Naslov
Comparison of the continuous L-malic acid production by isolated enzyme and permeabilized yeast cells

Autori
Vrsalović Presečki, Ana ; Vasić-Rački, Đurđa

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Enviromental Biocatalysis, From remeditaion with enzymes to novel green processes / Lopez-Cortes A, Alcalde M, Ferrer M, Rojas-Cervantes ML, Plou FJ, Ballesteros - Cordoba, 2006, P-4

Skup
International Symposium on Enviromental Biocatalysis

Mjesto i datum
Córdoba, Španjolska, 23.04.2006. - 26.04.2006

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
l-malic acid; yeast; fumarase

Sažetak
L-Malic acid is second most widely used acidulant in the food industry and holds about 10% of this market [1]. Commercially it is produced by chemical synthesis via hydratation of fumaric acid that results to the racemic mixture or by the environmentally friendly enzymatic process, which yields the L-isomer of malic acid. In this process fumaric acid is transformed into L-malic acid by addition of water to the double bond. The process is a typical equilibrium reaction and catalyzed by enzyme fumarase. Fumarase as a biocatalyst can be used as a whole cell [2] or as an isolated enzyme [3]. The permeabilization [4] of the cells removes the barrier for the free diffusion of the substrate/product across the cell membrane, and also empties the cell of most of the small molecular weight cofactors, thus minimizing the unwanted side reactions. This is very important for the L-malic production by whole cells, because both side reactions in which malic and fumaric acid are involved in the Krebs cycle producing oxalic either succinic acid, require the coenzymes. In this work continuous productions of L -malic acid were performed. The isolated fumarase from pig heart, the permeabilized cells of baker's yeast and the permeabilized cells of Saccharomyces bayanus (UVAFERM BC) were used as the biocatalysts. For each biocatalyst kinetic parameters were determined by measuring the reaction kinetic and were confirmed in a batch experiments. It was found out that this is equilibrium reaction which is inhibited by product. Conversion of around 80 % was achieved in a batch mode. No by product was detected during the L -malic production by permeabilized yeast cell. During the continuous L -malic production by isolated fumarase from pig heart no enzyme deactivation was occurred through the period of two days and at a residence time of 4 h conversion of cca. 80 % was accomplished. By using the permeabilized yeast cells for the L -malic production in a continuous mode, enzyme deactivation was noticed. In a permeabilized baker's yeast cell enzyme deactivation started after 10 hours while in the permeabilized cells of Saccharomyces bayanus (UVAFERM BC), it started after 27 hours. In a both cases deactivation lasted for approximately 20 hours. Afther that period enzyme activity was constant for six days. The conversion of cca. 50 % was achieved with the residual enzyme activity.

Izvorni jezik
Engleski

Znanstvena područja
Biotehnologija

POVEZANOST RADA