Vineibacter terrae gen. nov., sp. nov., an ammonium-assimilating and nitrate-reducing bacterium isolated from vineyard soil

Abstract

A polyphasic taxonomic approach was used to characterize a Gram-stain-negative bacterium, designated strain CC-CFT640^T, isolated from vineyard soil sampled in Taiwan. Cells of strain CC-CFT640^T were aerobic, non-motile, nitrate-reducing rods. Test results were positive for catalase, oxidase and proteinase activities. Optimal growth occurred at 30 °С and pH 7. Strain CC-CFT640^T showed highest 16S rRNA gene sequence similarity to members of the genus Enhydrobacter (90.0 %, n=1) followed by Hypericibacter (89.4-90.0 %, n=2), Reyranella (88.8-89.8 %, n=5) and Nitrospirillum (89.2-89.4 %, n=2), and formed a distinct phyletic lineage distantly associated with the clade that predominately accommodated Reynerella species. The DNA G+C composition of the genome (2.1 Mb) was 67.9 mol%. Genes involved in the reduction of nitrate to nitrite, nitric oxide and nitrous oxide were found. In addition, genes encoding dissimilatory nitrate reduction to ammonia, ammonium transport and ammonium assimilation were also detected. Average nucleotide identity values were 73.3 % (n=1), 74.0-74.6 % (n=2), 67.5-68.3 % (n=2) when compared within the type strains of the genera Enhydrobacter, Reyranella and Niveispirillum, respectively. The dominant cellular fatty acids (>5 %) included C_{16 : 0}, iso-C_{17 : 1} ω10c, C_{19 : 0} cyclo ω8c, C_{18 : 1} 2-OH and C_{18 : 1} ω7c/C_{18 : 1} ω6c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, three unidentified aminolipids, three unidentified phospholipids and an unidentified aminophospholipid. The major respiratory quinone was ubiquinone 10 and the major polyamine was spermidine. Based on its distinct phylogenetic, phenotypic and chemotaxonomic traits together with results of comparative 16S rRNA gene sequencing, digital DNA-DNA hybridization, average nucleotide identity and phylogenomic placement, strain CC-CFT640^T is considered to represent a novel genus and species of the family Rhodospirillaceae, for which the name Vineibacter terrae gen. nov., sp. nov. is proposed. The type strain is CC-CFT640^T (=BCRC 81219^T=JCM 33507^T).

Keywords: Rhodospirillaceae; ammonium assimilation; average nucleotide identity; denitrification; dissimilatory nitrate reduction.