Hokkaido University · Biochemistry, Genetics and Molecular Biology
Professor Tomoo Sawabe's research lab specializes in marine microbiology, with a focus on the taxonomy, phylogeny, and pathogenesis of vibrios and related bacteria in marine environments. The lab investigates the evolutionary relationships among vibrio species using multilocus sequence analysis and 16S rRNA gene sequencing, while also exploring the pathogenic mechanisms of vibrios in aquaculture, particularly in abalone and kelp. A key direction involves the characterization of novel marine bacterial species with unique physiological and pathogenic traits, such as prodigiosin-like pigment production and bacteriolytic activity. The lab integrates molecular, phenotypic, and ecological approaches to understand microbial roles in marine health and disease.
Figures are computed from collected data and may differ slightly.
We performed the first broad study aiming at the reconstruction of the evolutionary history of vibrios by means of multilocus sequence analysis of nine genes. Overall, 14 distinct clades were recognized using the SplitsTree decomposition method. Some of these clades may correspond to families, e.g., the clades Salinivibrio and Photobacteria, while other clades, e.g., Splendidus and Harveyi, correspond to genera. The common ancestor of all vibrios was estimated to have been present 600 million ye
[This corrects the article on p. 414 in vol. 4, PMID: 24409173.].
An aerobic, polarly flagellated marine bacterium that produces a prodigiosin-like pigment was isolated from the red-spotted culture beds of Laminaria japonica. Five isolates had unique bacteriolytic activity for both Gram-positive and -negative bacteria, which had never been observed among Alteromonas or related species. The isolates were identified as the causative agent of red spot disease of L. japonica seeds. The phenotypic features of the isolates were similar to these of Pseudoalteromonas
Six alginolytic, facultatively anaerobic, non-motile marine bacteria were isolated from the gut of abalone Haliotis discus hannai. DNA-DNA hybridization data showed that the six strains constituted a single genospecies. Phylogenetic analyses of 16S rDNA sequences indicated that the isolates should be assigned to the genus Vibrio. The phenotypic features of the isolates were closely related to Vibrio fischeri and Vibrio pelagius biovar I, but 13 traits (motility, luminescence, alginase production
A marine bacterium, Alteromonas elyakovii KMM 162T, which was described recently, and five strains isolated from spot-wounded fronds of Laminaria japonica have been subjected to phylogenetic analysis, and geno- and phenotypic characterization. The phenotypic features of Pseudoalteromonas elyakovii strains were closely related to that of Pseudoalteromonas espejiana IAM 12640T, but utilization of three carbon compounds (D-mannose, L-tyrosine and trehalose) distinguished both species. The G+C conte
Sixty thousand of deaths among cultured Ezo abalone Haliotis discus hannai occurred within a few days at an abalone farm in Japan in the middle of August, 2002. Dead animals were characterized by a hemolymphatic edema around the major circulatory system. Vibrios showing swarming motility dominated in the edema. The pathogenic vibrios were identified as Vibrio harveyi based on a phylogenetic analysis and a phenotypic characterization. In both immersion and injection experiments, the swarming vibr
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