Hydrolysis of inulin: a kinetic study of the reaction catalyzed by an inulinase from Aspergillus ficuum.

A kinetic study of the hydrolysis of inulin was performed by using as catalyst a commercial inulinase from Aspergillus ficuum. The reaction was studied carrying out initial rate as well as time course measurements. Both inulinase and invertase activities of the enzyme were taken into account, and the corresponding kinetic parameters were determined in the temperature range 30-50 degrees C. The activation energies of the turnover constant for inulinase and invertase activities were found to be similar (56-57 kJ x mol(-1)). The ratio S/I of invertase to inulinase activity was 1.6 regardless of temperature. The thermal degradation of the enzyme was also investigated up to 70 degrees C, and an activation energy of 350-370 kJ x mol(-1) was evaluated.

Inhibiting action of chlorophenols on biodegradation of phenol and its correlation with structural properties of inhibitors.

An activated sludge conditioned to a low concentration of phenol was used for the biodegradation of phenol in the presence of Chlorophenols, measuring the inhibiting action of all the latter compounds and expressing it as p/(50.) As a structural property to be correlated with the measured values, the lipophilicity (log P) of the Chlorophenols was reevaluated with a new apparatus. Values of p/(50)p are better correlated with the number of chloro substituents in the inhibitor, provided a specific effect of substituents ortho to the phenolic function is considered. New results are compared with previous measurements effected on a different activated sludge.