64 Microbes and You 



obtaining oxygen. All living cells must have oxygen, but the origin 

 of this oxygen varies with the type of respiration employed by the 

 cell. Some organisms have adjusted their lives in such a way 

 that they can respire either aerobically or anaerobically. Such 

 bacteria are termed facultative. Some persons go so far as to 

 subdivide the facultative microbes into the facultative aerobes, 

 which grow either aerobically or anaerobically but prefer aerobic 

 respiration, and facultative anaerobes which prefer anaerobic to 

 aerobic respiration. 



When bacterial cells are subjected to chemical analysis, a 

 number of elements can be detected. Sometimes an element may 

 be fortuitous, just entering the cell wall for the ride at the same 

 time that essential elements are being absorbed. Still other 

 elements, even in minute traces, are vital to survival and multiplica- 

 tion of the organism. The five pillar elements— carbon, hydrogen, 

 oxygen, phosphorous, and nitrogen— must be supplied in an avail- 

 able form to all living cells. In addition to these five, however, 

 trace amounts of other elements must be included in good 

 bacteriological media. The names of the essential elements for 

 cellular growth are conveniently remembered in the expression: 

 C HOPKINS CAFE MG, an abbreviation for Carbon (C), Hydro- 

 cren (H), Oxvgen (O), Phosphorous (P), Potassium (K), Iodine 

 (I), Nitrogen (N), Sulfur (S), Calcium (CA), Iron (FE), and 

 Magnesium (MG). Energy is required to blend these elements 

 into useful combination for cell substance, and this energy ma\' be 

 derived in one of two general ways. Bv directly absorbing energy 

 foods, such as available sugars, and breaking down these sub- 

 stances through the activity of enzymes, energy can be released 

 for cell use. Or the organism may liberate energy through oxida- 

 tion, a process tied up with respiration in all living cells. 



Fulfilling the prerequisite of providing readih' available food 

 in a microbiological medium is a great deal more involved than the 

 simple statement might lead you to believe, and unless the provider 

 understands these ramifications of nutrition, healthy, actively grow- 

 ing; crops cf microoro;anisms misiht not materialize. 



