756 LACTOBACILLUS 



Group A strains in the production of volatile acids and CO 2, and were inhibited by 

 relatively dilute solutions of phenol and indole. Group C strains differed from 

 Group A in growing at 20° C. and in a number of minor particulars. Of the 103 

 strains, Group A comprised 58, Group B 30, and Group C 15. With regard to their 

 source of origin, about three-quarters of the intestinal strains belonged to Group A, 

 while over half of the dental strains belonged to Group B. Group A probably 

 represented the typical L. acidophilus ; Group B probably included L. bul- 

 garicus and L. casei ; while Group C comprised a heterogeneous collection of strains 

 whose identity was doubtful, and whose classification into one group was largely 

 a matter of temporary convenience. Lewis and Eettger (1940) suggest a classifi- 

 cation of the anaerobic members into three groups. A, B and C — which do not, 

 of course, correspond to the similarly named groups of Curran, Rogers and Whittier 

 — based on morphology, minimum growth temperature, resistance to heat, and 

 the production of gas from fermentable carbohydrates. 



The identity of L. bulgaricus has often been under discussion. Sherman and 

 Hodge (1940) state that it differs from L. acidophilus in the following respects. 

 Freshly isolated strains of L. bulgaricus grow at 50° C, but are unable to grow 

 in serial culture in a simple medium containing 1 per cent, each of lactose, peptone 

 and yeast extract, or in broth of pH 7-8, or in broth containing 2-5 per cent, sodium 

 chloride. L. acidophilus, on the other hand, will not grow above a temperature 

 of 48° C, but will grow under the other conditions described. It need hardly 

 be mentioned that minor physiological differences of this type, however useful 

 in practice, can afford no satisfactory basis for permanent classification. 



A classification of the gas-producing strains has been suggested by Pedersen 

 (1938) based primarily on arabinose fermentation, and secondarily on the fermenta- 

 tion of lactose, sucrose and raflSnose. L. brevis (Synonym : L. pentoaceticus ; 

 B. acidophil-aerogenes) ferments arabinose, and varies in its effect on the other 

 three sugars ; its growth range is 10° to 45° C, and its optimum 30° to 35° C. 

 L. fermenti does not ferment arabinose, but usually ferments the three other 

 sugars ; its growth range is 15° to 50° C, and its optimum 35° to 40° C. L. buchneri 

 (Synonym : B. wehmeri) usually ferments arabinose, lactose, sucrose and rafiinose ; 

 its growth range is 10° to 48° C, and its optimum 44° to 48° C. L. pastorianus 

 (Synonym : L. berolinensis) usually ferments arabinose, lactose, sucrose and 

 raffinose ; its optimum temperature for growth is 27° to 32° C. No satisfactory 

 description, however, appears to have been given of this organism. 



Barker and Haas (1944) find that the Gram-positive, anaerobic, non-sporing 

 intestinal bacteria break down lactate with the production of volatile fatty acids, 

 and they therefore suggest that they should be classified in a separate genus, 

 Butyribacterium. Further work will clearly be required to find out whether there 

 is, in fact, a sharp cleavage in their type of metabolism among the organisms 

 hitherto classified as lactobacilli. In the meantime, we may point out the confusion 

 that is likely to be caused by using the termination " bacterium " for anaerobic 

 bacilli ; it would be much better to reserve this term for non-sporing aerobic 

 rods. Much the same criticism applies to the termination " bacillus," and it is 

 unfortunate that the generic name Lactobacillus should have been chosen for 

 organisms which are mainly anaerobic or microaerophilic. It would be better if 

 the name could be replaced by one more suitable, such, for instance, as Lactiformans. 



As has frequently happened with other groups, several members have been accredited 

 with specific names without an adequate description being given of them. Moreover 



