Organic phase screening for in‐stream reactive extraction of bio‐based 3‐hydroxypropionic acid: biocompatibility and extraction performances

Abstract : BACKGROUND: 3-Hydroxypropionic acid (3-HP) production through glycerol bioconversion by Lactobacillus reuteri suffers from low yields and productivities due to product inhibition. Reactive extraction assisted by a Hollow Fibre Membrane Contactor (HFMC) is a promising strategy for process intensification. However, the use of this integrated system is hindered by the extraction phase toxicity towards the microorganism. This study describes a solvent selection strategy based on extraction performance (extraction yield and viscosity, related to mass transfer), and a low solvent toxicity, in order to find an extraction phase composition that allows continuous in stream extraction of 3-HP. RESULTS: Inert diluent addition to a trioctylamine (TOA)-decanol mixture decreased its toxicity and viscosity but decreased extraction yield. The linear and ramified long-chain alcohols tested showed that increasing the number of carbon atoms decreased extraction performance as well as toxicity. Ramified alcohols showed the lowest extraction performance. Didodecylmethylamine (DDMA) gave higher extraction yield and lower solvent toxicity than TOA. Flow cytometry with dual staining for cell membrane integrity and enzymatic activity proved to give concordant and complementary information with cells bioconversion ability, being an adequate and quick method for solvent toxicity assessment. The selected organic phase consisted of 20% DDMA, 47% dodecanol and 33% dodecane by volume, and can be used for in stream extraction of 3-HP produced by L. reuteri. CONCLUSIONS: The integrated selection criteria proposed in this study - extraction yield, solvent viscosity and toxicity - provide key information for choosing an organic phase with the best trade-off between extraction performance and biocompatibility.