Nocardioides donggukensis sp. nov. and Hyunsoonleella aquatilis sp. nov., isolated from Jeongbang Waterfall on Jeju Island

Abstract

Two bacterial strains, designated MJB4(T) and SJ7(T), were isolated from water samples collected from Jeongbang Falls on Jeju Island, Republic of Korea. Phylogenetic analysis of 16S rRNA gene sequences indicated that the two strains belonged to the genera Nocardioides and Hyunsoonleella, owing to their high similarities to Nocardioides jensenii DSM 29641(T) (97.5%) and Hyunsoonleella rubra FA042 (T) (96.3%), respectively. These values are much lower than the gold standard for bacterial species (98.7%). The average nucleotide identity values between strains MJB4(T), SJ7(T) and the reference strains, Nocardioides jensenii DSM 29641(T), Nocardioides daejeonensis MJ31(T) and Hyunsoonleella flava T58(T) were 77.2, 75.9 and 75.4 %, respectively. Strains MJB4(T) and SJ7(T) and the type strains of the species involved in system incidence have average nucleotide identity and average amino acid threshold values of 60.1-82.6% for the species boundary (95-96%), which confirms that strains MJB4(T) and SJ7(T) represent two new species of genus Nocardioides and Hyunsoonleella, respectively. Based on phylogenetic and phenotypic data, strains MJB4(T) and SJ7(T) are considered to represent novel species of the genus Nocardioides and Hyunsoonleella, respectively, for which the names Nocardioides donggukensis sp. nov. (type strain MJB4(T)=KACC 21724T=NBRC 114402T) and Hyunsoonleella aquatilis sp. nov., (type strain SJ7(T)=KACC 21715(T)=NBRC 114486(T)) have been proposed.