Bacterial Spore Gerniination — 

 Definitions and Methods of Study^ 



L. Leon Campbell, Jr. 



Department of Horticulture, State College of JVashington, 

 Pullman, Washington 



DURING the past ten years considerable progress has been made in 

 unraveling the complexities of bacterial spore germination (see the 

 excellent reviews of Knaysi, 1948; Wynne, 1952; Schmidt, 1955; 

 and Stedman, 1956 a, b). Unfortunately, there is as yet no general agree- 

 ment as to the meaning of germination as applied to bacterial spores. Thus, 

 this term has been used in a variety of ways depending on the aim of the 

 investigation, the methods employed, and the preference of the investigator. 

 The purpose of this paper is to briefly review the methods which have been 

 used in studying spore germination and to arrive at a definition of this 

 process which will be acceptable to most of the investigators in this field 

 of study. 



Criteria of Germination 



Visible turbidity. The appearance of visible turbidity following the inoc- 

 ulation of a medium with spores was employed by early investigators as 

 a criterion of germination. The objection to this method stems largely from 

 the fact that it is qualitative in nature. Thus, it is of value only in estab- 

 lishing that some spores have or have not germinated, provided that the 

 environmental conditions are suitable for the subsequent propagation of the 

 vegetative cells. That this criterion of germination can be misleading is 

 demonstrated by the findings of numerous investigators that spores can 

 germinate under conditions which do not permit the germinated form to 

 survive (see Wynne, 1952; Schmidt, 1955; and Stedman, 1955 a, b). An- 

 other drawback to this method of study is that the environmental conditions 

 imposed upon germinating spores may not affect germination but may ap- 

 preciably influence subsequent vegetative development (Evans and Curran, 

 1943; Wynne and Harrell, 1951; Fitz-James, 1956; Levinson and Hyatt, 

 1956; O'Brien and Campbell, 1956). Thus, this method of studying spore 

 germination is of limited value and has been largely abandoned for more 

 precise quantitative methods. 



^Washington Agricuhural Experiment Stations. Pullman. Part of the work reported in 

 this paper was supported by funds provided for biological and medical research by the 

 State of Washington Initiative No. 171. Project No. 1222. 



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