474 ORDER IV. EUBACTERIALES 



methane, carbon dioxide and, under some Source: Isolated by enrichment proce- 



conditions, hydrogen. dures from black mud from the east shore 



Chemical tolerance: pH range for growth, of San Francisco Bay. 



7.4 to 9.2. Optimum pH, about 8.0. Habitat: Presumably found in similar 



Anaerobic. materials elsewhere. 



Genus VI. Peptococciis Kluyver and van Niel, 1936 * 



(Zent. f. Bakt., II Abt., 94, 1936, 400.) 



Pep.to.coc'cus. Gr. v. pepto to cook, digest; Gr. noun coccus a grain, berry; M.L. mas.n. 

 Peptococcus the digesting-coccus. 



Spherical bacteria occurring singly, in pairs, tetrads or masses. Non-motile. Gram-posi- 

 tive. Anaerobic. Chemoheterotrophic, fermenting a variety of organic compounds. With one 

 exception, the species here described are all from human sources. 



Cardon and Barker (Jour. Bact., 52, 1946, 633) have proposed the generic name Anaero- 

 coccus as a provisional name to include the Gram-positive, anaerobic occci which occur in 

 a more or less irregular and variable arrangement. 



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

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

 fatty acids and sulfur compounds exerts a marked influence on the morphology and/or 

 biochemical behavior of these organisms; consequently, in choosing criteria for the classifi- 

 cation 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 

 recognized and described; however, with standardized media, Hare and his associates have 

 divided the 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 each 

 other. (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; also see Foubert and Douglas, Jour. Bact., 56, 1948, 25.) 



The type species is Peptococcus niger (Hall) Kluyver and van Niel. 



Key to the species of genus Peptococcus. 



I. Produce gas in visible quantities in culture media. 



A. Agar colonies black. 



1. Peptococcus niger. 



B. Agar colonies not black. 



1. Gelatin liquefied. 



2. Peptococcus activus. 



2. Gelatin not liquefied. 



a. Indole produced, nitrate reduced, glutamate fermented. 



3. Peptococcus asaccharolyticus. 



4. Peptococcus aerogenes. 



aa. Indole not produced, nitrate not reduced, glutamate not fermented. 



5. Peptococcus prevotii. 

 II. Do not produce gas in visible quantities in culture media. 



A. Ferment sugars. Glycine not fermented. 



1. Lactose fermented. 



6. Peptococcus grigoroffii. 



2. Lactose not fermented. 



7. Peptococciis constellatus . 



8. Peptococcus saccharolyticus. 



* Prepared by Prof. H. C. Douglas, University of Washington, Seattle, Washington, 

 December, 1954. 



