Bioconversion of l-phenylalanine into 2-phenylethanol by Kluyveromyces marxianus in grape must cultures

A 2³ factorial design was employed to find the best conditions of pH, l-phenylalanine concentration and temperature for the production of 2-phenylethanol by Kluyveromyces marxianus CBS 6556. The cultivation was carried out on grape must, which contains a great amount of nitrogen compounds. Central composite design (CCD) was used for the analysis of treatment combinations. Results showed a second-degree polynomial regression model with good agreement of experimental data, with R ² = 0.92015 (p < 0.05). The maximum production of 2-phenylethanol was found at pH 7.0, temperature of 37 °C, and a concentration of 3.0 g of l-phenylalanine L-¹. Further experiments in bioreactors showed that oxygen concentration is also important to 2-phenylethanol production, with best results obtained at oxygen mass transfer rates of 2.0 h-¹.