Phylogenetic relationship and antifouling activity of bacterial epiphytes from the marine alga Ulva lactuca

It is widely accepted that bacterial epiphytes can inhibit the colonization of surfaces by common fouling organisms. However, little information is av ailable regarding the diversity and properties of these antifouling bacteri a. This study assessed the antifouling traits of five epiphytes of the comm on green alga, Ulva lactuca. All isolates were capable of preventing the se ttlement of invertebrate larvae and germination of algal spores. Three of t he isolates also inhibited the growth of a variety of bacteria and fungi. T heir phylogenetic positions were determined by 16S ribosomal subunit DNA se quencing. All isolates showed a close affiliation with the genus Pseudoalte romonas and, in particular, with the species P. tunicata. Strains of this b acterial species also display a variety of antifouling activities, suggesti ng that antifouling ability may be an important trait for members of this g enus to be highly successful colonizers of animate surfaces and for such sp ecies to protect their host against fouling.