Integrated approach coupling microbiological process and in situ product recovery for the production of 3-hydroxypropionic acid by Lactobacillus reuteri
Résumé
In the actual environmental and economic context, there is an increased interest in the microbial production at a large industrial scale of 3-hydroxypropionic acid (3-HP). Among its various applications, this compound is primarily sought for its direct use as building block mainly for the synthesis of bio-based polymers and the production of commercially valuable chemicals. Although 3-HP is currently of limited usage due to its exclusive synthesis via chemical pathways, its market is expected to significantly grow up to a volume of 20,000 tons per year in 2015 with a cost of 1,100 $ per ton. Moreover, in recent years, the tremendous growth of biodiesel manufacturing industries resulted in a large production of inexpensive and abundant available glycerol as by-product that could be used as substrate. Until now, only lactic acid bacteria from the Lactobacillus genus have been shown to produce 3-HP from glycerol, although at low productivity.
In the present work, the bioconversion of glycerol into 3-HP by Lactobacillus reuteri was studied. Product and its metabolic intermediate 3-hydroxypropionaldehyde (3-HPA) were identified to exhibit inhibitory effects on the producing microorganism, thus leading to a low productivity. A potential strategy to increase the performance of the microbial cells and to recover the molecule of interest is the “In Situ Product Recovery” (ISPR), by which upstream bioconversion is combined to downstream recovery. ISPR of 3-HP was implemented using reactive extraction with tertiary and quaternary amines diluted in n-decanol. Extraction in a hollow fiber-membrane contactor from a model binary solution of 3-HP in water was successfully performed. The effect of glycerol, 3-HPA and 1.3 propanediol, as being the molecules of the 3-HP pathway, was studied in terms of extraction kinetic, yield and selectivity. Results demonstrated the high potential of this integrated approach coupling microbiological process and membrane-supported reactive extraction for the biotechnological production of 3-HP.
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