f. Hydrobiol., Suppl. 5, 1925, 279) that the complex Chlorochromatium aggregatum may, especially in the presence of oxygen, disintegrate, whereupon the green constituents appear as small Pelodictyon aggregatum (Schmidlea luteola) colonies.
Suborder II. Pseudomonadineae Breed, Murray and Smith, Sub-Ordo Nov.
Pseu.do.mo.na.di′ne.ae. M.L. fem.n. Pseudomonas, -adis a genus of bacteria; -ineae ending to denote a suborder; M.L. fem. pl. n. Pseudomonadineae the Pseudomonas suborder.
Cells normally about 1 micron in diameter, but among the colorless sulfur bacteria they may be as much as 14 microns in diameter. The cells do not contain photosynthetic pigments, but diffusible, water-soluble pigments of a type not found elsewhere among bacteria occur in many species. Also, non-water-soluble yellow or red pigments occur in some genera. The motile species are invariably polar flagellate. Some groups are strictly autotrophic, oxidizing simple inorganic compounds; others are also oxidative but are facultatively heterotrophic or heterotrophic in their physiology. A few genera include species that ferment simple sugars, even producing H2 and CO2 as do the common acid- and gas-producing coliform bacteria. The organisms in one genus (Zymomonas) even carry out an alcoholic fermentation similar to that of yeasts. The majority of the species grow well and fairly rapidly on the surfaces of ordinary culture media. Some species that attack agar or cellulose or that show other unusual types of physiology are more fastidious in their requirements. Only a few species are strictly anaerobic as in Vibrio and Desulfovibrio. The species in this suborder are largely found in salt- or fresh-water or in soil. Some are parasitic and a few are pathogenic to vertebrates including man.
Key to the families of suborder Pseudomonadineae.
I. Coccoid to rod-shaped cells. Occasionally individual rods may be curved although the majority of the cells are straight.
- A. Cells not attached to a substrate.
- 1. Cells have the power to oxidize simple compounds such as ammonia, nitrites, methane, hydrogen, carbon monoxide, sulfur or sulfur compounds. Chemo-autotrophic or facultatively chemo-autotrophic.
- a. Do not secure their energy from the oxidation of sulfur compounds.
- b. Oxidize ammonia to nitrites or nitrites to nitrates. Autotrophic.
Family I. Nitrobacteraceae, p. 68.
- bb. Oxidize methane, hydrogen or carbon monoxide. Autotrophic.
Family II. Methanomonadaceae, p. 74.
- aa. Oxidize sulfur compounds, frequently with a deposit of free sulfur granules or crystals within or without the cells.
Family III. Thiobacteriaceae, p. 78.
- 2. Cells frequently oxidative, although they are sometimes fermentative in their physiology. Usually heterotrophic. Rarely facultatively autotrophic
Family IV. Pseudomonadaceae, p. 88.
- B. Cells in free-floating films or attached to a substrate.
- a. Cells attached to the substrate by means of a stalk, usually with a holdfast.
Family V. Caulobacteraceae, p. 212.
- aa. Cells in free-floating films or attached to the substrate by means of capsular material.
Family VI. Siderocapsaceae, p. 217.
II. Curved, vibrio-like to spiral-shaped cells.
Family VII. Spirillaceae, p. 228.
