Abstract
Owing to the introduction of the new sterilization theory of bacteria by Ball and Olson etc. in recent years, the method of heat-resistance of bacteria by the previously employed qualitative method now has come to be re-examined.
The author undertook several experimental studies on the above thesis by the quantitative method especially by the calculation of thermal death time, and obtained the following results. 1) The living cell of Escherichia coli reduced logarithmically according to the law of monomolecular reaction equation, and the heating with the pre-heating period accelerated the reduction of living cells.
2)No difference in the heat-resistance was recognized between the strain cultured in broth and that in milk when the same number of cells were used.
3)Sucrose and gelatin strengthened the heat-resistance of Escherichia coli, however, no changes in the thermal death time of this strain was recognized in case when living or dead cells of other bacteria were present in the number of cells used in this study.
4)Comparison was made between Escherichia coli after 145 successive daily transfers at 25°C and those at 37°C, and, no difference was recognized.
According to the above experiment undertaken with a new standpoint of view, new findings were added to the heat-resistance of Eschrichia coli.
