GROUP CHARACTERISTICS OF PFEIFFERELLA 487 



red ; films of the rough forms show no interstitial substance, and resemble PJ. 

 mallei more closely. 



Culturally, the growth of PJ. lohitmori is more rapid and more profuse 

 than that of Pf. mallei. On 



glycerol agar it may give a smooth - .'_„ " />, 



mucoid or a corrugated and ^ '' " , ' 



wrinkled growth. Stanton and ,r' ' >' ' ' ^''"*' 



Fletcher (1927) have also described . ' ' ^ ^ '' ' "^-y 



an ultra-rugose variant, with an ^ ^ ^ "f/ * ^ * 



extremely corrugated surface, and >;- -7 ' ^ - / "* 



a consistency so tenacious that ^ ' ^ <, ' 1 '" '' / ' 



if the colony is touched with a ''' ^ , / ^ '/1' ' 



needle, it adheres to it and peels ^ ^ > ^ ~ ^ ^"T" '' ^ ' 



bodily ofi the medium. Growth ' v ^^ ^ ^^ 



in gelatin at 20° C. is abundant, ^ * *' * ^ ^ ^ 



and liquefaction of the stratiform "" ^ ,«.r ''''', <^ 



type is apparent in 4 or 5 days ; - , ^ ' ^ 



Pj. mallei, on the other hand, grows 



>^. - 



i 



very poorly in gelatin at 20° C. " ^ / 



and never liquefies the medium, 

 though according to Stanton and Fig. 91.— Pfeifferella mallei. 



Fletcher (1925), if it is incubated From an agar culture, 48 hours, 37° C. ( X 1000). 

 at 37° C, permanent liquefaction 



occurs in 4 to 6 weeks. In broth the growth of the smooth form of Pf. whitmori 

 resembles that of Pf. mallei ; the rough form, however, gives rise to a wrinkled 

 surface pellicle. On potato the smooth form gives a cafe-au-lait growth resem- 

 bling that of Pf. mallei, whereas 

 the rough form gives a much 

 lighter growth of creamy or 

 ,*'*' creamy-yellow colour. On Mac- 



. Conkey's agar, Pf. whitmori grows 



J -^ freely, forming red colonies, while 



A li Pf. mallei entirely fails to grow. 



|f ^JP ' Biochemically, Pf. whitmori is 



an active fermenter on first isola- 



^^,;^»jp tion, producing acid in glucose, 



f^T j^ mannitol, lactose, sucrose and dul- 



W citol, and decolorizing Andrade's 



indicator ; but after long sub- 



cultivation in the laboratory it 



■ Tf loses its power of fermenting any 



^^ ;f sugars except glucose. In litmus 



milk acid is produced in 3 days ; 



Fig. 92.—Pfeifferella whitmori. later the casein is precipitated. 



From an agar culture, 24 hours, 37° C. ( X 1000). and may be digested ; the litmus 



is partly decolorized. Pf. mallei, 

 on the other hand, though it may produce acid and clot, never peptonizes 

 the medium. Freshly isolated strains of Pf. whitmori liquefy blood serum and 

 coagulated egg, but this property is often lost during cultivation in the laboratory. 



