FAMILY LACTOBACTERIACEAE 305 



FAMILY VII. LACTOBACTERIACEAE ORLA-JENSEN. 



(Orla-Jensen, Jour. Bact., 6, 1921, 271 ; Streptobacteriaceae Bergey, Breed and 

 Murray, Preprint, Manual, 5th ed., 1938, 71.) 



Long or short rods, or cocci which divide like rods in one plane only, producing 

 chains, but never tetrads or packets. Non-motile except for certain cultures of 

 streptococci. Gram-positive. Pigment production is rare; a few species form a 

 yellow, orange, red or rusty brown pigment. Surface growth on all media is poor or 

 absent. Some species are strictly anaerobic. Carbohydrates are essential for good 

 development; they are fermented to lactic acid, sometimes with volatile acids, alcohol 

 and CO2 as by-products (except for the non-fermenting Diplococcus magnus). Gela- 

 tin is very rarely liquefied. Nitrate is not reduced to nitrite. Found regularly 

 in the mouth and intestinal tract of man and other animals, dairy products, fer- 

 menting vegetable juices. A few are highly pathogenic. 



Key to the tribes of family Lactobacteriaceae. 



I. Cocci occurring singly, in pairs and in chains. 



Tribe I. Streptococceae, p. 305. 



II. Rods occurring singly, in pairs and in chains. Individual cells may be very 



long or even filamentous. 



Tribe II. Lactobacilleae, p. 349. 



TRIBE I. STREPTOCOCCEAE TREVISAN. 



(I generi e le specie delle Batteriacee, 1889, 29.) 



Cells spherical or elongate, dividing in one plane only, usually occurring in pairs or 

 chains. A few species are strict anaerobes; none grow abundantly on solid media. 

 Carbohydrates and polyalcohols are changed either by homofermentation to lactic 

 acid or by hetero fermentation to lactic and acetic acids, alcohol and carbon dioxide. 

 Some pathogenic species grow poorlj^ without blood serum or other enrichment fluids. 

 Catalase negative. 



Key to the genera of tribe Streptococceae. 



I. Parasites, growing poorly on artificial media. Cells usually in pairs, often 

 elongated. Anaerobic species rarely in tetrads or small clumps. 



Genus I. Diplococcus, p. 305. 



II. Parasites and saprophytes. Normally forming short or long chains. Fer- 



ment glucose to lactic acid with practically no other acids or CO2. 



Genus II. Streptococcus, p. 312. 



III. Saprophytes. Form chains of cocci to short rods in plant juices and milk. 



Ferment glucose with the production of CO2, lactic acid, acetic acid and 

 ethyl alcohol. Mannitol is formed from fructose. 



Genus III. Leuconostoc, p. .346. 



Genus I. Diplococcus Weichselbaum* 



(Weichselbaum, Wiener med. Jahrb., 82, 1886,483; Hyalococcus Schroeter, in Cohn, 

 Kryptogamen Flora v. Schlesien, 1886, 152 ;Pseudodiplococcus Bonome, Cent. f. Bakt., 



* Revised by Prof. E. G. D. Murray, McGill University, Montreal, Canada, Sep- 

 tember, 1938; anaerobic section adapted from papers by Dr. A. R. Prevot, Institut 

 Pasteur, Paris, France, 1938; further revision b}^ Lt. Col. Elliott S. Robinson, M.C., 

 Washington, D. C, January, 1944. 



