Phylogenetic analysis of algicidal bacteria (Family Flavobacteriaceae) andselective detection by PCR using a specific primer set

Sequencing the 16S rDNA and phylogenetic analysis were performed on algicid al bacteria belonging to the family Flavobacteriaceae, Chattonella-killing Cytophaga sp. strain J18/M01, Heterocapsa-killing Cytophaga sp. strains AA8 -2 and AA8-3, and Gymnodinium growth-inhibiting Flavobacterium sp. strain 5 N-3. These algicidal strains were clustered phylogenetically within the mar ine Cytophaga/Flavobacter/Bacteroides (CFB) group. Flavobacterium sp. 5N-3 was phylogenetically clustered with Psychroserpens burtonensis but not with the algicidal gliding bacteria. The sequence similarity between strain 5N- 3 and P. burtonensis was only 92%. The strains J18/M01 and AA8-2 (AA8-3) ex hibited the high level of sequence similarity of 98.5%. Despite the differe nces of host algae and of locality and year of isolation, these algicidal b acteria were phylogenetically located on the same terminal branch. The PCR amplification of the 16S rDNA of the CFB strains using a single set of J18/M01-specific primers resulted in specific detection of the J18/M01, indicating that the J18/M01-specific sequence in the 16S rDNA is useful fo r selective detection of the strain J18/M01.