Salmonid gill bacteria and their relationship to amoebic gill disease.
16S ribosomal RNA gene analysis was used to assess the bacterial community associated with Atlantic salmon, Salmo salar L., gills which were either affected by amoebic gill disease (AGD) or were AGD-negative, in order to determine the role that bacteria may play in the development of AGD. AGD-positive specimens were either infected in the laboratory with Neoparamoeba pemaquidensis, the causative agent of AGD, or were obtained from commercial salmon cages. Samples from laboratory fish maintained in sea water possessed a marine-type community while field samples which had been treated by a series of freshwater baths possessed a more diverse community which included variable proportions of different bacterial ecotypes, including groups typically associated with soil, skin surfaces and faeces. Samples from fish infected with AGD in the laboratory and a sample from one of two salmon cage fish specimens were dominated by a phylotype belonging to the strictly marine bacterial genus Psychroserpens (family Flavobacteriaceae, phylum Bacteroidetes). The phylotype was not detected in any of the AGD-negative samples or in one of two AGD-positive samples obtained from fish subjected to temporary freshwater immersion. The possibility of certain Psychroserpens species as potential opportunistic pathogens associated with salmonid AGD is proposed.
Australian Food Safety Centre of Excellence, School of Agricultural Sciences, University of Tasmania, Hobart, Tasmania, Australia. john.bowman@utas.edu.au
J P
JP
Bowman
B
B
Nowak
D000818:Animals; D017756:Aquaculture; D001483:Base Sequence; D017931:DNA Primers; D005393:Fish Diseases / Q000382:microbiology*; D041965:Flavobacteriaceae / Q000235:genetics*; D005880:Gills / Q000382:microbiology*; D016013:Likelihood Functions; D016840:Lobosea; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D011528:Protozoan Infections / Q000382:microbiology; D011529:Protozoan Infections, Animal; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020317:Salmo salar; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D012336:RNA, Ribosomal, 16S