3a. Acetobacter pasteurianus (Han- sen, 1879) Beijerinck, 1916. (Mycoderma pasteurianum Hansen, Compt. rend. d. Trav. d. Lab. d. Carlsberg, 1, 1879, 96; Bei- jerinck, Proc. Sect. Sci., Kon. Akad. v. Wetenschappen, Amsterdam, 18, 1916, 1199.) pas.teur.i.a'nus. Named for Pasteur, French chemist and bacteriologist; M.L. adj . pasteurianus of Pasteur. Rods, 0.4 to 0.8 by 1.0 micron, occurring singly and in chains, at times showing thick, club-shaped forms. Motility variable. Motile cells possess a single polar flagellum (Vaughn, Jour. Bact., 46, 1943, 394). Stain blue with iodine. Wort gelatin colonies: Small, circular, entire, gray, slimy. Forms a dry, wrinkled, folded pellicle on double beer with one per cent alcohol. Meat infusion gelatin: Growth wide- spread; later rosette form, toothed. Acid from glucose, ethanol, propanol and glycol. No acid from arabinose, fructose, galactose, sorbose, sucrose, maltose, lactose, raffinose, dextrin, starch, glycogen, inulin, methanol, isopropanol, butanol, isobutanol, pentanol, glycerol, erythritol, mannitol, dulcitol or acetaldehyde (Henneberg, Die deutsch. Essigind., 2, 1898, 147). Optimum temperature, 30° C. Growth occurs between 5° and 42° C. Habitat: Vinegar; beer and beer wort.
3b. Acetobacter kuetzingianus (Han- sen, 1894) Bergey et al., 1923. {Bacterium klitzingianum (sic) Hansen, Compt. rend. d. Trav. d. Lab. d. Carlsberg, 3, 1894, 191; Bergey et al.. Manual, 1st ed., 1923, 35.) kuet.zing.i.a'nus. Named for Kuetzing, a German botanist; AL L. adj. kuetzingianus of Kuetzing. Short, thick rods, occurring singly, rarely forming chains of notable length. Capsule stains blue with iodine and with potassium iodide. Non-motile. Double beer gelatin colonies: Small, en- tire, w'ith vermiform surface. Wort gelatin colonies: Small, entire, with surface free of wrinkles. Double beer: Forms a rather thick, folded pellicle. Distinguished from Acetobacter aceti in showing a heavier growth above the surface of the medium. Acid from glucose, ethanol, propanol and glycol. No acid from arabinose, fructose, galactose, sorbose, sucrose, maltose, lactose, rafiinose, dextrin, starch, glycogen, inulin, methanol, isopropanol, butanol, isobutanol, pentanol, glycerol, erythritol, mannitol, dulcitol or acetaldehyde (Henneberg, Die deutsch. Essigind., 2, 1898, 147). Optimum temperature, 34° C; minimum, between 6° and 7° C; maximum, 42° C. Habitat: Beer. Found in double beer.
4. Acetobacter melanogenus Beije- rinck, 1911. (Cent. f. Bakt., II Abt., 29, 1911, 175.) me.la.no'ge.nus. Gr. adj. melas, melanis black; Gr. v. gennao to produce; M.L. adj. inelanogenus black-producing. Rods. Non-motile or motile. Motile cells possess a single polar flagellum (Vaughn, Jour. Bact., 46, 1943, 394). Gelatin: Apparent liquefaction probably caused by acid, not an enzyme. When held on artificial media for some time, the power of liquefying gelatin is lost, probably due to a slower production of acid. Deep brown pig- ment produced; gelatin becomes insoluble in boiling water and in trypsin solution. Beer- or wort-gelatin plates: Characteris- tic dark brown, wide-spreading, diffuse areas. Tap water - agar - glucose - peptone - potas- sium phosphate-iron citrate-chalk medium: In 24 hours at 30° C, black, spreading, dif- fuse areas. Produces the pigment from peptone or yeast autolysate if maltose or glucose is present as a source of carbon. When grown in glucose-peptone broth or agar with CaCOa at 25° to 30° C, the pigment is produced after one to several weeks. Pigment : The pigment causing the brown coloration is an aromatic substance which is blackened by iron salts. Reduces alkaline solutions of silver and mercury, blackening them (Beijerinck, op. cit., 29, 1911, 175). Minimum nutritional requirements : Pan- tothenic acid, nicotinic acid, p-aminoben- zoic acid, thiamine, mineral salts and an oxidizable substrate such as alcohol, glu-
