title: Toxicity of Photobacterium damselae subsp. damselae strains isolated from new cultured marine fish.
abstract: The in vivo and in vitro toxicity of bacterial cells and their extracellular products (ECPs) from 16 strains of Photobacterium damselae subsp. damselae isolated from 7 epizootic outbreaks were evaluated. On the basis of their 50% lethal dose (LD50) values (about 1 x 10(50 CFU), these strains may be considered as moderately virulent. However, their ECPs were strongly lethal for redbanded seabream Pagrus auriga causing fish death within 2 h post-inoculation (protein concentration ranged between 2.1 and 6.41 microg g(-1) fish). The bacterial ECPs tested exhibited several enzymatic activities, such as amylase, lipase, phospholipase, alkaline phosphatase, esterase-lipase, acid phosphatase, and beta-glucosaminidase. These ECPs displayed a strong cytotoxic effect on 4 fish and 2 mammalian cell lines, although this activity disappeared when ECPs were heated at 100 degrees C. The virulence of the strains tested could not be related to the hemolytic activity or to the production of the toxin damselysin. Therefore, another unknown type of toxin could play an important role in the virulence mechanisms of this bacterial pathogen.
authors.affiliation: Department of Microbiology, Faculty of Sciences, University of Malaga, 29071 Malaga, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Labella
authors.forename: Nuria
authors.initials: N
authors.lastname: Sanchez-Montes
authors.forename: Concepcion
authors.initials: C
authors.lastname: Berbel
authors.forename: Manuel
authors.initials: M
authors.lastname: Aparicio
authors.forename: Dolores
authors.initials: D
authors.lastname: Castro
authors.forename: Manuel
authors.initials: M
authors.lastname: Manchado
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Borrego
mesh_terms: D000818:Animals; D002460:Cell Line; D004196:Disease Outbreaks / Q000662:veterinary*; D005393:Fish Diseases / Q000382:microbiology*; D005399:Fishes; D006801:Humans; D051379:Mice; D010776:Photobacterium / Q000145:classification*