8 Variations in Bacteria Caused by Change of Medium 



CARBOHYDRATES 



Preliminary. When the bacterial residue, after protein extraction, 

 is treated with concentrated sulphuric acid at ordinary temperature, 

 it becomes turbid, dark-brown, finally turning to clear deep-red. If this 

 reaction is hastened by gentle heat to 40 to 45 C, for one hour, 

 diluted with 5. per cent KOH, then neutralized, the solution gives 

 reaction for reducing substances. 



If the same process be carried on at a lower temperature, the activity 

 of the acid is decreased, as is evidenced by the color, but the amount 

 of reducing substance seems to increase. Also, whether normal bac- 

 teria or bacterial residue be employed in this process, it happens that 

 when the reaction has proceeded to the production of a deep-red colora- 

 tion without turbidity, if cold distilled water be slowly added, a heavy 

 gelatinous precipitate settles out of the solution. After neutralizing, 

 this solution may be filtered and the precipitate recovered. The 

 amount of reducing substances under these conditions is reported 

 as carbohydrate in terms of glucose. 



The precipitate here obtained, after being washed by decantation, 

 was found to yield a brown color with iodine, and not to be colored 

 blue by iodine-zinc chloride. It is soluble in ammoniacal cupric oxide 

 (Schweitzer's reagent); reprecipitated by acids, is soluble in zinc 

 chloride, from which it can be recovered on dilution with water. 

 On hydrolysis with sulphuric acid reducing substances are formed. 



These characteristics are essentially those of cellulose, and we 

 regard the material so obtained as similar to, if not identical to, that 

 substance. The presence of cellulose in bacterial bodies has been a 

 much discussed question as throwing possible light on the vegetable 

 nature of bacteria. The findings of Vaughan (Protein Split Prod. 

 pp. 66, 67) seem to indicate that cellulose is absent in bacteria, but we 

 are inclined to consider our results as confirming those of Dreyfuss, 

 Hammerschlag, and others (Zeitschrift fur physiologische Chemie, 

 1887, ix, 181). 



The precipitate here obtained and quantitatively estimated by 

 collecting it on a weighed filter and weighing was, therefore, reported 

 as cellulose-like substance. 



Determinations. After experimental examination, the above methods 

 were adopted uniformly and without modification. 



The material for these determinations was a nine days' growth of 

 B. Coli, collected at the stage of maximum development. 



