Horticoccus luteus gen. nov., sp. nov., A Novel Member of the Phylum Verrucomicrobia Isolated from a Dichlorodiphenyltrichloroethane (DDT)-Contaminated Orchard Soil

Strain KSB-15( T) was isolated from an orchard soil that had been contaminated with the insecticide dichlorodiphenyltrichloroethane for about 60 years. The 16S rRNA gene sequence of this strain showed the highest sequence similarities with those of Oleiharenicola alkalitolerans NVTT (95.3%), Opitutus terrae PB90-1( T) (94.8%), and Oleiharenicola lentus TWA-58( T) (94.7%) among type strains, which are members of the family Opitutaceae within the phylum Verrucomicrobia. Strain KSB-15( T) was an obligate aerobe, Gram-negative, non-motile, coccoid or short rod with the cellular dimensions of 0.37-0.62 mu m width and 0.43-0.72 mu m length. The strain grew at temperatures between 15-37 degrees C (optimum, 25 degrees C), at a pH range of 5.0-11.0 (optimum, pH 6.0), and at a NaCl concentration of 0-3% (w/v) (optimum, 0%). It contained menaquinone-7 (MK-7) as the major isoprenoid quinone (94.1%), and iso-C-15:0 (34.9%) and anteiso-C-15:0 (29.0%) as the two major fatty acids. The genome of strain KSB-15( T) was composed of one chromosome with a total size of 4,320,198 bp, a G + C content of 64.3%, 3,393 coding genes (CDS), 14 pseudogenes, and 52 RNA genes. The OrthoANIu values, In silico DDH values and average amino acid identities between strain KSB-15( T) and the members of the family Opitutaceae were 71.6 similar to 73.0%, 19.0 similar to 19.9%, and 55.9 similar to 62.0%, respectively. On the basis of our polyphasic taxonomic study, we conclude that strain KSB-15( T) should be classified as a novel genus of the family Opitutaceae, for which the name Horticcoccus luteus gen. nov., sp. nov. is proposed. The type strain is KSB-15( T) (= KACC 22271( T) = DSM 113638( T)).