PSEUDOALTEROMONAS BACTERIOLYTICA SP. NOV., A MARINE BACTERIUM THAT ISTHE CAUSATIVE AGENT OF RED SPOT DISEASE OF LAMINARIA-JAPONICA

An aerobic, polarly flagellated marine bacterium that produces a prodi giosin-like pigment was isolated from the red-spotted culture beds of Laminaria japonica. Five isolates had unique bacteriolytic activity fo r both Gram-positive and -negative bacteria, which had never been obse rved among Alteromonas or spot related species, The isolates were iden tified as the causative agent or reo disease of L. japonica seeds. The phenotypic features of the isolates were similar to these of Pseudoal teromonas rubra ATCC 29570(T), but they could be differentiated using 10 traits (growth at 37 degrees C, requirement for organic growth fact ors, bacteriolytic activity, utilization of sucrose, N-acetylglucosami ne, fumarate, succinate, D-galactose, L-proline and acetate). The G+C content of DNAs from the isolates was 44-46 mol%. The isolates constit ute a new species, distinct from the other Alteromonas and Pseudoalter omonas species, as shown by DNA-DNA hybridization experiments and phyl ogenetic clustering of 16S rRNA gene sequences, for which the name Pse udoalteromonas bacteriolytica sp. nov. (type strain = IAM 14595(T)) is proposed. A set of phenotypic features which differentiate this new s pecies from closely related Pseudoalteromonas and Alteromonas species is provided.