120 S. A. KOSER AND 'W. W. SKINNER 



The resistance of spores to the conditions described in this 

 paper is of some interest when compared to that of Bad. coli 

 and Bad. typhosum. The spores of both B. mesentericus and 

 Clost. sporogenes were found to be quite resistant, for after one 

 month in carbonated water no reduction in numbers could be 

 detected. In one experiment the spores of B. mesentericus 

 survived in a citric acid beverage (pH 3.0) for one month with 

 Uttle, if any, diminution in numbers. 



It must be stated emphatically that the results obtained in 

 this investigation do not warrant the conclusion that water of a 

 low sanitary quality can be used.by the industry in the prepara- 

 tion of carbonated beverages, or that carbonation can be relied 

 upon to destroy evidence of pollution. In many instances, 

 particularly during the summer months, beverages are consumed 

 within a few hours after their preparation and it is obvious 

 that under these conditions pathogenic organisms, if originally 

 present in the water, may survive carbonation and reach the 

 consumer. 



SUMMARY 



Under the conditions of these experiments carbonation exerts 

 a distinctly harmful effect upon the members of the colon-ty- 

 phoid group and their period of viability in carbonated water is 

 much shorter than that in plain tap water. The destructive 

 effect of the CO2 is especially marked at room temperature, 

 19° to 23°C., and less so at 1°C. 



In a "non-acid" beverage, the organisms may persist for a 

 slightly longer period than m carbonated water. In beverages 

 containing 0.094 per cent or greater amounts of citric or lactic 

 acids, the death-rate is very rapid and is apparently due to the 

 effect of these acids, irrespective of the CO2. 



Bad. typhosum and Bad. paratyphosum B are more readily 

 destroyed by CO2 than is Bad. coli. 



The spore forms of a common aerobe, B. mesentericus, and 

 of a common anaerobe, Clost. sporogenes, were found to be quite 

 resistant to carbonation, surviving one month at room tempera- 

 ture with no apparent diminution in numbers. 



