THE REACTION OF CULTURE MEDIA IN RELATION TO THE 

 MORPHOLOGY OF THE CHOLERA ORGANISM.' 



By Y. K. Ohno. 

 {From the Biological Laboratory, Bureau of Science, Manila, P. I.) 



During the previous year, on making a microscopical examination of a 

 direct smear of the faeces from a case of cholera I was able to observe 

 organisms which appeared to be cholera vibrios and was able to cultivate 

 the cholera vibrio in plating a loop of the stool in 1 per cent alkaline agar. 

 However, when a loop of the stool was jfirst added to cholera peptone solu- 

 tion according to the enriching method of Schottelius-Koch,- I failed to 

 isolate the cholera organism. Investigation of the peptone solution 

 revealed the fact that its reaction upon titration was 1.75 per cent acid 

 to phenolphthalein. The cholera vibrio, isolated from the same stool 

 by plate culture, failed to grow in this peptone solution. 



This experience led me to study the behavior of this organism in 

 culture media of different degrees of acidity and alkalinity. I began 

 these experiments with a few cultures of the cholera vibrio Avhich I had 

 at that time, and found that the vitality of the different strains varied 

 and that the same strain changed its morpholog}'' in solutions of peptone 

 of different reaction. The degree of acidity or alkalinity of the peptone 

 in which the morphology of the vibrio is most likely to appear typical 

 may be different for different strains of the cholera organism. In general, 

 in acid media, the vibrio tends to lose its curve and to appear as a rod, 

 while in strongly alkaline media it becomes short and appears oval or 

 even spherical. 



Having carried on experiments of this nature with the strains of the 

 cholera vibrio on hand in the laboratory, I decided to use media of 

 different reaction in the bacteriological examination of cholera stools and 

 of faeces from suspected cholera cases sent to the laboratory for diagnosis 

 during the recent epidemic. In this M^ay I hoped to identify the cholera 



^ Read at the Sixth Annual Meeting of the Philippine Islands Medical Associa- 

 tion, February 12, 1909, Manila, P. I. 



'Deutsche med. Wochnsch. (1885). 14, 213. 



341 



