Phylogenetic analysis of algicidal bacteria (family Flavobacteriaceae) and selective detection by PCR using a specific primer set

Sequencing the 16S rDNA and phylogenetic analysis were performed on algicidal 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 5N-3. These algicidal strains were clustered phylogenetically within the marine 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) exhibited the high level of sequence similarity of 98.5%. Despite the differences of host algae and of locality and year of isolation, these algicidal bacteria 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 for selective detection of the strain J18/M01.