YANDRI, T. SUHARTATI, S. D. YUWONO, H.I. QUDUS, E.R. TIARSAAND S. HADI
Abstract
This research aims to increase the stability of -amylase obtained from B. subtilis ITBCCB148 by immobilization process using Bentonite matrix. The research phases performed were: production, isolation, purification, immobilization and characterization of purified and immobilized enzymes. The results showed that the purified -amylase had optimum temperature of 60oC, KM = 6.18 mg mL-1 substrate, and Vmax. =909.09 mol mL-1 min.-1. The immobilized -amylase gave optimum temperature 75oC, KM = 12.19 mg mL- 1 substrate, and Vmax. = 88.50 mol mL-1 min.-1. The residual activities of the purified and immobilized enzymes on thermal stability test at 60°C for 100 minutes were 12 and 43%, respectively. The repetition used of the immobilized enzyme was 5 times. The thermodynamic data of the immobilized enzyme was t½ = 88.85 min., ki = 0.0078 min.-1, and Gi 106.65 kJ mol-1. Based on the decrease of ki and the increase of Gi and half-life (t½) the immobilization process with Bentonite has successfully increased the stability of -amylase from B. subtilis ITBCCB148.