772 PASTEURELLA 



very toxic to animals, suggesting that endotoxins are liberated by the autolysis 

 of the bacilli. 



Biochemical Reactions. — (MacConkey 1908, Vourloud 1908, Magnusson 1914, 

 Kakehi 1915-16, Besemer 1917, Brooks and Rhodes 1923, Pons 1925, Colas-Belcour 

 1926, Csontos 1926, Tanaka 1926, Morch and Krogh-Lund 1931.) 



Past, pestis and Past, pseudotuberculosis produce acid, without gas, in glucose, 

 maltose, mannitol, and salicin within 14 days ; salicin is not usually fermented for 

 about 10 days. Some strains of Past, pestis fail to attack maltose, and some strains 

 of Past, pseudotuberculosis ferment sucrose. Past, pseudotuberculosis is stated 

 (Colas-Belcour 1926, Zlatogorofi and Moghilewskaja 1928o) to form acid from 

 glycerol, but so also do some strains oi Past, pestis (Bessonowa 1928). Bessonowa 

 (1930), and Russo (1939), say that Past, pseudotuberculosis ferments rhamnose, while 

 Past, pestis does not ; Kauffmann (1932), however, says that Past, pestis may 

 ferment rhamnose, though its reaction in this sugar is inconstant. Past, aviseptica 

 produces acid in glucose, mannitol and sucrose ; some types also produce acid 

 in maltose. Tanaka (1926) found that Past, bubaliseptica (from buffaloes) formed 

 acid in lactose and clotted milk ; the same observation was made by Magnusson 

 (1914) for a reindeer strain, and by Besemer (1917) for a calf strain of Pasteurella. 

 We have encountered a strain of Past, lepiseptica that fermented lactose, and to 

 a less extent salicin. Newsom and Cross (1932) found differences in the fermenta- 

 tion of arabinose, dulcitol, and glycerol ; and Rosenbusch and Merchant (1939) 

 were able on the basis of fermentation of xylose, arabinose, or both, to divide 

 114 strains of Past, septica of diverse origin into three sub-groups, each of which 

 showed a considerable degree of antigenic homogeneity. In practice great care 

 is required in determining the fermentation reactions, since growth in sugar peptone 

 water media is very poor. 



In plain broth Past, pestis produces alkali ; the maximum production is not 

 reached for 6 to 8 weeks (Bannerman 1908) in a litre flask of medium. In peptone 

 water containing 0-5 per cent, glucose the hydrogen-ion concentration reached 

 in 7 days is pH 4'6-4-9 for Past, pestis, pH 4-6-4-8 for Past, pseudotuberculosis, 

 and pH 5-6-6-1 for Past, aviseptica (Often 1926). That is to say the first two 

 give a positive, the last a negative methyl-red reaction. But in peptone water 

 containing 0-05 per cent, glucose the final hydrogen-ion concentration is pH 

 5- 1-5-5 for Past, pestis, 7 -0-7 -3 for Past, pseudotuberculosis, and pH 5-8-6-1 

 for Past, aviseptica. After exhausting the sugar Past, pseudotuberculosis would 

 therefore appear to produce alkali more rapidly than the other two. According 

 to Zlatogorofi and Moghilewskaja (1928a), cultures of the rough variant form of 

 Past, pseudotuberculosis return to neutral more rapidly than those of the smooth 

 variant form. It is not yet certain whether the different end-reactions in glucose 

 broth can be used for differentiating between Past, pestis and Past, pseudotuberculosis; 

 according to d'Aunoy (1923) the results obtained depend to some extent on the 

 initial H-ion concentration of the medium. 



Past, aviseptica forms indole and gives a negative M.R. reaction ; Past, pestis 

 and Past, pseudotuberculosis form no indole, and give a positive M.R. reaction. 

 Past, pestis and Past, aviseptica have no action on litmus milk ; Past, pseudotuber- 

 culosis turns it slightly alkaline. All members reduce nitrates, form ammonia and 

 a small amount of HgS, and give a positive catalase test. According to our observa- 

 tions Past, pestis does not reduce methylene blue, whereas Past, aviseptica and Past, 

 pseudotuberculosis are able to do so. In confixmation of this Iwanowsky and Sassy- 



