Starch hydrolyzed. Acetylmethylcarbinol produced (37° C. better incubation temperature than 32° C). pH of glucose broth cultures is 5.2 to 8.2 in 7 days. Citrates utilized. Nitrites produced from nitrates. Gas produced from nitrates under anaerobic conditions. Growth factors not essential. Lecithinase not produced. Aerobic, facultatively anaerobic. Growth in glucose broth under anaerobic conditions ; pH is 5.2 or lower at 14 days. Usually a small amount of gas is produced. Temperature relations: Optimum, be- tween 32° and 45° C. Maximum, between 50° and 56° C. (in water bath). Antibiotics obtained from cultures of certain strains are bacitracin (Johnson, Anker and Meleney, Science, 102, 1945, 376) and licheniformin (Callow and Hart, Na- ture, 157, 1946, 334). Source: Isolated from cheese. Habitat: Widely distributed in soil and food; also common as a laboratory con- taminant. 6. Bacillus subtilis Cohn, 1872, emend. Prazmowski, 1880. (Cohn, Beitr. z. Biol. d. Pflanzen, 1, Heft 2, 1872, 174; also see Heft 3, 1875, 188; and 2, Heft 2, 1876, 249; Praz- mowski, Untersuchungen iiber die Entwick- lungsgeschichte und Fermentwirkung eini- gen Bakterien-Arten. Inaug. Diss., Leipzig, 1880.) sub'ti.lis. L. adj. stibtilis slender. The identity of this species has been the subject of considerable controversy owing to the great variations in cultural charac- ters exhibited by various strains, to the distribution of mislabeled cultures and to confusion with Bacillus cereus. In cases in which an organism is said to be "anthrax- like" or "similar to the anthrax bacillus," it should be remembered that these terms apply to Bacillus cereus and not to Bacillus subtilis. Conn (Jour. Inf. Dis., 46, 1930, 341) concluded that the so-called Marburg strain fitted the earliest recognizable descriptions of this species. His interpretation was ac- cepted by the International Committee on Bacteriological Nomenclature (Jour. Bact., 33, 1937, 445). Rods, 0.7 to 0.8 by 2.0 to 3.0 microns, not in chains, uniformly stained. Not encap- sulated. No shadow-forms. Motile. Gram- positive. Variations: Rods, 0.6 to 1.0 by 1.3 to 6.0 microns, or filaments. Long chains. Encapsulated. Shadow-forms. Budding from end of cells. Occasionally non-motile. Rarely Gram-variable. Spores, 0.6 to 0.9 by 1.0 to 1.5 microns, ellipsoidal to cjdindrical, central or para- central, thin-walled. Many are formed in 48 hours. Variations: 0.5 to 1.0 by 1.0 to 2.0 microns. Few are formed in 15 to 21 days. Sporulation poor on media made with highly refined agar; much better when crude agar is used or when soil extract is added to the refined agar (Smith and Gordon, un- published data). Spore germination is equatorial with splitting of the spore coat along the trans- verse axis (Lamanna, Jour. Bact., 44, 1942, 611; Burdon and Wende, Bact. Proc, 1952, 46). Sporangia not definitely swollen; fre- quently show bipolar staining. Gelatin stab : Liquefaction crateriform to stratiform. Gelatin agar streak plate: Wide zone of hydrolysis. Agar colonies: Rough, opaque, dull, spreading, offwhite. Variations: Smooth to slimy, soft, thin, translucent, dendroid. Yellow, orange or brown. Agar slants: Growth abundant, rough, opaque, dull, waxy, spreading. Cream-col- ored to light brown. Variations: Smooth, slimy, thin, translucent, dendroid. Yellow or orange (some strains show a greenish yellow, diffusing pigment when incubated at45°C.). Glucose agar slants: Growth heavier and softer than on agar, sometimes pink or brown. Glucose asparagine agar slants: Growth abundant. Variation: Scant growth. Glucose nitrate agar: Usually abundant, cream-colored growth. Soybean agar slants: Growth more abun- dant and softer than on agar.
