Effect of moderated pressure on the activity and termostability of three microbial enzymes : catalase, β-galactosidase and alcohol dehydrogenase

Abstract

The effect of moderate gas pressure on the activity and termostability of three microbial enzymes: catalase from Aspergillus niger, β-galactosidase from Escherichia coli and alcohol dehydrogenase from Saccharomyces cerevisiae was study. Batch assays were carried out in a hyperbaric bioreactor at increased pressure up to 9 bar using the activity at atmospheric pressure as pattern. Interactions between the effects of pressure and temperature on the activity of β-galactosidase and alcohol dehydrogenase were also studied. Experiments with air, N2 and CO2 were performed with catalase. It was observed that the increase of air pressure didn’t affect the activity of catalase. When the pressuring gas was CO2 at 3 bar or higher, a large loss of activity was observed. However, an increase of catalase activity between 3 bar to 6 bar of pure N2 was found. Among all the three enzymes, β-galactosidase was the most sensitive to pressure rise from 1 bar to 9 bar, since its activity was reduced by long periods of pressure exposure and it was the only enzyme that showed termostability reduction by pressure increase. Studies with β-galactosidase and alcohol dehydrogenase didn’t show any interaction between air pressure effects and temperature in the reaction velocity.