Egibacter rhizosphaerae gen. nov., sp nov., an obligately halophilic, facultatively alkaliphilic actinobacterium and proposal of Egibaceraceae fam. nov and Egibacterales ord. nov.

A novel obligately halophilic, facultatively alkaliphilic actinobacterium, designated EGI 80759(T), was isolated from the rhizosphere of Tamarix hispida Willd, Karamay, Xinjiang province, north-west China. Cells of strain EGI 80759(T) were Gram-stain-positive, non-motile and non-endospore-forming rods. Strain EGI 80759(T) showed obligately halophilic growth with a tolerance to 8-25 % (w/v) NaCI (optimum growth at 10-12 %, w/v) and facultatively alkaliphilic growth within the pH range 7.0-11.0 (optimum growth at pH 9.0-10.0). Cell-wall hydrolysates of the isolate contained meso-diaminopimelic acid (peptidoglycan type A1 gamma), with glucose, glucosamine, ribose and mannose as the major sugars. The major fatty acids identified were 10-methyl-C-17 : 0, C-17 : 1 omega 8c and C-17 : 0. The predominant menaquinone was MK-9(H-4). The G + C content of the genomic DNA was 72.1 mol%. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that strain EGI 80759(T) clustered with members of the class Nitriliruptoria and showed highest 16S rRNA gene sequence similarities with Euzebya tangerina F10(T) (90.3 %) and Nitriliruptor alkaliphilus ANL-iso2(T) (88.1 %). On the basis of the data obtained from phenotypic and chemotaxonomic studies and the phylogenetic analysis, the isolate is proposed to be a representative of a novel genus and a novel species, Egibacter rhizosphaerae gen. nov., sp. nov., of a proposed novel family, Egibacteraceae fam. nov., and order, Egibacterales ord. nov., within the class Nitriliruptoria. The type strain of the type species, Egibacter rhizosphaerae, is EGI 80759(T) (=CGMCC 1.14997(T)=KCTC 39588(T)).