This study sought to carry out bacterial community analysis and examine the identification of a novel bacterium isolated from the surface of Umbraulva japonica, which is a marine algae collected in Jeju Island. A total of 79 strains were isolated from U. japonica and cultivated using Marine agar, 1/10 Marine agar, R2A. The 16S rRNA gene sequence of the isolated bacteria were analyzed using NCBI and EzbioCloud. Based on the result, the major groups were classified into 4 phyla as Proteobacteria (α-proteobacteria, β-proteobacteria, γ -proteobacteria) (74.7%), Bacteroidetes (20.3%), Actinobacteria (2.5%) and Firmicute (2.5%) along with 7 classes, 13 order, 17 families and 31 genera. The phylogenetic analysis showed 3 strains were showed similarity of <97% with the previously identified strains, and could be reported as a new genus or species. Therefore, it is considered that additional experiments should be conducted together with the standard strain. The novel strain, UJT9T, was identified as an orange colony, gram-negative, rod-shaped, non-motility and aerobic bacterium. Strain UJT9T grew at a temperature range of 15-35℃ (optimum, 20-25℃), a pH range 5.5-8.0 (optimum, pH 6.0-7.0) and in the presence 1.0-3.0% (w/v) NaCl (optimum, 1.0-2.0%). The 16S rRNA gene sequence- based phylogenetic analysis showed that strain UJT9T belong to the Nonlabens and was most closely related to Nonlabens arenilitoris M-M3T, Nonlabens ulvanivorans PLRT with a sequence similarity of 97.7%, 97.6%, respectively. Strain UJT9T contained menaquinones type 6 (MK-6) as the major quinones and Fatty acids (>5%) were iso-C15:0 (20.1%), iso-C16:0 3-OH (14.1%), iso-C16:0 (10.2%), iso-17:0 3-OH (7.8%), anteiso-C15:0 (6.3%), iso-C16:1 H (5.6%). The major polar lipids were phosphatidylenthanolamine (PE), two unidentified lipids and two unidentified amino lipids. The DNA G+C content of strain UJT9T was determined to be 38.50 mol%. The DNA-DNA hybridization values for strain between N. arenilitoris M-M3T and N. ul vanivorans PLRT were 67.42 ± 1.41%, 48.21 ± 4.53%, respectively. On the basis of the data presented, strain UJT9T is considered to represented a novel species of the genus Nonlabens. The type strain is Nonlabens sp. UJT9T (=KACC 19635T = JCM 32766T). The antibacterial activity of 79 strains including the novel bacterium was evaluated. Strain UJT7, UJT20 and UJR17 showed antibacterial activity against Vibrio vulnificus, while UJR17 showed antibacterial activity against Streptococcus parauberis. UJT7 and UJT20, UJR17 have been identified as Bacillus sp. and Pseudomonas sp. and it can be safely presumed that it is beneficial to carry out additional experiments for various applications.