Moritella viscosa
| Moritella viscosa | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Kingdom: | Pseudomonadati |
| Phylum: | Pseudomonadota |
| Class: | Gammaproteobacteria |
| Order: | Alteromonadales |
| Family: | Moritellaceae |
| Genus: | Moritella |
| Species: | M. viscosa |
| Binomial name | |
| Moritella viscosa Benediktsdóttir et al., 2000 | |
Moritella viscosa is a species of gram-negative, psychrophilic, halophilic marine bacterium that is best known as the primary causative agent of winter ulcer disease in farmed Atlantic salmon (Salmo salar).[1][2] The bacterium is distributed throughout the North Atlantic and has been isolated from both cultured and wild marine fishes, particularly in cold-water aquaculture systems.[3][4] The species was previously called Vibrio viscosa before being reclassified under the genus Moritella.[2][1]
Taxonomy
Prior to formal description, the bacterium was recognized as an unidentified Vibrio taxon associated with winter ulcer outbreaks in Atlantic salmon. Phenotypic and genotypic analyses demonstrated that these isolates represented a distinct species within the family Vibrionaceae, separate from previously described fish-pathogenic vibrios, and the bacterium was subsequently named Vibrio viscosa.[2]
Comparative studies subsequently showed that V. viscosus was most closely related to Vibrio marinus, a species that had been transferred to the genus Moritella as Moritella marina. 16S rRNA gene sequence analysis showed approximately 99.1% sequence similarity between V. viscosus and M. marina. On the basis of phylogenetic evidence and the taxonomic reassignment of Vibrio marinus, Vibrio viscosus was transferred to the genus Moritella and reclassified as Moritella viscosa in 2000.[1]
Description
Moritella viscosa is a gram-negative, motile, fermentative halophilic bacterium. The bacterium is psychrophilic and grows optimally below 30 °C. Colonies on bovine blood agar containing 2% NaCl are round, translucent, and gray.[2] M. viscosa is catalase- and oxidase positive.
Role in aquaculture
Distribution and host range
Moritella viscosa is distributed throughout the North atlantic, where it is associated primarily with marine aquaculture in cold-water regions.[4] The species has been isolated from farmed Atlantic salmon in Norway, Scotland, the Faroe islands, Iceland, and Atlantic Canada, where it is recognized as the principal agent of winter ulcer disease.[2][4]
Although Atlantic salmon is considered the principal host, M. viscosa has also been isolated from rainbow trout,[2] and Atlantic halibut.[5]
Pathogenesis
Moritella viscosa is transmitted through seawater and infects fish primarily under cold-water conditions. Experimental infection studies indicate that the bacterium initially colonizes the skin and gills. Following invasion, the bacterium can disseminate to internal organs, including the head kidney, spleen, liver, and skeletal muscle, resulting in systemic infection.[4][6]
The molecular mechanisms responsible for virulence in M. viscosa remain incompletely understood. Several extracellular products contribute to tissue injury, including the metalloprotease MvP1, a vibriolysin with cytotoxic activity toward fish tissues.[7]
References
- 1 2 3 Benediktsdóttir, E; Verdonck, L; Spröer, C; Helgason, S; Swings, J (2000). "Characterization of Vibrio viscosus and Vibrio wodanis isolated at different geographical locations: a proposal for reclassification of Vibrio viscosus as Moritella viscosa comb. nov". International Journal of Systematic and Evolutionary Microbiology. 50 (2): 479–488. Bibcode:2000IJSEM..50..479B. doi:10.1099/00207713-50-2-479. ISSN 1466-5034. PMID 10758850.
- 1 2 3 4 5 6 Lunder, T.; Sørum, H.; Holstad, G.; Steigerwalt, A. G.; Mowinckel, P.; Brenner, D. J. (2000). "Phenotypic and genotypic characterization of Vibrio viscosus sp. nov. and Vibrio wodanis sp. nov. isolated from Atlantic salmon (Salmo salar) with 'winter ulcer'". International Journal of Systematic and Evolutionary Microbiology. 50 Pt 2 (2): 427–450. Bibcode:2000IJSEM..50..427L. doi:10.1099/00207713-50-2-427. ISSN 1466-5026. PMID 10758846.
- ↑ Grove, S.; Reitan, L. J.; Lunder, T.; Colquhoun, D. (2008-11-20). "Real-time PCR detection of Moritella viscosa, the likely causal agent of winter-ulcer in Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss". Diseases of Aquatic Organisms. 82 (2): 105–109. doi:10.3354/dao01972. ISSN 0177-5103. PMID 19149373.
- 1 2 3 4 Ghasemieshkaftaki, Maryam (2024-08-11). "A Review of Winter Ulcer Disease and Skin Ulcer Outbreaks in Atlantic Salmon (Salmo salar)". Hydrobiology. 3 (3): 224–237. doi:10.3390/hydrobiology3030015. ISSN 2673-9917.
- ↑ Colquhoun, D.J.; Hovland, H; Hellberg, H; Haug, T; Nilsen, H (2004). "Moritella viscosa isolated from farmed Atlanticcod (Gadus morhua)" (PDF). Bull. Eur. Ass. Fish Pathol. 24 (2): 109–114.
- ↑ Løvoll, M.; Wiik-Nielsen, C. R.; Tunsjø, H. S.; Colquhoun, D.; Lunder, T.; Sørum, H.; Grove, S. (2009). "Atlantic salmon bath challenged with Moritella viscosa--pathogen invasion and host response". Fish & Shellfish Immunology. 26 (6): 877–884. Bibcode:2009FSI....26..877L. doi:10.1016/j.fsi.2009.03.019. ISSN 1095-9947. PMID 19361559.
- ↑ Bjornsdottir, Bryndis; Fridjonsson, Olafur H.; Magnusdottir, Steinunn; Andresdottir, Valgerdur; Hreggvidsson, Gudmundur O.; Gudmundsdottir, Bjarnheidur K. (2009-05-12). "Characterisation of an extracellular vibriolysin of the fish pathogen Moritella viscosa". Veterinary Microbiology. 136 (3–4): 326–334. doi:10.1016/j.vetmic.2008.11.020. ISSN 0378-1135. PMID 19147307.