Isolation and characterization of a novel agar-degrading marine bacterium, Gayadomonas joobiniege gen, nov, sp. nov., from the Southern Sea, Korea

An agar-degrading bacterium, designated as strain G7^T, was isolated from a coastal seawater sample from Gaya Island (Gayado in Korean), Republic of Korea. The isolated strain G7^T is gram-negative, rod shaped, aerobic, non-motile, and non-pigmented. A similarity search based on its 16S rRNA gene sequence revealed that it shares 95.5%, 90.6%, and 90.0% similarity with the 16S rRNA gene sequences of Catenovulum agarivorans YM01^T, Algicola sagamiensis, and Bowmanella pacifica W3-3A^T, respectively. Phylogenetic analyses demonstrated that strain G7^T formed a distinct monophyletic clade closely related to species of the family Alteromonadaceae in the Alteromonas-like Gammaproteobacteria. The G+C content of strain G7^T was 41.12 mol%. The DNA-DNA hybridization value between strain G7^T and the phylogenetically closest strain YM01^T was 19.63%. The genomes of G7^T and YM01^T had an average ANIb value of 70.00%. The predominant isoprenoid quinone of this particular strain was ubiquinone-8, whereas that of C. agarivorans YM01^T was menaquinone-7. The major fatty acids of strain G7^T were Iso-C_15:0 (41.47%), Anteiso-C_15:0 (22.99%), and C_16:1ω7c/iso-C_15:0 2-OH (8.85%), which were quite different from those of YM01^T. Comparison of the phenotypic characteristics related to carbon utilization, enzyme production, and susceptibility to antibiotics also demonstrated that strain G7^T is distinct from C. agarivorans YM01^T. Based on its phenotypic, chemotaxonomic, and phylogenetic distinctiveness, strain G7^T was considered a novel genus and species in the Gammaproteobacteria, for which the name Gayadomonas joobiniege gen. nov. sp. nov. (ATCC BAA-2321 = DSM25250^T = KCTC23721^T) is proposed.