Effect of Liquid Air Temperature on Bacteria

Abstract

1. Twenty-four-hour cultures of B. typhi, B. coli, Staph. albus, B. subtilis on agar slants and in beef tea were immersed in liquid air. In addition, strips of sterile filter paper that had been impregnated with the above cultures were also placed in liquid air. At the end of one week, the cultures and the filter paper were removed from the liquid air. They were then transferred to new media. After incubation all tubes showed growth.2. A suspension of a 24-hour culture of B. typhi was made in physiologic saline solution and standardized to one million bacteria per cc. by cytometric count. Five cc. of the suspension were placed in sterile test tubes 150×13 mm. The tubes were sealed in a blast-lamp and then placed in liquid air. Daily, for a period of 10 days, a tube was removed and melted and the number of survivors determined by the McCrady most-probable-number method, using 3 tubes of beef tea for each dilution. There was a drop from one million to 10,000 bacteria per cc. at the end of one day. The succe...