Selection of Yeasts for the Production of L-phenyl-acetil-carbinol Bybiotransformation in Shake Flasks.

L-phenylacetylcarbinol (L-PAC) is an intermediate in the production of L-ephedrine and pseudoephedrine, which are pharmaceutical compounds used as decongestants and anti-asthmatics. L-PAC can be produced by chemical synthesis from cyanohydrins but the biotransformation route for its production from benzaldehyde is preferred industrially. Several microorganisms in nature are capable of producing L-PAC, from bacteria to fungi. There are a large number of yeasts that carry out this biotransformation route, which is why they are the most studied organisms in the production of L-PAC. This work aims to select the best yeast producer among 22 potential strains belonging to the genera Saccharomyces, Kluyveromyces, Pichia and Candida and to increase L-PAC production by improving process conditions in shake flasks. The production medium contained initially (in grams per liter): glucose 25, peptone 20, yeast extract 10; MgSO4.7H2O 1; CaCl2.2H2O 0.05, Na2HPO4, citric acid 10.7 and benzaldehyde 1. L-PAC production was performed at 200 rpm, at 30°C for 1 day. The substrate, the product and by-products were analysed in HPLC column (Hipersil ODS C18). Among all the species/strains studied five were selected as good producers, one specie of Kluyveromyces and four species of Saccharomyces. The results indicated that the best time to add benzaldehyde in the production medium was at 3 h of cultivation, which is during the exponential cell growth phase. Beside, yeasts were inhibited by high concentrations of benzaldehyde. The maximum concentration of L-PAC obtained was 0.6 g / L at 4.5 h cultivation.