Azoarcus taiwanensis sp. nov., a denitrifying species isolated from a hot spring.

The strain NSC3(T), a novel, facultative, chemolithotrophic, denitrifying, alkaliphilic, sulfide-oxidizing bacterium isolated from a hot spring in Yang-Ming Mountain, Taiwan, was Gram negative, rod shaped, and motile by single polar flagella and grew facultatively by adopting a denitrifying metabolism. The 16S rRNA sequence analysis revealed that strain NSC3(T) belongs to beta subclass of the Proteobacteria and most closely related to Azoarcus evansii KB740(T) (95.44 %), Azoarcus toluvorans Td-21(T) (95.21 %), Azoarcus tolulyticus Tol-4(T) (95.08 %), and Azoarcus toluclasticus MF63(T) (94.94 %). The phylogenetic analyses based on 16S rRNA gene sequences indicated that the strain NSC3(T) formed a distinct lineage in the Betaproteobacteria and that it exhibited the highest level of sequence similarity with species of the genera Azoarcus (95.28-93.13 %). The major fatty acids of the type strain were C16:0 (26.9 %), C16:1w7c (28.9 %), C18:0 (9.6 %), and C18:1w7c/w6c (29.9 %). The DNA G+C content of genomic DNA was 63.7 mol%. On the basis of the 16S rRNA sequence similarity, phenotypic and genotypic characteristics, and chemotaxonomic data, the strain NSC3(T) could be differentiated from other species of the genus Azoarcus. Therefore, strain NSC3(T) (equal to BCRC 80111(T) and DSM 24109(T)) is proposed as a novel species in genus Azoarcus, for which the name Azoarcus taiwanensis sp. nov. is proposed. The strain NSC3(T) is deposited in Bioresource Collection and Research Center, Taiwan, under the reference number BCRC 80111(T), and German Collection of Microorganisms and Cell Cultures, Germany (DSMZ), with DSM 24109(T).