José Aróstegui Moreno

Oxygen Kinetic and Metabolic Parameters for the Yeast Trigonopsis variabilis

The metabolic and kinetic parameters of oxygen consumption by the yeast Trigonopsis variabilis under conditions of induced and non-induced D-amino acid oxidase are described for the first time. These parameters can be calculated from the results of a single batch fermentation running at an oxygen-limiting condition. The values obtained for the parameters may be used as a basis for the calculation of the aeration and stirring requirements and optimal oxygen conditions for the growth of T. variabilis in batch, fed-batch or continuous fermentations.

Inhibition of D-amino Acid Oxidase by α-Keto-γ-Methiolbutyric Acid, product of the reaction with D-Methionine

SummaryThe inhibition of D-Amino Acid Oxidase by α-Keto Acid, product of the reaction with D-Amino Acid is described for the first time. Inhibition of the enzyme by α-Keto-γ-Methiolbutyric Acid (4-methylthio-2-oxobutanoic acid), product of the reaction with D-Methionine, was studied. From the results obtained it is deduced that inhibition is competitive with the substrate, the value of the inhibition constant being 1.85 10−3 M.

Production of Bio-Esters by Immobilized Lipases

Publisher Summary This chapter describes the production of bio-esters by immobilized lipases. Two different systems for production are described: in organic solvent and membrane bioreactor. From experiments, it is suggested that the ester yield highly depends on the water produced during the reaction. Its removal needs to be solved. In the two systems, studied different methods were found to be ideal. In the esterification in organic solvent water, content was maintained at a constant level by circulating the mixture through a molecular sieve. After the saturation, water can be desorbed from the zeolite. Using two parallel columns, the process can be continuous. In the enzyme membrane reactor, on the other hand, water produced passed through the membrane spontaneously because of the hydrophilic character of the aqueous ethanol solution circulated in the other side of the membrane.