LACTOBACILLUS BULOARICUS 763 



Gelatin Shake. — If incubated at 37° C. for 24 hours, and then left at room temperature 

 for some daj' s, fine discrete colonies appear ; no liquefaction. 



Broth. — 24 hours, 37° C. Granular turbidity. 



Olvcose Broth.- — 24 hours, 37° C. More abundant growth ; in 3 or 4 days the organisms 

 fall to the bottom of the tube, producing an abundant loose flocculo-granular 

 deposit, easily disintegrated on shaking. 



Blood Agar. — White colonies surrounded by a greenish halo of a-hsemolysis. 



Olvcose Blood Liver Agar Plates. — 48 hours, 37° C. Raised, globular, opaque colonies, 

 1-3 mm. in diameter, buff to reddish-browTi in colour. 



Resistance. — Cultures live for about a month at room temperature. Broth cidtures are 

 killed by heat at 55° C. in half an hour, and at 70° C. in 5 minutes. Is resistant 

 to acids ; will withstand 0-5-1 -0 per cent, acetic or lactic acid in broth for 2 to 3 days. 



Metabolism. — Strict anaerobe on first isolation ; later it may be grown in air. Verj'^ slight 

 or no growth at 20° C. ; optimum temperature 37° C. No pigment or toxin formed, 

 a-hsemolysis on blood agar. Growth improved by glucose, serum, and blood. 



Biochemical.— Sugar reactions variable. Produces acid in glucose, mannose. maltose, 

 inulin, and generally in lactose, sucrose, sahcin, and raffinose ; sometimes in 

 mannitol and dextrin ; occasionally in dulcitol ; not in arabinose, xylose or 

 melezitose. Produces mainly lactic acid, of the inactive variety, and some acetic 

 acid. L.M. grows well and produces an acid clot. Indole negative. Methyl-red 

 positive. Voges-Proskauer negative. Nitrates very slight reduction, or none at 

 all. Catalase very sMght positive. NH3 sUght production or none at all. 



Antigenic Structure. — Not fully worked out. By agglutination they appear to fall into 

 more than one group. Some relationship to L. acidophilus. 



Pathogenicity. — Non-pathogenic to man and laboratory animals. 



Lactobacillus bifidus II 



Synonyms : Bacteroides bifidus (Eggerth, Group II, 1935) ; Bacterium bifidum (Orla- 

 Jensen ; see Orla-Jensen et. al. 1936). 

 Differs from L. bifidus I mainly in the following characters. It is found in the intestine 

 of the adult hving on a mixed diet, in which it may form quite a high proportion of the 

 total flora. It branches more readily, and continues to branch on subculture. It is 

 an obUgate anaerobe, and rarely becomes accustomed to aerobic conditions. Deep 

 colonies in tomato agar have an entire, not a filamentous, edge (Weiss and Rettger 1938). 

 Mannose is not usually fermented, but most strains ferment arabinose, xylose, and melezi- 

 tose. It produces lactic acid, of the dextro-variet}!-, and about 50 per cent, of acetic acid. 

 It appears to be antigenicaUy more strain-specific. 



Lactobacillus bulgaricus 



Synonyms.— MassoVs bacillus. Probably identical with L. caucastcus. 



Lsolation. — Isolated by Grigoroff in 1905 from kisselo-mleko, the fermented milk of Bul- 

 garia ; described originally as " Bacillus A." 



Habitat. — Found in milk, particularly the fermented milks of Bulgaria, Turkey, Egj'pt, 

 and Sardinia. 



Morphology. — Large rods, 2-20 /ii long and about 1 /t broad, with parallel sides and slightly 

 rounded ends ; arranged singly or in short chains. Non-motile. Gram-positive. 

 Two morphological tj^Des are described by White and Avery (1910) in whey. Type 

 A consists of chains of short bacilli with oval or reniform nodules extruding from 

 the cell substance ; the bacilh stain uniformly ; Type B forms long bacilh arranged 

 singly, having spherical bodies attached to the cell wall, not stemmed nodules as 

 in A ; the bacilh show intense granular staining with Loeffler's methylene blue 

 or Neisser's stain. 



