Halomicroarcula Amylolytica Sp. Nov., A Novel Halophilic Archaeon Isolated From A Salt Mine

A halophilic archaeon named strain LR21(T) was isolated from a salt mine in Yunnan Province, PR China. Cells were spherical, Gram-stain-negative and motile. Strain LR21(T) grew at 20-50 degrees C (optimum. 42 degrees C). with 8-30% (w/v) NaCl (optimum, 23%) and at pH 5.5-9.5 (optimum, pH 7.5-8.5). Mg2+ was not required for growth. The major polar lipid profile comprised phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol sulfate. Strain LR21(T) had two dissimilar 16S rRNA genes (rrnA and rrnB) and they were closely related to Halomicroarcula limicola YGHS32(T), Hma. pellucida BNERC31(T) and Hma. salina YGHS18(T) with sequence similarities of 95.3-99.0, 93.0-96.2 and 93.2-95.9%, respectively, and much lower values to other members. The rpoB' gene sequence similarities between strain LR21(T) and Hma. limicola YGHS32(T), Hma. pellucida BNERC31(T) and Hma. saline YGHS18(T) were 95.2, 91.2 and 91.2% respectively. The values of average nucleotide identity (ANI) and average amino-acid identity (AAI) between strain LR21(T) and Hma. limicola YGHS32(T), were 89.0 and 90.1%, respectively. DNA relatedness between strains LR21(T) and Hma. limicola YGHS32(T) determined by in silico DNA-DNA hybridization was 36.8%. Values of ANI and AAI between strain LR21T and other members in the genus Halomicroarcula were far below 95% and the DNA-DNA relatedness values between strain LR21(T) and its close relatives were much lower than 70%, which is far below the boundary for delineation of a new species prokaryote. The DNA G+C content of strain LR21(T) was 62.0 mol% (genome). The results suggested that strain LR21(T) represents a novel species of the genus Halomicroarcula, for which the name Halomicroarcula amylolytica sp. nov. is proposed. The type strain is LR21(T) (=CGMCC 1.13611(T)=NBRC 113588(T)).