FAMILY X. LACTOBACILLACEAE 533 



Agar colonies: Small, gray, entire, slightly arabinose, rhamnose, raffinose, glycerol, 



raised. dextrin, inulin, starch, salicin, mannitol or 



Agar slant: Small, gray, discrete colonies. sorbitol. 



Glucose broth: Slight gray sediment. Uggg ^-^^^-^^ ^cid in milk. 



Litmus milk: Slightly acid with partial ^-^^-^^^ ^^^ produced from nitrates, 



reduction of litmus. , ,. , .,. ,,,,-, , . 



„ , , ^.-r . ., , ,, Microaerophilic, facultatively anaerobic. 



Potato: No visible growth. ^ . 



Indole not produced. Optimum temperature, between 20° and 



Grows poorly on ordinary media without 

 the addition of yeast extract or other Distinctive character: Non-slime pro- 

 growth-accessory substance. ducer. 



Acid from glucose, fructose, galactose Source: Isolated from dairy products, 



and lactose. Generally does not form acid Habitat: Found in milk and dairy prod- 



from mannose, sucrose, maltose, xj^lose, ucts. 



Genus V. Peptostreptococcus Kluyver and van Niel, 1936 * 

 (Zent. f. Bakt., II Abt., H, 1936, 391, 395 and 401.) 



Pep.to.strep.to.coc'cus. Gr. v. pepio to cook, digest; M.L. mas.n. Streptococcus a generic 

 name;M.L. mas.n. Peptostreptococcus the digesting streptococcus. 



Spherical cells which occur in pairs or in chains. Non-motile. Gram-positive. Chemohet- 

 erotrophic, fermenting protein decomposition products, organic acids and usually carbo- 

 hydrates with the production of carbon dioxide, hydrogen and other products. Anaerobic. 

 Found in septic and gangrenous conditions in man and other animals and as part of the 

 normal bacterial flora of respiratory and digestive tracts. May be pathogenic. 



The present classification of the species in this genus is based on morphological and va- 

 rious physiological characters. However, recent work has shown that the presence of fatty 

 acids and sulfur comijounds exerts a marked influence on the morphology and/or biochem- 

 ical behavior of these organisms; consequently, in choosing criteria for the classification 

 of the species in this genus, it seems exigent to use those obtained with standardized media. 

 With the use of rather ill-defined media, at least thirty anaerobic cocci have been recog- 

 nized and described; however, with standardized media, Hare and his associates have di- 

 vided a very large number of anaerobic cocci into only nine groups. Thus, future work may 

 show that some or even many of the species here regarded as distinct are, in reality, identical 

 with one another. (See Hare, Wildy, Billett and Twort, Jour. Hyg., 50, 1952, 295; Hare, Atti 

 del VI Congresso Internaz di. Microbiologia, Roma, 1, 1953, 55; and Thomas and Hare, 

 Jour. Clin. Path., 7, 1954, 300.) 



The type species is Peptostreptococcus anaerohius (Kronig emend. Natvig) Kluyver and 

 van Niel. 



Key to the species of genus Peptostreptococcus. 



I. Cells occur in chains. 

 A. Strict anaerobes. 



1. Gas and fetid odor produced. 



a. No general turbidity in broth, 

 b. Acid from maltose. 



1. Peptostreptococcus anaerohius. 

 bb. No acid from maltose. 



2. Peptostreptococcus foetidus. 

 aa. Turbidity in broth. 



* Revised by Dr. Louis DS. Smith, ^lontana Agricultural Experiment Station, Boze- 

 man, Montana, February, 1955. 



