Efficient Expression of Recombinant L-phenylalanine Ammonia-lyase From Rhodosporidium toruloides using Escherichia coli

Abstract

We explored simple and cost effective method to obtain recombinant PAL of Rhodosporidium toruloides using E. coli expression system. E. coli strain BL21 (DE3) was transformed by pET28 plasmid containing L-phenylalanine ammonia-lyase (PAL) gene from Rhodosporidium toruloides and cultured in different conditions. To assess the physiological activity of microbial cells, we studied the growth kinetics in a series of batch fermentation and changes in its activity after the induction. The kinetics of the process of cultivation of recombinant E. coli strain was studied by the Ludeking-Paire model. A growth and induction regimen was established for use in bioreactor which results in the accumulation of 1,9 g l^-1 of recombinant PAL. The point of maximum activity of the PAL produced was determined at 38.0-38.5 h after induction. The optimum concentration of inducer (IPTG) was 2 mM, we recommend to add the inducer at OD540=1.3. This simple and cost effective production process could be recruited for large scale production of PAL.