Modelling of Continuous L-Malic Acid Production by Porcine Heart Fumarase and Fumarase in Yeast Cells

A. Vrsalović Presečki, B. Zelić and Đ. Vasić-Rački

Abstract
Continuous production of L-malic acid will be presented in this paper.The fumarase isolated from porcine heart, fumarase in the permeabilized non-growing cells of baker’s yeast and Saccharomyces bayanus (UVAFERM BC) were used as biocatalysts.In the production of L-malic acid with fumarase isolated from porcine hearts, there was no enzyme deactivation for a period of two days.At the average residence time of 4 hours, the conversion of about 80 % was achieved.Inactivation of the enzyme was observed using permeabilized cells.Thi s inactivation is described as a reversible process.C onversion of about 50 % was achieved with the remaining enzyme activity.A mathematical model that describes the production of L-malic acid, which contains the enzyme inactivation rate, was developed. Based on simulations, the used biocatalysts were compared.The results show that in the continuous production of L-malic acid, one milligram of purified enzyme corresponds to 68 g (wet weight) cells of Saccharomyces bayanus or 120 g (wet weight) cells of baker’s yeast.

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Keywords
L-malic acid, fumarase, baker’s yeast, permeabilization, modeling