76 



ORDER I. PSEUDOMONADALES 



Broth: Turbid, somewhat slimy; pellicle 

 occasionally produced. 



Milk: No coagulation. A yellow pellicle 

 forms. Medium becomes slimy and assumes 

 a dirty flesh color. 



Potato: Moist, yellow, glistening. 



Indole not produced. 



Hydrogen sulfide not produced. 



Nitrites not produced from nitrates. 



Carbohydrates not utilized. 



Aerobic. 



Optimum temperature, between 28° and 

 30° C. 



Facultatively autotrophic. 



Distinctive characters: Develops auto- 

 trophically in inorganic medium under an 

 atmosphere of H2 , O2 and CO2 . Oxidizes 

 hydrogen to water and uses CO2 as the 

 source of carbon for growth. 



Source: Isolated from soil near Vienna. 



Habitat: Probably widely distributed in 

 soil. 



2. Hydrogenomonas facilis Schatz and 

 Bovell, 1952.* (An undescribed Hydrogeno- 

 monas, Schatz, Proc. Soc. Amer. Bact., 

 Baltimore Meeting, 1950, 124; Schatz and 

 Bovell, Jour. Bact., 63, 1952, 87.) 



fa'ci.lis. L. Sid\.Jacilis ready, quick. 



Rods 0.3 bj^ 2.0 microns in autotrophic 

 and 0.4 by 2.5 microns in heterotrophic cul- 

 tures. Occur singly, in pairs and in short 

 chains. Motile by means of one or two polar 

 flagella. Gram-negative. 



Gelatin stab: Rapidly liquefied. 



Agar colonies: Round, raised, glistening, 

 translucent, non-fluorescent and non-mu- 

 coid. No distinctive odor developed. 



Autotrophic media: Cultures readily 

 maintained in media of this type. 



Autotrophic gas uptake : The same overall 

 reaction is effected as that carried out by 

 certain anaerobically adapted green algae 

 (6H2 + 2O2 + CO2 -^ CH2O + 5H2O). In an 

 atmosphere of CO 2 and H2 , no CO2 fixation 

 accompanies the quantitative reduction of 

 nitrate to nitrite by molecular H2 ; nor is 

 there any change in concenti-ation of bicar- 

 bonate or in total gas pressure (Warburg 

 apparatus) when acetone, pyruvate ora-ke- 



toglutarate are added (Schatz, Jour. Gen. 

 Microbiol., 6, 1952, 329). 



Broth: Turbid with pellicle. 



Milk: Slowly digested with alkalinization. 



Potato: Abundant, spreading, non-pig- 

 mented growth. 



Indole not produced. 



Hydrogen sulfide not produced. 



Acetylmethylcarbinol not produced. 



Nitrites produced from nitrates. 



Aerobic, obligate. 



Non-hemolytic. 



Optimum temperature, 28° C. 



Source: Isolated from soil. 



Habitat: Presumably widely distributed 

 in soil. 



3. Hydrogenomonas flava Niklewski, 

 1910. (Jahrb. f. wissensch. Botanik, 48, 

 1910, 113; emend. Kluyver and Manten, An- 

 tonie V. Leeuwenhoek, 8, 1942, 71.) 



fla'va. L. flavus yellow. 



Rods 1.5 microns in length. Motile by 

 means of polar flagella. Gram-negative. 



Agar colonies on inorganic medium in 

 presence of H2 ,02andC02 : Small, smooth, 

 yellow, shining, adhering to medium. De- 

 velop well below surface of medium, but 

 growth is paler. 



Gelatin not liquefied. 



Inorganic liquid medium in presence of 

 H2 , O2 and CO2 : No pellicle formation. 

 Good development when there is from 2 to 8 

 per cent oxygen in the gas. At higher O2 

 concentrations good growth occurs only in 

 association with H. vitrea or other bacteria. 



Oxidizes hydrogen to water. 



Microaerophilic, growing in an atmos- 

 phere of low oxygen tension, not exceeding 

 8 per cent. 



Facultatively autotrophic. 



Distinctive characters: Found singly on 

 slides whereas the rod-shaped cells of Hydro- 

 genomonas vitrea tend to cling together in 

 masses. Colonies on agar opaque, not trans- 

 parent. 



Source: Isolated from mud, garden soil, 

 pasture land, vegetable mold and peat. 



Habitat: Presumably widely distributed 

 in soil. 



* Prepared by Prof. Albert Schatz, National Agricultural College, Farm School P.O., 

 Bucks Co., Pennsylvania, December, 1953. 



