Abstract
A novel Gram-positive, moderately halophilic bacterium, designated strain P4BT, was isolated from water of the hypersaline lake Aran-Bidgol in Iran and characterized taxonomically using a polyphasic approach. Cells of strain P4BT were rod-shaped, nonmotile rods and producing ellipsoidal endospores at a central position in non-swollen sporangia. Strain P4BT was a strictly aerobic bacterium and catalase- and oxidase-positive. The strain was able to grow at NaCl concentrations of 0.5-12.5 % (w/v), with optimum growth occurring at 5-7.5 % (w/v) NaCl. The optimum temperature and pH for growth were 35 °C and pH 7.0. On the basis of 16S rRNA gene sequence analysis, strain P4BT was shown to belong to the phylum Firmicutes and the closest phylogenetic similarities were with the species Bacillus persepolensis HS136T (97.1 %) and Bacillus salarius BH169T (95.1 %); however, the 16S rRNA gene sequence similarity with Bacillus subtilis subsp. subtilis DSM 10T was only 91.3%, indicating that it might not be a member of the genus Bacillus. The DNA G+C content of this new isolate was 38.9 mol%. DNA-DNA hybridization experiments revealed a low level of relatedness between strain P4BT and Bacillus persepolensis HS136T (6 %). The major cellular fatty acids of strain P4BT were iso-C15:0 (24.4 %) and anteiso-C15:0 (24.3 %), similarly to those determined for Bacillus persepolensis HS136T but different to those determined for Bacillus salarius DSM 16461T or Bacillus subtilis subsp. subtilis DSM 10T. Its polar lipid pattern consisted of phosphatidylglycerol, an aminoglycolipid, and an unknown phospholipid. This polar lipid profile was quite similar to that obtained for Bacillus persepolensis DSM 21632T but different to those of Bacillus salarius DSM 16461T or Bacillus subtilis subsp. subtilis DSM 10T. The isoprenoid quinones were MK-7 (88 %) and MK-8 (2 %). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All these features reveal the placement of isolate P4BT within Firmicutes, closely related to Bacillus persepolensis but with features that clearly distinct them from those of the genus Bacillus or other related genera. On the basis of polyphasic evidence from this study, we propose the placement of strain P4BT within a new genus, as Alteribacillus bidgolensis gen. nov., sp. nov. (type strain P4BT = DSM 25260T = IBRC-M 10614T = KCTC 13821T) and the transfer of Bacillus persepolensis to this new genus, as Alteribacillus persepolensis comb. nov. The type strain of Alteribacillus persepolensis is HS136T (=CCM 7595T =DSM 21632T = JCM 15720T = LMG 25222T).