Design of hybrid systems with in-situ product removal from fermentation broth: Case study for 2-phenylethanol production

Abstract

Abstract Many natural compounds used as flavours and aromas, such as 2-phenylethanol, can be produced both synthetically and biotechnologically. Large amounts of cheap product can be synthesised, however, a substance to be used in food and pharmaceutical industry or perfumery has to be produced from natural precursors. Biotechnologically, this can be accomplished in a classic batch process - by transforming L-phenylalanine into 2-phenylethanol using Saccharomyces cerevisiae as a production strain followed by the product separation. The major downside of the configuration is the inhibition effect of the product on the production strain – concentration of 2-phenylethanol above 4 g L−1 is fatal for the yeasts. One way of solving the problem is to combine the fermentation and separation processes and continuously remove the product from the bioreactor during fermentation. This process configuration is called hybrid system. In this work, two batch configurations and three hybrid systems are presented and compared considering overall production rate, cost of operation units, raw materials and energy consumption. It has been shown that hybrid systems in which microfiltration is not present during in-situ product removal perform better than traditional batch systems or hybrid system with microfiltration.