1 8. Aerontonas 



Tlie genus Aeromoims has fairly recently been created for a 

 group of organisms formerly classified as Pseudomonos. These or- 

 ganisms differ from the type species of Pseudomonos, Pseiido- 

 monas aeruginosa, by their fermentative metabolism of carbohy- 

 drates, absence of pigmentation, and a tendency to produce lateral 

 flagella in addition to the polar flagellum in young cultures. In 

 this group are found bacteria which are pathogenic for frogs 

 {Pseudomonas hydrophila, Proteus hydrophila, etc.), for fish, and 

 other cold blooded animals. 



Cultures 



Ten cultures have been studied. Six of these were isolated in 

 the United States and supplied by Dr. S. F. Snieszko of the U.S. 

 Fish and Wildlife Service. They were isolated mainly from dis- 

 eased fish. Three of the cultures originated from Holland and 

 were isolated from water. One culture, Aeromonas formicans, was 

 received from Dr. H. Pivnich, University of Nebraska. All the 

 cultures were physiologically typical of the genus. One culture 

 was peritrichously flagellated (Kluyver strain L-418) when re- 

 ceived and has remained unchanged over a period of several years. 

 From personal communication this culture apparently was polar 

 flagellated when first isolated. It has the typical physiology of 

 Aeromonas and appears to be a stable variant (?). The coiled 

 shape of the flagella is also found in the polar flagella of other 

 strains as may be observed from the illustrations. 



Flagellar Characteristics 



In cultures which were incubated past the logarithmic phase 

 of growth, i.e. overnight at temperatures between 20° and 37° C, 

 all strains of Aeromonas studied showed mainly polar monotrichous 

 flagellation. Some strains produced only the normal type of polar 

 flagellum while in the other strains several types of polar flagella 

 were produced: undulant, normal, and coiled. The undulant type 

 has a wavelength averaging 3.5 microns and the normal type a 



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