Pseudoalteromonas ulvae sp nov., a bacterium with antifouling activities isolated from the surface of a marine alga

A dark-purple marine bacterium that inhibits the germination of marine alga l spores and the settlement of invertebrate larvae has been characterized a nd assessed for taxonomic assignment. Two strains, designated UL12(T) and U L13, were isolated from the surface of the common marine alga Ulva lactuca. Based on 16S rDNA sequencing, UL12T and UL13 were found to show the highes t similarity (97%) to members of the genus Pseudoalteromonas. DNA-DNA hybri dization studies demonstrated less than 28% genomic DNA relatedness between these isolates and closely related Pseudoalteromonas species and greater t han 65% homology between UL12T and UL13. The two isolates were found to dis play identical characteristics and are strict aerobes, motile by means of s ingle polar flagella, exhibit non-fermentative metabolism and require sodiu m ions for growth. The isolates hydrolyse gelatin and can utilize citrate, maltose, mannose and glucose but not trehalose, sucrose, fructose, lactose or glycerol as sole carbon sources. The molecular evidence together with th e phenotypic characteristics show that this bacterium constitutes a new spe cies within the genus Pseudoalteromonas. The name Pseudoalteromonas ulvae s p. nov. is proposed for this bacterium and the type strain is UL12(T) (= UN SW 095600(T) = NCIMB 13762(T)).