1) Using a thermophilic bacterium isolated from compost, new and reliable methods for determining the exact viable count of the organism were developed. By using these methods, systematic studies were made on the viability and growth of the bacterial cells at different temperatures as well as their responses to the change of temperature.
2) It was observed that the organism grew at temperatures between 35°C and 72°C (optimum at 65°C), and died instantly at temperatures above 75°C, and gradually at those below 35°C. In the lower lethal range (10°C- 30°C) bacterial viability was found to be increased by the application of an optimal temperature (65°C) "shock", lasting only for a short period (1.0-1.5 minutes).
3) The importance of these phenomena for comprehension of the mechanism of thermophilic nature of temperature-tolerant organisms was discussed.