616 



ORDER IV. EUBACTERIALES 



1. Bacillus megaleriuni de Bary, 1S84. 

 (DeBary, Vergleichende Morph. und Biol, 

 der Pilze, 1884, 499; Bacillus megatherium 

 (sic) Schroeter, in Cohn, Kryptogamen- 

 Flora V. Schlesien, 3, 1, 1886 (1889), 160.) 



me.ga.te'ri.um. Gr. adj. mega large; Gr. 

 noun teras, teratis monster, beast; M.L. 

 noun megaterium big beast. The second 

 stem has been claimed to be a faulty trans- 

 literation of the Gr. noun therium an animal. 

 The Judicial Commission of the Interna- 

 tional Committee on Bacteriological No- 

 menclature has ruled, however, that the 

 original spelling is to be preferred (Internat. 

 Bull. Bact. Nomen. and Taxon., 1, 1951, 35). 



Rods, 1.2 to 1.5 by 2.0 to 4.0 microns, with 

 rounded ends, occurring singly or in short 

 chains. When lightly stained, protoplasm 

 granular or foamy. Occasional shadow- or 

 ghost-forms. Motile. Gram-positive. Vari- 

 ations: 0.9 to 2.2 by 1.0 to 5.0 microns, oc- 

 curring in filaments or long and tangled 

 chains. Ends square. Protoplasm evenly 

 stained. Many shadow-forms. Buds at 

 end or side of rods. Non-motile. Gram-var- 

 iable. 



On glucose agar, rods are usually larger, 

 longer and more vacuolated because of 

 numerous, large, fat globules, sometimes 

 irregular in shape with pointed ends or 

 corkscrew-shaped (in wet mount) . 



Spores, 1.0 to 1.2 by 1.5 to 2.0 microns, 

 ellipsoidal, central to para-central. Thin- 

 walled. Many formed in 48 hours. Varia- 

 tions: Diameters 0.8 to 1.4 microns. Shapes 

 are irregular, reniform, oviform, almost 

 spherical and cylindrical. Lateral. Only a 

 few are formed in 3 to 6 days. 



Sporangia not distinctly swollen. 



Gelatin stab: Slow liquefaction. 



Gelatin agar streak plate: Wide zone of 

 hydrolysis. 



Agar colonies: Large, smooth, soft, glis- 

 tening, round, convex, entire, non-spread- 

 ing, dense, creamy white to yellow. Varia- 

 tions: Rough, concentrically or radially 

 ridged, thin edged. 



Agar slants: Growth abundant, smooth, 

 soft to butyrous, opaque, glistening, slightly 

 spreading, non-adherent, creamy white to 

 yellow. Some browning with pellucid dots 

 on aging. Variations: Rough, slightly wrin- 

 kled, tough, adherent, non-spreading. 



Glucose agar slants: Growth usually more 

 abundant and softer (somewhat slimy) than 

 on agar. Variations : Gummy, coarsely wrin- 

 kled. Pellucid dots more distinct than on 

 agar. 



Glucose nitrate agar slants: Growth very 

 heavy, raised. 



Soybean agar slants: Growth abundant. 

 Better sporulation and fewer shadow-forms 

 than on agar. 



Tyrosine agar slants: Deep black pigment 

 b}^ few strains. 



Broth: Turbidity medium to heavy, uni- 

 form, with or without abundant sediment. 

 No pellicle. Variations: Turbidity flocculent 

 or granular. Pellicle thin and friable. Broth 

 clear with flocculent sediment. 



Milk: Peptonized. 



Milk agar streak plate : Wide zone of hy- 

 drolysis of the casein. 



Potato: Growth abundant, smooth, soft 

 to slimy, glistening, spreading, creamy 

 white, pale to lemon-yellow or pink. Vari- 

 ations: Rough, wrinkled. Potato blackened 

 or orange-colored. No growth. 



Acid but no gas (with ammonium salts as 

 source of nitrogen) from glucose, sucrose 

 and mannitol. Acid usually produced from 

 arabinose, xylose and glycerol. Acid pro- 

 duction variable from lactose. 



Starch hydrolyzed. 



Acetylmethylcarbinol not produced. 



Citrates utilized as sole source of carbon. 



Nitrites usually not produced from ni- 

 trates. No gas from nitrates under anaerobic 

 conditions. 



Growth factors not essential.* 



Lecithinase not produced. f 



Aerobic. No growth in glucose broth under 

 anaerobic conditions. 



Temperature relations: Optimum, be- 



* Information on the nutritional requirements of this as well as of the succeeding species 

 was supplied by Knight and Proom (Jour. Gen. Microbiol., 4, 1950, 508). 



t The lecithinase reaction of this and succeeding species was reported by Colmer (Jour. 

 Bact., 55, 1948, 777), McGaughey and Chu (Jour. Gen. Microbiol., 2, 1948, 334) and Knight 

 and Proom {op. cit., 1950, 508). 



