Effect of Gamma-ray upon Food Microorganisms

Part VII. Studies on the Effect of Gamma-ray upon Food Bacteria under Some Conditions

Abstract

In case of using a nutrient agar medium, all three conditions resulted in protective upon three strains same as in case of E. coli. However, in case of using a pure agar, the conditions which show higher survivals of E. coli in a nutrient medium were divided into three conditions. The first showed the protective effect same as in case of nutrient medium. The second showed no influence, and the last showed, on the con-trary, lower survivals of the strain than those from the control.
The results of this experiment are summarized as follows:
(1) Three conditions which were the addition of each of succinic acid, thio-urea and amino-acid in a nutrient agar medium showed the same protective effect on the survivals of the above three strains as in case of E. coli.
(2) In case of using a pure agar medium for irradiation, the effects of these conditions differed from each other. Higher survivals, similar survivals and lower survivals of the strains were observed.
(3) The addition of succinic acid in a pure agar resulted in higher survivals of the straines.
(4) The addition of thio-urea in a pure agar caused lower survivals.
(5) The addition of amino-acid in a pure agar brought no influence on the survivals.
(6) In case of E. coli in a pure agar containing thio-urea, the higher concentration resulted in higher survivals than the control, however, the lower concentration than a certain limit gave lower survivals than those from the control.