Page:Bergey's manual of determinative bacteriology.djvu/97

 CH$4$ and 321 ml O$2$ to the following:


 * CH$4$ 0 ml
 * CO$2$ 78 ml
 * O$2$ 172 ml

In addition, 21 ml CO$2$ were dissolved in the liquid.

Habitat : Presumably widely distributed in soil.

Hy.dro.ge.no.mo′nas. Gr. hydro water; Gr. genus race, offspring; whence, M.L. hydrogenum hydrogen, that which produces water; Gr. monas a unit, monad; M.L. fem. noun Hydrogenomonas hydrogen monad.

Short rods that are polar flagellate when motile. Cells capable of deriving energy from the oxidation of hydrogen. They may grow well on organic media without hydrogen although this has not been shown to be true in all cases. Gram-negative. Found in soil and water.

This group of bacteria is characterized by the ability to grow in substrates containing no organic matter and to use elemental hydrogen as the source of energy for growth. Under these conditions CO$2$ is used as the source of carbon. Bacteria with similar physiological characteristics but differing in morphology are placed in the genera Bacillus and Clostridium. Although other bacteria and even certain algae have enzyme systems which can activate hydrogen and reduce CO$2$ in the process, there is no evidence that these organisms are able to grow in inorganic media with hydrogen as the exclusive source of energy (see Stephenson and Strickland, Biochem. Jour., 25, 1931, 205–215; Woods, Biochem. Jour., 30, 1936, 515; Lee and Umbreit, Zent. f. Bakt., II Abt., 101, 1940, 354; Gaffron, Amer. Jour. Bot., 27, 1940, 273).

The type species is Hydrogenomonas pantotropha (Kaserer) Orla-Jensen.

I. Not sensitive to high concentrations of O$2$.
 * A. When growing autotrophically, no pellicle on liquid media.


 * B. When growing autotrophically, pellicle formed on liquid media.

II. Sensitive to high concentrations of O$2$.


 * A. When growing autotrophically, no pellicle on liquid media.


 * B. When growing autotrophically, pellicle formed on liquid media.

1. Hydrogenomonas pantotropha (Kaserer, 1906) Orla-Jensen, 1909. (Bacillus paniotrophus Kaserer, Cent. f. Bakt., II Abt., 16, 1906, 688; Orla-Jensen, Cent. f. Bakt., II Abt., 22, 1909, 311.)

pan.to′troph.a. Gr. prefix panto all; Gr. trophus feeder; M.L. adj. pantotrophus omnivorous.

Rods, 0.4 to 0.5 by 1.2 to 1.5 microns, with rounded ends. Occur singly, in pairs and in chains. Encapsulated. Actively motile by means of a single, long, polar flagellum. Gram stain not recorded. Bipolar staining in old cultures.

Inorganic solution: When cultivated under an atmosphere of O$2$, CO$2$ and H$2$, the liquid becomes turbid without pellicle formation.

Inorganic solid media: When cultivated under an atmosphere of O$2$, CO$2$ and H$2$, the colonies are yellow and slimy, and the agar plates have an odor resembling hot, soapy water.

Gelatin colonies: Yellow, smooth, rarely concentrically ringed or greenish.

Gelatin stab: Growth only at surface. As a rule no liquefaction.

Agar colonies: Same as on gelatin, greenish, often slimy.