Radiation effects on activity and storage stability of endo-polygalacturonase

Irradiation of the enzyme was carried out in powdered form, under aerobic conditions with a 60Co radiation source. Doses of 5 and 10 kGy gamma rays decreased the initial viable cell count of the preparation by 4 and 6 orders of magnitude, respectively. The survival level showed no significant differences when the preparation was irradiated with doses of 5, 10 and 20 kGy, while the dose of 40 kGy resulted in a practically germ-free preparation. The loss of endo-PG activity, found as a result of irradiation, was compensated by better storage stability of the irradiated samples. The use of the doses of 5, 10, 20 and 40 kGy resulted in a 6.4, 24, 30 and 40% decrease in the activity of the enzyme. On the other hand, the preparations treated with 5, 10, 20 and 40 kGy proved to be stable, and showed only a slight loss in their respective activity, compared to the 18% activity loss of the control. (author)