DECOMPOSITION OF SURFACTANTS BY BACTERIA 79 • 100 0 80- • 60- . • 40- 30'øC 4bøC 6'0øC 8'0oc 160øC 1:•0øC Temperature Figure 12. Effect of heat on enzyme activity THE ENZYME ACTIVITY AT VARIOUS CONDITIONS Reaction time The relation between reaction time and enzyme activity at 37øC during 24 hr, proceeded quite regularly for the first 3 hr after 4 hr it started to deviate gradually from the straight line (Figure 9). lOO 80- 60- • 40- 7ooc 20 40 60 Min. Heating time ! 3weeks Figure 13. Effect of heat on enzyme activity

80 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 100- 1'2 2'4 Hrs. Irradiation Time Figure 14. Effect of U.V. irradiation on enzyme activity Temperature Although the optimum temperature for the enzyme activity was found to be about 50øC (Figure 10), we used 37øC for these tests because it allowed the enzyme reaction to take place and also is routinely used. pH The optimum pH for enzyme activity was found to be between 7.0 and 8.0 by using three buffer solutions (Figure 11). The activity of the enzyme decreased rapidly as the pH declined below 5.0. 00J 80- 60- 40- 20- lb 2'0 30 Concentration of Alcohol (%) Figure 15. Effect of alcohol on enzyme activity

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