engleski

Fully integrated production of L-malic acid

L-malic acid is a dicarboxylic acid and an intermediate of cell metabolism. It belongs to a group of „bulk“ chemicals with estimated consumption of 40, 000 tons per year. It is widely distributed in nature where it occurs in very low concentrations. It can be prepared by extraction from natural fruit juices or by bioconversion of fumaric acid with an enzyme fumarase. L-malic acid is used in pharmaceutical, food, animal food and cosmetic industry as preservative (substitute for citric acid). It is effective in treating liver diseases particularly hyperammonemia, and it is used as one of the components in infusion solutions with amino acids. In this work a completely integrated production of L-malic acid from fumaric acid with permeabilized cells of baker's yeast was developed. Bakers' yeast was used because it is an inexpensive and accessible source of the enzyme fumarase which is a biocatalyst in this chemical reaction. Process was composed of (i) continuous bioconversion with recirculation of biomass, (ii) acidification of permeate containing mixture of fumaric and L-malic acids, (iii) sedimentation and (iv) electrodialysis. Crystals collected in the sedimentation were (v) neutralized and transferred in the bioreactor as well as depleted diluate from electrodialysis. Using this process approach overall conversion and volumetric productivity were significantly improved in the comparison with continuous bioconversion without in situ separation of L-malic acid.

fumaric acid; L-malic acid; permeabilized baker's yeast; in-situ product recovery

Ovaj se tekst temelji na radu koji je financirala Nacionalna zaklada za znanost, visoko školstvo i tehnologijski razvoj Republike Hrvatske.