PI. XXXIX, fig. 1-2; Tokuda, Botan. Magaz., Tokyo, 50, 1936, 339, fig. 1-23.
12. Chromatium minutissimum Winogradsky, 1888. (Schwefelbacterien, Leipzig, 1888, 100.)
mi.nu.tis'si.mum. L. sup. adj. minutissimus very small.
Cells about 1 to 1.2 by 2 microns. Also from 0.5 to 0.7 by 0.6 to 1 micron (Issatchenko, Recherches sur les microbes de l'océan glacial arctique, Petrograd, 1914, 253), and 1 to 3 by 2 to 5 microns (Issatchenko, Borodin Jubilee Volume, 1929?, 9).
Illustrations: Winogradsky, op. cit., 1888, Pl. IV, fig. 8; Miyoshi, Jour. Coll. Sci., Imp. Univ., Tokyo, Japan, 10, 1897, Pl. XIV, fig. 18.
FAMILY II. ATHIORHODACEAE MOLISCH, 1907.
(Die Purpurbakterien, Jena, 1907, 28.)
A.thi.o.rho.da′ce.ae. Gr. pref. a without; Gr. noun thium sulfur; Gr. noun rhodum the rose; -aceae ending to denote a family; M.L. fem. pl. n. Athiorhodaceae (probably intended to mean) the family of the non-sulfur red bacteria.
Unicellular bacteria, of relatively small size, occurring as spheres, short rods, vibrios, long rods and spirals. Motility is due to the presence of polar flagella. Gram-negative. They produce a pigment system composed of bacteriochlorophyll and one or more carotenoids, coloring the cells yellowish brown, olive-brown, dark brown or various shades of red. Color usually not observable with single cells but only with cell masses. Generally microaerophilic, although many representatives may grow at full atmospheric oxygen tension. Capable of development under strictly anaerobic conditions, but only in illuminated cultures by virtue of a photosynthetic metabolism. The latter is dependent upon the presence of extraneous hydrogen donors, such as alcohols, fatty acids, hydroxy- and keto-acids, and does not proceed with the evolution of molecular oxygen. Those members which can grow in the presence of air can also be cultivated in darkness, but only under aerobic conditions.
The growth requirements of some of the species in this family have been reported by Hutner (Arch. Biochem., 3, 1944, 439; Jour. Bact., 52, 1946, 217; Jour. Gen. Microbiol., 4, 1950, 286); his findings are incorporated in the descriptions which follow.
Key to the genera of family Athiorhodaceae.
I. Cells rod-shaped or spherical, not spiral-shaped.
Genus I. Rhodopseudomonas , p. 53.
II. Cells spiral-shaped.
Genus II. Rhodospirillum, p. 58.
Genus I. Rhodopseudomonas Kluyver and van Niel, 19S7, emend, van Niel, 1944.
(Includes Rhodobacillus Molisch, Die Purpurbakterien, Jena, 1907, 14; Rhodobacterium Molisch, ibid., 16; Rhodococcus Molisch, ibid., 20; Rhodovibrio Molisch, ibid., 21; Rhodocystis Molisch, ibid., 22; Rhodonostoc Molisch, ibid., 23; Rhodosphaera Buchanan, Jour. Bact., 3, 1918, 472; Rhodorhagus (sic) Bergey et al.. Manual, 2nd ed., 1925, 414; Rhodomonas Kluyver and van Niel, Zent. f. Bakt., II Abt., 94, 1936, 397; not Rhodomonas Orla-Jensen, Cent. f. Bakt., II Abt., 22, 1909, 331 ; Kluyver and van Niel, in Czurda and Maresch, Arch, f . Mikrobiol., 8, 1937, 119; Rhodorrhagus Bergey et al.. Manual, 5th ed., 1939, 905; van Niel, Bact. Rev., 8, 1944, 86.)
Rho.do.pseu.do.mo′nas. Gr. noun rhodum the rose; Gr. adj. pseudes false; Gr. noun monas monad, unit; M.L. fem. n. Pseudomonas a bacterial genus; M.L. fem. n. Rhodopseudomonas the rose Pseudomonas.
Spherical and rod-shaped bacteria, motile by means of polar flagella. Gram-negative.
