EFFECT OF CARBON DIOXIDE ON BACTERIA 



zi7 



after 48 hours at Z3 pounds pressure and 

 Z4°C. At i°C. the same organism was 

 found to be alive in 10 cc. after 10 days. 

 The spores of B. mesentericus and B. subtilis 

 were found to persist in carbonated water 

 in their original numbers after one month. 



Prucha, Brannon and Ambrose (19ZZ) 

 investigated the effect of carbon dioxide on 

 bacteria in milk and ice cream. It was 

 found that there was no destruction of 

 bacteria when the milk containing Bact. 

 coli and Bact. typbosum was subjected to 

 from 10 to 30 pounds extra pressure, under 

 carbon dioxide. Under zo pounds pres- 

 sure there was an increase from 47,000,000 

 to 153,000,000 per cc. of milk. They 

 also showed that there was no decrease of 

 bacteria in ice cream, due to carbon 

 dioxide. Even after six months in storage 

 the carbonated ice cream had as many 

 bacteria per cc. as the plain ice cream. 



Erickson and Albert (19ZZ) reported 

 their experiments with various methods 

 of producing reduced oxygen-tension for 

 the gonococcus, and came to the conclu- 

 sion that the beneficial effects are entirely 

 due to an increased amount of moisture. 

 Fitch (19ZZ), when using Huddleson's 

 method for enriching the atmosphere with 

 C0 2 , found difficulty from liberated 

 chlorine. He grew duplicate sets of 

 cultures, one in carbon dioxide and the 

 other set in hydrogen, and evidently found 

 no difference in favor of carbon dioxide. 

 He concluded that Huddleson's claim for 

 a specific action of C0 2 is not proven, and 

 that this gas probably does nothing more 

 than to dilute the oxygen. 



Lorentz (19x3) observed that the diph- 

 theria organism, when grown under C0 2 , 

 became longer and more slender. The 

 granules were increased in size and 

 thickened. The number of positive 

 diphtheria cases was found to be 30 per 

 cent higher when the field cultures 



were grown under added C0 2 , instead of 

 ordinary air. 



Rockwell (19Z3) reported additional 

 work on gaseous environmental studies, 

 on ten different organisms. The list 

 comprises B. subtilis, M. tuberculosis (sap- 

 rophytic strain), Prot. vulgaris, Staph, 

 aureus, CI. welchii, an anaerobe from hide, 

 pneumococcus pus, streptococcus pus, 

 and the meningococcus. Throughout the 

 experiment, conducted under aerobic con- 

 ditions, with nitrogen gas, nitrogen and 

 carbon dioxide, and under conditions of 

 anaerobiosis with pyrogallol and partial 

 tension, growth was obtained under 

 nitrogen and carbon dioxide with all of 

 the various organisms used. Further 

 division of partial-tension organisms was 

 made by him according to their tolerance 

 for oxygen. 



Donald, Jones and MacLeon (19x4) 

 reported experimental work on artificially 

 inoculated beverages. Bact. coli and Bact. 

 typbosum were used as the test organisms. 

 A study of the curves shows a very 

 interesting relationship between high 

 pressure and storage. The decline in 

 bacterial numbers seems directly propor- 

 tional to both. With a pressure of 95 

 pounds the beverages were apparently 

 sterile after 5 days at room temperature. 

 The curve shows that with 15 pounds 

 bottling pressure there was a decline, but 

 after 6 weeks the curve is still above the 

 zero line. At 37.5°C. the bactericidal 

 effect of C0 2 caused sterilization in one 

 week. In general, it is apparent that 

 after 34 days at zo°C, and at 37.5^., the 

 beverages showed bacteria present under all 

 conditions and pressures of the experiment. 

 The pressures were 70 and 45 pounds re- 

 spectively. A second series of beverages 

 was prepared and inoculated very lightly. 

 Bact. typbosum did not show any rise in 

 numbers under high pressure (70 pounds). 





