Abstract: To analyze the diversity of epiphytic bacteria in Arctic algae, a red algae sample (Polysiphonia sp.) was collected from Ny-Ålesund, Svaldbard, Arctic in July 2019. A total of 60 cultivable strains of epiphytic bacteria were isolated from the sample using the dilution plating method. Analysis of 16S rRNA gene sequences revealed that the isolated strains mainly belonged to the class γ-Proteobacteria (39 strains, 65% of the total strains isolated from the red algae samples), followed by the classes Actinobacteria (10 strains, 17%), Flavobacteriia (eight strains, 13%), α-Proteobacteria (two strains, 3%) and Bacilli (one strain, 2%). The strains were affiliated with 12 genera with the predominant genera being Psychrobacter (22 strains, 37%) and Pseudoalteromonas (12 strains, 20%). The results preliminarily illustrate the diversity of cultivable epiphytic bacteria in Arctic red algae (Polysiphonia sp.), laying a foundation for studies on the ecological functions and exploitation of these particular Arctic microbial resources.

Key words: Arctic algae, Polysiphonia sp., epiphytic bacteria, 16S rRNA gene, diversity