FAMILY XIII. BACILLACEAE FISCHER, 1895. 

 (Jahrb. f. wiss. Bot., 21, 1895, 139.) 



Ba.cil.la'ce.ae. M.L. noun Bacillus type genus of the family; -aceae ending to denote a 

 family; M.L. fem.pl.n. Bacillaceae the Bacillus family. 



Rod-shaped cells capable of producing endospores which are cylindrical, ellipsoidal or 

 spherical, and which are located in the center of the cell, subterminally or terminally. 

 Sporangia do not differ from the vegetative cells except when bulged by spores larger than 

 the cell diameter; such sporangia are spindle-shaped when spores are central and wedge- 

 or drumstick-shaped when spores are terminal. Motile by means of peritrichous flagella or 

 non-motile. Usually Gram-positive. Pigment formation isjare. Gelatin is frequently hy- 

 drolyzed. Sugars are generally fermented, sometimes with the production of visible gas. 

 Aerobic, facultatively anaerobic; anaerobic; or anaerobic, aerotolerant. Some species are 

 capable of growth at 55° C. Mostly saprophytes, commonly found in soil; a few are animal 

 or insect parasites or pathogens. 



Key to the genera of family Bacillaceae. 



I. Aerobic or facultatively anaerobic; catalase-positive. 



Genus I. Bacillus, p. 613. 

 II. Anaerobic or aerotolerant; catalase not known to be produced. 



Genus II. Clostridium, p. 634. 



Gemis I. Bacillus Cohn, 1872.* 

 (Beitrage z. Biol. d. Pflanzen, 1, Heft 2, 1872, 146 and 175.) 



Ba.cil'lus. L. dim. noun bacillum a small rod; M.L. noun Bacillus a rodlet. 



Rod-shaped cells, sometimes in chains, capable of producing endospores. Sporangia do 

 not differ from the vegetative cells except when bulged by spores larger than the cell di- 

 ameter; such sporangia are spindle-shaped when the spores are central and wedge- or drum- 

 stick-shaped when the spores are terminal. Motile by means of peritrichous flagella or 

 non-motile. Gram-positive, some species being Gram-variable or Gram-negative. Some 

 species usually occur in the rough stage, forming a pellicle on broth, whereas other species 

 are smooth and the rough stage is rarely seen. Usually proteins are decomposed with the 

 production of ammonia. Carbohydrates are generallj^ fermented with the production of 

 more or less acidity; a few also produce visible gas. Catalase-positive. Aerobic or faculta- 

 tively anaerobic. Maximum temperatures for growth vary greatly, not only between spe- 

 cies but also between strains of the same species. Variations in other characters frequently 

 occur within a species. Mostly saprophytes, commonly found in soil; a few are animal, 

 especially insect, parasites or pathogens. 



The type species is Bacillus subiilis Cohn emend. Prazmowski. 



Key to the species of genus Bacillus. 



I. Sporangia not definitelj^ swollen. f Spores ellipsoidal to cylindrical, central to termi- 

 nal. Spore walls thin and not easily stained. Gram-positive. 



* Revised by Dr. Nathan R. Smith, St. Armands Key, Sarasota, Florida, and Dr. Ruth 

 E. Gordon, N. J. Agricultural Experiment Station, New Brunswick, N. J., September, 

 1954. The arrangement and the descriptions of the species, unless otherwise noted, have 

 been taken from the work of Smith, Gordon and Clark (Agricultural Monograph 16, U. S. 

 Department of Agriculture, 1952). 



t Nearly 50 per cent of the strains of Bacillus coagulans studied by Smith, Gordon and 

 Clark (op. cit., 1952) had definitely swollen sporangia; the species was placed in group I 

 because of other characteristics. 



613 



