Natronococcus roseus sp. nov., a haloalkaliphilic archaeon from a hypersaline lake.

A novel halophilic archaeon, strain CG-1(T), belonging to the genus Natronococcus was isolated from sediment of the soda lake Chagannor in Inner Mongolia, China. The colonies of this strain were pink pigmented, the intensity of the colour decreased when the cells grew at salt saturation levels. The cells were non-motile cocci and strictly aerobic. Hypotonic treatment did not cause cell lysis, even in distilled water. Strain CG-1(T) grew at 15-30.0 % (w/v) NaCl and at 30-50 °C and pH 8.0-11.0, with optimal growth occurring at 25-30 % (w/v) NaCl, 37-45 °C and pH 9-9.5. MgCl(2) was not required for growth. Strain CG-1(T) was most closely related to the type strains of Natronococcus amylolyticus Ah-36(T), Natronococcus jeotgali B1(T) and Natronococcus occultus SP4(T), with which it shared 98.4 %, 96.2 and 95.7 % 16S rRNA gene sequence similarity, respectively. The polar lipids consisted of C(20)C(20) and C(20)C(25) derivatives of phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and minor phospholipid components. No glycolipids were detected. The DNA G+C content of strain CG-1(T) was 62.1 mol%. DNA-DNA hybridization with N. amylolyticus DSM 10524(T), phylogenetically the most closely related species, was 39 %; this value showed that strain CG-1(T) constituted a different genospecies. The comparison of 16S rRNA gene sequences, detailed phenotypic characterization, polar lipid profile and DNA-DNA hybridization studies revealed that strain CG-1(T) belongs to the genus Natronococcus and constitutes a novel species for which the name Natronococcus roseus sp. nov. is proposed. The type strain is CG-1(T) (=CECT 7984(T)=IBRC-M 10656(T)=JCM 17958(T)).

[Analysis of partial sequence of the gene for a novel Br protein].

A strain of halophilic archaeum AB1 was isolated and purified from Aibi Lake located in the north of Xinjiang Uygur Autonomous Region. Partial DNA fragment encoding a bacteriorhodopsin (Br) protein as well as 16S rRNA of AB1 was amplified by PCR, and their nucleotide sequences were determined subsequently. On the basis of homology and phylognetic analysis about 16S rRNA gene (16S rDNA), it could be speculated that the strain AB1 is a novel member of the genus Natronococcus. The hydropathy analysis of Br fragment revealed that the AB1 Br had a transmembrane heptahelical structure similar to that of other Brs. On the other hand, homology alignment using the deduced partial amino acid sequence of Br protein of AB1 with other Br proteins showed that AB1 Br protein is obviously different to others. These facts indicated that the Br in halophilic archaeum AB1 is a new Br protein.

Natronococcus jeotgali sp. nov., a halophilic archaeon isolated from shrimp jeotgal, a traditional fermented seafood from Korea.

A novel halophilic archaeon (strain B1(T)) belonging to the genus Natronococcus was isolated from shrimp jeotgal, a traditional fermented food from Korea. Colonies of this strain were orange-red and cells were non-motile cocci that stained Gram-variable. Strain B1(T) grew in 7.5-30.0 % (w/v) NaCl and at 21-50 degrees C and pH 7.0-9.5, with optimal growth occurring in 23-25 % (w/v) NaCl and at 37-45 degrees C and pH 7.5. Strain B1(T) was most closely related to the type strain of Natronococcus occultus, with which it shared 97.91 % 16S rRNA gene sequence similarity. Within the phylogenetic tree, this novel strain shared a branching point with N. occultus and occupied a phylogenetic position that was distinct from the main Natronococcus branch. The degree of DNA-DNA hybridization with the type strain of N. occultus, the most closely related species phylogenetically, was 16.4 %. On the basis of these results, it is concluded that strain B1(T) represents a novel species of the genus Natronococcus, for which the name Natronococcus jeotgali is proposed. The type strain is B1(T) (=KCTC 4018(T)=DSM 18795(T)=JCM 14583(T)=CECT 7216(T)).