L-Fenilalanina amonio liasa (PAL) de Rhodosporidium toruloides NBRC 0559. Producción, caracterización e inmovilización por encapsulación en membranas celulósicas.

Abstract

For the design of a biocatalyst capable of reducing the L-Phenylalanine content to produce formulas for Phenylketonuria patients, PAL was obtained from Rhodosporidium toruloides NBRC 0559. PAL was produced, recovered from the culture medium, purified, immobilized by encapsulation in semipermeable membranes and used in: a) column reactor with recirculation and b) stirring tank reactor. The bioconversion was spectrophotometrically monitored (OD₂₉₀) by t-cinnamic acid production. PAL demonstrated to have high activity and affinity for L-Phenylalanine, with an optimal temperature of ~ 43°C. In relation to PAL utilization, the stirring tank reactor was the most appropriate system for bioconversion because of agitation effect in the diffusion of substrate and products to the membrane. In addition, membrane wall thickness was a key factor in bioconversion rate, reaching the complete removal of 0,1 mM L-Phenylalanine in 6 h. These results indicate that purified PAL immobilized by encapsulation in semipermeable membranes can be applied for the reduction of L-Phenylalanine content in diluted solutions. It could be potentially used with protein hydrolysates as a model substrate in the development of low L-Phenylalanine foodstuff.