Tenacibaculum maritimum is the aetiological agent of an ulcerative disease known as tenacibaculosis, which affects a large number of marine fish species in the world and is of considerable economic significance to aquaculture producers. Problems associated with epizootics include high mortality rates, increased susceptibility to other pathogens, high labour costs of treatment and enormous expenditures on chemotherapy. In the present article we review current knowledge on this bacterial pathogen, focusing on important aspects such as the phenotypic, serologic and genetic characterization of the bacterium, its geographical distribution and the host species affected. The epizootiology of the disease, the routes of transmission and the putative reservoirs of T. maritimum are also discussed. We include a summary of molecular diagnostic procedures, the current status of prevention and control strategies, the main virulence mechanisms of the pathogen, and we attempt to highlight fruitful areas for continued research.
TAXONOMYThe taxonomy of Tenacibaculum maritimum was a matter of controversy and confusion for decades, and it has only recently been clarified by Suzuki et al. (2001). Masumura & Wakabayashi (1977) isolated a gliding bacterium that had caused mass mortalities among certain cultured marine fish. These strains were characterized by Hikida et al. (1979), who announced their intention to make a separate formal proposal of the name Flexibacter marinus. Since the epithet marinus had already been used in the name Vibrio marinus, the authors changed their mind on the use of this epithet, and the eventual formal proposal was a taxon called Flexibacter maritimus (Wakabayashi et al. 1986, Holmes 1992. Reichenbach (1989) listed the pathogen as Cytophaga marina, but the priority of the name Flexibacter maritimus was later recognized (Holmes 1992). These results were confirmed by Bernardet & Grimont (1989), who also validated the name Flexibacter maritimus based on DNA-DNA hybridisation methods.However, the resolution of phenotypic characterization and 16S ribosomal RNA (rRNA) sequence analysis is insufficient to distinguish closely related organisms. Thus, Suzuki et al. (2001), based on the nucleotide sequence of the gyrB, proposed that Flexibacter maritimus should be transferred to the new genus Tenacibaculum, in which 7 members are currently included. Table 1 shows the main differential characteristics of the described species of the genus Tenacibaculum.
GEOGRAPHICAL DISTRIBUTION AND HOST SPECIESThe geographical distribution of Tenacibaculum maritimum in wild and farmed fish is shown in Table 2. 256
Characteristic
T. maritimum T. ovolyticum T. mesophilum T. amilotyticum T. skagerrakense T. lutimarisOrigin Diseased red sea Halibut egg, Sponge and Macroalgae, Pelagic, Tidal flat, bream fingerling, Japan Norway macroalgae, Japan Japan Denmark Korea Cells size (µm) 2-30 × 0.5 2-20 × 0.5 1.5-10 × 0.5 2-4 × 0.4 2-15 × 0.5 2-10 × 0. Percentage of NaCl in the medium Table 1. Differential phenotypic characteris...
