Pertraction-adsorption in situ product removal system: Intensification of 2-phenyelthanol bioproduction

Abstract

Bioproduction of 2-phenylethanol from L-phenylalanine using yeasts Saccharomyces cerevisiae has been extensively studied in recent years because this production system is suitable for research, development and implementation of various in situ product removal (ISPR) techniques. 2-Phenylethanol is a valuable product used in food, cosmetic or pharmaceutical industry and when produced in a biotechnological way it can be considered as natural. Bioproduction of 2-phenylethanol by yeasts is afflicted by its strong inhibition effect which restrains the production. Experiments performed in this work present possible 2-phenylethanol production intensification with implemented product removal techniques such as pertraction and combined pertraction-adsorption. In a classical fed-batch bioreactor without ISPR, the highest average 2-phenylethanol production rate was 0.160 g/L/h in comparison to 0.498 g/L/h reached in a bioreactor with integrated pertraction-adsorption removal system. Advantage of the developed pertraction-adsorption system is in facilitation of further separation since pertraction supports selective separation of 2-phenylethanol from L-phenylalanine and also around 90% of produced 2-phenylethanol was accumulated on the adsorbent surface at the end of experiments. However, analysis of experimental data showed that ethanol produced during fermentation in the bioreactor was separated together with 2-phenylethanol by pertraction and adsorbed on the adsorbent surface, reducing thus its capacity for 2-PEA. Nonetheless, pertraction performance was more stable compared to microfiltration, which is troubled by flux decline due to fouling and it does not provide separation of dissolved compounds.