546 



ORDER IV. EUBACTERIALES 



Bact., 46, 1943, 12) describe a variety of this 

 species from the feces and intestinal con- 

 tents of guinea pigs. 



Source : Isolated from the feces of milk-fed 

 infants. Also found in the feces of older 

 persons on high milk-, lactose- or dextrin- 

 containing diets. 



Habitat: Same as for the source. 



5. Lactobacillus bifidus (Tissier, 1900) 

 Holland, 1920. (Bacillus bifidus communis 

 and Bacillus bifidus Tissier, Recherches sur 

 la flore intestinal des nourrissons, Paris, 

 1900, 85; Holland, Jour. Bact., 5, 1920, 223.) 



bi'fi.dus. L. adj. bifidus cleft, divided. 



Description supplemented from Weiss 

 and Rettger (Jour. Bact., 28, 1934, 501). 



Small, slender rods, the average length 

 of which is 4.0 microns, 0.5 to 0.7 by 2 to 8 

 microns (Weiss and Rettger), occurring 

 singly or in pairs and short chains, parallel 

 to each other, very variable in appearance. 

 Branched and club forms develop in some 

 cultures. Non-motile. Gram-positive but 

 stains irregularly in old cultures (Tissier). 



Little or no growth in carbohydrate-free 

 agar (Weiss and Rettger). 



Deep sugar-agar colonies: After 3 days, 

 solid with slightly irregular edge, whitish. 

 Grow up to 3 cm from the surface forming 

 a ring. Average diameter 3 mm. No gas. 



Sugar broth: Good growth. Turbid within 

 3 days. Clears with fiocculent precipitate. 



Milk: Good growth with large inoculum. 

 No coagulation (Tissier). May or may not 

 coagulate milk (Weiss and Rettger). 



Acid but no gas from glucose (Tissier). 

 Acid from glucose, fructose, galactose, su- 

 crose, inulin and usually from dextrin, 

 starch, maltose, raffinose and trehalose. A 

 few strains form acid from lactose and sali- 

 cin. The acid consists of optically inactive 

 lactic acid and 18 to 25 per cent of volatile 

 acid (Weiss and Rettger). Orla-Jensen (The 

 Lactic Acid Bacteria, 1919, 192), Eggerth 

 (Jour. Bact., 30, 1935, 295) and Weiss and 

 Rettger (Jour. Bact., 85, 1938, 17; Jour. Inf. 

 Dis., 62, 1938, 115) describe a more anaerobic 

 variety of this species which produces more 

 volatile acid as well as dextro rotatory lactic 

 acid and which ferments arabinose, xylose 

 and melezitose but not mannose. 



Strict anaerobe (Tissier). Strict anaerobe 



in primary culture, becoming microaero- 

 philic (Weiss and Rettger). 



Optimum temperature, 37° C. May show 

 slight growth at 20° C. Killed at 60° C. in 

 15 minutes. 



Non-pathogenic for mice or guinea pigs. 



Distinctive characters: Bifurcations and 

 club-shaped forms (Tissier), particularly 

 in infant feces and in primary culture (Weiss 

 and Rettger). 



Comment: A variety of this species that 

 grows more readily in human than in cow's 

 milk is discussed by Gyorgy and Rose (Jour. 

 Bact., 69, 1955, 483) and in papers listed in 

 the bibliography of this report. This differ- 

 ence appears to be due to a specific growth 

 factor, the so-called bifidus factor. 



Source: Isolated from feces of nursing 

 infants. 



Habitat: Very common in the feces of 

 infants. May constitute almost the entire 

 intestinal flora of breast-fed infants. Also 

 present in smaller numbers with bottle-fed 

 infants. Possibly more widely distributed 

 than indicated in the intestines of warm- 

 blooded animals. 



6. Lactobacillus biilgaricus (Luerssen 

 and Kiihn, 1907) Holland, 1920. {Bacillus A, 

 Grigoroff, Revue M6d. Suisse romande, 25, 

 1905; Bacillus biilgaricus Luerssen and 

 Kuhn, Cent. f. Bakt., II Abt., 20, 1907, 241; 

 Holland, Jour. Bact., 5, 1920, 215.) 



bul.ga'ri.cus. M.L. adj. bulgaricus Bul- 

 garian. 



Description of Luerssen and Kiihn sup- 

 plemented by Grigoroff {op. cit., 1905), Co- 

 hendy (Compt. rend. Soc. Biol. Paris, 58, 

 1906, 364), Kuntze (Cent. f. Bakt., II Abt., 

 21, 1908, 737), Bertrand and Duchacek (Ann. 

 Inst. Past., 23, 1909, 402), White and Avery 

 (Cent. f. Bakt., II Abt., 25, 1910, 161), Rahe 

 (Jour. Bact., 3, 1918, 420), Orla-Jensen (The 

 Lactic Acid Bacteria, 1919, 164), Kulp and 

 Rettger (Jour. Bact., 9, 1924, 357) and Sher- 

 man and Hodge (Jour. Dairy Sci., 19, 1936, 

 494). 



Slender rods with rounded ends, often in 

 chains. Non-motile. Gram-positive, older 

 cultures showing unstained portions (Lu- 

 erssen and Kiihn). 



Whey gelatin: No liquefaction (White and 

 Avery). 



