Alteribacillus bidgolensis gen. nov., sp. nov., a moderately halophilic bacterium from a hypersaline lake, and reclassification of Bacillus persepolensis as Alteribacillus persepolensis comb. nov.

Abstract

A novel Gram-stain-positive, moderately halophilic bacterium, designated strain P4B(T), was isolated from water of the hypersaline Aran-Bidgol lake in Iran and characterized taxonomically by using a polyphasic approach. Cells of strain P4B(T) were non-motile rods producing ellipsoidal endospores at a central position in non-swollen sporangia. Strain P4B(T) was strictly aerobic and catalase- and oxidase-positive. It 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 P4B(T) was shown to belong to the phylum Firmicutes and shared highest similarity with Bacillus persepolensis HS136(T) (97.1%) and Bacillus salarius BH169(T) (95.1%). However, it shared only 91.3% 16S rRNA gene sequence similarity with Bacillus subtilis subsp. subtilis DSM 10(T), indicating that strain P4B(T) 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 P4B(T) and B. persepolensis HS136(T) (6%). The major cellular fatty acids of strain P4B(T) were iso-C(15:0) and anteiso-C(15:0), as for B. persepolensis HS136(T) but in contrast to B. salarius DSM 16461(T) and B. subtilis subsp. subtilis DSM 10(T). Its polar lipid pattern consisted of phosphatidylglycerol, an aminoglycolipid and an unknown phospholipid. This polar lipid profile was similar to that obtained for B. persepolensis DSM 21632(T) but different from those of B. salarius DSM 16461(T) and B. subtilis subsp. subtilis DSM 10(T). 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 indicate placement of strain P4B(T) within the Firmicutes, closely related to B. persepolensis but with features clearly distinct from those of the genus Bacillus and other related genera. On the basis of these data, strain P4B(T) is considered to represent a novel species of a new genus, for which the name Alteribacillus bidgolensis gen. nov., sp. nov. is proposed. The type strain of Alteribacillus bidgolensis is P4B(T) (=CCM 7963(T)=CECT 7998(T)=DSM 25260(T)=IBRC-M 10614(T)=KCTC 13821(T)). It is also suggested to transfer B. persepolensis to this new genus, as Alteribacillus persepolensis comb. nov. The type strain of Alteribacillus persepolensis is HS136(T) (=CCM 7595(T)=DSM 21632(T)=JCM 15720(T)=LMG 25222(T)).