43, Serratia 



Species of the genus Serratia generally produce a characteristic 

 red pigment. Colorless variants are common and these are difficult 

 to identify with certainty. The genus has been separated into 

 several species but the differences between these species is not 

 great and bacteriologists in general tend to label any red pig- 

 mented gram negative rod with the proper physiological charac- 

 teristics as Serratia marcescens. 



Eight strains labeled S. marcescens were studied. Three of 

 these came from Dr. MacDonald Fulton and were isolated from 

 clinical material. The other five strains were of diverse origin 

 and came from the National Collection of Industrial Bacteria in 

 England. All these strains were pigmented and physiologically 

 typical of the genus. From the American Type Culture Collection 

 were obtained five cultures which appeared typical of the genus: 

 Serratia kiliensis 992, Serratia plijmiithica 183, and Serratia indica 

 4002 were well flagellated; S. indica 4003 and Serratia urinae 11111 

 were nonflagellated. From W. B. Haynes of NRRL were obtained 

 two cultures: Serratia anolium B-1700 was well flagellated and 

 physiologically typical except for lack of pigmentation; S. indica 

 B-341 was nonflagellated. 



Flagellar Characteristics 



Three of the fifteen cultures studied were nonflagellated which 

 would indicate that nonflagellated variants of Serratia are fairly 

 common. With one exception the flagellated strains showed more 

 or less identical flagellation with coiled peritrichous flagella. From 

 an occasional uncoiled flagellum a mean wavelength of 4.5 microns 

 was obtained. In S. marcescens, NCIB 2302, was seen a flagellum 

 which was curly in its proximal part with a coil at the end. This 

 organism is illustrated in Fig. 45a. The curly waves measured 1.1 

 microns. The culture of S. indica, NCIB 4002, showed two types 

 of individuals, one with the typical coiled flagella and one with 

 normal peritrichous flagella. On plating a culture was obtained 

 with organisms having normal flagella only. This culture was 

 physiologically typical of the genus. The wavelength of the 

 normal flagella averaged 2.3 microns. 



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