80 BACTERIAL METABOLISM 



Sugar-free broth. Sugar broth. 



Ten-day observations. Reaction. 1 NH.s Reaction. 1 NH.s 



B. alcaligenes ...... -1.25 +3.50 1.15 +5.30 



B. dysenterise (Shiga) ... -0.30 +4.20 +2.80 0.00 



B. dysenterise (Flexner) ... -0.25 +3.10 +2.45 0.00 



B. typhosus ...... -0.45 +5.40 +3.30 +0.60 



B. diphtherias ...... -0.50 +3.10 +2.80 ' +1.05 



B. of hemorrhagic septicemia . -0.20 +4.70 +2.25 +0.35 



B. paratyphosus alpha and beta -0.10 +7.50 +3.90 +1.20 



B. icteroides ...... -0.10 +4.20 +3.80 +2.10 



B. of hog cholera avirulent . . -1.25 +16.45 +3.70 +1.05 



B. of hog cholera virulent . . -0.75 +8.40 +2.65 +1.05 



B. of fowl cholera .... -1.00 +13.65 +3.35 +0.70 



B. of Morgan ...... -1.33 +29.50 +3.90 +29. 66 2 



B. coli ........ -1.00 +24.40 +4.90 +0.35 



B. cloaca? ....... -1.20 +39.20 -0.30 +36. 40 2 



B. proteus ....... . -1.98 +58.40 +3.55 +1.40 



Sp. cholerse ...... -1.45 +62.80 +2.00 +0.70 



Sp. of Finkler and Prior . . . - 1 . 00 +27 . 30 +1.50 +0 . 70 



Sp. of Metchnikoff . . . . -4.30 +41.30 +2.70 +0.70 



B. pyocyaneus ..... -1.85 +30.30 -1.33 +41.50 



Streptococcus ...... +0.70 +1.40 +5.00 +0.70 



Staphylococcus ..... -0.75 +38.70 +3.75 +0.70 



Mic. tetragenus ..... +1.00 +2.10 +3.00 +0.70 



Mic. melitensis ..... -0.10 +6.30 +3.50 +0.70 



SIGNIFICANCE OF BACTERIAL METABOLISM, WITH SPECIAL 

 REFERENCE TO THE SPARING ACTION OF UTILIZABLE 

 CARBOHYDRATE FOR PROTEIN. 



Considerable emphasis has been placed upon the sparing action 

 of utilizable carbohydrate for protein in the preceding pages. It now 

 remains to summarize the salient features of this aspect of bacteriology 

 and to indicate briefly by means of a few illustrations precisely how 

 a comprehension of the principles underlying bacterial metabolism 

 may be made use of in controlling, or at least influencing the action 

 of these microorganisms upon their environment. The examples 

 selected are chosen rather with a view of indicating the extreme range 

 of the subject than for completeness along any limited line of inves- 

 tigation. 



1. The Composition of Bacteria. Experiments quoted previously 

 (page 60) show very clearly that the percentage of composition of the 

 bacterial cell varies according to the medium in which it is grown. 

 Particularly striking is the difference in nitrogen content when the 

 same bacterium is grown in media of the same nitrogenous composition 

 and reaction with and without the addition of utilizable carbohydrate. 



1 Neutral red, = alkaline reaction, + = acid reaction. 



2 These organisms can utilize 1 per cent, of dextrose without forming enough acid 

 to inhibit their growth; after the dextrose is used up they attack the protein for their 

 fuel needs hence the ammonia production in a medium containing utilizable sugar. 

 During the initial period when sugar is present, the ammonia value is very little, and 

 the reaction is acid. 



