Nocardia halotolerans sp. nov., a halotolerant actinomycete isolated from saline soil.

Abstract

A novel halotolerant actinomycete, strain Chem15(T), was isolated from soil around Inche-Broun hypersaline wetland; its taxonomic position was determined based on a polyphasic approach. Strain Chem15(T) was strictly aerobic and tolerated NaCl up to 12.5%. The optimum temperature and pH for growth were 28-30 °C and pH 7.0-7.5, respectively. The cell wall of strain Chem15(T) contained meso-diaminopimelic acid as diamino acid and galactose, arabinose and ribose as whole-cell sugars. The major phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The cellular fatty acids profile consisted of C16 : 0, iso-C18 : 0, C18 : 0 10-methyl and C18 : 1ω9c, and the major respiratory quinone was MK-8(H4cycl). The G+C content of the genomic DNA was 68.0 mol%. The novel strain constituted a distinct phyletic line within the genus Nocardia, based on 16S rRNA gene sequence analysis, and was closely associated with Nocardia sungurluensis DSM 45714(T) and Nocardia alba DSM 44684(T) (98.2 and 98.1% 16S rRNA gene sequence similarity, respectively). However DNA-DNA relatedness and phenotypic data demonstrated that strain Chem15(T) was clearly different from closely related species of the genus Nocardia. It is concluded that the organism should be classified as a representative of a novel species of the genus Nocardia, for which the name Nocardia halotolerans sp. nov. is proposed. The type strain is Chem15(T) ( = IBRC-M 10490(T) = LMG 28544(T)).