising, Germany Recently, the features of a group of strains isolated from Dead Sea enrichments obtained in 1936 by one of us (B. E. Volcani) were described. They were Gram-positive, moderately halophilic, spore-forming rods, and were placed in a new species, Bacillus marismortui . At the same time, the new genus Salibacillus was proposed for the halophilic species Bacillus salexigens. B. marismortui and Salibacillus salexigens have similar phenotypic characteristics and the same peptidoglycan type. Phylogenetic analysis based on 16S rRNA sequence comparisons showed that they are sufficiently closely related (966 % similarity) as to warrant placement in the same genus. However, DNA–DNA hybridization experiments showed that they constitute two separate species (41 % DNA similarity). Therefore the reclassification of Bacillus marismortui as Salibacillus marismortui comb. nov. is proposed. Keywords : Bacillus, Salibacillus marismortui, moderately halophilic bacteria, 16S rRNA sequence, taxonomy In a recent study, we characterized taxonomically 91 moderately halophilic, Gram-positive, rod-shaped strains isolated from 57-year-old enrichments obtained from Dead Sea water samples by B. E. Volcani (Arahal et al., 1999). All of the isolates grouped in a single phenon according to the results of the numerical analysis, since they had very similar phenotypic charac- teristics. At the same time, we observed significant differences relative to previously described moderately halophilic, Gram-positive rods (Fendrich et al., 1990 ; Garabito et al., 1997 ; Spring et al., 1996; Ventosa et al., 1989). All strains were Gram-positive, motile, endospore-forming rods and all were strictly aerobic. Their cell wall peptidoglycan contained meso- diaminopimelic acid and they had a DNA GC content between 390 and 428 mol % (Arahal et al., 1999). Thus, they can be considered as members of the genus Bacillus sensu lato (Claus & Berkeley, 1986). The DNA–DNA relatedness found between the strains chosen as representatives of the group was  70%, ................................................................................................................................................. § Deceased 6 February 1999. The GenBank/EMBL/DDBJ accession number for the 16S rDNA sequence of Salibacillus marismortui strain 123 T is AJ009793. while only low values (0–45 %) were obtained between those strains and the reference strains used in the study. All these results, together with the phylogenetic analysis, supported the inclusion of the 91 isolates into a new species for which the name Bacillus marismortui was proposed (Arahal et al., 1999). The high levels of 16S rRNA sequence similarity found between B. marismortui and its closest relatives corre- sponded to those for Virgibacillus pantothenticus (978 % similarity) and Bacillus salexigens (966% similarity). V. pantothenticus (formerly Bacillus panto- thenticus) was recently proposed as the single member of the new genus Virgibacillus, mainly on the basis of its phylogenetic differences (Heyndrickx et al., 1998). B. marismortui cannot be included in this genus because of the many phenotypic and genotypic differences that can be found between this species and V. pantothenticus. For instance, whereas B. marismortui is a moderately halophilic bacterium (with optimal growth at 10 % salts) which needs aerobic conditions for growth and has a DNA GC content of 390–428 mol %, V. pantothenticus grows well in media without NaCl, in anaerobic conditions and has a lower GC content (369–383 mol %) (Arahal et al., 1999 ; Heyndrickx et al., 1998) (Table 1). 01414  2000 IUMS 1501