Juvenile steelhead trout (Salmo gairdneri), coho salmon (Oncorhynchus kisutch), and spring chinook salmon (O. tshawytscha) were infected by intraperitoneal or intramuscular injection with Aeromonas salmonicida or A. hydrophila at seven temperatures from 3.9 to 20.5 °C. At 3.9 and 6.7 °C, mortality in fish infected with A. salmonicida varied from 2 to 26% among the three salmonid species. At 20.5 °C 93–100% of these animals died within 2 or 3 days; at 6.7 °C or lower the fish survived for 12–23 days. Growth of A. salmonicida in vitro was influenced by temperature in a manner very similar to its influence on the in vivo infection. Comparable experiments with A. hydrophila gave results much like those with A. salmonicida, though some differences were noted. At a temperature of 20.5 °C percent mortality ranged from 64 to 100%. At 9.4 °C or below no deaths attributed to A. hydrophila occurred. Fatally infected fish died more rapidly at the higher temperatures. Key words: Aeromonas salmonicida, A. hydrophila, water temperature, furunculosis, motile aeromonas septicemia, coho salmon, chinook salmon, steelhead trout

The hitherto unknown growth essential has been isolated in pure, crystalline form, san indentified as one of the four optically isomeric α‐amino‐β‐hydroxy‐n‐butyric acids. Several of its derivatives have been prepared and described. On reduction of new amino acid yields d‐α‐amino‐n‐butyrie acid. The spatial configuration around the β‐carbon atom remians to be determined, and is now being investigated. With an otherwise adequate diet, appromiately 0.6 per cent of α‐amino‐β‐hydroxybutyric acid is the minimum amount necessary to induce maximum growth. The feeding trails herein described constitute the first successful attempt to rear animals on a ration contraining purified a mino acids as the sole source of nitrogen. Inasmuch as satisfactory growth has been secured by the use of diets devoid of hydroxyglutamic acid and citruiline, these two amino acids are not indispensable components of the food. Experiments designed to determine the physological importance of the remaining amino acids are now under way.

Bacteriological analyses were performed on fecal swabs and the aquarium water of 27 individually purchased specimens of the small green pet turtle, Pseudemys scripta elegans. Representatives of Aeromonas, Citrobacter, Enterobacter, Klebsiella, Proteus, Salmonella, and Serratia were isolated. Enterobacter, Klebsiella, and Salmonella were encountered in 20% or more of the specimens, whereas Aeromonas was isolated from 63%. Klebsiella pneumoniae counts ranged from 103 to 104 per milliliter of aquarium water, whereas Aeromonas routinely exceeded 104 per milliliter. Aeromonas cultures from turtles were identical to 7 human isolates in some 29 biochemical tests. On the basis of our findings, we question whether the Salmonella-free certification program alone is sufficient to render these reptiles as safe pets. An association of the human pathogen Salmonella with reptiles has been a bacteriological fact for over a quarter of a century (14). Salmonellae have been isolated from turtles, snakes, and even from lizards (4, 14). Recently, Congress enacted federal legislation to effectively prohibit the interstate shipment of turtles harboring Salmonella and Arizona (26). Our interest in the microflora of pet turtles results from an interest in the ecology and taxonomy of Aeromonas bacteria. Aeromonads are gram-negative, fermentative, and oxidasepositive bacteria which have classically been associated with diseases in fish, frogs, and reptiles (2). In recent years, these opportunistic pathogens have also been isolated from numerous diseased animals from insects to man (1, 6, 9, 20, 24). During the course of acquiring a collection of Aeromonas cultures for ongoing taxonomic studies, one culture was received from R. M. Wood of the California State Department of Public Health. This isolate, designated CPHL in this paper, had been isolated from aquarium water containing a small green pet turtle which we believed to be Pseudemys scripta elegans. The owner of the 'Technical paper no. 3438, Oregon Agricultural Experiment Station.

Studies directed toward the formulation of a selective/differential pour plate medium for Aeromonas species resulted in the following composition (in grams per liter): Bacto-peptone, 10; Bacto-beef extract, 10; glycogen, 4; NaCl, 5; sodium lauryl sulfate, 0.1; bromthymol blue, 0.1; agar, 15. The pH of the medium after autoclaving was 6.9–7.1. After the agar had gelled and the surface had dried, plates were overlaid with 2% nonnutrient agar in distilled water.Aeromonas colonies were recognized by their characteristic size and yellow color in this medium. It has been used to monitor the concentrations of A. hydrophila and A. salmonicida in hatchery waters, to recover these organisms from the intestines and lesions of experimentally infected fish, to isolate A. hydrophila from fish mucus and pet turtles, and to determine aeromonad survival times in water.

Bacteriological analyses were performed on fecal swabs and the aquarium water of 27 individually purchased specimens of the small green pet turtle, Pseudemys scripta elegans . Representatives of Aeromonas, Citrobacter, Enterobacter, Klebsiella, Proteus, Salmonella , and Serratia were isolated. Enterobacter, Klebsiella , and Salmonella were encountered in 20% or more of the specimens, whereas Aeromonas was isolated from 63%. Klebsiella pneumoniae counts ranged from 10 3 to 10 4 per milliliter of aquarium water, whereas Aeromonas routinely exceeded 10 4 per milliliter. Aeromonas cultures from turtles were identical to 7 human isolates in some 29 biochemical tests. On the basis of our findings, we question whether the Salmonella -free certification program alone is sufficient to render these reptiles as safe pets.