sp. nov., Isolated from Freshwater and Characterization of Bacteriophage BK-30P-The First Phage That Infects Genus .

A Gram-stain-negative, non-motile, non-pigmented, rod-shaped bacterium was isolated from a freshwater sample of Nakdong River in South Korea and designated as strain BK-30. An analysis of the 16S rRNA gene sequence of strain BK-30 revealed its closest phylogenetic neighbors were members of the genus . Specifically, the strain formed a robust clade with DSM 12705, sharing 98.4% similarity in their 16S rRNA gene sequences. The average nucleotide identity value between strain BK-30 and DSM 12705 was 79.8%, and the genome-to-genome distance averaged 21.3%, indicating the representation of a novel genomic species. Strain BK-30 exhibited optimum growth at 30 °C and pH 7.0, in the absence of NaCl. The major respiratory isoprenoid quinone identified was ubiquinone-8 (Q-8). The principal fatty acids detected were C7 and/or C6 (49.6%), C (27.5%), and C7 and/or C ω6c (9.2%). The DNA G+C content of the strain was determined to be 67.3 mol%. Based on these data, we propose a novel species within the genus , named sp. nov., to accommodate the bacterial isolate. Strain BK-30 is designated as the type strain (=KCTC 52161 = JCM 31376 = FBCC-B1). Additionally, we present the isolation and complete genome sequence of a lytic phage infecting strain BK-30, named BK-30P. This bacteriophage is the first reported to infect , leading us to propose the name "Macromonasphage".