Lactobacillus piscicola, a New Species from Salmonid Fish

Abstract

The name Lactobacillus piscicola sp. nov. is proposed for a group of 17 bacterial strains that were isolated from diseased rainbow trout (Salmo gairdneri), cutthroat trout (Salmo clarki), and chinook salmon (Oncorhynchus tshawytscha). This bacterium was found most frequently in infected fish which had suffered some form of stress, such as that which occurs at spawning. Occasionally, pathological signs in the internal organs or skin were observed. Phenotypically, L . piscicola belongs to the family Lactobacillaceae and can be distinguished from other species of Lactobacillus by its morphology and physiological characteristics. DL-Lactic acid was produced homofermentatively from glucose. Diaminopimelic acid was present in the cell wall peptidoglycan. The 17 isolates were closely related genetically, as demonstrated by similar percent guanine-plus-cytosine contents (35 mol%) and high deoxyribonucleic acid reassociation values, both characteristics of a single species. The isolates exhibited less than 10% deoxyribonucleic acid reassociation with other reference Lactobacillus strains with similar guanine-plus-cytosine contents. Strain B270 (= ATCC 35586), which was isolated in 1970 from diseased cutthroat brood trout at Bandon Hatchery in Oregon, is designated the type strain of this new species of Lactobacillus.A bacterium with characteristics resembling those of a Lactobacillus has been isolated by workers in our laboratory from rainbow trout (Salmo gairdneri) and cutthroat trout (Salmo clarki) for more than 25 years at various hatcheries in Oregon. These isolations have occurred most frequently from fish 1 year old and older which may have experienced stress, such as that associated with handling and spawning. The pathological signs have been varied and include septicemia, distention of the abdomen, splenomegaly, accumulation of ascites fluid, large muscular abcesses, internal hemorrhaging, and blood cavities or blisters under the skin. Various combinations of these disease signs have been observed in chronically infected trout. Lactobacilli have been isolated from a variety of salmonid (14) and nonsalmonid species (43). Two strains isolated in our laboratory from diseased brood trout were examined previously, but the taxonomic status of the isolates was never determined (N. Sriranganathan, Ph.D. thesis, Oregon State University, Corvallis, 1974).Lactobacilli are commonly found in fermenting plant and animal products and also in the oral cavities and intestinal tracts of warm-blooded animals, including humans (4). Pathogenicity in warm-blooded animals, although rare, has been reported (2,20,50). The possible role of lactobacilli as the cause of disease in salmonid fish has been described previously (8, 40, 41), but the bacterium associated with the condition has not been identified. In this study, biochemical tests and deoxyribonucleic acid (DNA) hybridization data were used to compare and classify the Lactobacillus strains found in salmonid fish. Our results indicate that this organism represents a new species of ...

Classification of Lactobacillus divergens, Lactobacillus piscicola, and Some Catalase-Negative, Asporogenous, Rod-Shaped Bacteria from Poultry in a New Genus, Carnobacterium

“…piscicola in the same DNA homology group was unexpected. Biochemical and chemical data, however, reinforce this relatedness and indicate that these species should be reduced to synonymy (the specific epithet piscicola [9] has priority over carnis [19,201). The biochemical and nucleic acid data showed that the remaining group 2 strains were unrelated to the other species examined and warrant separate specific status.…”

“…nov. The full description of C. piscicola is as given by Hiu et al (9) but should be extended and emended as follows. Under certain conditions exhibits heterofermentative properties.…”

“…divergens. The recently described salmonid fish pathogen Lactobacillus piscicola was also included in the study because this species shares many properties with the atypical lactobacilli from poultry and meat (9).…”

Carnobacterium inhibens sp. nov., isolated from the intestine of Atlantic salmon (Salmo salar)

“…The C18: 1 compound is a cis9,12 isomer. Members of the genus Carnobacterium have been isolated from a wide range of environments such as refrigerated meat products (Monte1 et al, 1991), salmonid fish (Hiu et al, 1984) and anoxic lake water in Antarctica (Schroder et al, 1980). They are difficult to distinguish from Lactobacillus sp.…”

Characterization of Carnobacterium species by pyrolysis mass spectrometry

“…mobile, which were isolated from poultry (Thornley and Sharpe 1959). Carnobacterium piscicola strains have also been recognized as fish pathogens (Hiu et al 1984;Baya et al 1991;Starliper cl al. 1992).…”