Phylum Proteobacteria, Class Gammaproteobacteria, Order Pseudomonadales, Family Pseudomonadaceae, Genus Pseudomonas,
Pseudomonas fragi (Eichholz 1902) Gruber 1905.
Old synonyms: Bacterium fragi Eichholz 1902, Pseudomonas fragariae Gruber 1905.
Gram negative rods, 0.5-1.0 x 0.75-4.0 µm, occurring singly, in pairs and in chains.
Motile by a polar flagellum.
Colonies are convex, glistening, generally butyrous, occasionally viscid. Rough,
smooth and intermediate forms are recognized in the description quoted. The rough
forms are less proteolytic and less active in the hydrolysis of fats. On agar slant
growth is abundant, spreading, raised, white, shiny, generally butyrous. Sweet
ester-like odor resembling that of the flower of the May apple.
In broth produce turbidity and sediment with a thin pellicle.
Aerobic. Growth temperature 10-30 ºC. No growth at 37 ºC. Very sensitive to heat.
Isolated from milk and other dairy products, dairy utensils, water and soil. Widely distributed.
- Burkholder, Walter H. 1957. Genus I. Pseudomonas Migula, 1894 in: Robert S. Breed, E. G. D. Murray, Nathan R. Smith: Bergey’s
Manual of Determinative Bacteriology, seventh edition, 1957, The Williams & Wilkins Company, 89-151.
Positive result for acid production from glucose & galactose. Variable for arabinose.
Litmus milk: Acid ring followed by acid coagulum at surface.
Negative results for H2S production, indole production, nitrate reduction, Voges-Proskauer reaction, acid production from: glycerol,
inulin, lactose, fructose, maltose, mannitol, raffinose, salicin & sucrose.
(c) Costin Stoica