Study On The Biotransformation Of 2-phenylethanol By Saccharomyces Cerevisiae

2-phenylethanol is an important flavour and fragrance compound with a rose-like odour. It is widely used in food, pharmaceutical, cosmetics, tobacco and chemical industries. It is not only the basic component of all the rose-like flavours, but also has the effects of synergy and efficiency, is required for a variety of flavors. The biotransformation of 2-phenylethanol by microorganism has a greater market prospect and application value with the increasing market demand of natural 2-phenylethanol.This paper focused on the biotransformation of 2-phenylethanol from L-phenylalanine by microorganisms. The yeast strain was treated with ultraviolet radiation; the method transformation of 2-phenylethanol and the culture medium was optimized; the transformation process in oleic acid/aqueous biphasic system was studied; immobilization of yeast was associated with absorb of PEA by macroporous resin.Saccharomyces cerevisiae, Kluyveromyces marxianus and Kluyveromyces sinensis were reported to be three of the best strains which could produced more 2-phenylethanol than others. The results showed that Saccharomyces cerevisiae CICIMY0086(T) was the best strain which had the bigger transform capacity and resistance of 2-phenylethanol among the three stains tested. A yeast strain named Saccharomyces cerevisiae CICIMY0086-16 whose PEA yield reach 2.41g/L steadily was obtained after UV treat. The study about inhibition of ethanol and PEA on the growth of yeast showed that, yeast could hardly grow when PEA concentration bigger than 4g/L, and the exist of ethanol will enhance this inhibition in a low contains(<50mL/L).The transformation of PEA by yeast cells was studied in order to increase the conversion rate and yield. the optimum medium composition was obtained by the experiments of single factors and orthogonal design, which is 55g/L glucose, 8g/L L-phenylalanine, 2.7g/L YNB, 0.6g/L Na2HPO4·12H2O,0.7g/L MgSO4·7H2O. Inoculate yeast cells with a 0.8g/50mL concentration in the culture medium above-mentioned, PEA concentration reached 3.67g/L in 15 hours, the yield was 52.3% higher and the period was 33 hours shorter than before, the substrate conversion efficiency is 85%. Adding oleic acid to the conversion system, it showed that oleic acid has a good effectiveness on extraction of PEA, Inoculated 0.6g cells to 250mL triangular flask holding 25mL medium under 30℃and 100r/min, input 25mL oleic acid at 9h, the content of 2-phenylethanol reached 4.55g/L 27h later, the substrate conversion efficiency is 92%.The cells of Saccharomyces cerevisiae were entrapped into calcium alginate. The immobilized conditions were alginate 3.0%, cells 20g/L, Ca2+ 1mol/L. Using the immobilized yeast to transform PEA in batches repeated showed that the PEA yields reached 3.45g/L in the second, third, and fourth batch, and it was above 3g/L until the ninth batch, showing obvious superiority than free yeast. In addition, PEA concentration was below 1g/L after added H103 macroporous resin to the system and reached 5.4g/L in the desorption solution.