LABOEATORY MANUAL 



OF 



MICROBIOLOGY 



PART I 

 CULTURE MEDIA 



PRINCIPLES OF MICROBIAL NUTRITION AND COMPOSITION OF 

 CULTURE MEDIA FOR MICROORGANISMS 



Since the work of Pasteur in the 'fifties and 'sixties of last 

 century on pathogenic and non-pathogenic microbes and since 

 1881, when the first soUd culture medium was suggested by R. 

 Koch for the isolation and cultivation of bacteria, numerous 

 solid, liquid, and semi-solid media have been recommended. 

 The composition of these media depends entirely upon the food 

 requirements of the specific organism that is to be isolated or 

 cultivated. Since microorganisms vary in reference to the 

 nature of the nutrients which they require for their growth and 

 reproduction, the composition of the media which are to be used 

 for the isolation and cultivation of different organisms will 

 therefore vary. Some media are adapted to the growth of a 

 maximum number of different organisms, not favoring any 

 particular kind in preference to others. These are the media 

 which are used for counting the numbers of microorganisms in the 

 soil. Other media are highly selective in nature, allowing the 

 development of only one very limited group of organisms. 

 These selective or enrichment media are used largely for the 

 isolation of certain specific organisms, utilizing their specific 

 physiology. 



In general, a medium must contain a source of energy, a source 

 of carbon, a source of nitrogen, and various mineral elements 



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