Pengaruh suhu terhadap aktivitas enzim pereduksi Cr(VI) Bacillus cereus isolat AB56ACr10 dari tanah serpentin

Abstract

Optimation of temperature to aim the optimal temperature in bacterial enzyme activity. Bacteria basically used for bioremediation process of Cr (VI) hexavalent chromium because many of it is able to reduced harmless Cr(VI) to Cr(III). Studied the effect of temperature was carried out by measured the growth curve for 24 hours in a UV-VIS spectrophotometer by turbidimetry method and determined the Cell fraction. Enzyme activity is measured by calculating the amount of Cr before reduction is reduced by the amount of Cr after reduction in incubation for 1 hour and is called the enzyme unit (U.mgl).  The different of temperatures are made by multiple range of 5˚C, that is 25˚C, 30˚C, 35˚C, 40˚C, 45˚C, 50˚C and 55˚C. The determination of enzyme-specific activity was done by calculating the value of the enzyme unit divided by the value of protein concentration. The growth curve of AB56ACr10 bacterial isolate was showed the results of the isolate is be able to survived in medium with Cr concentration of 50 to 150 mg.L-1. The highest activity of enzyme was found in free cell media fraction to be 0,0686 Unit.mg-1 and its means the bacteria enzyme was secreted by extracellularly. The determined of the effect of temperature showed that bacteria AB56ACr10 isolate was to be able to live optimally at temperatures between 35˚C based on the graph of optimum temperature rise in enzyme activity.