Padina pavonica and Jania rubens Associated Bacteria: Biodiversity and Antibacterial Potential

Seaweed surfaces harbor diverse epibiotic bacterial communities. These bacteria play a crucial role in the morphogenesis and growth of seaweeds. In the present study, epiphytic culturable bacteria from brown algae (Padina pavonica) and red alga (Jania rubens) were isolated and identified. A total of 37 different bacterial strains were isolated by cultivation-based methods, 18 from P. pavonica surface and 19 from J. rubens. Antibacterial potential of these isolates was also tested against 19 fish and human pathogenic bacteria. Isolates were identified according to 16Sr RNA gene sequence similarities as Proteobacteria (Gamma and Alpha subclasses), Bacteroidetes, Firmicutes, and Actinobacteria. Proteobacteria and Firmicutes groups were represented on both algae surfaces. Actinobacteria phylum, however, was only isolated from P. pavonica while Bacteroidetes phylum was only represented on J. rubens surface. Besides, 27% and 36% of the P. pavonica and J. rubens isolates, respectively, demonstrated antibacterial potential. This study demonstrated differences between P. pavonica and J. rubens (harvested in the same geographic site and the same period) isolates communities. Moreover, bacterial isolates of both seaweeds may be of biotechnological interest.