ISOLATION AND ACTIVITY TEST OF THERMOSTABLE AMYLASE ENZYME OF THERMOPHILIC BACTERIA AFTER MERAPI ERUPTION

Amylase is one of essential enzymes in industrial field. Industrial processes which mainly use high temperatures make it requires to do a thermostable enzyme isolation which is resistant to high temperatures. Hence, this research aims at isolating thermostable amylase enzyme of thermophilic bacteria and determining its specific activity. The isolation of thermophilic bacteria was carried out by the pour plate method, a selection of amylase-producing bacteria shown by the presence of a clear zone around the colony after added with iodine solution of 1% and incubated at the temperature of 70oC. The two largest clear zone-producing isolates were grown in medium NB and NB added with starch, then, the amylase enzyme was isolated and the activity test was done at temperatures of 60 oC, 70oC, and 80oC and at pH 5, 7, and 9. A unit of the enzyme activity was shown by the number of starch hydrolyzed into glucose. Results obtained show that the isolated enzyme activity grown in the medium with starch is higher than one not grown in the medium with starch. The best enzyme activity result was gained from Isolate D91 grown in the medium with starch at the temperature of 70oC and pH 7 with glucose level of 416,41 µg/mL and the enzyme activity of 115,67 unit/mL enzyme filtrate. Keywords : amylase, thermophilic bacteria, thermostable enzyme, glucose, enzyme activity